July 2013
PUBLISHED BY THE AMERICAN WELDING SOCIETY TO ADVANCE THE SCIENCE, TECHNOLOGY, AND APPLICATION OF WELDING AND ALLIED JOINING AND CUTTING PROCESSES WORLDWIDE, INCLUDING BRAZING, SOLDERING, AND THERMAL SPRAYING
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CONTENTS 28
July 2013 • Volume 92 • Number 7
AWS Web site www.aws.org
Features
Departments
28
Inverters Improve Control for AC Gas Tungsten Arc Welding Advances in switching devices, microchips, and tungsten technology are making the inverter the power source of choice R. L. Bitzky and J. Garraux
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A New Development in Aluminum Welding Wire: Alloy 4943 A new filler metal is designed to give a higher-strength alternative to 4043 T. Anderson
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How to Improve GTAW Performance Some pros offer advice on gas tungsten arc welding of thin steel, aluminum, and stainless steel M. Franklin
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Induction Heating for Stress Relieving Shortens Lead Times An oil and gas equipment manufacturer finds production help with induction heating J. Ryan
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Automated Welding Applied in Deep-Water Pipelines Pipeline laying in the South China Sea is aided by dualcarriage automated gas metal arc welding J. Xiang-Dong et al.
Editorial ............................4 Press Time News ..................6 News of the Industry ..............8 International Update ............14 RWMA Q&A ......................16 Book Review ......................18 Stainless Q&A ....................20 Product & Print Spotlight ......22 Coming Events....................52 Certification Schedule ..........56 Conferences ......................58 Welding Workbook ..............60 Society News ....................63 Tech Topics ......................65 Interpretation AWS 3.0 ........65 Guide to AWS Services ........83 Personnel ........................84 Classifieds ........................97 Advertiser Index..................98
32 Welding Research Supplement 197-s Vacuum-Assisted Laser Welding of Zinc-Coated Steels in a Gap-Free Lap Joint Configuration A stabilized keyhole allowed zinc vapors to escape in laser welding of zinc-coated steels S. Yang et al.
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205-s Active Droplet Oscillation Excited by Optimized Waveform Active droplet oscillation is studied as a means of droplet detachment at peak currents lower than the transitional current J. Xiao et al. 218-s High-Temperature Corrosion Behavior of Alloy 600 and 622 Weld Claddings and Coextruded Coatings Thermogravimetric and solid-state testing demonstrated better corrosion resistance with Alloy 622 under simulated gaseous conditions J. N. DuPont et al.
On the cover: The preferred technique for adding filler metal during gas tungsten arc welding is to touch the end of the filler rod to the leading edge of the molten pool. (Photo courtesy of Victor Technologies.)
Welding Journal (ISSN 0043-2296) is published monthly by the American Welding Society for $120.00 per year in the United States and possessions, $160 per year in foreign countries: $7.50 per single issue for domestic AWS members and $10.00 per single issue for nonmembers and $14.00 single issue for international. American Welding Society is located at 8669 Doral Blvd., Ste. 130, Doral, FL 33166; telephone (305) 443-9353. Periodicals postage paid in Miami, Fla., and additional mailing offices. POSTMASTER: Send address changes to Welding Journal, 8669 Doral Blvd., Suite 130, Doral, FL 33166. Canada Post: Publications Mail Agreement #40612608 Canada Returns to be sent to Bleuchip International, P.O. Box 25542,London, ON N6C 6B2 Readers of Welding Journal may make copies of articles for personal, archival, educational or research purposes, and which are not for sale or resale. Permission is granted to quote from articles, provided customary acknowledgment of authors and sources is made. Starred (*) items excluded from copyright.
WELDING JOURNAL
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EDITORIAL Founded in 1919 to Advance the Science, Technology and Application of Welding
Working Together to Build a Better Tomorrow
Officers President Nancy C. Cole NCC Engineering Vice President Dean R. Wilson Well-Dean Enterprises
How can we best effect change? I’ve given that question a lot of thought over the past couple of years as I have become more involved with the leadership of the American Welding Society. And while our tendency as business people in a competitive world is to go it alone, I’ve come to the conclusion that on many issues, Author Simon Mainwaring was right when he said, “Effectively, change is almost impossible without industry-wide collaboration, cooperation, and consensus.” The current welding industry workforce development situation poses opportunities and challenges of unprecedented complexity. No single society, organization, person, agency, or government can single-handedly solve the issues at hand. These groups must work together to effectively and efficiently solve these tough problems. The AWS Foundation is heavily invested in workforce development for the welding industry. Working with other organizations, with a collaborative spirit, has made a significant impact on these workforce development efforts. Recently, the American Welding Society and the Manufacturing Institute of the National Association of Manufacturing (NAM) met at AWS World Headquarters in Doral, Fla., to not only establish workforce development objectives, but develop action plans both organizations could work toward jointly. This meeting confirmed and identified the following: • 82% of manufacturers report a moderate or serious shortage in skilled production workers. • 75% of manufacturers say the skills shortage has negatively impacted their ability to expand. • 600,000 jobs in manufacturing are unfilled today because employers can’t find workers with the right skills. • More than 200,000 welding-related jobs will be left unfilled by 2019 because companies won’t be able to find workers with the correct skill sets. It’s obvious that to close the skills gap, we need to take action now. To that end, the Manufacturing Institute, in partnership with the AWS Foundation, has launched the NAM-endorsed Manufacturing Skills Certification System. This system of nationally portable, industry-recognized credentials validates both the “book” and the “street” smarts needed to be productive and successful on the job. I won’t list specific projects being considered. After all, some ideas won’t pan out and will be dropped; other not-yet-imagined projects will prove highly successful. However, I will tell you that those who participated in the recent joint meeting in Doral identified nine objectives to support this certification system, and badge (welding process) credentialing, master welder certification, women in welding, and weld career data collection are some of the key areas the two organizations will be working on together. This push by AWS and NAM to solve the workforce development issue is but one of many collaborative efforts in which AWS participates. Your Society is actively involved with trade unions, professional societies, educational institutions, and government agencies to advance the science, technology and application of welding, and allied joining and cutting processes. These efforts occur at the local, national, and international levels. Collaboration isn’t easy. Cooperation takes a lot of hard work. It requires us to set aside our natural inclination to compete with others and instead find satisfaction in how our actions will benefit our industry. When done well, collaborative efforts can produce amazing results. We see that all the time at AWS. As you know, all of the AWS codes, standards, and specifications are consensus standards produced by disparate groups within the welding industry who set aside their differences to work together. We have a proven track record of success through collaboration.◆
Dean R. Wilson AWS Vice President 4
JULY 2013
Vice President David J. Landon Vermeer Mfg. Co. Vice President David L. McQuaid D. L. McQuaid and Associates, Inc. Treasurer Robert G. Pali J. P. Nissen Co. Executive Director Ray W. Shook American Welding Society
Directors T. Anderson (At Large), ITW Global Welding Tech. Center U. Aschemeier (Dist. 7), Miami Diver J. R. Bray (Dist. 18), Affiliated Machinery, Inc. R. E. Brenner (Dist. 10), CnD Industries, Inc. G. Fairbanks (Dist. 9), Fairbanks Inspection & Testing Services T. A. Ferri (Dist. 1), Victor Technologies D. A. Flood (At Large), Tri Tool, Inc. S. A. Harris (Dist. 4), Altec Industries K. L. Johnson (Dist. 19), Vigor Shipyards J. Jones (Dist. 17), The Harris Products Group W. A. Komlos (Dist. 20), ArcTech, LLC T. J. Lienert (At Large), Los Alamos National Laboratory J. Livesay (Dist. 8), Tennessee Technology Center M. J. Lucas Jr. (At Large), Belcan Engineering D. E. Lynnes (Dist. 15), Lynnes Welding Training C. Matricardi (Dist. 5), Welding Solutions, Inc. J. L. Mendoza (Past President), Lone Star Welding S. P. Moran (At Large), Weir American Hydro K. A. Phy (Dist. 6), KA Phy Services, Inc. W. A. Rice (Past President), OKI Bering R. L. Richwine (Dist. 14), Ivy Tech State College D. J. Roland (Dist. 12), Marinette Marine Corp. N. Saminich (Dist. 21), Desert Rose H.S. and Career Center K. E. Shatell (Dist. 22), Pacific Gas & Electric Co. T. A. Siewert (At Large), NIST (ret.) H. W. Thompson (Dist. 2), Underwriters Laboratories, Inc. R. P. Wilcox (Dist. 11), ACH Co. J. A. Willard (Dist. 13), Kankakee Community College M. R. Wiswesser (Dist. 3), Welder Training & Testing Institute D. Wright (Dist. 16), Zephyr Products, Inc.
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PRESS TIME NEWS Competition Launched for Three Manufacturing Institutes The Obama Administration is launching competitions to create three new manufacturing innovation institutes with a federal commitment of $200 million across these five agencies: Defense, Energy, Commerce, NASA, and the National Science Foundation. The president’s manufacturing agenda starts with his vision for a National Network for Manufacturing Innovation. His fiscal year 2014 budget includes a $1 billion investment at the Department of Commerce to create this network, a model based on approaches that other countries have successfully deployed. Each would serve as a regional hub designed to bridge gaps between basic research and product development, bringing together companies, universities and community colleges, and federal agencies to invest in technology areas encouraging investment and production in the United States. The Department of Defense will lead two of the new institutes on Digital Manufacturing and Design Innovation and Lightweight and Modern Metals Manufacturing, while the Department of Energy will be leading one new institute on Next Generation Power Electronics Manufacturing. Winning teams will be selected and announced later this year. Federal funds will be matched by industry investment, support from state and local governments, and other sources.
Victor® Celebrates 100 Years, Launches Two Contests Victor Technologies™, St. Louis, Μο., has announced the 100th anniversary of its Victor® brand. The lineup consists of oxyfuel cutting and gas control equipment; Thermal Dynamics®, encompassing manual and automated plasma cutting systems; TurboTorch®, including air-fuel products for brazing and soldering; and Arcair®, representing manual and automated gouging systems. Company founder, L. W. Stettner, Victor Technologies honors the 100th anniversary who lost an eye in a welding accident, of its Victor brand by launching a contest for stu- set out to design and build safer cutdents and schools, plus a photo/caption challenge. ting and welding products. Stettner’s As shown, a student and instructor train with oxy- designs resulted in numerous indusfuel cutting using a Journeyman system. try firsts. For example, Victor cutting and welding torches were assembled with screws, not soldered, to provide a stronger connection in the event of overheating. Also, the company has launched two contests. A Cut Above is open to students in cutting, welding, and related programs at secondary and postsecondary schools, and will award more than $30,000 in equipment and cash prizes. Beginner students will write a 500-word essay supporting the contest theme, while advanced students will submit a team metal fabrication project incorporating an oxyfuel, airfuel, or plasma cutting process. The Show Us Your Innovations 2014 calendar contest will award 12 Victor® Medalist 250 cutting outfits, and a Victor® Thermal Dynamics® Cutmaster® 42 plasma cutting system as the grand prize, for the best photos and associated captions of the entrant using any Victor or Victor Thermal Dynamics cutting equipment. Both contests run through September, with winners announced at the Victor Technologies booth at FABTECH 2013 in Chicago, Ill. Contests are open to individuals who are residents of the United States or Canada (excluding Quebec). Visit www.victortechnologies.com/victor100.
Publisher Andrew Cullison Editorial Editorial Director Andrew Cullison Editor Mary Ruth Johnsen Associate Editor Howard M. Woodward Associate Editor Kristin Campbell Editorial Asst./Peer Review Coordinator Melissa Gomez Publisher Emeritus Jeff Weber Design and Production Production Manager Zaida Chavez Senior Production Coordinator Brenda Flores Manager of International Periodicals and Electronic Media Carlos Guzman Advertising National Sales Director Rob Saltzstein Advertising Sales Representative Lea Paneca Advertising Sales Representative Sandra Jorgensen Senior Advertising Production Manager Frank Wilson Subscriptions Subscriptions Representative Tabetha Moore
[email protected] American Welding Society 8669 Doral Blvd., Ste. 130, Doral, FL 33166 (305) 443-9353 or (800) 443-9353 Publications, Expositions, Marketing Committee D. L. Doench, Chair Hobart Brothers Co. S. Bartholomew, Vice Chair ESAB Welding & Cutting Prod. J. D. Weber, Secretary American Welding Society D. Brown, Weiler Brush T. Coco, Victor Technologies International L. Davis, ORS Nasco D. DeCorte, RoMan Mfg. J. R. Franklin, Sellstrom Mfg. Co. F. H. Kasnick, Praxair D. Levin, Airgas E. C. Lipphardt, Consultant R. Madden, Hypertherm D. Marquard, IBEDA Superflash J. F. Saenger Jr., Consultant S. Smith, Weld-Aid Products D. Wilson, Well-Dean Enterprises N. C. Cole, Ex Off., NCC Engineering J. N. DuPont, Ex Off., Lehigh University L. G. Kvidahl, Ex Off., Northrup Grumman Ship Systems D. J. Landon, Ex Off., Vermeer Mfg. S. P. Moran, Ex Off., Weir American Hydro E. Norman, Ex Off., Southwest Area Career Center R. G. Pali, Ex Off., J. P. Nissen Co. N. Scotchmer, Ex Off., Huys Industries R. W. Shook, Ex Off., American Welding Society
Hobart Brothers Co. Consolidates Filler Metal Brands Hobart Brothers Co., Troy, Ohio, has unveiled a new logo for its Hobart® brand of filler metals. The redesign decision coincides with consolidating the company’s five brands of filler metals — Hobart, McKay®, Tri-Mark®, Corex®, and Maxal® — under the single Hobart brand. The company’s brand of filler metals includes a product line of tubular wires (metal and flux cored), solid wires and covered electrodes for welding carbon and low-alloy steels, stainless steels and aluminum, as well as hardfacing options.◆
Copyright © 2013 by American Welding Society in both printed and electronic formats. The Society is not responsible for any statement made or opinion expressed herein. Data and information developed by the authors of specific articles are for informational purposes only and are not intended for use without independent, substantiating investigation on the part of potential users.
MEMBER
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“We’ve had such outstanding success
with Koike that we haven’t spoken to anyone else.” Jim Farley, Project Manager
To be the preferred supplier of welding positioning equipment to Liebherr USA, you have to do a lot of things right. And Koike Aronson does. The Virginia facility of Liebherr, one of the world’s leading manufacturers of mining equipment, has been buying welding positioners from Koike for years. “Some of the original machines are still in operation,” reports Jim Farley, project manager. “And the service support is terrific. When it comes to responsiveness we can get directly to a person who can help.” The guys on the floor are sold on Koike, too. “I love the Head and Tailstock,” says Fabrication Lead Man Charles Moler. “Koike worked with us so it was designed to fit our needs and reduce set-up time for each rotation.”
Koike Aronson Ransome Head and Tailstock positioning a Liebherr mining truck frame.
Left to Right: Jim Farley Project Manager
Charles Moler Fabrication Lead Man
Jim Pfizenmayer Fabrication Supervisor
Robert Egloff Fabrication Manager
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NEWS OF THE INDUSTRY
Hypertherm Hosts Building America Conference Hypertherm presented the Building America Conference May through the company’s Technical Training Institute, plus printed 7 and 8 at its new manufacturing facility in Lebanon, N.H. About circuit board assemblers and technicians. Future goals include 80 invited guests attended to hear numerous speakers and tour making the facility a key place for listening to customers and the property. making continued improvements for them. Evan Smith, president of Hypertherm, introduced “Built in Event sessions centered on strategic planning, branding, America: Strategies for Success.” He asked what is driving dyLEAN manufacturing, continuous improvement programs, cusnamics by showing a 2004 Business Week cover titled “The three tomer experience management, motivating and engaging your scariest words in U.S. industry: ‘The China Price’” and a recent team, a new measure of cutting efficiency, and the future of air TIME magazine cover featuring “Made in the USA.” In the U.S. plasma. “manufacturing renaissance” part of his talk, Smith quoted The In addition, Sydney Finkelstein, Steven Roth professor of Boston Consulting Group: “By 2015...Manufacturing in China management and faculty director of the Tuck Executive Program will be only 10 to 15% cheaper than in the U.S. — even before at the Tuck School of Business at Dartmouth College, reviewed inventory and shipping costs are considered.” He stated a bright lessons on research he conducted during “Why Smart Executives spot is manufacturing employment has grown faster in the U.S. Fail.” Four red flags in decision making include are your personal since the recession than in any other developed economy. For experiences misleading you, is your personal self interest cloudsuccess strategies, as a North American manufacturer, vital facing your thinking, have you made a dangerous prejudgment that tors are creating collaborative workforce development and buildyou are locked into, and are inappropriate attachments pushing ing strong supply/distribution infrastructures and partnerships. you in the wrong direction. Finkelstein gave examples of relying Kevin Duggan, president of Duggan Associates, discussed on intuition, experience, and training; the surprise of how com“Design for Operational Excellence.” His questions focused on mon it is to act in a self-interested matter and not realize it; inthe best way to produce continuous improvement, and asked how tellectual honesty with adaptability and open mindedness; and do you know where to improve next, why do you strive to create reinforcing values you care about. He listed executive mindset flow and what causes its death, what would your shop floor/ failures, organizational breakdowns, delusions of a dream comoffice/supply chain look like if you applied every continuous impany, and leadership pathologies as reasons why smart execuprovement tool, and where will your improvement journey take tives fail. you. The steps Duggan listed to achieve operational excellence Hypertherm Founder and CEO Dick Couch concluded the concerned designing a lean flow, implementing a lean flow and event. He recalled the company’s start in 1968 with Bob Dean making it visual, creating standard work for the lean flow, makand tough early years facing hardships in obtaining funding, but ing abnormal flow visual and creating standard work for it, teachsaid this was a good learning opportunity for designing equiping employees to maintain and improve the flow to the customer, ment. “We’ve had this no layoff policy for 45 years,” Couch menand free management to work on offense. tioned as a milestone. Presently, more than 1300 associates deThe guests toured the 160,000-sq-ft facility led by Leadership liver products and services worldwide. in Energy and Environmental Design principals. Videos from the conference can be found on the company’s The extra space is expected to facilitate creating up to 500 YouTube channel. new jobs for New Hampshire. The plant includes a reliability lab to test products and manual system assembly lines to make plasma — Kristin Campbell, associate editor machines with parts close to associates. Ergonomic additions consist of height-adjustable benches. Other featured areas include a piece-by-the-hour board that monitors performance; a cutting technology center offers demonstrations on small/ large machines and nesting software; training classrooms; and room for nozzle and electrode expansion. “We’ve had rapid global growth and needed the space,” Smith said. Since the new location opened, he thinks it has been going remarkably well and added the biggest ongoing need there is to Hypertherm’s eco-friendly building in Lebanon, N.H., built Associates work inside the new location on train CNC operators manual system assembly lines making plasma long and narrow, leaves the property’s wetlands untouched. machines for cutting and gouging metal.
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an architectural/ornamental metal fabricator, fabricated the top 40 ft of the spire and pinnacle for the building. At 1776 ft, the height pays tribute to the year the United States declared its independence and establishes the center as the tallest building in the Western Hemisphere. The spire’s glass and stainless steel structure, featuring a rotating beacon to illuminate the Manhattan skyline at night, was laser cut on a TRUMPF TruLaser 1030 machine.
One World Trade Center Receives Its Stainless Steel Spire
KUKA Systems Acquires Utica’s Plant Engineering Business KUKA Systems Group, Sterling Heights, Mich., has acquired the plant engineering business of privately owned Utica Companies, Shelby Township, Mich. The purchase price was not disclosed but is in the low double-digit million euro range. It will absorb Utica’s body structure business that builds car body assembly lines and subsystems as well as products like laser welding heads, net forms, and pierce systems; standard press room automation for metal stamping; and hang-on technologies. About 300 Utica employees have joined the more than 1300-member KUKA Systems team in southeastern Michigan. Kammetal fabricated the top 40 ft of the spire and pinnacle for the new One World Trade Center. The spire’s glass and stainless steel structure was laser cut on a TRUMPF 2D system. (Photo courtesy of DMC Erectors, Inc.)
Hobart Institute Breaks Ground for Additional Welding Training Area Driven by demand for welding training and increasing enrollment, Hobart Institute of Welding Technology, Troy, Ohio, is expanding. The 6360-sq-ft structure will house between 50 and 60
On May 10, the spire for the One World Trade Center building in New York City was permanently installed. Kammetal – Kusack Architectural Metal Inc., Brooklyn, N.Y.,
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A rendering by Ferguson Construction Co. shows the Hobart Institute of Welding Technology’s new building addition in Troy, Ohio.
arc welding booths equipped for all processes and an extensive fume-exhaust system. With a goal to match the original building architectural and aesthetic integrity, construction is set to begin soon. The first classes are expected to utilize the building in late fall 2013. The contract went to Ferguson Construction Co., Sidney, Ohio.
Wall Colmonoy Celebrates 75th Anniversary Wall Colmonoy, Madison Heights, Mich., an American Welding Society Supporting Company Member, is celebrating its 75th anniversary. Albert F. Wall founded the materials engineering company in 1938 in Detroit, Mich. Today, it is a global organization with offices and manufacturing facilities in the United States,
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Wall Colmonoy has been owned and operated by the same family for 75 years. Shown is a step for the manufacturing of nickel- and cobalt-based alloys for powder and casting products.
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United Kingdom, and France with close to 400 employees. Developing new products and technologies with customers, universities, and local government is the driving innovation force. It has been owned and operated by the same family for 75 years.
Manitowoc Welders Improve Technical Skills Using New Training Program
nearly 500 welders who build its cranes, the RealWeld Trainer™ provided an answer. Using patent-pending technology by EWI, it digitally records motions and objectively measures/scores critical welding technique while performing real arc-on welds, plus allows practicing arc-off welds with feedback. According to Jake Sensinger, manager of weld process engineering at Manitowoc’s Shady Grove factory, the system was incorporated into operations in July 2012. Since then, two machines at the company’s Pennsylvania facility have provided customization advantages, material cost savings, and faster individualized training. “It’s going to have a tremendous impact on how we put our curriculum together going forward,” he added.
Cee Kay Executives ‘Slowly’ Create a Snail Sculpture during Cleanup Event
Paul Boulware, an EWI welding engineer, uses the RealWeld Trainer™ to explain welding technique fundamentals to a trainee. When Manitowoc’s Grove brand recently looked for a costeffective way to teach, train, and evaluate welding skills of the
Cee Kay Supply, St. Louis, Mo., sponsored the 11th annual Mission: Clean Stream and Stream Trash Art™ program with the General Motors (GM) Earth Day Festival on April 6 at GM’s plant in Wentzville, Mo. Approximately 1088 tons of trash have been removed from streams and rivers to date. This is the fifth year in a row the company has participated. Each year, Regional Vice President of Sales Heath Wells and Western Regional Manager Dave Teson create a metal art sculpture from cleanup pieces. This time, they fabricated a snail from an old piece of cast iron, which was also converted into a flower pot. It took about 8 h to complete. Company CEO and Owner Tom Dunn also made chocolate ice cream with liquid nitrogen. Additionally, the American Welding Society’s St. Louis Section held its 11th annual Mini Weld Show on March 28 at Cee
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WELDING JOURNAL
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Industry Notes • CertainTeed Corp. has selected Jonesburg, Mo., as the home for a new asphalt roofing shingle manufacturing/distribution facility and plans to invest $100 million there. It is anticipated an estimated 400 ancillary local jobs in welding, trucking, and maintenance services will support operations when completed.
• SGL Group – The Carbon Co. recognized an investment in its Ozark, Ark., facility to construct new graphitization for manufacturing graphite electrodes, used in producing steel in electric arc furnaces, with a volume of approximately $26 million.
• Koike Aronson, Inc./Ransome, Arcade, N.Y., is sponsoring “Steaming Toward a Cure for Diabetes” benefitting the American Diabetes Association’s Step Out: Walk to Stop Diabetes® campaign of Western New York. The event is set for July 13.
• CRC-Evans Pipeline International, Inc., has opened its new pipeline supply store and warehouse in Tulsa, Okla. The 9000sq-ft storefront houses a large inventory with standard pipeline construction items. Also, the warehouse carries accessories.
• Optrel is offering prizes at www.facebook.com/OptrelUSA. Heath Wells and Dave Teson recently fabricated a snail from an old piece of cast iron, which was converted into a flower pot. Kay’s headquarters. Representatives from more than 20 companies provided hands-on demos and expertise. More than 250 students, instructors, and industry professionals attended.
Welders who like its page and send their best welding photos will be eligible for a monthly drawing to win a new welding helmet plus an iPod Touch through August. At the contest’s end, all entries will be redrawn for a grand prize of a free trip to Wattwil, Switzerland, where the company is headquartered. — continued on page 91
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INTERNATIONAL UPDATE Qualification Center to Support Automotive Welding Certification
The new Heywood facility’s laser cutting unit.
Pictured is the inaugural session held at I-Car Canada’s national welding qualification center. I-Car Canada, a training and recognition program, is establishing a national welding qualification center to serve as a hub for Canadian automotive welding certification. The center will operate in conjunction with a Canada-wide network of welding qualification instructors that is being established this year. The new qualification center will be located at CARSTAR’s Vision Park in Hamilton, Ontario. It will serve an immediate audience of repair facilities and insurance staff in the Greater Toronto/Southern Ontario region, but its impact will eventually extend coast to coast. CARSTAR Automotive Canada, Inc., NAPA Auto Parts, and 3M Canada are each contributing to the operation of the center. Marc Brazeau, president and CEO of the Automotive Industries Association, which operates I-CAR Canada, noted the new center will meet a critical need in the industry. He said, “Most technicians learned how to weld in their apprenticeship program ten, twenty, or even thirty years ago. Given how much vehicle technology has changed in that time with the introduction of aluminum, highstrength steels, and new bonding technologies, it is imperative to offer opportunities for continued learning. Welding is one of the most important skills in the collision repair industry, and it must be done right.”
Park in Heywood, Great Manchester, UK. The facility has been operational since April, with a current staff of 40 employees. When fully staffed, it is expected to employ more than 100 people in engineering, manufacturing, and support positions. Lee Morgan, company president, said, “Camfil APC has developed into a global dust collection company over the past five years, with our biggest growth in the UK and European industrial markets. This strategically located facility allows us to expand our manufacturing capacity and service our European customer base more effectively.” The plant includes a four-bay welding area, fabrication capacity, powder paint line, assembly room, and storage space.
Center Promotes Development of Pipeline Technologies
Sciaky Announces Strategic Partnership Sciaky, Inc., a subsidiary of Phillips Service Industries and provider of additive manufacturing products, has entered into a business partnership with EVOBEAM GmbH of Mainz, Germany, to further expand its electron beam (EB) welding product portfolio. Sciaky specializes in large vacuum chamber EB welding systems with internal moving guns. These systems utilize low voltage and high power useful for large-scale parts. EVOBEAM specializes in high throughput, small vacuum chamber EB welding systems with external guns. These systems utilize low voltage and low power useful for rapid production of small-scale parts. Under terms of the new agreement, Sciaky and EVOBEAM will market and sell each other’s EB welding technology.
New Dust Collection Facility to Serve the UK and European Industrial Markets Camfil Air Pollution Control (APC), a global manufacturer of dust and fume collection equipment, celebrated the grand opening of its new 40,000-sq-ft facility in the United Kingdom to serve industrial customers throughout the UK and Europe. Camfil APC worked closely with the Rochdale Development Agency to find the optimal site for the plant, which is located in the Birch Business
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The Global Pipeline Welding Development Center employs more than 30 skilled welding technicians on site. Subsea 7, a seabed-to-surface engineering, construction, and services contractor, has opened the new Global Pipeline Welding Development Center that will develop subsea pipeline technologies for the oil and gas markets. It is the culmination of a $15.5 million investment by Subsea 7 in the company’s operations base in Clydebank, Scotland. The development was supported with a grant of $1.2 million from Scottish Enterprise. The center has brought 30 new skilled jobs to the area, as Subsea 7 creates pipeline technologies to satisfy market needs associated with oil and gas discoveries increasingly made in deeper water and tougher conditions. The new center comprises two main operational buildings — Pipeline Development Center 1, a welding inspection center, and Center 2, which houses the R&D and screened radiographic and ultrasound nondestructive examination facilities. The entire Subsea 7 facility in Clydebank employs 150 people, including more than 65 engineering and project management staff, and has more than 30 skilled welding technicians working on site. The technology developed in Scotland will be deployed by the subsea oil and gas industry across the globe, including the UK, Norway, United States, Brazil, and West Africa.◆
/ Battery Charging Systems / Welding Technology / Solar Electronics
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RWMA Q&A Q: We are considering changing our steel source for several of the parts we produce; however, one of the new materials is not approved by the automotive original equipment manufacturer (OEM). What approval process are they talking about? The proposed replacement appears to be the same as our existing one. A: The process of joining two materials together is something that never really crosses your mind when you purchase a motor vehicle. In fact, it is almost something that is assumed since your driving of the final product is proof that it can be done. However, as with many things, a little digging reveals there can be much more to this process than meets the eye. In fact, the idea behind trying to determine how weldable a material is begins to make real good sense once you understand what it entails and its potential impact on the assembly of the final product. In actuality, the determination of a material’s weldability is really a subset of a much broader characterization process the automotive OEM employs to ensure the material in question is suitable for the intended application. In other words, material characterization is really a methodology used to classify or describe a material that is based on an objective analysis of measurable characteristics. While this discussion focuses on weldability, with the engagement of the right personnel, it could just as easily be a conversation about determining corrosion resistance, formability, or any of a dozen or more other manufacturing traits that need to be accounted for and addressed in order to successfully assemble the final product. An analogy for the process of material characterization is that of a building inspector. Building inspectors work behind the scenes and their existence never really crosses your mind. But once you understand they are looking at the structure before the drywall goes up to ensure that all of the other supporting elements of the building (electrical, plumbing, ventilation, etc.) are in place and functional, you begin to understand why their role is so important from the point of view of protecting the eventual final customer. The welding characterization process works in much the same way as it affords the automotive OEM an opportunity to verify if the material is truly capable of being processed Fig. 1 — A resistance spot weld lobe.
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BY DONALD F. MAATZ JR.
in its manufacturing environment, thus protecting you, their customer, and helping to ensure that they have made, and you are purchasing, a quality product.
Characterization Methodology The predominate method utilized by all of the automotive OEMs for welding characterization is resistance spot welding (RSW). For completeness, gas metal arc welding (GMAW) and laser beam welding (LBW) are now also being considered or utilized for OEM characterization. Additionally, and as one would expect, each OEM typically wants the weldability characterization performed in a manner that is consistent with its processes and standards. As a result, the weldability characterization process is often performed on specific types of equipment so as to replicate the unique manufacturing environment in which the material will be used. A partial list of these unique manufacturing elements could include the following: • Electrode Caps. The list of requirements in this area alone can be quite extensive and runs the gambit from taper types (male, female), taper standards (RWMA, ISO), body diameters, contact face geometry (RWMA A-nose, ISO-5821 Type-B, etc.), and last, but not least, the actual material (RWMA Class-1 or RWMA Class-2, in all their variations). • Weld Control. The requirements in this area can cover the make of the control (manufacturer), the type of current [alternating current vs. midfrequency direct current (AC vs. MFDC)], and/or the methodology of using the control (automatic voltage compensation or constant current). As an aside, our experience has
shown there can be some slight variation in weldability when utilizing different AC controls, but not so with the MFDC units. • Transformer. Once the weld control has been determined, the selection of the transformer is really driven by the welding machine. However, care must be exercised in the selection as the lack of weldability variation seen in MFDC weld controls can reappear by the selection of the wrong MFDC power supply. This is especially true when performing aluminum characterizations. • Electrode Cooling. Both the water temperature and flow rate may be specified for a particular characterization. While both are critical elements to be monitored and controlled, our experience has shown the actual physical condition and arrangement of the cooling system (water tube placement, size, integrity, etc.) are far more important than the actual temperature or flow rate. An important point to keep in mind is that no one characterization evaluation can cover all possibilities. In fact, despite the performance of a thorough weldability characterization, it may be difficult to predict the necessary weld setup parameters for production operations. The reason for this is that each test is a singular condition among many possibilities and cannot account for the potential litany of material combinations, root opening or fitup concerns, general condition of the tooling, or other production variables. However, if the weldability characterization is conducted in a consistent manner, the process will allow for the determination of significant material traits that, when compared to other similar materials, can reveal where deviation from the norm has occurred and permit the OEM
Acknowledgment The author would like to thank Eric Pakalnins for his invaluable perspective on resistance weldability material characterization. References
Final Thoughts
1. AWS D8.9:2012, Test Methods for Evaluating the Resistance Spot Welding Behavior of Automotive Sheet Steel Materials. Doral, Fla.: American Welding Society.
It is hoped these descriptions have served to illustrate the challenges facing both the steel and automotive OEM organizations as they strive to produce a quality product in a very competitive environment. At the least it should help illustrate there is a great deal that does occur behind the scenes as a product moves from concept to design and that one of the biggest challenges is the selection of the right material for the application. Just as consumers have a choice with regard as to what they consider important in a vehicle (passenger and/or cargo room vs. performance), the product designer must decide which of the above elements has more credence for their application.◆
DONALD F. MAATZ JR. is a laboratory manager, RoMan Engineering Services. He is past chair of the AWS Detroit Section, serves on the D8.9 and D8D Automotive Welding committees, is vice chairman of the Certified Resistance Welding Technician working group, and is an advisor to the C1 Resistance Welding Committee. He is a graduate of The Ohio State University with a BS in Welding Engineering. This article would not have been possible were it not for the assistance from members of the RoMan team. Send your comments/questions to Don at
[email protected], or to Don Maatz, c/o Welding Journal, 8669 Doral Blvd., Ste. 130, Doral, FL 33166.
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Once it has been determined how the material will be welded, the next step is to select the necessary characterization elements that are to be evaluated. The desired elements to be evaluated may vary based on the material gauge, coating, and substrate strength. A partial list of these unique characterization elements could include the following: • Weld Range/Lobe. A weld lobe is a means of graphically expressing the numerous combinations of weld current and weld time that produce satisfactory welds for a specific set of conditions (weld force, electrode cap configuration, metal stackup, etc.) (see Fig. 1 and the March 2012 RWMA Q&A for more details on weld lobes). • Fracture Mode. This is the appearance of the weld after a destructive separation or peel test. (See the May 2010 RWMA Q&A for more details on fracture modes.) • Weld Strength. This may be determined by either a quasi-static or dynamic test, with the latter being either a fatigue or impact test. The mechanical samples constructed for these evaluations typically test the weld in two directions, either full shear (0 deg) or normal to the weld (90 deg). • Hold Time Sensitivity. This characterization element is related to a change in the weld’s cooling rate and is really a man-made phenomenon related to processing. The changeover from multifixture, cascade-fire gun stations to almost complete robot welding has reduced the likelihood for this to occur. Consequently, some OEM tests no longer evaluate hold time sensitivity performance. • Electrode Endurance. This element really focuses on the coating of the material and its wear effect on the electrode. As weld processing has changed, so has this evaluation. Almost entirely gone are the days of open-ended characterization tests that might go for 10,000 (or more) welds, replaced instead by more manageable, but still meaningful, sprints of just 500–1000 welds. • Current Sensitivity. The advent of MFDC has brought to the fore the fact that some materials weld better with one current type than the other. While the vast majority of materials do not exhibit a preference, this is still an important evaluation element as the selection of current type is one area where the large OEMs and the smaller Tier 2 and 3 suppliers are
A
Characterization Elements
most likely to approach welding from divergent points of view. An important point to consider is that the descriptions of the above-mentioned elements do not contain one word regarding acceptability criteria. This was done on purpose as each OEM evaluates the material’s performance of each element against its particular needs, and it would be impossible to try and provide more than the most generic of guidance in this area.
CD
to screen for potential issues. An excellent source for more detailed information about RSW material weldability characterization testing of sheet metal is AWS D8.9 (Ref. 1).
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BOOK REVIEW Brazing Book Opens New Technology Horizons, Gives Practical Information
BY ALEXANDER E. SHAPIRO modern brazing technology is described. This is illustrated by examples from automotive and cutting tool industries to applications in aerospace, nuclear power, and fuel cells. In addition, all chapters include substantial numbers of reference of data regarding wetting, microstructure, strength, and corrosion properties of brazed joints, which means that this volume can easily be used as a reference book appropriate both in academic research laboratories and everyday engineering practices.
Improving Brazing in Practical Applications
Advances in brazing: Science, technology and applications, edited by Dušan P. Sekulić, published in March 2013 by Woodhead Publishing Ltd. (www.woodheadpublishing.com), Cambridge, UK. ISBN-13: 978 0 85709 423 0. 628 pages. Price $305. Advances in brazing: Science, technology and applications presents three original chapters on the fundamentals of brazing and sixteen chapters that consist both of new studies done by their respective authors as well as state-of-the-art overviews featuring brazing processes used in today’s industry.
What Else Does the Publication Offer? This book covers the basics and specifics of brazing technologies related to joining traditional structural materials such as aluminum alloys, nickel superalloys, oxide ceramics, cemented carbides, diamonds, cubic boron nitride, and new materials that offer challenges to engineers such as titanium and nickel intermetallic alloys, ceramic composites, carbon-carbon composites, brazing coatings, special glasses, and glass-ceramics. All chapters present an analysis of convenient industrial processes and new, effective approaches to join similar and dissimilar combinations of base materials. A broad range of applications regarding
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Publication of this book is apparently an important event in the present brazing engineering community, as well as in the welding industry, because many new nonweldable but brazeable structural materials appear in the industrial market every year. Most of these materials are required to be joined by brazing. The authors represent different countries and universities but all of them demonstrate one approach to writing: They apply fundamental knowledge to explain methods of improving brazing in practical applications. The effectiveness of this approach to conveying knowledge is important, especially today, precisely because so many new materials that are challenging to join have entered the industry. If this approach becomes accepted convention, it can be a strong impulse to improving depth of knowledge in brazing, not only as a technology, but as a science. The Value Theoretical Conceptions Bring
In the last several years, numerous journal publications have analyzed general practical case studies (procedures of brazing individual materials and properties of their brazed joints), but discussion of new theoretical conceptions is rare. The first three chapters of this book fill in this gap. They overview the following: fundamental questions of wetting and reactivity at the interface of base materials (chapter 1), criteria of strength and reliability of brazed structures (chapter 2), and systematic modeling of general procedures in the field of brazing on macro- and micro-scale levels (chapter 3). The importance of these theoretical conceptions cannot be overestimated. They shall certainly enter into future textbooks and university courses on brazing. At the same time, theoretical methods discussed in the first three chapters may al-
ready be used in the field while constructing new systems, assessing their reliability, and testing the appropriateness or suitability of new base materials and filler metals. Additional Chapter Breakdowns, Including New Approaches to Brazing Superhard Tooling Materials and Processes for Joining Aluminum Alloys
Brazing nickel-based superalloys and stainless steels is discussed in three chapters. Chapter 4 demonstrates successful application of boron-free Ni-Cr-Zr filler metals, while chapter 5 is focused on the application of amorphous foils in traditional Ni-Cr-Si-B systems and metallurgical paths in joint formation. Also, two chapters are designated to joining new prospective intermetallic alloys — titanium and nickel aluminides. The authors of chapter 4 introduce new creep-resistant braze alloys of the Ti-ZrCr, Ti-Zr-Fe, Ti-Hf-Fe, and Ti-Zr-Mn systems, while chapter 8 discusses the property effects of base materials on the brazing procedure and microstructure of brazed joints made with traditional filler metals such as BAg-8, Ticuni®, CusilABA®, BNi-2, and others. Specifics for applying nickel-based filler metals in manufacturing steel pipes and brass or bronze components contacting drinking water are described in chapter 18. Chapter 6 describes industrial processes and new approaches to brazing superhard tooling materials — diamond and cubic boron nitride. The physics of formation of carbide film on diamond is an essential aspect of the corresponding brazing process, and it is discussed in detail. The technology of brazing cemented carbides and superhard materials for cutting tool applications is also considered in chapter 14. Both chapters are supported by the analysis of wetting and metallurgical interactions of filler metals with tool materials. Several chapters are designated to different aspects of joining ceramics and high-temperature composite materials; these summarize practical experience and scientific knowledge accumulated in the world to date. At the same time, all authors include results of their original investigations that make these publications especially interesting, because a general review is illustrated by case studies. Chapters 7, 12, and 16 discuss design, metallization, microstructure, and properties of brazed ceramics both in ceramicto-ceramic and ceramic-to-metal joints for the needs of the electronic and aerospace
industries. Chapters 11 and 13 are focused on brazing approaches and joint properties of high-temperature ceramic matrix composites, including carbon-carbon composites applied now in aerospace and nuclear industries. Despite sometimes similar base materials mentioned there, a reader will not find any overlapping scientific and technical information in these chapters; this reflects an original research and engineering vision by the authors on obtained results. The original technology and application of brazed hard coatings by infiltration in cemented carbide particles with silver- and copper-based filler metal is discussed in chapter 15. Applications of glass and glass-ceramic sealants for solid oxide fuel cells and joining SiC-based ceramics described in chapter 17 is opening a new prospective in manufacturing energy sources. Three chapters are designated to new materials and processes of joining aluminum alloys widely used in the world. Chapter 9 covers the popular topic of brazing aluminum to steel, as well as soldering aluminum. Both subjects are combined together due to a similar approach of application with reactive fluxes. The chemistry of fluxes is discussed in details that are unique in brazing publications. High-productive technology in controlled atmosphere brazing (CAB) of aluminum is described in chapter 10 featuring the focus of interaction oxides with a flux and furnace atmosphere. This chapter can be used in the next edition of the Brazing Handbook as is. Finally, the original technology of fluxless brazing aluminum alloys and features of this promising process are discussed in chapter 19.
Conclusion For those just starting to work in the brazing industry, this book is a great primary source of scientific and practical information regarding important procedures and tendencies in our technology. A great team of scientists and engineers is collected under the cover of this book. It’s no doubt this publication shall become “a work-table reference book” for many professionals of the brazing industry because it is not only a source of useful technical information but also opens new horizons in our technology.◆
ALEXANDER E. SHAPIRO (ashapiro@ titanium-brazing.com) is brazing products manager at Titanium Brazing, Inc., Columbus, Ohio. He is a member of the C3 Committee on Brazing and Soldering, has contributed to the 5th edition of the AWS Brazing Handbook, and the Brazing Q & A column. For info go to www.aws.org/ad-index
WELDING JOURNAL
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STAINLESS Q&A
BY DAMIAN J. KOTECKI
Q: We did weld cladding (two layers) with E309LT0-4 flux-cored electrodes on a low-alloy steel pressure vessel, then stress relieved it for 8 h at 1150°F. When we removed the vessel from the furnace and allowed it to cool, we found that the weld had separated from the base metal over a large area. It appeared that the weld metal had not adhered to the base metal. When we examined the separated weld, we found that the underside of the cladding was only slightly attracted to a magnet, while the surface of the vessel underneath was strongly attracted to a magnet, which makes us wonder if the weld cladding actually fused to the base metal in the first place. What happened, and what can we do about it?
A: This phenomenon is known as disbonding. While its history indicates that it is most common with strip cladding, weld cladding by use of weave beads with other welding processes have also been known to be affected by disbonding. Disbonding is most common when the weld is made with a method that produces wide, flat deposits with low dilution. Nelson et al. (Refs. 1–3) have studied disbonding to a considerable extent. The mechanism seems not to be entirely clear, but carbide precipitation, impurity segregation, a long continuous grain boundary perpendicular to the principal stress, a considerable difference in thermal expansion coefficient between the low-alloy steel and the weld cladding, and hydrogen-induced cracking may all be involved in the disbonding. The characteristic of disbonding is cracking in the fusion zone very close to the fusion boundary along a particular grain boundary termed a “Type II boundary.” Figure 1, taken from Ref. 3, shows the special nature of the Type II boundary that extends parallel to the fusion boundary, only a few microns from the fusion boundary, and several grain diameters in length. Figure 2, taken from Ref. 3, shows the disbonded cladding side of the fracture. The crack path is exactly along the Type II boundary. When this cracking occurs along the Type II boundary, only a very thin layer of the weld (perhaps 10 microns or so in thickness) remains attached to the base metal, and no base metal remains attached to the cladding. This accounts for your observation that the weld metal side shows very little attraction to a magnet 20
JULY 2013
Fig. 1 — Type 309 cladding over ASTM A508 low-alloy steel. Note that the Type II grain boundary extends continuously along the fusion boundary a few microns into the weld deposit from the fusion boundary.
Fig. 2 — Disbonded Type 309 cladding separated from ASTM A508 low-alloy steel.
(only the ferrite in the weld metal is ferromagnetic, and there is much more ferrite in the second layer than in the first layer), while the base metal side is strongly attracted to a magnet.
There are several approaches you can use to reduce the tendency for disbonding. Since diffusible hydrogen is often involved, it is helpful to reduce available diffusible hydrogen. The flux-cored stain-
less steel electrodes of E309LT0-4 type are not always manufactured to low-hydrogen practice, and exposure to humid air can cause even a low-hydrogen electrode to absorb enough moisture to result in a problem. It is not possible to consistently measure diffusible hydrogen with austenitic filler metals like 309L because hydrogen does not diffuse appreciably in austenite. However, the transition from the ferritic base metal to the austenitic weld metal will invariably include a martensitic layer adjacent to the fusion boundary, which sometimes extends from the base metal to the Type II boundary. In this zone, hydrogen is mobile enough to cause cracking. The zone between the Type II boundary and the fusion boundary consists in part of melted filler metal, and if this filler metal contains enough hydrogen, the potential for cracking is there. So, it is important to maintain lowhydrogen conditions for the filler metal. This includes sourcing filler metal that was baked at the end of manufacture and protecting that filler metal from exposure to moist air. I would also note that the E309LT0-4 electrodes are intended to operate in 75% argon – 25% CO2 shielding which tends to produce higher diffusible hydrogen than 100% CO2 shielding. You might consider switching to CO2 shielding to reduce diffusible hydrogen. A second approach to the prevention of disbonding is to manipulate the welding procedure to avoid a nearly planar interface between weld metal and base metal. A nearly planar interface occurs when the individual weld runs are wide and shallow, as tends to occur in strip cladding and in weld cladding with a weave pattern. It is better to accept a little higher dilution, with flux-cored arc welding using your E390LT1-4 electrodes or other welding methods by depositing the weld metal in stringer beads instead of weave beads because the stringer beads produce a scalloped fusion boundary rather than a planar fusion boundary, and the scalloped fusion boundary is more resistant to disbonding. Only the first layer of weld cladding needs to be deposited by stringer beads. A second and any subsequent layers can be deposited with any welding pattern because the geometry of the fusion boundary with the base metal is already established before subsequent layers are deposited. A third approach is to replace stainless steel filler metal with nickel-based alloy filler metal. This is a more expensive approach due to the cost of the nickelbased alloys as compared to that of stainless steel filler metal. Once a layer of
nickel-based alloy, such as NiCr-3 type filler metal has been deposited, it is necessary to continue the cladding with the nickel-based alloy because transitions of nickel-based alloy to stainless steel are quite susceptible to solidification cracking. The main functions of the nickelbased alloy are to reduce the thickness of any martensitic layer in the transition zone as compared to the thickness of the martensitic layer in the transition zone when stainless steel is deposited, and to reduce the mismatch in coefficient of thermal expansion between the ferritic steel base metal and the weld metal. This latter in turn reduces the stresses at the Type II boundary. If you choose this approach, it is still important to treat the filler metal with good low-hydrogen practice. None of these approaches will guarantee freedom from disbonding, but chances are that you can be successful because many other fabricators have been.◆
References 1. Nelson, T. W., Lippold, J. C., and Mills, M. J. 1999. Nature and evolution of
the fusion boundary in ferritic-austenitic dissimilar metal welds — Part 1: Nucleation and growth. Welding Journal 78(10): 329-s to 337-s. 2. Rowe, M. D., Nelson, T. W., and Lippold, J. C. 1999. Hydrogen-induced cracking along the fusion boundary of dissimilar metal welds. Welding Journal 78(2): 31-s to 37-s. 3. Nelson, T. W., Lippold, J. C., and Mills, M. J. 2000. Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar metal welds — Part 2: On-cooling transformations. Welding Journal 79(10): 267-s to 277-s. DAMIAN J. KOTECKI is president, Damian Kotecki Welding Consultants, Inc. He is treasurer of the IIW and a member of the A5D Subcommittee on Stainless Steel Filler Metals, D1K Subcommittee on Stainless Steel Structural Welding; and WRC Subcommittee on Welding Stainless Steels and Nickel-Base Alloys. He is a past chair of the A5 Committee on Filler Metals and Allied Materials, and served as AWS president (2005–2006). Send questions to damian@ damiankotecki.com, or Damian Kotecki, c/o Welding Journal Dept., 8669 Doral Blvd., Ste. 130, Doral, FL 33166.
INDUCTION HEATING SYSTEMS Sales, Rentals, Lease Programs Weld Preheating, Post-Weld Heat Treatment, Coating Removal, Shrink Fit, Liquid- and Air-Cooled Systems
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WELDING JOURNAL
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PRODUCT & PRINT SPOTLIGHT
Focus on Stress Relieving, PWHT, and GTAW
GTA Torch Provides Cooling Capacity The WP-280 water-cooled GTA torch has been designed with the company’s Super Cool™ technology. Its body also includes an antirotation feature to prevent handle movement during welding and improve operator control. The TriFlex™ hose and cable assembly has been designed to remain flexible in cold weather, improve operator control, and prevent cracking. ColorSmart™ hose and cable sets differentiate input water, water/power cable, and gas hoses to simplify torch installation. Extra features include copper components to maximize current capacity and high-temperature silicone rubber insulation to minimize high-frequency voltage leaks. Mechanical fittings provide a secure gas and water connection to prevent leakage and allow users to easily replace hoses. Weld-Ready™ torch package has installed front-end parts, including a nozzle, medium back cap, 3⁄32-in. collet and collet body, and 3-in.-long ceriated tungsten electrode. The torch packages include a cable cover that offers a hook and loop closure to prevent slippage and provide cable protection, while also allowing access for remote finger control cables. Packages with part numbers ending in MFD50 include a cable cover that reaches to the power source to reduce cable clutter and offer additional cable protection, as well as a 50-mm Dinse connector. The torch is compatible with 13N front-end consumables. Weldcraft www.weldcraft.com (800) 752-7620
Metal-Cored Electrode Designed for Oil Field Uses
Laser System Cuts Steel Plate
The 4130C — a metal-cored, nickelbased, low-alloy steel electrode — matches the properties of certain quench and tempered steels following postweld heat treatment (PWHT). It is a nickel/chromium/molybdenum bearing wire that provides these weld metal properties. In addition, it contains less than 1% nickel in the weld deposit and delivers smooth arc transfer with minimal spatter. It is designed to weld 4130, 4140, 8630, and similar alloy steels that are to be PWHT. The low-nickel deposit makes the product suited for most oilfield applications. The electrode is available in 0.045 and 1⁄16 in. diameters.
The CL-400 CO2 laser cutting system uses water-cooled, high-speed linear motor drives with the same HMI touchscreen control and nesting software found on the company’s other CO2 and fiber laser cutting systems. Dual 5 × 10 ft pallets and an optional modular material handling system reduce beam-off time. It delivers fast positioning speeds of 12,000 in./min and up to a 1 in. processing range on mild steel. Other features include a 4000-W resonator; fourth-generation linear motor drives; and 0.75- to 1.5-in. steel plate frame.
Select-Arc, Inc.
Cincinnati, Inc.
www.select-arc.com (800) 341-5215
www.e-ci.com (513) 367-7100
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JULY 2013
Brochure Highlights Service Program
The company’s new four-page brochure offers an overview of its 5-Star Service® program and service center. It explains that whether it’s an emergency service call or a complete rebuild, the service program will have customers operating at original equipment standards. The service center is equipped to remanufacturer complex systems. It employs trained
E71T-12M-JH8 requirements for aswelded and stress-relieved conditions. It is a choice for pressure vessel fabrication and other applications requiring postweld heat treatment (PWHT) of mild steel. Extra features include arc performance and bead shape making it easy to use for welders of all skill levels. The wire is offered in 15- and 33-lb packages, and comes in the standard 0.045 in. diameter.
technicians, and the machining, fabricating, and welding capabilities necessary to rebuild equipment. According to the brochure, 5-Star Service also includes onsite testing and repair. All work is done with original parts, components, and assemblies. Eriez® www.eriez.com (888) 300-3743
The Lincoln Electric Co.
Tungsten Suits Alternating and Direct Current GTAW
www.lincolnelectric.com (888) 355-3213
Orbital Welding of Sanitary Process Lines made EZ SIMPLE OPERATION Making a perfect weld is now as simple as selecting tube/fitting O.D. and wall thickness, and pressing Start Weld! The intuitive symbolbased touch screen interface minimizes operator training and qualification time.
The LaYZrTM (color code chartreuse) tungsten electrodes (A5.12M/A5.12:2009AWS Class EWG) are nonradioactive and can be used in alternating as well as direct current GTAW applications. They have a chemical specification of 98.34% tungsten, + 1.5% lanthanum, 0.08% zirconium, and 0.08% yttrium, plus work in mechanized or robotic GTAW applications. Additionally, the 2% lanthanated (color code blue) tungsten electrodes (A5.12/A5.12:2009-AWS Class EWLa-2) are nonradioactive and perform in alternating current (aluminum) applications. They have a chemical composition of 1.8–2.2% lanthanum-balance tungsten and provide an option as a general purpose electrode for most GTAW applications.
AFFORDABLE TECHNOLOGY The modular EZ Orbital System is used with standard GTAW power sources. Priced at 1/3 of industry standards, this affordable tool should be in every welder’s toolbox.
CK Worldwide, Inc. www.ckworldwide.com (800) 426-0877
www.MagnatechLLC.com
Flux-Cored Wire Works for PWHT The UltraCore® SR-12 is a gasshielded flux-cored wire that meets AWS
E-mail:
[email protected] • Phone: (+1) 860 653-2573 For info go to www.aws.org/ad-index
WELDING JOURNAL
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Needle Scaler Suitable for Stress Relieving
The Trelawny™ TVS™ needle scaler with integrated vacuum shroud enables dust-free working in hazardous applications when used with a dust-extraction vacuum. Model 3BPG uses 28 needles to supply 2200 blows/min, making it suitable for cleaning and stress relieving welds. Other applications include removing coatings, corrosion, and other accumulated materials, as well as texturing concrete. Designed with a pistol grip, this pneumatic tool consumes 8 ft³/min of air at 90 lb/in.². The model weights 9.9 lb and has a vibration level of 19.9 m/s². CS Unitec, Inc. www.csunitec.com (800) 700-5919
Catalog Focuses on Switch-Rated Plugs For info go to www.aws.org/ad-index
WELDHUGGER COVER GAS DISTRIBUTION SYSTEMS Includes 6 nozzles, manifold, gooseneck assembly & magnet
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• Flows gas evenly over and behind the weld pool. • Reduces oxidation and discolorization • Designed for trailing shield and a variety of other applications. • 316L Stainless steel nozzles and manifolds.
Snake Kit
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Simulated nozzle flow
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The company’s 239-page product catalog features Decontactor Series switchrated plugs, receptacles, and connectors. It also provides information about the company’s other plug and receptacle product offerings, including the new CS1000 single-pole plugs and receptacles (up to 400 A, 600 VAC) and a wide variety of multipin devices (from 7 to 37 contacts). The switch-rated plugs and receptacles allow technicians to quickly change out motors, welding machines, and other
electrical equipment with plug and play simplicity. Meltric Corp. www.meltric.com (800) 433-7642
GTAW Machine Offers High-Frequency Start
The TIG 200 DC welding machine has high-frequency Mosfet inverter technology with a high-frequency start feature that provides an instant arc strike with no tungsten contamination. The voltage selfsensing circuitry automatically detects a power source range of 110 or 220 V, 50 to 60 Hz, and delivers 10 up to 200 A DC. It welds steel as well as stainless steel up to 3 ⁄16 in. thick and includes preset post and preflow gas, overload protection, and adjustable amperage control for panel (trigger switch) or foot pedal operation. Eastwood Co. www.eastwood.com (800) 343-9353
Furnace Performs Preheating and PWHT
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WELDING JOURNAL
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Manufacturin Manufacturing uring
Flux Cored Welding elding Wire W COBALT LT NICKEL
prior to welding and various postweld heat treatments (PWHT). Workspace dimensions measure 60 × 60× 60 in. Heat to the load is provided by 180-kW nickel-chrome wire coils supported by a stainless steel framework. The unit includes a rear wallmounted, heat-resisting alloy recirculating fan, powered by a 25-hp motor with V-belt drive and water-cooled bearings. It features an air-operated vertical lift door and safety/control components, including a programming and recording temperature recorder, SCR power controller, manual reset excess temperature controller with separate contactors, and a recirculating blower airflow safety switch. The Grieve Corp. www.grievecorp.com (847) 546-8225
Cooling Vests Come in Eight Different Models
bility. The Vortex cooling or heating vest may be adjusted to provide warm or cool air; the flame-retardant, low-profile cooling vest may be connected to any clean compressed-air source and worn under protective clothing. The Standard vest for cooling inserts is useful to wear under HazMat suits, and the Standard and Economy Poncho cooling vests may be soaked in cold water to provide all-day comfort. The vests are durable, breathable, lightweight, and available in a variety of safety colors. Other products include cool offs, doo rags, and bandanas. Allegro Industries www.allegrosafety.com (800) 622-3530
Catalog Includes Extensometers
HARDFACE E STAINLESS TAINLESS ALLOY Y STEEL EEL TOOL STEEL STEE EEL MAINTENANCE MAINTENAN CE FORGE ALLO ALLOYS OYS
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Inverters Improve Control for AC Gas Tungsten Arc Welding Inverter technology in GTAW applications has evolved to offer a costeffective, easytouse, hightech answer that has broad appeal
nverter technology for alternating current (AC) gas tungsten arc welding (GTAW) has traditionally been thought of as expensive, complicated, and even problematic. Recent advances in switching devices, microchips, and tungsten technology have changed the playing field, making inverter technology for AC GTAW applications more affordable and accessible, offering a high-tech welding solution to a broader range of users from the average welder to any size of industrial fabrication shop.
I
The Early Days of AC GTAW For a better understanding of inverters and the benefits they offer, it’s important to reflect on the early days of AC GTAW. During GTAW’s development in the early 1940s, it was discovered that AC reverse polarity could remove the tenacious oxide layer from aluminum, making it easier to weld. Alternating current GTAW employed simple transformer technology that utilized 60-Hz incoming
Fig. 1 — Inverter power supplies make welding frequencies of upward of 200 Hz available, providing more control of the AC waveform. As the frequency is in creased, the arc column becomes more concentrated. This allows the welder to put in smaller beads. With a more con centrated arc, the cleaning side of the cycle is also better concentrated, produc ing a narrower oxide etch zone. 28
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sine wave power to generate an arc suitable for the process. This consisted of a heavy transformer to supply the proper power and an equally heavy magnetic amplifier as a means of output control. A drawback to using AC sine wave power was the long time period at low current as the current changed polarity. High frequency (HF) was required to
BY ROBERT L. BITZKY AND JEFF GARRAUX ROBERT L. BITZKY (
[email protected]) is manager, Training & Process Center, and JEFF GARRAUX (
[email protected]) is process & training welding engineer, ESAB Welding & Cutting Products, Florence, S.C.
help ensure reignition of the arc during the alternation of the current flow. If the arc didn’t reignite, typically on the electrode positive half cycle, rectification occurred and cleaning action was lost. It was a constant fight to try to keep the polarity balanced to ensure sufficient cleaning action on the aluminum surface. This balanced polarity caused the tip of
Fig. 2 — The higher balance control and frequency provided by modern inverterbased systems allows the welder to tune the arc from traditional square wave to a concentrated arc in AC, rivaling DC arc char acteristics. This helps the welder maintain a very sta ble and concentrated arc to produce small, highqual ity welds not achievable with older style equipment.
the tungsten electrode to form a molten ball and the arc to be quite broad. As a secondary detriment, the rectification sometimes caused the tungsten to actually spit a small piece of the molten material into the weld pool. Moreover, the characteristic of the magnetic devices caused a further distortion (deterioration) in the sine wave, making this a lessthan-perfect process. It was obvious the sine wave process was not the answer. Faster switching through the current reversal offered a better solution. The square wave era (circa late 1970s) introduced fast switching, which helped lessen many of the arc issues of balance and rectification, but the welding machines remained very heavy and not very power efficient.
Better Frequency and Balance While the introduction of square wave technology offered better control of the polarity balance compared to sine wave technology, this technology was limited
to approximately 75% direct current electrode negative (DCEN) and 25% direct current electrode positive (DCEP), allowing less time on the DCEP side of the cycle and reducing the overall heating of the tungsten. What was needed was faster switching and technology that was more efficient and weighed less. This came to pass with the era of inverter technology. The advent of inverter power supplies made welding frequencies of upward of 200 Hz available — Fig. 1. The increase in frequency provides greater control of the AC waveform. As the frequency is increased, the arc column becomes more concentrated. This allows the welder to put in smaller beads. With a more concentrated arc, the cleaning side of the cycle is also better concentrated, producing a narrower oxide etch zone. In addition to a more concentrated arc, the capabilities for pulsing are also greatly increased. Inverter power supplies through the nature of their design introduced superior electronics. These advanced electronics allow for increased balance con-
trol with balance adjustable up to 90% DCEN and 10% DCEP. Increasing the balance control permits a greater control over the arc. Balance above 75% DCEN minimizes overheating of the electrode. This allows the welder to prepare and maintain a pointed electrode. A pointed electrode allows for a more concentrated arc and the ability and convenience to switch from an AC to a DC process without changing the electrode. The advanced electronics used in inverter technology also provide a much more stable arc without the need for continuous HF. In these systems, HF is only used to initiate the arc and is turned off for the duration of the weld. This reduces electrical interference with the machine and other electronics in the vicinity of the power source. Advanced electronics and increased balance control and frequency directly impact overall weld performance and combined offer greater benefits. Higher balance control and frequency found in modern inverter-based systems allow the welder to tune the arc from traditional square wave up to a concentrated arc in WELDING JOURNAL
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Fig. 3 — Inverter technology eliminates the need to use two types of tungsten electrodes. Inverter power sources use rare earth elements such as lanthanum and cerium alloyed with tungsten. With these newer tungstens, welders can use the same tungsten type for AC and DC.
AC that rivals DC arc characteristics — Fig. 2. This helps the welder maintain a stable, concentrated arc for some of the smallest, highest-quality welds that are not achievable with older style equipment.
A Superior Solution There are several other areas in which modern inverter-based welding systems offer the welder advantages: Tungsten selection: Inverter technology provides the added benefit of sharpened tungsten during AC welding and the ability to switch back and forth from AC to DC without changing the tungsten. What tungsten should be used? Conventional systems instructed welders to use pure tungsten (green) for AC and thoriated tungsten (red) for DC. Inverter technology eliminates the requirement to use two types of tungsten electrodes. In fact, inverter power sources have ushered in a new age of tungsten with the use of rare earth elements like lanthanum and cerium alloyed with tungsten — Fig. 3. Other special alloys have also been added to the list of tungsten sources. With these newer tungstens, welders can use the same tungsten type for AC and DC. This allows the user to carry a single type of tungsten, which reduces operating costs as well as confusion as to which type of tungsten to select for AC vs. DC welding. Energy savings: The superior arc control that inverters supply should be reason enough to make the switch from older style equipment, but inverter-based welding machines have more to offer. Compared to older style welding machinery, inverters are much more energy efficient; so much so that they typically use only half of the input amperage of older systems. This amounts to significant savings in electricity, which directly reduces operating costs and increases the user’s return on investment. Lower power consumption also makes these machines suitable for smaller shops that do not have high-amperage service. Typical input amperage available in a
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smaller shop or house is about 50 A. Older style welding machines draw an average of 100 A on the input, making them unsuitable for such environments. Newer inverter machines at the same rated outputs draw less than 40 A, well within the available service in these locations. In addition, for field applications, inverter-based machines can be operated using smaller generators than older welding equipment can. Ability to run on three-phase power: Prior to the introduction of inverter technology, AC GTAW required the use of single-phase power. In most industrial applications, three-phase power is available and large single-phase loads tend to cause unbalanced line currents in the three-phase supply lines. This further degrades efficiency and can disturb the operation of sensitive equipment. Lower cost of acquisition: While many industrial fabricators assume that inverter-based welding systems featuring high-end electronics and high-speed switching devices come at a high price tag, the opposite is true. Typically, transformers are composed of copper and iron, and the larger the transformer, the higher the price tag of the equipment. Inverters employ transformers that are typically only one-sixth the weight of traditional machines. Significantly smaller transformers, like those used on inverter-based welding systems, mean greatly reducing manufacturing cost. This in turn makes inverterbased equipment less expensive to manufacture than traditional machines and a more cost-effective investment.
Improved portability: The smaller transformer used on an inverter-based system reduces the overall weight and size of the machine, which improves the system’s portability. A reduced machine footprint saves on valuable floor space and makes the unit easily transportable for field work. Increased program storage: Modern inverter-based welding machines also feature increased program storage with some systems offering up to 60 parameter sets. Built-in program storage reduces operator input and ensures a quick, consistent setup and exact processing conditions to achieve repeatable weld quality and high productivity no matter the welder’s skill level.
Changing the Rules Modern inverter-based welding systems are changing the rules of traditional AC gas tungsten arc welding, providing better control over the AC arc, more programmability, longer electrode life, and greater ease of use than old-style welding systems. Inverter technology addresses the need of every welder to control the arc and heat, and to have flexibility in the welding process. From small job shops welding a variety of short- to medium-run jobs to large oil refineries welding miles of pipeline, inverter technology for AC GTAW has evolved to offer greater functionality at a lower cost of acquisition, putting a hightech welding solution within the reach of a broader range of welders.◆
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A New Development in Aluminum Welding Wire: Alloy 4943 BY TONY ANDERSON
A new aluminum filler metal for wrought commercial applications offers higher strength TONY ANDERSON (
[email protected]) is director of Aluminum Technology, ITW Welding North America, Appleton, Wis.
lloy 4943 is the first aluminum filler metal in 50 years to be developed in the USA for wrought commercial applications and to receive an Aluminum Association Registered International Designation (the last being 4643, which was registered with the Aluminum Association in 1963 and then later added to the AWS A5.10 specification in 1988). The 4943 aluminum filler metal has recently received the AWS A5.10 classifications of ER4943 and R4943, along with an ASME filler metal material group allocation of F23 (the same F number as 4043 and 4643) and CWB and ABS approvals. The new 4943 filler metal was designed primarily to provide a consistently high-strength alternative to filler metal 4043 while maintaining the ease of welding and other advantages of 4043, and also to provide higher postweld heattreated strength when compared to 4643. To fully appreciate the technological merits associated with this new filler metal, it is necessary to understand the
A
history associated with the 4xxx series silicon-based filler metals, how base metal and filler metal chemical compositions combine and influence weld strength, and the metallurgy of aluminum-silicon filler metals.
The History of Aluminum Silicon Filler Metals Brazing Starting in the 1930s, the brazing process was adapted to aluminum joining on a commercial scale. The brazing filler metals have liquidus temperatures above 800°F but below the melting temperature of the base metal. During the brazing process, typically no base metal melting occurs and, consequently, there is no dilution of base metal and filler metal. During this period, Alcoa developed two basic silicon-based brazing alloys
Table 1 — Two Early Silicon-Based Brazing Alloys AWS/ASTM Class
Aluminum Association Designation
%Si Range
%Mg Max.
Melting Range °F
BAlSi-1 BAlSi-4
4043 4047
4.5–6.0 11.5–13.0
0.05 0.10
1070–1165 1070–1080
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(Table 1). These silicon alloys are still used for the successful brazing of aluminum.
Arc Welding Arc welding of aluminum began on a commercial basis in the early 1940s with the introduction of the gas tungsten arc welding (GTAW) process followed by the gas metal arc welding (GMAW) process. Unlike in brazing, the arc welding processes melt the metal under the arc, both filler metal and base metal, followed by solidification of the weld bead. For this reason, most arc weld beads have a rapidly solidified cast structure that is comprised of both filler metal and base metal. As the arc welding process was developed for aluminum, filler metals were developed for welding the various types of aluminum base metals. Unlike steel welding, for reasons associated with weld integrity and strength, filler metals with significantly different chemical compositions than that of the base metal are often used when arc welding aluminum. When arc welding with the 4043 filler metal, particularly on the 6xxx series base metals, it is important to recognize that the completed weld bead chemical composition, resultant weld integrity, and mechanical properties are dependent on the mixture of the base and filler metals in the weld bead.
Effect of Porosity on Tensile Strength
How base metal and filler metal chemical compositions combine and influence weld strength when using 4043 filler metal. The strength of a weld made with filler metal 4043, which has no other strengthening additives other than silicon, is often dependent on dilution with the base metal. Weld beads (that are a mixture of filler metal and base metal) can acquire small amounts of magnesium from the 6xxx series base metals. The addition of magnesium to the 4043 filler metal, obtained from dilution of the base metal, combines with the silicon in the 4043 and produces magnesium-silicide (Mg2Si), an effective strengthening precipitate. One problem associated with this method of weld bead strengthening is its unpredictability. When arc welding the 6xxx series aluminum base metals with the 4043 silicon-based filler metal, there are many situations in which the dilution ratio between base metal and filler metal can fluctuate and influence the strength of the completed weld. The probability of producing weld metal with consistent mechanical properties is further diminished when we consider the variations in base metal/weld metal dilution ratios associated with various weld joint designs, welding procedures used, and material thicknesses welded. There are situations where it becomes difficult to ensure dilution from a base metal in order to modify the filler metal chemistry and improve the strength of the deposited weld. Two very good examples of these types of applications are when welding thick or thin base material. When welding thick material, it is possible to produce a section within a multipass weld that is significantly removed from the base metal material so that lit-
Fig. 1 — Effect of porosity on tensile strength. The effect of porosity on the tensile strength of welds made with 4043 and 4943 filler metal in comparison with the design allowable limit for 6061-T6 base (24 ksi) is shown.
tle, if any, base metal chemistry is transferred into the weld filler metal. When welding thin material, it is often necessary to design welding procedures to provide absolute minimum penetration into the base metal in an attempt to prevent melt-through and distortion problems. In both cases, we would expect to see weld beads comprised of large amounts of filler metal and very little base metal dilution, with corresponding reductions in strength. Most filler metal alloys contain all the alloying elements necessary to meet the physical and mechanical property requirements of a base metal and filler metal combination without the need for base metal chemistry dilution. AWS A5.10/A5.10M:2012, Welding Consumables — Wire Electrodes, Wires and Rods for Welding of Aluminum and AluminumAlloys — Classification, lists all filler metal classifications for both aluminum GMAW and GTAW joining methods. All of the listed filler metal alloys have been specifically developed for arc welding except Alloys 4043, 4047, and 4145. These three filler metals were originally developed as brazing alloys. One development related to this dilution phenomenon was the introduction of filler Alloy 4643 in the early 1960s. Alloy 4643 was introduced to address the specific challenge of obtaining sufficient dilution from base Alloy 6061 and to meet mechanical property requirements when using filler Alloy 4043 in the postweld heat-treated and aged condition. Alloy 4643 was designed by Alcoa to be a blend of 80% 4043 and 20% 6061 chemistry in the filler metal. However, filler metal 4643 still requires some dilution from the base alloy (approximately 20%) for postweld heat-treat and aging appli-
cations in order to obtain optimum mechanical properties. Filler metal 4643, as compared to 4043, has reduced silicon content, which increases the hot cracking sensitivity, lowers the fluidity of the molten metal and the ability for bead contour control that can significantly impact the strength and fatigue life of the weld. Also, lower free-silicon content negatively impacts strength. As a result, 4643 properties can typically only achieve 90% of the base metal 6061-T6 properties when in the postweld heat-treated and aged condition.
Development of Filler Metal 4943 Filler metal 4943 has been developed specifically for arc welding processes and to be used for welding wrought aluminum base alloys. It was developed with the objective of providing a consistently higher tensile, yield, and shear strength alternative to 4043 and 4643 while maintaining the same proven welding characteristics of 4043. The 4043 filler metal is a popular aluminum/silicon filler alloy for general-purpose welding applications. However, it has lower strength when compared to the 5xxx series filler metals, and can show significant variability in strength based on welding conditions and the level of base metal dilution obtained during welding, as described previously. The 4943 filler metal has been formulated to be welded with similar weld procedure specifications as 4043, provide improved strength, and address variability in strength issues associated with 4043. While improving weld strength, 4943 will also maintain the same excellent corro-
WELDING JOURNAL
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sion characteristics, low melting temperature, low shrinkage rate, higher fluidity, and low hot-cracking sensitivity as the 4043 filler metal, and also exhibit low welding smut and discoloration. In addition to consistently higher as-welded strength, the new 4943 filler metal is also heat treatable and has demonstrated its improved strength characteristics in the postweld solution heat-treated and artificially aged condition when compared to the currently used heat-treatable filler Alloy 4643 (which has been generally employed for welding the 6xxx series base materials that are postweld heattreated).
Shear Strength 4943
Strength Benefits Groove Welds In complete-joint-penetration groove weld applications, the as-welded strength of 4043 without dilution is typically adequate to support the 24 ksi minimum transverse tensile strength requirement of 6061-T6, which is set as a result of the depleted strength of the base material heat-affected zone (HAZ). However, the lower strength weld produced by 4043 leaves less room for discontinuities (porosity, for example) in a weld before the weld drops to below the acceptance strength level — Fig. 1. Although 4943 will provide improved strength in groove welds, this is not its principal intended benefit. The principal benefit of 4943 is to provide higher-strength fillet welds.
Fillet Weld Strength The most important benefit of 4943 is to provide consistently higher-strength fillet welds. There are far more fillet welds than groove welds used in struc-
Fig. 2 — Filler metal shear strength comparison chart shows the positioning of 4943 filler metal based on fillet weld shear strength.
tural welded components; of all aluminum welds in industry, approximately 80% are fillet welds. Fillet welds, by design, are partial penetration joints that are assumed to have minimal base metal dilution. Unlike complete-joint-penetration groove weld transverse tensile strength, which is controlled by the base metal HAZ, fillet weld shear strength is directly controlled by the strength of the filler metal used during welding. Tests comparing 4043 to 4943 have shown 4943 to have an ultimate tensile strength that is conservatively 20% higher than 4043. One potential benefit of this increase in weld strength may be the opportunity for a manufacturer to decrease the size of fillet welds while maintaining the same strength. This may provide potential savings to a manufacturer from the reduced amount of weld wire needed to be purchased for a project, and
also, in the labor cost that could be reduced from the time saved by making smaller welds (increased productivity). One other side benefit to smaller welds, which is often important, is reduced distortion. With the increased strength of 4943 over 4043, it is quite plausible to consider a one-pass fillet weld made with 4943 having the same strength as a threepass weld made with 4043. Figure 2 shows the relative shear strengths of 4043, 4643, 4943, and 5356.
As-Welded, Postweld Aged, and Postweld Heat-Treated and Aged Properties Alloy 4943 has been evaluated alongside Alloys 4043 and 4643. The evaluation was performed using various weld joint designs welded in accordance with AWS D1.2, Structural Welding Code — Aluminum. Tensile test specimens were taken in the longitudinal direction in the all-weld-metal region, and were tensile tested per ASTM B557. A number of tests were performed using fairly wide joints with Alloy 1100 base plates to prevent any favorable base metal dilution.
Fig. 3 — All-weld-metal/all-filler-metal longitudinal tensile strength of 4043, 4643, and 4943 in the as-welded, postweld artificially aged, and solution heattreated and artificially aged to -t6 temper.
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This is important so as to recreate the little to no dilution conditions obtained on many thick welds, on very thin joints where heat input has to be limited, and, more frequently, on fillet welds in the field. Figure 3 summarizes the results. Note: The data in Fig. 3 represent a 25% gain observed on ultimate tensile strength and a 50% gain on tensile yield strength for 4943 over 4043 in the aswelded condition. All welds were completed using the same welding procedure and with the GMAW process. Consideration should be given to the fact that 28 ksi tensile strength for an all-weld-metal 4043 test is achieved in these samples tested using the GMAW process with a reasonably low heat input. Any substantial increase in heat input and associated slow cooling rate, such as with GTAW, may have the potential to reduce the 4043 weld metal tensile strength to below the minimum design allowable strength.
How the Filler Metal Provides Higher Strength Alloy Design The 4943 alloy was designed around two principal ideas. The first was the addition of a strengthening element — in this case magnesium, which combines with the available silicon in the filler metal to form Mg 2Si, an effective strengthening phase as demonstrated in 6XXX series alloys. The range of the magnesium addition was set at 0.1 to 0.5% to achieve a specific amount of Mg 2Si precipitation while staying away from the crack sensitivity peak. The second idea was to adjust the 4943 silicon range to 5.0–6.0% to ensure the level of free silicon is maintained at the same level as 4043, typically 4.5–6.0%, knowing that up to 0.5% silicon will precipitate as Mg 2Si phase. Keeping the amount of free silicon to the level of 4043 is essential in maintaining fluidity characteristics and resistance to hot cracking during solidification. This also has a beneficial effect on strength and allows designing for fracture toughness and fatigue performance similar to Alloy 4043 with higher fatigue strength proportional to the increase in tensile strength.
Metallurgy of AluminumSilicon Alloys Silicon is one of the most common alloying elements in commercial alu-
Although 4943 will provide improved strength in groove welds... the principal benefit is to provide higher-strength fillet welds. minum. Silicon’s benefits of increasing fluidity, reducing solidification temperature and solid-state shrinkage, reducing welding distortion, strengthening, wear resistance, etc., are taken advantage of in many markets and applications such as castings, wrought products, and welding rods and electrodes. The effect of the silicon on strength is significant. A small percentage of the silicon addition contributes to strength via solid-solution strengthening and a small percentage via silicon-phase precipitation, but most of the strengthening comes from the rather large hard and brittle silicon particles. The strength of the alloy is proportional to the silicon content up to a range of 12 to 14% (dependent on the silicon constituent morphology), up to a point where the morphology and distribution of silicon precipitates offsets the effect of more additions. Currently, the main Al-Si filler metal in terms of volume usage is 4043, with a range of 4.5–6.0% silicon. This alloy offers very good resistance to hot cracking while maintaining practical levels of fracture toughness, fatigue, strength, and ease of manufacturing. The hot cracking performance is a result of the alloy’s high fluidity, lower melting temperature, and reduced shrinkage rate obtained from the silicon content. It is easy to weld with and produces smooth, great looking welds. Alloy 4047 is the second most commonly used 4xxx series filler metal, with 12% silicon. The increased fluidity of 4047 makes it suitable for applications requiring superior leak proofing, such as heat exchangers. The improved fluidity comes at a cost, as fracture toughness and ductility are negatively impacted by the higher silicon content. Alloys with silicon content greater than 12% are common in the foundry industry but not in
the wrought or weld wire product forms as the very high silicon content makes these alloys extremely difficult for hot or cold working. Alloys 4643 (developed in the 1960s by Alcoa) and 4943 (recently developed by Maxal-Hobart/ITW) take advantage of magnesium additions to increase the strength of the soft matrix, in addition to all of the above strengthening means from the silicon. The magnesium combines with the free silicon to precipitate as Mg2Si. The Mg2Si precipitates are very effective at strengthening the matrix. Alloy 4043 takes advantage of this to a lesser extent when it is welded to a base metal that contains magnesium, as some magnesium from the base metal is diluted into the fusion zone. In this case, the welding practice and the type of weld have a significant impact on the amount of dilution. Alloy 4043 fillet welds and very thin/thick welds are especially susceptible to variations in the degree of dilution, resulting in variations in weld strength. The smaller strength variation for 4943 is because the magnesium is already in the alloy and not dependent solely on base metal dilution diffusion.
Intended Use Filler metal 4943 is suitable for all applications currently using Alloys 4043 or 4643. These applications typically use 1xxx, 3xxx, and 5xxx alloys with less than 2.5% magnesium (such as 5052), and 6xxx series base metals. Filler metal 4943 may be useful for applications such as automotive and motorcycle frames, wheels, ship decks, pleasure boats, bicycles, scooters, 356 casting repair, and high end ladders. The 4943 filler metal has demonstrated higher weld strength than Alloys 4043 and 4643 in the as-welded, postweld aged, or postweld solution heat-treated WELDING JOURNAL
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and artificially aged conditions. The 4943 filler metal will exceed the strength of 6061-T6 base metal upon postweld heat treatment and aging.
Conclusion Aluminum-silicon alloys of the 4xxx series are widely used in GMAW and GTAW because of their excellent welding characteristics, fluidity, reduced shrinkage distortion, and resistance to hot cracking. The moderate and variable strength of 4043 can be improved via magnesium additions to the filler alloy itself, and this was achieved to some extent with Alloy 4643. The magnesium addition was optimized with a silicon addition in Alloy 4943 for improved characteristics relating to strength, fluidity, shrinkage, and hot cracking resistance. Tests have shown that when using filler metal 4043 for complete-joint-penetration groove welds, we can come very close to the minimum design strength allowable for 6061 base metal and that this concern becomes far less significant if we use the higher strength 4943 filler metal. However, the principal advantage of the 4943 filler metal over 4043 would appear to be when used for fillet welds. In the fillet weld application, there is a distinct opportunity for improving weld strength, reducing welding costs, and improving productivity. Welds made using the new filler metal 4943 can exhibit substantial improvements in strength when compared with 4043 and/or 4643 filler metals in both the as-welded and postweld heat-treated conditions.◆ Acknowledgments The author would like to thank Matthew Stephens, mechanical engineer, Goddard Space Flight Center, for providing test results and feedback of comparison tests for the 4943 filler metal used on the James Webb Space Telescope Project; and the following contributors from Maxal International: Bruce Anderson, research and development consultant, for the design and development of 4943 filler metal and all the technical support during the extensive testing program; Patrick Berube, QA manager/metallurgical engineer, for designing test programs, technical support, and preparing test data; and Galen White, senior welding engineer, for producing and testing many weld samples during many months of extensive testing of the 4943 filler metal.
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NASA Chooses Filler Metal 4943 for the James Webb Space Telescope Project During development and testing of this new filler metal, a number of aluminum fabricators evaluated its performance, but perhaps the most interesting and comprehensive series of tests was conducted at the Goddard Space Flight Center for the James Webb Space Telescope (JWST) project. The James Webb Space Telescope will be the scientific successor to Hubble; its science goals were motivated by results from Hubble. The telescope, scheduled for launch in 2018, will “go beyond” what Hubble has already done by looking at light with longer wavelengths (infrared). This ability will allow it to see light from more distant objects whose visible light is degraded over the vast distance of space from ultraviolet and optical into near-infrared. To optically “see” these vast distances a larger mirror is required. The JWST primary mirror is 6.5 m wide, which is about seven times the collecting area of Hubble’s 2.4-m-wide primary mirror — Fig. 4. To support such a large mirror, JWST itself is a massive engineering feat. This project includes a sun shield almost as big as a Boeing 737 to protect the heat-sensitive telescope from our own sun’s radiation. The science that JWST will explore goes farther and deeper into our knowledge of the universe than ever before by having the capability to study the assembly galaxies, observe the birth of stars and protoplanetary systems, analyze the chemical properties of planetary systems including our own, and see the first bright objects that formed in the early universe. All of these amazing capabilities will be achieved by the telescope’s cutting-edge cameras, which are called science instruments (SI). But don’t be fooled, these SI cameras are about as similar to your digital camera as a Ferrari is to a moped. All four of the SIs are supported by a precision-optical frame called the Integrated Science Instrument Module (ISIM). Currently, the ISIM is being prepared for integration and testing at NASA’s Goddard Space Flight Center in Greenbelt, Md. One of the multiple testing operations is known as a cryovac test in which the functionality of the ISIM is evaluated in Goddard’s Space Environment Simulator (SES) where the cryogenic temperatures (18 K or –427°F) and vacuum of space are recreated.
Developing Welding Procedures to Meet Strength Requirements While safely supporting the ISIM during integration, performing cryovac, and other testing was an extreme engineering challenge in itself, imposed test requirements, strength margins, and design envelopes demanded a strong, lightweight aluminum 6061 frame that was termed the SES Integration Frame (SIF) — Fig. 5. Early
An artist’s rendering of the James Webb Space Telescope. (Image courtesy of NASA.)
Fig. 4 — Size comparison between the Hubble and James Webb telescope mirrors. (Photo courtesy of NASA.)
design iterations revealed that a welded frame was needed to achieve the weight requirement but standard welding strength values did not achieve the design margins needed. It was learned that the postweld aging process used in specialized industries could achieve the strength needed. The SIF matured as a multirolled integration and testing frame that would support and lift the ISIM as well as hold needed test equipment in close proximity around it. An in-depth development study was completed to determine which filler metal (4043, 4643, or 4943) would meet the design needs. After conducting tests to compare the new 4943 filler metal with 4043 and 4643, the test results identified significant improvements in strength from the 4943 filler metal over the other filler metals tested and also established that the 4943 weld wire would maximize the frame’s performance. The SIF fabrication has been completed and is currently in preparation for the first ISIM cyrovac test expected to start this summer.
Fig. 5 — Imposed test requirements, strength margins, and design envelopes demanded a strong, lightweight aluminum 6061 frame. (Photo courtesy of NASA.)
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Fig. 1 — To prevent contamination, this grinder is dedicated to the one purpose of shaping tungsten electrodes.
How to Improve GTAW Performance L
ike many others in 2008, welder Mike Balboni became a statistic of the recession. Laid off from work, he applied his nearly 20 years of experience and numerous welding certifications for structural steel (SMAW), sheet metal (GMAW), and general fabrication (including aluminum GTAW) to accepting a variety of metal fabrication projects. He often took the projects that others wouldn’t do. His shop, Northeast Welding and Coating Services (www.northeastwelding. com), is located about 40 miles south of Boston in Attleboro, Mass. His company also provides media blasting, powder coating, electrostatic powder spray, gal-
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vanizing, and thermoplastic spraying services. Some of his recent projects include building four 20-ft-tall solar towers for a local professional sports team in two weeks, building a massive decorative park fence project for a local municipality, hardfacing an excavator bucket, stainless steel artwork, and construction of a stainless steel conveyor system for a bakery that required 80,000 1⁄2-in.-long gas tungsten arc welds. Today, Balboni relies on two portable multiprocess inverters with DC outputs for gas tungsten arc (GTA), gas metal arc (GMA), and shielded metal arc (SMA) welding, as well as a portable inverter with an advanced AC/DC GTAW output
and high-frequency (HF) arc starting capabilities. “TIG (GTA) welding enabled me to grow my business,” he said. “This includes thin-gauge stainless steel, process piping, and aluminum fabrication. Whether the work is in the field, under an emergency vehicle, or on a tuna tower, having a GTAW inverter with advanced capabilities lets me take on work that I used to have to sub-out or turn away.” So that other fabricators in his position don’t have to turn away GTAW work for lack of knowledge, Balboni recently teamed up with Thomas Ferri, a district manager with Victor Technologies, as well as an AWS Certified Welding In-
An entrepreneur became competitive by mastering the advanced functions on GTAW power supplies for more control over his welding of thin steel, aluminum, and stainless steel
spector (CWI) and AWS District 1 director. The following are some of their most important tips to improve GTA welding performance. The applications selected for demonstration purposes include 18gauge, Type 304 stainless steel, 304 stainless steel pipe (1 1⁄4-in. diameter, Schedule 40), and 1⁄8-in. 6061 aluminum.
select a nonradioactive tungsten such as ceriated, lathanated, or the new “tri-mix” type. They offer similar performance, including easy arc starting, arc stability, long life, and similar current capacities. For Schedule 40 pipe, Balboni selects a 3 ⁄32-in. tungsten; for 18-gauge stainless steel, he selects a 1⁄16-in. tungsten.
Tungsten Basics
Blunted Point
Dedicated Grinder A grinding wheel dedicated to shaping tungsten electrodes is essential to prevent contamination from other metals. Figure 1 shows the proper angle for shaping. For GTA welding without the concerns caused by radioactive thorium dust,
For AC welding of 1⁄8-in. aluminum with an inverter-based power source, Balboni selects a 3⁄32-in. ceriated tungsten electrode and creates a blunted point. To create a blunted point, he sharpens the tungsten as he would for welding stainless or mild steel, but then puts a slight flat spot on the end of it — Fig. 2. This provides better directional control over
BY MELISSA FRANKLIN MELISSA FRANKLIN is a brand manager at Victor Technologies (www.victortechnologies.com), St. Louis, Mo.
the arc compared to the traditional ball used for GTAW on AC current for welding aluminum with his previous conventional AC GTA welding machine.
Gas Lens A gas lens (Fig. 3) uses a mesh screen to distribute the shielding gas more evenly around the tungsten electrode, the arc, and the weld pool. It also enables a longer electrode extention, which helps when welding on inside corners or other spots with tight access. This photo also illustrates tungsten extention. As a general rule, the tungsten should not extend any farther than the measurement of the inside diameter of the cup. For example, for the No. 8 cup shown here, which has a 1⁄2-in. ID, the
Fig. 2 — Tungsten tip properly “blunted.”
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Fig. 3 — (Top) The screen surrounding the tungsten electrode serves as a gasdiffusing lens. Fig. 4 — (Bottom) Balboni carefully braces his arms and hands prior to welding.
tungsten should extend no more than 1⁄2in. That said, the gas lens does permit increasing the extension by about 50%.
Setting Gas Flow When it comes to shielding gas flow, more is not better. Excessive gas flow creates a swirling venturi-like effect that can draw in atmospheric air and contaminate the weld. For GTAW, set the gas flow between 15 and 20 ft3/min. When welding outdoors or in drafty areas, set up wind baffles or even a tent if necessary, but do not increase the gas flow beyond the recommended values.
Aluminum-Only Brush When exposed to the atmosphere, aluminum (melting point 1221°F) immediately forms aluminum oxide, which melts at 3762°F. To remove the aluminum oxide, Balboni uses a stainless steel wire brush dedicated to this task that is clearly labeled “Aluminum Only” to prevent cross contamination from carbon steel. He makes sure the aluminum filler rods are kept dry in a storage container and not exposed to shop dust or other sources of contamination.
Getting Started Arc Start Options When procedures specify a noncontact, HF arc start, operators have no choice but to use a power source with this option. Many of today’s GTA inverters have both HF start and “Lift TIG” arcstart options. With the touch method, it is a mistake to apply the old-fashioned scratch-start technique; scratching the tungsten like a match poses a greater risk of tungsten contamination. To start the arc using Lift TIG, perform the following steps: Rest the back edge of the cup on the workpiece, then rock the cup forward and touch the tungsten to the workpiece. Depress the torch switch/foot control and maintain contact between the tungsten and the workpiece for a “one-thousand-one” count to establish the circuit. Rock the cup back to cre-
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Fig. 5 — Tungsten arc welding a pipe joint.
ate a small gap and ignite the arc. Once the arc is established, move the torch to the proper arc length, which is generally the same or slightly less than the diameter of the tungsten. After practicing several starts, operators may find they no longer need to rest the cup on the workpiece.
Brace Yourself Before striking an arc, get into a comfortable position. Brace your body, then practice the moves required for the joint at hand. Notice how Balboni braced his arms on the edge of the table and his hands close to the weldment — Fig. 4.
More Tacks On material prone to warping, such as thin-gauge stainless steel, use additional tacks. Here, the tacks are only about 11⁄2 in. apart.
Angles One of the larger challenges when learning to GTA weld is maintaining the correct angle between the torch and the
workpiece (5 to 15 deg back from the direction of travel) and the angle between the torch and the filler rod (90 deg, or 15 deg off the workpiece) — Fig. 5. Tilting the torch too far back leads to poor shielding gas coverage at the back of the weld pool, inviting contamination. Too steep of a filler rod angle may prematurely melt the filler metal. This photo also shows the gap and bevel used to promote good penetration. Note that in a stainless steel application, the pipe would also be back-purged to promote weld quality.
Head Position In order to read the weld pool, you have to be able to see it clearly. Position your head to the side and/or in front of the arc for maximum visibility — Fig. 6. A common mistake is to move the torch when it blocks your vision, which may then direct the energy of the arc at the wrong spot on the joint.
Adding Filler Metal Do not use the heat of the arc to di-
rectly melt the filler metal. It will form a ball on the end of the rod, drop into the molten weld pool with a splash, and reduce pool control. The preferred technique is to touch the end of the filler rod to the leading edge of the molten pool. The heat of the pool will melt the rod, and capillary action will pull it into the weld pool/joint. When moving forward, move the torch and filler rod in harmony, being sure to keep the end of the rod inside the flow of the shielding gas to prevent contamination.
Advanced Settings Counting Cadence Just like the military counts cadence to teach new soldiers how to march in step, beginners can use the pulsing control functions of an advanced GTAW inverter to develop a rhythm for adding filler rod and moving forward. Generally, 1 pulse/s is a good place to start. Dab the filler metal during the pulse of peak current and slide the torch and filler rod forward during the background current. WELDING JOURNAL
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Fig. 6 — Head position is critical for a clear view of the weld pool.
Pulse to Reduce Heat Stainless steel, thin-gauge metal, and out-of-position GTA welds all benefit from pulsed GTAW. It can reduce heat input by 30% while maintaining good penetration. Here are some general guidelines for setting pulsing parameters: • Peak current: Use the traditional rule of thumb: 1 A for every 0.001 in. of thickness, increase the current as necessary to achieve good penetration. When using a foot control, add 20% more amperage to provide wiggle room at the top end. • Pulse width (technically percentage of time at peak amperage): Between 40 and 65% works well in most applications, using less time on thinner metals. • Pulse frequency: Start at 100 pulses/s and adjust upward from there without 42
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changing any other pulsing variables. Higher frequencies increase penetration and narrow the bead width without increasing total heat input. Many applications benefit from a frequency of 200 pulses/s. • Background current: Start at about one-third of the peak current, adjusting upward to perhaps 45 or 50%, if needed.
Adjusting for Aluminum Increasing AC frequency has the same effect as increasing pulse frequency; it narrows and concentrates the arc cone to create a narrower bead and deeper penetration while increasing travel speed. Following are general guidelines for
setting advanced AC controls for GTAW of aluminum. • Current: Set as normal, using slightly more current for fillet welds than for butt-joint welds. • Frequency: Thinner materials and fillet welds generally benefit from a frequency of 80 to 150 Hz. For butt-joint welds and outside corners where a wider arc cone will help catch both plates, start with a frequency of 80 Hz. • Set the wave balance control, or percentage of electrode positive (which provides cleaning action to remove oxides) to electrode negative (which provides penetration): 30% cleaning action is a good starting point. Black, pepper-like flakes in the weld may be an indication of oxidized aluminum and may require
using the advanced GTAW functions, I hardly ever GTA weld thin steel, stainless steel, or aluminum using standard technology. The advanced functions give me that much more control over the weld process.”
Fig. 7 — Setting the frequency on a typical inverter power supply control panel.
Hold Steady
more cleaning. Before starting to weld aluminum, it’s worth the time to clean it with a stainless steel wire brush or a solvent cleaner specifically used on aluminum. After striking the arc, wait until the weld pool becomes shiny before beginning to add filler metal and moving forward. The shiny surface indicates the aluminum oxides have been removed.
After breaking arc, hold the torch and filler rod in position so that the shielding gas postflow can do its job of protecting the weld, the filler metal, and extending electrode life. For this stainless application, as well as aluminum of similar thickness (1⁄8 in. and greater), set postflow duration between 11 and 13 s. Thicker metals will require more time.
Understanding 4T
More Control
Everyone understands the 2T (“normal”) GTAW controls. If bulletin board chatter is any indication, there is some confusion about 4T, or “latch” control, that operators use to reduce hand fatigue on long welds, or for repeatability. When using 4T, the power source goes through these steps: • Press and hold trigger: Gas preflow, arc initiation, and establishment of initial current. • Release trigger: Current upslope (a measure of time) to the base current. This will be the welding current set for regular welding or the background current for pulsed welding (upon which the power source will automatically enter the pulse mode). • Press and hold trigger: Current downslope (a measure of time) to the crater current. Ramping down the current helps prevent the formation of a crater that could promote cracking. • Release trigger: Arc terminated, gas postflow initiated.
Advanced GTAW power sources, like smartphones, are full of useful functions that many people fail to use — Fig. 7. Balboni was not one of those people. “It takes a little time to learn the controls, but the setup is pretty intuitive once you dive into it,” he said. “Since I started
Editor’s note: Two weeks after the interview for this story, Mike Balboni died in a motorcycle accident. At the request of his family, this article is presented in its original version so his story of building Northeast Welding and Coating Services may inspire others to overcome adversity, pursue their dreams, and start a welding business of their own. After being laid off, Balboni was just one guy working out of the back of his Jeep. With hard work, he eventually grew his business into a 2000-sq-ft shop that created jobs for others as well. His boundless energy helped him meet demanding deadlines, and he drew upon the many skills he acquired as a Navy aircraft mechanic with certifications in electrical, pumps, mechanics, and safety. In short, if it had hydraulics, wheels, wiring, or needed welding, Mike could fix it. He started shop in an old barn, gaining welding skills from a brother-in-law who passed on many valuable lessons and helped him handle the tougher jobs. Even during the depths of the recession, he grew his customer base by never turning down work. No job was too small or too large, and he always offered a reasonable price and excellent service. “We don’t wait for someone else to solve our problems,” Balboni said during the interviews for this article, “and I’m not going to let this economy knock me down. We’ll figure out a way and get the job done.”
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Induction Heating for Stress Relieving Shortens Lead Times
Fig. 1 — As a manufacturer of oil and gas production equipment (like the natural gas separator shown here), Pride of the Hills has grown and evolved with increased production levels, locally and nationwide.
BY JOE RYAN
An oil and gas production equipment manufacturer uses the process to expedite schedules
ride of the Hills Manufacturing, Big Prairie, Ohio, is largely sustained by what is stored thousands of feet beneath those hills: shale gas. Set in the heart of Marcellus and Utica Shale country, the company has grown with the region’s shale gas production boom. As a manufacturer of oil and gas production equipment, it has grown
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and evolved with increased production levels, locally and nationwide — Fig. 1. There was once a time when a good well in the area produced 100,000 ft3 of natural gas per day. A great shale well now produces 60 million ft 3 per day. Pride of the Hills has responded, moving from smaller, low-pressure equipment to the larger, higher-pressure systems it now
JOE RYAN is a market segment manager for process pipe welding with Miller Electric Mfg. Co. (www.millerwelds.com), Appleton, Wis.
takes to operate a shale gas well. With increased production comes an expedited demand for Pride of the Hills’ products: production equipment that sits at the well head, separates the oil, gas, and water, and turns them into salable products. These systems are complicated networks of pressure vessels and highpressure piping. As the company looked
small footprint in its manufacturing facility.
Managing High Pressures The gas stream comes out of a shale gas well at between 3000 and 6000 lb of pressure. The stream then passes through a sand separator rated between 5000 and 6000 lb, allowing the solids to settle out of the oil, water, and gas stream. That stream is then depressurized, which causes rapid cooling, dropping the temperature by as much as 150 deg. The stream is then reheated and brought back through the separator, removing the fluids and sending the natural gas down the line. Pride of the Hills also designs systems that can take the bulk liquid remains and turn the oil into a stable, salable product. “Our challenges are that we’re dealing with high pressures, high volumes of dirty product that we have to clean, regulate, produce safely, monitor, and put down into a sales line into a place where it can be used for your home or my factory or trucked off someplace,” said Curt Murray Jr., vice president of Pride of the Hills Manufacturing and president/ founder of Grace Automation.
Adhering to Regulations
for new ways to shorten product lead times, one focus became the stress relieving process for large pressure vessels. The current practice involved shipping the vessels 2 h away to an oven in Cleveland. This added significant time challenges, scheduling, and hard costs associated with trucking. In searching for new ways to conduct stress relieving, Pride of the Hills was introduced to induction heating, a process that generates heat electromagnetically in the part — Fig. 2. The company was able to take several days out of total product development and limit these challenges by bringing the process in house all while taking up a relatively
Pride of the Hills’ products are extensively regulated due to the volatility of the oil and gas extraction process. Piping is typically constructed of an A/SA106 Grade B or C carbon steel, while pressure vessels are typically built of SA516 Grade 70 material. The company’s work is regulated under numerous codes from the American Petroleum Institute (API); B31.3 along with Section VIII Division 1 of the American Society of Mechanical Engineers (ASME); as well as the strict requirements of each customer.
Welding the Pressure Vessel A key component of the systems it manufactures is the sand separator, which is a pressure vessel that ranges in thickness from 11⁄2 to 4 in., depending on the model. The vessel is welded with a root pass and two hot passes. This is done
to build up the root with enough material to support a submerged arc, or subarc, welding process that completes the rest of the joint. The subarc process takes approximately 8 h, as a dual-headed system welds both heads simultaneously.
Stress Relieving with Induction Heating Cuts out the Middleman Under the guidelines of ASME Section VIII Division 1, any pressure vessel exceeding 11⁄2 in. in thickness is required to undergo postweld stress relief. Depending on the vessel’s thickness, this typically involves ramping up its temperature to approximately 1150°F. “When we’re putting four inches of weld (into a very large gap), that puts a lot of stresses into the weld, which puts undue stress on the material,” said Murray. “So we’re going up to 1150 degrees, which allows for stress relieving. We’re not baking anything out or going high enough in temperature to change grain structure. We’re just relieving stresses that were put into the part.” “Our choices were to ship that product out to a third party that has an oven able to do the work,” said Murray. “In Northern Ohio, there are only a couple of places that have the ability to do that. One of the first things we started looking at was just how can we do this process in house?”
Implementing the Process The company began looking at ovens of their own, until they were introduced to the Miller ProHeat™ 35 induction heating system. With an induction heating system, heat is created electromagnetically in the part by placing it in an alternating magnetic field created by liquid-cooled induction heating cables. The induction cables are wrapped around the part, or on the part, and do not heat up themselves, but create eddy currents inside the part that generate heat. “We’re able to basically pinpoint the heat where it’s needed and not waste energy heating the rest of the vessel,” said Murray. “These vessels weigh anywhere from 5000 up to 10,000 pounds. The oven technology forces us to heat the whole vessel where the induction heating prod-
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uct can just pinpoint that to those areas. So we decided to buy the product, bring it in, and start implementing it. It saved us a tremendous amount of time in just trucking and handling the product.” He added the biggest thing is having control over their own product and the process doing the stress relief. “With the recorder on it and the way we set up…it’s particularly easy to meet the ASME code requirements. It’s been a big advantage,” said Murray. Induction heating gives Pride of the Hills control to ramp up the temperature as fast or as slow as dictated by the code. Similarly, after spending the prescribed amount of time at its soak temperature, the system can ramp down the temperature to code requirements. This overall process can last 5 to 12 h, depending on the thickness of the vessel. Having that control, and being able to document the entire process through a digital recorder, is important to the quality control process and, ultimately, in documenting to the customer that the part was fabricated properly. “Our quality control department looks at it and then our authorized inspector looks at it, and then — as on all of our equipment — we send our customer an as-built document (that includes these data),” said Murray.
Ending Thoughts While quality is paramount, the ability to do it all in house and not rely on third-party vendors has helped to noticeably shorten lead times. Aside from the 6 h of trucking and handling previously associated with getting a vessel to the oven, Murray also took into account the labor, diesel fuel, truck wear and tear, and being at the mercy of the oven owner’s schedule, which could add considerable downtime to the process. All together, it added up to a smart change. “We were literally able to cut at least a couple of days (out of the process),” concluded Murray.◆
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Fig. 2 — Pride of the Hills was able to take numerous days out of total product development, while taking up a relatively small footprint in its manufacturing facility, by using induction heating.
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Automated Welding Applied in Deep-Water Pipelines A system that utilized two automated carriages and two guns was used for gas metal arc welding pipe to API standards
n the past few decades, interest in deepwater oil and gas exploration has received increased attention. China intends to explore resources in the South China Sea, and in order to lay oil and gas pipelines, a variety of high-quality and efficient welding technologies have been developed that use the gas metal arc welding (GMAW) process, which is currently widely used in industrial applications (Ref. 1). Besides pipeline laying, automated welding also can be applied in some other offshore operations, such as the J-type laying in the welding installation of steel catenary risers (SCR) (Ref. 2). Semiautomatic welding technology was introduced to China in laying subsea pipelines in the 1990s. Gradually, more advanced welding technologies were used in offshore industries (Ref. 3). As part of a major research program supported by the Chinese government, subsea pipeline welding was investigated (Refs. 4, 5). In this study, automatic welding equipment used in deepwater pipeline laying was manufactured, a series of girth welds, which satisfy requirements of API STD 1104, were produced, and a sea trial was successfully carried out.
I
BY JIAO XIANG-DONG, ZHOU CAN-FENG, CHEN JIA-QING, JI WENG-GANG, LI ZHI-GANG, ZHAO DONG-YAN, AND CAO JUN
Development of Automatic Welding Equipment General Design of Automatic Welding Equipment For subsea S-type pipeline laying, several welding stations are distributed along the main laying line to complete the root pass, fill passes, and cap pass sequentially. As shown in Fig. 1, each welding station is comprised of two automatic welding machines with dual welding guns. Two welding vehicles were arranged on both sides of the pipe, installed on the same rail, and moved from
the top of the pipe to the bottom, each of which finished welding a half segment, respectively. The automatic welding vehicle depicted in Fig. 2 has two torches with a space of about 50 mm. Two weld pools are formed during the welding process. Compared to single gun welding, double gun welding can significantly increase the metal deposition rate.
Automatic Welding Vehicle The welding vehicle is comprised of mechanisms locking travel, torch oscillation, and welding torch height adjustment; a chassis; and torch components. Different from pipelines on land, sub-
Welding Vehicle
Circular Guide
Fig. 1 — Schematics of equipment for each welding station.
Fig. 2 — The automatic welding vehicle.
JIAO XIANG-DONG, ZHOU CAN-FENG (
[email protected]), CHEN JIA-QING, and JI WENG-GANG are with Beijing Higher Institution Engineering Research Center of Energy Engineering Advanced Joining Technology, Beijing Institute of Petrochemical Technology, Beijing, China. LI ZHI-GANG, ZHAO DONG-YAN, and CAO JUN are with Offshore Oil Engineering Co., Ltd., Tianjin, China. This article is reprinted with permission from Modern Welding, published by Chengdu ONLY Welding Industry Development Co. Ltd., Chengdu, Sichuan Province, China. 48
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required by welding movements. The integration of drive and motor reduced the number of connection cables in the system. A tilt sensor installed on the vehicle captured the welding position of the vehicle on the rail, and transfered welding position data to the drive directly. The intelligent drive can finish computation independently and transfer computation results to the main controller via the CAN bus. The main controller sends commands to the welding power Fig. 3 — The block diagram of an automatic welding source, which can adaptively adjust the welding equipment control system. current according to welding position. sea pipelines have a thick concrete to in3) CAN-open bus technology. The concrease weight in the water. To ensure the trol system utilizes a CAN-open bus, efficiency and control the cost of laying which reduces the connection cables and the pipeline, the length of pipe end where increases the expansibility of the weldthe concrete is removed must be strictly ing system. controlled. Thus, the size of the welding vehicle is limited to 370 mm (length) × Welding Process 285 mm (width) × 175 mm (height). The Specification weight of the vehicle is also controlled to less than 16 kg, which can reduce physical labor during the pipeline laying.
4 deg groove angle, root face of 2 mm, and no joint clearance between the two ends. The welding wire selected was AWS A5.18 ER70S-6 with a diameter of 1.0 mm. The shielding gas was a mix of CO2 50% + Ar 50%. The internal clamp was used to align the two pipe ends, which controlled alignment within tolerance. The groove and nearby areas were preheated by induction heating before the welding process began. Each dual gun vehicle welded a half segment of the pipe, and a completed joint weld was made up of one root pass, two fill passes, and one cap pass. The TPS4000 welding power source has a control where if the wire feed speed is set, then the welding current and welding voltage are automatically matched. Half of the circumference of the pipe is divided into 12 segments on average from top to bottom. Adaptive welding parameters are set at different segments of the pipe. Welding parameters consist of welding speed, wire feed speed, and welding gun oscillation. For example, the welding speed for the root was 109–113 cm/min, the wire feed speed for the first welding gun was 11.8–13 m/min, and the wire feed speed for the second welding gun was 10–11.2 m/min. The welding gun oscillating speed was 80–110 cm/min, with a width of 1.6 mm, and the dwelling time on both sides was 0.1 s.
Control System Design
Performance of the Pipe Girth Welds
The block diagram of the automated welding control system is illustrated in Fig. 3. An industrial PC is used as the main controller of the system. All connections between the main controller and peripheral devices, such as drive motors for vehicle propulsion and welding power source, are realized via CAN bus, which can transfer data from the welding equipment to a supervisory computer through the Ethernet network. Compared to most automatic welding control systems designed on I/O, this control system has several advantages as follows: 1) Synchronization of two travel servo motors. To save space for the welding vehicle, two small servo motors were selected to replace a big servo motor to drive the vehicle on a round rail. The synchronization of the two motors was achieved through a synchronizing control program. 2) Vehicle computation. Four drives with high intelligence are integrated into the vehicle to propel four servo motors
General Scheme for Welding Efficiency
The basic requirement of welding in subsea pipeline laying is that the efficiency be as high as possible to ensure weld quality. The use of two welding vehicles and two welding guns for root, fill, and cover passes increases welding efficiency. A set of copper liners is specifically designed to integrate with the internal clamp, which gives backing support during root welding, and allows a high current needed for complete joint penetration to be selected. The high current for the root pass also improves metal deposition. A narrow groove with the bevel angle of 4–5 deg is machined to replace the traditional V-groove, which reduces weld metal for the fill passes, increasing production efficiency.
The pipe girth welds satisfied the requirements of API STD 1104-2005, which includes visual, ultrasonic, and mechanical testing. The weld tensile strength was 550–570 N/mm2. After surface bending, lateral bending, and root bending, the weld surfaces showed no visible defects. The average impact energy was 150–376 J at –20°C.
Automatic Girth Welding of Subsea Pipeline The test pipes were API 5L X65 seamless steel pipes with an outside diameter of 323.9 mm, wall thickness of 12.7 mm,
Fig. 4 — The sea trial ship BH108.
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Fig. 5 — (Left) The sea trials with automatic welding equipment installed on BH108.
Fig. 6 — (Right) Welded joints performed during sea trials.
Test at the Construction Site before Sea Trials
were produced and tested successfully by ultrasonic inspection — Figs. 5, 6.
The automatic welding equipment was tested at the fabricating facility of Offshore Oil Engineering Co., Ltd., before the sea trial was carried out. The pipe girth welds passed the ultrasound examination successfully.
Summary
Environment of Sea Trial The sea trial for the automatic welding equipment was conducted at Tanggu, Bohai Bay, with coordinates of 38 deg 59 min latitude and 117 deg 43 min longitude. The wind was coming from the NW at a speed of 8 m/s. The automatic welding equipment was arranged in a temporary work shed on the sea trial ship BH108 — Fig. 4. The ship was anchored in water at a depth of 5 m, with a flow velocity of 17 cm/s, and temperature of –6°C.
The Process for the Sea Trials The welding sea trials were carried out according to the plan. Four girth welds
In this investigation, automatic pipeline welding equipment was manufactured and welding parameters were developed. Several conclusions are drawn as follows: 1) The two vehicle, two gun technology utilized in the welding workstation significantly reduces the cost of offshore welding operations. 2) The welding vehicle was compact and light weight, which helps meet special requirements for subsea pipeline laying. 3) Several advanced technologies were adopted in the control system of the automatic welding equipment, such as synchronization of two traveling motors, vehicle computation, and all-position welding. 4) The control system was designed based on CAN-bus technology, which not only reduces the connection cables, but also makes the welding system more flexible. 5) Copper liners for the root welding
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ensured good weld backing and a high welding efficiency. 6) A specially designed narrow groove improved welding efficiency and reduced the amount of weld metal needed. 7) The joint was completed with a root pass, two fill passes, and one cap pass. Welding parameters were set depending on the different positions of the welding vehicle, which were measured by a tilt sensor installed on the vehicle. 8) Pipe girth welds produced by the dual vehicle, dual welding gun equipment met all requirements of API STD 11042005, such as visual, ultrasonic, and mechanical performance testing. 9) After the experiment in the laboratory and before the sea trial, the automatic welding equipment was tested successfully in a fabricating plant. 10) The welding sea trials were successfully carried out in the China Sea, and all girth welds were tested by ultrasonic inspection.◆
References 1. Yapp, D., and Blackman, S. A. 2004. Recent developments in high productivity pipeline welding. Journal of the Brazilian Society of Mechanical Sciences and Engineering XXVI(1): 89–97. 2. Graaf, J.van der, Wolbers, D., and Boerkamp, P. Field experience with the construction of large diameter SCR in deep water. Offshore Technology Conference, OTC 17524, Houston, Tex. 3. Xiao-jun, Liu. 2003. Submarine pipeline and welding technology in our country. Shipbuilding of China 44: 65–70. 4. Jing Xi-zhao, Cao Jun, Zhou Canfeng, et al. 2010. Study on welding procedure and equipment applied in subsea pipeline laying. Ship and Ocean Engineering (3): 128–132. 5. Zhou Can-feng, Jiao Xiang-dong, Chen Jia-qing, et al. 2010. Design of welding system applied in deepwater subsea pipeline laying. Welding and Joining (7): 16–20.
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COMING EVENTS
NOTE: A DIAMOND ( ♦) DENOTES AN AWS-SPONSORED EVENT.
♦Codes and Standards Conf. July 16, 17. Orlando, Fla. To include AWS D1, Structural Welding Code — Steel, ASME Boiler and Pressure Vessel Code, API pipeline codes, MIL specs, and ISO standards. Sponsored by the American Welding Society (800/305) 443-9353, ext. 264; www.aws.org/conferences. Laser Technology Days. July 24, 25. Mazak Optonics Corp., Elgin, Ill. Seminars and demonstrations. Call (847) 252-4500. Register at www.mazakoptonics.com/td13.html. 59th Annual UA Assn. of Journeymen and Apprentices of the Plumbing and Pipefitting Industry’s Instructor Training Program. Aug. 11–17, Washtenaw Community College, Ann Arbor, Mich. www.visitannarbor.org/news/detail/ann-arbor-welcomes-the59th-annual-united-association-instructor-training-p. Int’l Conf. on Solar Energy Materials and Energy Engineering (SEMEE2013). Sept. 1, 2. Hong Kong. www.semme-conf.org.
♦16th Annual Aluminum Conf. Sept. 4, 5. Chicago, Ill. Sponsored by the American Welding Society (800/305) 443-9353, ext. 264; www.aws.org/conferences. 12th Int’l Conf. on Application of Contemporary Non-Destructive Testing in Engineering. Sept. 4–6. Grand Hotel Metropol, Portoroz, Slovenia. Sponsored by The Slovenian Society for Non-Destructive Testing. www.fs.uni-lj.si/ndt.
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LPPDE-North America. Sept. 9–11. Savannah, Ga. Lean Product & Process Development Exchange, Inc. Address e-mail to
[email protected]. Lasers for Manufacturing Event® (LME 2013). Sept. 11, 12. Schaumburg Convention Center, Schaumburg, Ill. Laser Institute of America. www.laserevent.org;
[email protected]. 66th IIW Annual Assembly. Sept. 11–17. Essen, Germany. Organized by DVS (German Welding Society). www.dvsev.de/IIW2013/. GAWDA Annual Convention. Sept. 15–18. Orlando, Fla. Gases and Welding Distributors Assn. www.gawda.org. ASM Heat Treating Society Conf. and Expo. Sept. 16–18. Indiana Convention Center, Indianapolis, Ind. www.asminternational.org/ content/Events/heattreat/. IIW Int’l Conf. on “Automation in Welding.” Sept. 16, 17. Essen, Germany. www.iiw2013.com. Event in the IIW Annual Assembly. Schweissen & Schneiden 2013 Int’l Trade Fair — Joining, Cutting, Surfacing. Sept. 16–21. Essen, Germany. Sponsored by DVS, German Welding Society. www.schweissenuschneiden.de/en/schweissen_schneiden/index.html.
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9th Annual Northeast Shingo Prize Conf. Sept. 24, 25. The Resort & Conference Center at Hyannis, Hyannis, Mass. www.neshingoprize.org. POWER-GEN Brasil 2013, HydroVision Brasil, and DistribuTech Brasil. Sept. 24–26. Transamerica Center, São Paulo, Brazil. www.power-gen.com. Canadian Manufacturing Technology Show (CMTS) 2013. Sept. 30–Oct. 3. The International Centre, 6900 Airport Rd., Mississauga, Canada. Society of Manufacturing Engineers. (888) 3227333, ext. 4426; www.cmts.ca. Brazil Welding Show 2013. Oct. 1–4. São Paulo, Brazil. Sponsored by DVS, German Welding Society. www.brazil-welding-show.com/. National Manufacturing Day. Oct. 4. Events held nationwide. Sponsored by Fabricators & Manufacturers Assn. To find events planned near you, visit www.mfgday.com for interactive map. ICALEO — Int’l Congress on Applications of Lasers & ElectroOptics. Oct. 6–10, Hyatt Regendy Miami® Resort, Miami, Fla. www.lia.org/conferences/icaleo. The Int’l WorkBoat Show. Oct. 9–11, Morial Convention Center, New Orleans, La. www.workboatshow.com. WESTEC. Oct. 15–17. Los Angeles Convention Center, Los Angeles, Calif. The Society of Manufacturing Engineers. (800) 7334763; www.westeconline.com. Canadian Int’l Aluminum Conf. Oct. 21–25, Palais des Congrès de Montréal, Montreal, Que., Canada. www.ciacmontreal.com. For info go to www.aws.org/ad-index
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WELDING JOURNAL
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12th Inalco Int’l Aluminum Conf. Oct. 21, 22, Palais des Congrès de Montréal, Montreal, Que., Canada. www.inalco2013.com. FFA Annual Convention. Oct. 30–Nov. 3, Kentucky Exposition Center, Louisville, Ky. Future Farmers of America. www.ffa.org/Pages/default.aspx. ASNT Fall Conf. and Quality Testing Show 2013. Nov. 4–7, Rio Hotel, Las Vegas, Nev. The American Society for Nondestructive Testing. www.asnt.org. POWER-GEN Int’l Event. Nov. 12–14, Orange County Convention Center, Orlando, Fla. www.power-gen.com/event-info.html.
♦FABTECH 2013. Nov. 18–21, McCormick Place, Chicago, Ill. This exhibition is the largest event in North America dedicated to showcasing the full spectrum of metal forming, fabricating, tube and pipe, welding equipment, and myriad manufacturing technologies. American Welding Society. (800/305) 443-9353, ext. 264; www.fabtechexpo.com. ♦5th Thermal Spray Technology: High-Performance Surfaces. Nov. 19. McCormick Place, Chicago, Ill. Sponsored by Int’l Thermal Spray Assn., an AWS Standing Committee.
[email protected]. American Welding Society. (800/305) 443-9353, ext. 264; www.fabtechexpo.com.
♦FABTECH India colocated with Weld India. April 10–12, 2014, Pragati Maidan Exhibition Complex, New Delhi, India. Concurrent with the 2014 Int’l Congress of the IIW. Cosponsored by AWS, FMA, SME, PMA, CCAI, and India Institute of Welding. www.fabtechexpoindia.com.
Educational Opportunities Fundamentals of Welding Engineering. Aug. 5–9, EWI, Columbus, Ohio. www.ewi.org/events;
[email protected]. Laser Welding and Equipment Fundamentals. Sept. 19, EWI, Columbus, Ohio. www.ewi.org/events;
[email protected]. Aluminum Welding Technology School. Oct. 1–3, AlcoTec, Traverse City, Mich. For brochure and to register, visit www.alcotec.com/us/en/education/Training-Alcotec.cfm. Brazing School — Fundamentals to Advanced Concepts. Oct. 22–24 (Greenville, S.C.); Nov. 19–21 (Simsbury, Conn.). www.kaybrazing.com/seminars.htm;
[email protected]; (860) 651-5595. CWI Preparation Courses. Aug. 19–23, Nov. 11–15. D1.1 Endorsement: Aug. 23, Nov. 15; D1.5 Endorsement: Aug. 16; API Endorsement: Nov. 8. All courses and endorsements held at Welder Training & Testing Institute, 1144 N. Graham St., Allentown, Pa. www.wtti.com; (610) 820-9551, ext. 204. Fundamentals of Welding Engineering. Aug. 5–9, EWI, Columbus, Ohio. www.ewi.org/events;
[email protected]. Grounding and Electrical Protection Courses. Aug. 15, 16, Chantilly, Va.; Oct. 17, 18, Albuquerque, N.Mex. Lyncole XIT Grounding, www.lyncole.com/courses;
[email protected]. Introduction to Friction Stir Welding. Nov. 6, EWI, Columbus, Ohio. www.ewi.org/events;
[email protected]. Laser Vision Seminars. Aug. 28, 29; Oct. 2, 3; Nov. 6, 7; Dec. 4, 5. Servo-Robot, Inc. www.servorobot.com. Laser Welding and Equipment Fundamentals. Sept. 19, EWI, Columbus, Ohio. www.ewi.org/events;
[email protected]. ASM Int’l Courses. Numerous classes on welding, corrosion, failure analysis, metallography, heat treating, etc., presented in Materials Park, Ohio, online, webinars, on-site, videos, and DVDs; www.asminternational.org, search for “courses.” Automotive Body in White Training for Skilled Trades and Engineers. Orion, Mich. A five-day course covers operations, troubleshooting, error recovery programs, and safety procedures for automotive lines and integrated cells. Applied Mfg. Technologies; (248) 409-2000; www.appliedmfg.com. Basic and Advanced Welding Courses. Cleveland, Ohio. The Lincoln Electric Co.; www.lincolnelectric.com. Basics of Nonferrous Surface Preparation. Online course, six hours includes exam. Offered on the 15th of every month by The Society for Protective Coatings. Register at www.sspc.org/training. Best Practices for High-Strength Steel Repairs. I-CAR courses for vehicle repair and steel structural technicians. www.i-car.com. Boiler and Pressure Vessel Inspectors Training Courses and Seminars. Columbus, Ohio; (614) 888-8320; www.nationalboard.org. Canadian Welding Bureau Courses. Welding inspection courses and preparation courses for Canadian General Standards Board and Canadian Nuclear Safety Commission certifications. The CWB Group, www.cwbgroup.org.◆
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CERTIFICATION SCHEDULE Certified Welding Inspector (CWI) LOCATION SEMINAR DATES Chicago, IL Aug. 4–9 Baton Rouge, LA Aug. 4–9 Portland, ME Aug. 4–9 Las Vegas, NV Aug. 4–9 Mobile, AL Aug. 11–16 Charlotte, NC Aug. 11–16 Rochester, NY Exam only San Antonio, TX Aug. 11–16 Seattle, WA Aug. 11–16 San Diego, CA Aug. 18–23 Minneapolis, MN Aug. 18–23 Salt Lake City, UT Aug. 18–23 Anchorage, AK Exam only Miami, FL Sept. 15–20 Idaho Falls, ID Sept. 15–20 St. Louis, MO Sept. 15–20 Houston, TX Sept. 15–20 New Orleans, LA Sept. 22–27 Fargo, ND Sept. 22–27 Pittsburgh, PA Sept. 22–27 Indianapolis, IN Sept. 29−Oct. 4 Corpus Christi, TX Exam only Long Beach, CA Oct. 6–11 Tulsa, OK Oct. 6–11 Cedar Rapids, IA Oct. 6–11 Miami, FL Exam only South Plainfield, NJ Oct. 13–18 Portland, OR Oct. 13–18 Nashville, TN Oct. 13–18 Atlanta, GA Oct. 20–25 Shreveport, LA Oct. 20–25 Detroit, MI Oct. 20–25 Roanoke, VA Oct. 20–25 Cleveland, OH Oct. 27–Nov. 1 Spokane, WA Oct. 27–Nov. 1 Sacramento, CA Nov. 3–8 Corpus Christi, TX Exam only Miami, FL Nov. 10–15 Anapolis, MD Nov. 10–15 Dallas, TX Nov. 10–15 Chicago, IL Exam only Miami, FL Exam only Los Angeles, CA Dec. 8–13 Orlando, FL Dec. 8–13 Reno, NV Dec. 8–13 Houston, TX Dec. 8–13 St. Louis, MO Exam only
Certification Seminars, Code Clinics, and Examinations
EXAM DATE Aug. 10 Aug. 10 Aug. 10 Aug. 10 Aug. 17 Aug. 17 Aug. 17 Aug. 17 Aug. 17 Aug. 24 Aug. 24 Aug. 24 Sept. 21 Sept. 21 Sept. 21 Sept. 21 Sept. 21 Sept. 28 Sept. 28 Sept. 28 Oct. 5 Oct. 12 Oct. 12 Oct. 12 Oct. 12 Oct. 17 Oct. 19 Oct. 19 Oct. 19 Oct. 26 Oct. 26 Oct. 26 Oct. 26 Nov. 2 Nov. 2 Nov. 9 Nov. 16 Nov. 16 Nov. 16 Nov. 16 Nov. 21 Dec. 5 Dec. 14 Dec. 14 Dec. 14 Dec. 14 Dec. 14
Certified Welding Engineer; Senior Certified Welding Inspector Exams can be taken at any site listed under Certified Welding Inspector. No preparatory seminar is offered.
9-Year Recertification Seminar for CWI/SCWI (No exams given.) For current CWIs and SCWIs needing to meet education requirements without taking the exam. The exam can be taken at any site listed under Certified Welding Inspector. LOCATION SEMINAR DATES Orlando, FL Aug. 18–23 Denver, CO Sept. 15–20 Dallas, TX Oct. 6–11 New Orleans, LA Oct. 27–Nov. 1 Seattle, WA Nov. 3–8 Miami, FL Dec. 8–13 Certified Welding Supervisor (CWS) LOCATION SEMINAR DATES Miami, FL Sept. 23–27 Norfolk, VA Oct. 14–18 CWS exams are also given at all CWI exam sites.
EXAM DATE Sept. 28 Oct. 19
Certified Radiographic Interpreter (CRI) LOCATION SEMINAR DATES EXAM DATE Dallas, TX Aug. 19–23 Aug. 24 Chicago, IL Sept. 23–27 Sept. 28 Pittsburgh, PA Oct. 14–18 Oct. 19 The CRI certification can be a stand-alone credential or can exempt you from your next 9-Year Recertification. Certified Welding Sales Representative (CWSR) CWSR exams will be given at CWI exam sites. Certified Welding Educator (CWE) Seminar and exam are given at all sites listed under Certified Welding Inspector. Seminar attendees will not attend the Code Clinic portion of the seminar (usually the first two days). Certified Robotic Arc Welding (CRAW) The course dates are followed by the location and phone number Dec. 9–13 at ABB, Inc., Auburn Hills, MI; (248) 391–8421 Aug. 19–23, Dec. 2–6 at Genesis-Systems Group, Davenport, IA; (563) 445-5688 Oct. 14 at Lincoln Electric Co., Cleveland, OH; (216) 383-8542 July 15–19, Oct. 21–25 at OTC Daihen, Inc., Tipp City, OH; (937) 667-0800 Training: July 22–24, Sept. 23–25, Nov. 18–20 Exams: July 25–26, Sept. 26–27, Nov. 21–22 at Wolf Robotics, Fort Collins, CO; (970) 225-7736 On request at MATC, Milwaukee, WI; (414) 297-6996
International CWI Courses and Exams Schedules Please visit www.aws.org/certification/inter_contact.html. IMPORTANT: This schedule is subject to change without notice. Applications are to be received at least six weeks prior to the seminar/exam or exam. Applications received after that time will be assessed a $250 Fast Track fee. Please verify application deadline dates by visiting our website www.aws.org/certification/docs/schedules.html. Verify your event dates with the Certification Dept. to confirm your course status before making travel plans. For information on AWS seminars and certification programs, or to register online, visit www.aws.org/certification or call (800/305) 443-9353, ext. 273, for Certification; or ext. 455 for Seminars. Apply early to avoid paying the $250 Fast Track fee.
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CONFERENCES Codes and Standards Conference July 16, 17 Orlando, Fla. For the first time, the American Welding Society is holding a conference on Codes and Standards. The timing is right for this long-awaited conference, based on the important changes that are taking place throughout the broad range of codes and standards. Leading the group of 16 speakers will be Rich Campbell of Bechtel who will discuss the changes in both AWS D1.1, Structural Welding Code — Steel, and D1.6, Structural Welding Code — Stainless Steel. Thom Burns from AlcoTec will cover the activity within D1.2, Structural Welding Code — Aluminum. About half of the presentations will be on AWS codes and standards. Walt Sperko’s presentation, Section IX of the ASME Code — New and Improved, will be the first of several talks concerning the ASME code, and Matt Boring will provide an update on the API 1104 Code. Paul Blomquist, the on-site chairman of the conference, will discuss Qualification of Hybrid Laser Arc Welding — How Do We Get There. David Bolser of the Boeing Co. will provide updates on a variety of standards, including AWS D17.3, Specification for Friction Stir Welding of Aluminum Alloys for Aerospace Applications. Other presentations will cover such topics as robot safety, the Tip Tig process, standards for the newer NDE technologies, a repair document from the National Board of Boiler and Pressure Vessel Inspectors, and a revision to AWS A5.32, Welding Consumables — Gases and Gas Mixtures for Fusion Welding and Allied Processes.
16th Annual Aluminum Conference September 17, 18 Chicago, Ill. A distinguished panel of industry experts will survey the state of the art in aluminum welding technology and practice. Attendees will have several opportunities to network informally with speakers and other participants, as well as visit an exhibition showcasing products and services available to the aluminum welding industry. Aluminum lends itself to a wide variety of industrial applications because of its light weight, high strength-to-weight ratio, corrosion resistance, and other attributes. However, because its chemical and physical properties are different from those of steel, welding of aluminum requires special processes, techniques, and expertise.
Welding Dissimilar Metals Conference November 18 FABTECH 2013, Chicago, Ill. Trying to figure out how to weld those various combinations of dissimilar metals has been described as welding’s severest challenge. Sometimes a new or existing process will do it. Other times, one of a handful of filler metals or even one of many transition joints will provide the answer. Whether it’s stainless steel to carbon steel or steel to aluminum, there’s a solution somewhere. The conference will be guided by a hand-picked group of knowledgeable welding metallurgists. ◆ For more information, please contact the AWS Conferences and Seminars Business Unit at (800) 443-9353, ext. 223, or e-mail
[email protected]. You can also visit the Conference Department Web site at www.aws.org/conferences for upcoming conferences and registration information.
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WELDING WORKBOOK
Datasheet 341
Postweld Heat Treatment of Welds in Piping and Tubing In the manufacture, field fabrication, and/or repair of piping and tubing, it may be necessary to heat components before welding (bake-out or preheating), between passes (interpass heating), or after welding (postheating or postweld heat treatment). Table 1 compares processes used for localized heating. This column concentrates on local postweld heat treatment (PWHT). Code requirements and/or concerns regarding the service environment drive the need for PWHT. Generally, so-called “code required” PWHT is aimed at improving resistance to brittle fracture. To accomplish this, PWHT attempts to improve notch toughness and relax residual stress. When service requirements dictate the need for PWHT, additional objectives such as hardness reduction and/or stress relaxation aimed to be below a specific threshold level become important, depending on the environment. Postheating encompasses all heating performed after welding has been stopped — this can be after completion and at an intermediate point — including PWHT. However, it is generally recognized that postheating is performed at a lower temperature, generally 300°–600°F (149°–316°C) vs. 1000°–1400°F (538°–760°C) for PWHT, and with a different primary objective than PWHT. The primary objective of postheating is removal of hydrogen and prevention of hydrogen-induced cracking (also known as delayed cracking since it can occur up to 48 h after the weldment has cooled to ambient temperature). As with postheating, PWHT may need to be applied without allowing the temperature to drop below the minimum for preheat/interpass. Local PWHT of carbon and low-alloy steels is typically performed below the lower critical transformation temperature and is therefore referred to as subcritical. The lower and upper critical transformation temperatures indicate where the crystal structure of steel begins and finally completes a change from bodycentered cubic to face-centered cubic upon heating (the reverse upon cooling).
There are several reasons why local supercritical PWHT (above the upper critical transformation temperature) such as annealing or normalizing is undesirable. First, the temperature gradients inherent to local PWHT would produce subcritical, intercritical, and supercritical temperature regions. Depending on the prior heat treatment of the material, this could result in a detrimental effect on properties such as tensile/yield strength and impact toughness, and/or local inhomogeneity. Also, reduced material strength at supercritical temperatures creates a greater likelihood of distortion. For reasons related to carbide precipitation and the need for rapid cooling, localized solution anneal of austenitic alloys such as 300 series stainless steels is also generally undesirable. Postweld heat treatment can have both beneficial and detrimental effects. The primary benefits of PWHT are tempering, relaxation of residual stress, and hydrogen removal. Avoidance of hydrogen-induced cracking, dimensional stability, and improved ductility, toughness, and corrosion resistance are consequences of the primary benefits. It is important that PWHT conditions be determined based upon the desired objectives. Excessive or inappropriate PWHT temperatures and/or long holding times can adversely affect properties. These adverse effects can include reduced tensile strength, creep strength, and notch toughness (generally caused by embrittlement due to precipitate formation). The influence of PWHT on properties primarily depends upon the composition of the weld metal and base metal, and prior thermal and mechanical processing of the base metal. The need for PWHT is usually driven by either a direct requirement with a particular fabrication or repair code, or by service environment concerns. Within the fabrication codes, material type and thickness generally trigger the requirements to apply PWHT. Such code-required PWHT is generally aimed at reducing susceptibility to brittle fracture.♦
Table 1 — Comparison of Heating Processes Attribute
Induction
Applicability to Bake-out Yes Applicability to Preheat/Interpass Yes Applicability to Postheating Yes Applicability to PWHT Yes Main Advantages A, B Main Disadvantages G, H, I
Electric Resistance
Flame
Exothermic
Gas Infrared
Quartz Infrared
Yes Yes Yes Yes C, D J
Limited Yes Limited No E, F K
Very Limited No Very Limited Very Limited E, F L, M, N
Yes Limited Yes Yes A, F G, I, O
Yes Limited Yes Yes A, F G, I, O, P
Key to Advantages A = high heating rates; B = ability to heat a narrow band adjacent to a region that has temperature restrictions; C = ability to continuously maintain heat from welding operation to PWHT; D = good ability to vary heat around the circumference; E = low initial equipment cost; F = good portability and ease of setup. Key to Disadvantages G = high initial equipment cost; H = equipment large and less portable; I = limited ability to create control zones around the circumference; J = elements may burn out or arc during heating; K = minimal precision, repeatability, and temperature uniformity; L = no adjustment possible once started; M = limited ability to vary heating rate, hold time, and cooling rate; N = available systems currently limited to one weld configuration; O = separate equipment required for each diameter; P = equipment is fragile and sensitive to rough handling.
Excerpted from D10.10/D10.10M:2009, Recommended Practices for Local Heating of Welds in Piping and Tubing. 60
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A 360º VIEW OF THE MOST INNOVATIVE TECHNOLOGY AND PROCESSES. FABTECH 2013.
METAL FORMING | FABRICATING | WELDING | FINISHING FABTECH represents every step of the metal manufacturing process from start to finish. It’s where new ideas, products and technology are highlighted through interactive exhibits, education and networking. Compare solutions from 1,500+ exhibitors, find tools to improve quality and productivity, and learn ways to increase profit. REGISTER NOW for the show with a degree of difference.
November 18–21, 2013 | Chicago, IL | fabtechexpo.com
North America’s Largest Metal Forming, Fabricating, Welding and Finishing Event
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16
ANNUAL ANN UAL
CONFERENCE CONF FERENCE
September September 4 4 – 5, 2013 / Chicago
A dis distinguished panel of aluminum-industry experts will survey the state of the art in aluminum welding technology and practice. The 16th Aluminum Welding Welding Conference will also provide several opportunities for you to network informally with speakers and other participants, and to visit an exhibition showcasing products and services available to the aluminum welding industr industry. y. Aluminum lends itself to a wide variety of industrial applications because of its light weight, high strength-to-weight ratio, corrosion resistance, and other attributes. Howeve However, r, because its chemical and physical properties are di different fferent f from those of steel, st welding of aluminum requires special processes, techniques and expertise.
Register Re egister early and a save. save. Visit www.aws.org/conferences w.aws.org/conferences .aws.org/confere . Visit ww or call (800) 443-9353 ext 223. 223.
SOCIETYNEWS BY HOWARD WOODWARD
[email protected]
National and District Officers Nominated for 2014
Dean Wilson president
David Landon vice president
The 2012–2013 Nominating Committee has announced its slate of candidates who will stand for election to AWS national offices for the 2014 term, which begins January 1, 2014. Nominated are the following candidates: Dean Wilson, for president; David Landon, David McQuaid, and John Bray for vice presidents; and W. Richard Polanin and Robert Roth for directors-at-large. Three vice presidents, and two directorsat-large are to be elected. The National Nominating Committee was chaired by Past President John Mendoza. Serving on the committee with Mendoza were John Bruskotter, Thomas Ferri, Dale Flood, Donald Howard, J. Jones, Thomas Lienert, Sean Moran, Robert Pali, Neil Shannon, Robert Wilcox, Michael Wiswesser, and Dennis Wright. Gricelda Manalich served as secretary. The Nominating Committees for Districts 2, 5, 8, 11, 14, 17, and 20 have selected the following candidates for election/reelection as District directors for the threeyear term Jan. 1, 2014–Dec. 31, 2016. The nominees are Harland Thompson, District 2; Carl Matricardi, District 5; D. Joshua Burgess, District 8; Robert Wilcox, District 11; Robert Richwine, District 14; Jerry Knapp, District 17; and Pierrette Gorman, District 20. Dean Wilson, currently completing his third term as a vice president, is nominated for president. Currently, he is vice president of Well-Dean Enterprises and earlier served as vice president of welding business development at Jackson Safety Products and president, CEO, and owner of Wilson Industries, Inc.
David McQuaid vice president
John Bray vice president
David Landon is nominated to serve a third term as a vice president. Currently, he is manager of welding engineering and missions support at Vermeer Mfg. Co. and an AWS Senior Certified Welding Inspector. Previously, he had his own welding business and worked as a welding engineer for Chicago Bridge and Iron Co. He has served on many AWS technical committees and as a Delegate to the IIW Commission XIV, Welding Education and Training. David McQuaid is nominated to serve a second term as a vice president. Currently, he heads D. L. McQuaid and Associates, Inc., which he founded in 1999. He has chaired the AWS D1 Structural Welding and the Technical Activities Committees. At American Bridge Div. of U.S. Steel Corp., he served as senior welding engineer and corporate engineer. In 2009, he received the American National Standards Institute Finegan Standards Medal for his outstanding contributions to industrial standards. John Bray, currently serving as District 18 director, is nominated to serve his first term as an AWS vice president. He is president of Affiliated Machinery, Inc., in Pearland, Tex., where he has served as president for the past 17 years. He is a 12-year AWS member and a former chairman of the Houston Section. W. Richard Polanin, a recent District 13 director, has been nominated to serve as a director-at-large. Polanin is a professor and program chair of Manufacturing Engineering Technology at Illinois Central College, president of WRP Associates, and serves on the adjunct faculty at Bradley University. He is an AWS Certified Weld-
W. Richard Polanin director-at-large
ing Inspector, Welder, and Welding Educator, and is a SME Certified Manufacturing Engineer. He has served as chair of the Peoria Section, and a member of the AWS D16 Committee on AutoRobert Roth mated and Rodirector-at-large botic Welding, and AWS Robotic Technician Certification Committee. He has served as an instructor for the AWS Welding Instructors Institute for three years. Robert Roth, president and CEO of RoMan Manufacturing, Inc., has been nominated to serve as a director-at-large. Roth, a long-time AWS member, serves on the AWS Finance Committee and is a past chair of WEMCO (An Association of Welding Equipment Manufacturers) and its executive committee, and has also chaired a number of RWMA (Resistance Welding Manufacturing Alliance) subcommittees. He has served as board chair of the Grand Rapids Area Chamber of Commerce and sits on the boards of the SE YMCA, and several health and civic associations. Harland Thompson is nominated to serve a second term as District 2 director. Thompson is senior project engineer and welding supervisor for Underwriters Laboratories (UL), Inc., in Melville, N.Y. Prior to joining UL in 2006, he worked in engineering and quality assurance positions at WELDING JOURNAL
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Harland Thompson District 2 director
Jerry Knapp District 17 director
Carl Matricardi District 5 director
Pierrette Gorman District 20 director
Belle Transit Div., the Long Island Railroad, Thompson Transit Services, Ronkonkoma, N.Y.; and LTK Engineering Services. Carl Matricardi is nominated to continue serving as District 5 director. He is founder and president of Welding Solutions, Inc., in Lawrenceville, Ga. In the welding industry for 37 years, he is an AWS Certified Welding Inspector and Welding Educator, and vice chair of the Atlanta Section. He has worked as a shipyard welder before earning his master’s degree in education. He has taught welding and manufacturing processes in technical colleges and state universities, and served as an expert witness. D. Joshua Burgess has been nominated to serve his first term as District 8 director. He has served as District 8 deputy director since 2009, holds a master’s in materials science and expects to defend his PhD thesis this year. He competed in the VICA welding contests where he won the regional and district levels to become the Tennessee state champion. He worked as a welder, a welding engineer technician at Aqua Chem, and currently is a consultant engineer for Ma-
AWS Bylaws Article IX, Section 3 Section 3. Nominations. Nominations, except for Executive Director and Secretary, shall proceed as follows: (a) Nominations for District Directors shall be made by the District Nominating Committees [see Article III, Section 2(c)]. The National Nominating Committee shall select nominees for the other offices falling vacant. The names of the nominees for each office, with a brief biographical sketch of each, shall be published in the July issue of the Weld64
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D. Joshua Burgess District 8 director
Robert Wilcox District 11 director
terials Applications, Inc. An Expert Welder, he has earned the AWS SENSE Level III Certificate. Robert Wilcox, an AWS member since 1974, is nominated to serve a second term as District 11 director. He has served in many Detroit Section officer positions including chair. He received his master’s degree at Central Michigan University. He has worked in the automobile industry as a cost estimator, buyer, and quality manager. Wilcox serves on the advisory committees for William D. Ford Vocational High School and Schoolcraft Community College where he studied industrial welding and fabrication technology. Currently, he owns and operates Warriors of Faith Martial Arts Academy. Robert Richwine, an AWS Distinguished Member, with the Indiana Section, is nominated to serve his second term as District 14 director. With Ivy Tech Community College since 1994, he currently serves as director of its new Welding Institute. He began his welding career in 1965 at Delco Remy Division of General Motors with a pipefitter-steamfitter apprenticeship. He has received the District CWI of the Year, Meritorious, Private Sector Educator, and the District Educator and District Director Awards, the National Meritorious and the National Image of Welding Awards.
ing Journal. The names of the members of the National Nominating Committee shall also be published in this issue of the Welding Journal, along with a copy of this Article IX, Section 3. (b) Any person with the required qualifications may be nominated for any national office by written petitions signed by not less than 200 members other than Student Members, with signatures of at least 20 members from each of five Districts, provided such petitions are delivered to the Executive Director and Secretary before August 26 for the elections to be held that year. A biogra-
Robert Richwine District 14 director
Jerry Knapp, an AWS member for more than 35 years, is nominated for his first term as District 17 director. Knapp has served as Tulsa Section chair for two years and is presently a board advisor. He has extensive experience as a salesman in the gas and welding supply industry. He has worked for Alloy Welding Supply, Arkansas Specialty Co., Jimmie Jones, National Welding Supply, Bell Helicopter, Adair Sheet Metal, Hobbs Trailers, and American Mfg. of Texas. Earlier, he worked as a grinder, welder’s helper, and in sheet metal welding, Pierrette Gorman has been nominated to serve her first term as District 20 director. She has chaired the New Mexico Section twice and received the Section and District Meritorious Awards. Most recently, she served ten years at Sandia National Laboratories as a lead process engineer involved with lean manufacturing and laser processing. Earlier, she worked as a research and applications engineer at Optomec, Inc.; welding engineer at Wilson Greatbatch, Ltd.; and a research technician at Edison Welding Institute where she explored resistance welding of dissimilar and plated materials. She holds two patents on forming structures from CAD solid models.
phical sketch of the nominee (and acceptance letter) shall be provided with the petition. Any such nominee shall be included the election for such office. A District Director may be nominated by written petitions signed by at least 10 members each from a majority of the Sections in the District, provided such petitions are delivered to the Executive Director and Secretary before August 26 for the elections to be held that year. A biographical sketch and acceptance letter of the nominee shall be provided with the petition. Any such nominee shall be included in the election.
Tech Topics Official Interpretation AWS 3.0 Standard Welding Terms and Definitions Subject: Overlap at the ends of welds Document: A3.0M/A3.0:2010, Standard Welding Terms and Definitions Provision: Page 30, Definition for overlap, fusion welding; and Page 47, Definition for weld toe. Inquiry: Due to the absence of discussion and figures related to weld end-conditions, it is unclear whether requirements for overlap are applicable at the ends of a weld bead, where the arc starts and stops. Response: The overlap condition (as currently defined) does apply to the ends of welds, not just the sides which are illustrated in the referenced figures.
Standard for Public Review A5.01M/A5.01:201X (ISO 14344:2010 MOD), Procurement Guidelines for Consumables — Welding and Allied Processes – Flux and Gas Shielded Electrical Welding Processes. Revised. $32.50. 7/1/13. Staff secretary R. Gupta,
[email protected], ext. 301. AWS was approved as an accredited standards-preparing organization by the American National Standards Institute (ANSI) in 1979. AWS rules, as approved
Definitions and Symbols Committees Meet in Nashville
The A2 Committees on Definitions and Symbols held their spring meeting in Nashville, Tenn. Shown from left are (front row) John Gullotti and Chris Lander, (back row) Chuck Ford, Secretary Stephen Borrero, Rob Anderson, Pat Newhouse, Brian Galliers, Dick Holdren, J. P. Christein, and Dave Beneteau. by ANSI, require that all standards be open to public review for comment during the approval process. The above standard is submitted for public review. A draft copy may be obtained from the staff secretary. ISO Standards In the United States, if you wish to participate in the development of International Standards for welding, contact A. Davis,
[email protected], ext. 466.
Technical Committee Meetings All AWS technical committee meetings are open to the public. Persons wishing to attend a meeting should contact the committee secretary listed. July 30, International Standards Activities Committee. Houston, Tex. A. Davis,
[email protected], ext. 466. July 30, 31, Technical Activities Committee. Houston, Tex. A. Alonso,
[email protected], ext. 299.
Opportunities to Serve on AWS Technical Committees Volunteers are sought to contribute to the following technical committees. Visit www.aws.org/technical/jointechcomm.html. Safety and Health Committee seeks educators, users, general interest, and consultants. S. Hedrick,
[email protected]. Oxyfuel gas welding and cutting, C4 Committee seeks educators, general interest, and end users; Friction welding, C6 Committee seeks professionals; H i g h energy beam welding and cutting, C7 Committee seeks professionals. P. Henry,
[email protected]. Magnesium alloy filler metals, A5L Subcommittee seeks professionals. R. Gupta,
[email protected].
Robotic and automatic welding, D16 Committee seeks general interest and educational members; Local heat treating of pipe, D10P Subcommittee seeks professionals; Mechanical testing of welds, B4 Committee seeks professionals. B. McGrath,
[email protected]. Reactive Alloys, G2D Subcommittee seeks volunteers; Titanium and zirconium filler metals, A5K Subcommittee seeks professionals; Welding qualifications, B2B Subcommittee seeks members; Friction stir welding of aluminum alloys for
aerospace applications, D17J Subcommittee seeks members. A. Diaz,
[email protected]. Resistance welding equipment, J1 Committee seeks educators, general interest, and users; Thermal spraying and automotive welding, The D8 and C2 Committees seek educators, general interest, and end users; Machinery and equipment, and Surfacing and reconditioning of industrial mill rolls, D14 Committee and D14H Subcommittee seek professionals. E. Abrams,
[email protected].
Nominations Sought for National Officers AWS members who wish to nominate candidates for President, Vice President, and Director-at-Large on the AWS Board of Directors for the term starting Jan. 1, 2015, may: 1. Send their nominations electronically by Oct. 8, 2013, to Gricelda Manalich at
[email protected], c/o W. A. Rice, chairman, National Nominating Committee; or 2. Present their nominations in person at the open session of the National Nominating Committee meeting scheduled for 2:00 to 3:00 P.M., Tuesday, Nov. 19, 2013, at McCormick
Place, Chicago, Illinois, during the 2013 FABTECH Expo. Nominations must be accompanied by biographical material on each candidate, including a written statement by the candidate as to his or her willingness and ability to serve if nominated and elected, letters of support, plus a 5- × 7-in. head-and-shoulders color photograph. Note: Persons who present their nominations at the Show must provide 20 copies of the biographical materials and written statement. WELDING JOURNAL
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Actions of Districts Council On May 19, 2013, after due consideration, Districts Council approved the charter of the AWS Central Louisiana Section, District 9, and the AWS Malaysia International Section. The AWS Central Nebraska Section, District 16, and the AWS West Zone India–Vadodara International Section were approved for disbandment.
Approved for Student Chapter charters were the AWS Parkside Career and Technology Education Center Student Chapter, District 2; AWS Riverside Parishes Community College Student Chapter, District 9; AWS University of Wisconsin-Stout Student Chapter, District 15; AWS Oklahoma Technical College Student Chapter,
District 17; and the AWS Laney College Student Chapter, District 22. The AWS Ozark Mountain Technical Center Student Chapter, District 17, and the AWS Brigham Young University Student Chapter, District 20, were approved for reinstatement.
Student Chapter Member Award Presented The AWS Beaver Valley Student Chapter, Pittsburgh Section, District 7, has selected Matt Tempalski to receive the Student Chapter Member Award. Tempalski, who served as the Chapter’s
vice chairman, received the school’s 2013 perfect attendance award and is a National Technical Honor Society inductee. He is also qualified to the requirements of AWS D1.1 3 & 4 limited thickness, and B2.1.001-90. Matt Tempalski
Five Members Receive District Director Awards District 16 Director Dennis Wright has nominated the following AWS members to receive this award: Chris Beaty — Nebraska Section Karl Fogleman — Nebraska Section Brent Wohl — SE Nebraska Section
District 22 Director Kerry Shatell has nominated the following AWS members to receive this award: Ken Morris — Sacramento Section Brad Bosworth — Fresno Section The District Director Award provides
a means for District directors to recognize individuals and corporations who have contributed their time and effort to the affairs of their local Section and/or District.
Candidates Sought for Annual Masubuchi Award November 1, 2013, is the deadline for submitting nominations for the 2014 Prof. Koichi Masubuchi Award. This award includes a $5000 honorarium. It is presented each year to one person, 40 years old or younger, who has made significant contributions to the advancement of materials
joining through research and development. Nominations should include a description of the candidate’s experience, list of publications, honors, and awards, and at least three letters of recommendation from fellow researchers. The award is sponsored by the Massachusetts Insti-
tute of Technology Dept. of Ocean Engineering. E-mail your nomination package to Todd A. Palmer, assistant professor, The Pennsylvania State University,
[email protected].
Nominate Your Candidate for the Distinguished Welder Award August 1 is the deadline to submit your nominations for the AWS Distinguished Welder Award. The award recognizes professionals with a minimum of 15 years’ ex-
perience whose skills and achievements warrant special recognition. For details on the full description, selection criteria, and the nomination form,
visit the AWS Web site, www.aws.org, and select the awards category. Or, e-mail Wendy Sue Reeve, senior manager, awards programs,
[email protected].
Name Your Candidates for These AWS Awards The deadline for nominating candidates for the following awards is December 31 prior to the year of the awards presentations. Contact Wendy Sue Reeve,
[email protected]; (800/305) 443-9353, ext. 293. William Irrgang Memorial Award This award is given to the individual who has done the most over the past five years to enhance the Society’s goal of advancing the science and technology of welding. It includes a $2500 honorarium and a certificate. Honorary Membership Award This award acknowledges eminence in the welding profession, or one who is credited with exceptional accomplishments in the development of the welding art. Honorary Members have full rights of membership. National Meritorious Certificate Award This award recognizes the recipient’s counsel, loyalty, and dedication to AWS affairs, assistance in promoting cordial rela66
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tions with industry and other organizations, and for contributions of time and effort on behalf of the Society. George E. Willis Award This award is given to an individual who promoted the advancement of welding internationally by fostering cooperative participation in technology transfer, standards rationalization, and promotion of industrial goodwill. It includes a $2500 honorarium. International Meritorious Certificate Award This honor recognizes recipients’ significant contributions to the welding industry for service to the international welding community in the broadest terms. The award consists of a certificate and a one-year AWS membership.
New AWS Supporters Sustaining Members Airgas, Inc. 259 N. Radnor Chester Rd., Ste. 100 Radnor, PA 19087 Representative: David Levin www.airgas.com Avenal State Prison 1 Kings Way, PO Box 8 Avenal, CA 93204 Representative: Michael Valdez Calif. Correctional Center 711-045 Center Rd., PO Box 790 Susanville, CA 96130 Representative: Michael Valdez Calif. Correctional Institution 24900 Hwy. 202, PO Box 1031 Tehachapi, CA 93581 Representative: Michael Valdez Calif. Institution for Men 14901 Central Ave., PO Box 128 Chino, CA 91710 Representative: Michael Valdez Calif. Men’s Colony Hwy. 1, PO Box 8101 San Luis Obispo, CA 93409 Representative: Michael Valdez Calif. State Prison-Corcoran 4001 King Ave., PO Box 8300 Corcoran, CA 93212 Representative: Michael Valdez Calif. State Prison-Solano 2100 Peabody Rd., PO Box 4000 Vacaville, CA 95696 Representative: Michael Valdez
Affiliate Companies Alpha Iron Fabrication LLC 5880 W. 59 Ave., Ste. G Arvada, CO 80003 Fastenal Mfg. Co. 1801 Theurer Blvd. Winona, MN 55987 Goodbody Gear, Inc. 10546 Valle Vista Rd. Lakeside, CA 92040 H. A. Fabricators 349 W. 2500 N. Logan, UT 84341
Calif. Substance Abuse Treatment 900 Quebec Ave., PO Box 7100 Corcoran, CA 93212 Representative: Michael Valdez Centinela State Prison 2302 Brown Rd., PO Box 731 Imperial, CA 92251 Representative: Michael Valdez Chuckawalla Valley State Prison 19025 Wiley’s Rd., PO Box 2289 Blythe, CA 92226 Representative: Michael Valdez Greystone Adult School - Lowar Yard PO Box 71, 300 Prison Rd. Represa, CA 95671 Representative: Michael Valdez Greystone Adult School - P.I.A. 300 Prison Rd., PO Box 71 Represa, CA 95671 Representative: Michael Valdez Hood - EIC, LLC 45 Vista Blvd., Ste. 102 Sparks, NV 89434 Representative: Michael Labahn www.hoodeic.com Kern Valley State Prison 3000 W. Cecil Ave., PO Box 3150 Delano, CA 93216 Representative: Michael Valdez Mule Creek State Prison 4001 Hwy. 104, PO Box 409009 Ione, CA 95640 Representative: Michael Valdez Pleasant Valley State Prison 24863 W. Jayne Ave., PO Box 8500 Coalinga, CA 93210 Representative: Michael Valdez
Rasmussen Mechanical Services 3215 Nebraska Ave. Council Bluffs, IA 51501 Representative: Greg Schroeter www.rasmech.com Richard J. Donovan Correctional Facility 480 Alta Rd. San Diego, CA 92179 Representative: Michael Valdez Sierra Conservation Center 5100 O’Byrnes Ferry Rd., PO Box 497 Jamestown, CA 95327 Representative: Michael Valdez Techcrane International, LLC 17639 Hard Hat Dr. Covington, LA 70435 Representative: Ardalan Farahmand www.techcrane.com Valley State Prison 21633 Ave. 24, PO Box 92 Chowchilla, CA 93610 Representative: Michael Valdez
AWS Member Counts June 1, 2013 Sustaining ......................................588 Supporting .....................................332 Educational ...................................623 Affiliate..........................................507 Welding Distributor........................53 Total Corporate ..........................2,103 Individual .................................59,002 Student + Transitional .................9,352 Total Members .........................68,354
Minth Mexico SA de CV Carretera Los Arellanos No. 214 Parque Industrial Siglo XXI Aguascalientes 20283, Mexico
Charter College 2221 E. Northern Lights Blvd., Ste. 120 Anchorage, AK 99508
Rail Mechanical Services, Inc. PO Box 848 Columbia, PA 17512
Garrett College - CEWD 687 Mosser Rd. McHenry, MD 21541
Supporting Companies Great Plains Mfg., Inc. 1525 E. North St. Salina, KS 67401 Petrustech Oil & Gas 5500 N. Sam Houston Parkway W., Ste. 200 Houston, TX 77086
Idaho Precision Welding, Inc. 555 Hwy. 52 Horseshoe Bend, ID 83629
Educational Institutions
La Forge De Style 57 Romanelli Ave. S. Hackensack, NJ 07606
Area Career Center 5727 Sohl Ave. Hammond, IN 46320
Mason High School 1105 W. College Ave. Mason, TX 76856 Wylie High School 4502 Antilley Rd. Abilene, TX 79606
Welding Distributor Airgas USA, LLC 5635 International Dr. Rockford, IL 61109
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Member-Get-A-Member Campaign Listed are the members participating in the 2012–2013 campaign. Standings as of May 18. See page 81 of this Welding Journal for campaign rules and prize list or visit www.aws.org/mgm. For information, call the Membership Dept. (800/305) 443-9353, ext. 480.
Winner’s Circle Sponsored 20 or more Individual Members per year since June 1, 1999. The superscript denotes the number of times the status was achieved if more than once. E. Ezell, Mobile10 J. Compton, San Fernando Valley7 J. Merzthal, Peru2 G. Taylor, Pascagoula2 L. Taylor, Pascagoula2 B. Chin, Auburn S. Esders, Detroit M. Haggard, Inland Empire M. Karagoulis, Detroit S. McGill, NE Tennessee B. Mikeska, Houston W. Shreve, Fox Valley T. Weaver, Johnstown/Altoona G. Woomer, Johnstown/Altoona R. Wray, Nebraska President’s Guild Sponsored 20+ new Individual Members M. Pelegrino, Chicago — 36 E. Ezell, Mobile — 32 President’s Roundtable Sponsored 9–19 new Individual Members R. Fulmer, Twin Tiers — 10 W. Blamire, Atlanta — 9 A. Tous, Costa Rica — 9 P. Strother, New Orleans — 9 President’s Club Sponsored 3–8 new Individual Members D. Galigher, Detroit — 7 W. Komlos, Utah — 7 J. Smith, San Antonio — 6 C. Becker, Northwest — 5 R. Thacker Jr., Oklahoma City — 5 L. Webb, Lexington — 4 D. Wright, Kansas City — 4 T. Baber, San Fernando Valley — 3 J. Bain, Mobile — 3 A. Bernard, Sabine — 3 J. Blubaugh, Detroit — 3 P. Brown, New Orleans — 3 D. Buster, Eastern Iowa — 3 C. Daon, Israel Section — 3 G. Gammill, NE Mississippi — 3 B. Hackbarth, Milwaukee — 3 S. Jaycox, Long Island — 3 D. Jessop, Mahoning Valley — 3 D. Saunders, Lakeshore — 3 T. Sumerix, Dayton — 3 J. Turcott, Rochester — 3 A. Winkle, Kansas City — 3 R. Wright, San Antonio — 3 R. Zabel, SE Nebraska — 3
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President’s Honor Roll Sponsored 2 Individual Members G. Cornell, St. Louis M. Depuy, Portland M. Douville, Central Mass./R.I. D. Hayes Jr., Louisville J. Helfrich, Tri-River P. Host, Chicago H. Hughes, Mahoning Valley J. Kline, Northern New York L. Kvidahl, Pascagoula W. Larry, Southern Colorado G. Lawrence, N. Central Florida J. Mansfield, Philadelphia E. Norman, Ozark A. Sam, Trinidad C. Shepherd, Houston G. Solomon, Central Pennsylvania A. Sumal, British Columbia C. Villarreal, Houston J. Vincent, Kansas City A. Vogt, New Jersey J. Vorstenbosch, International M. Wheeler, Cleveland L. William, Western Carolina W. Wilson, New Orleans J. Winston, St. Louis Student Member Sponsors Sponsored 3+ new Student Members H. Hughes, Mahoning Valley — 106 A. Theriot, New Orleans — 47 B. Scherer, Cincinnati — 39 D. Saunders, Lakeshore — 36 W. England, W. Michigan — 33 R. Zabel, SE Nebraska — 33 R. Bulthouse, Western Michigan — 31 D. Pickering, Central Arkansas — 31 R. Gilmer, Houston — 29 T. Rivera, Corpus Christi — 29 R. Hammond, Greater Huntsville — 28 A. Stute, Madison-Beloit — 28 T. Geisler, Pittsburgh — 24 S. Siviski, Maine — 24 B. Cheatham, Columbia — 23 C. Kochersperger, Philadelphia — 23 M. Arand, Louisville — 22 R. Hutchinson, Long Bch./Or. Cty. — 22 D. Bastian, Northwestern Pa. — 21 G. Gammill, NE Mississippi — 21 J. Falgout, Baton Rouge — 20 F. Oravets, Pittsburgh — 20 J. Theberge, Boston — 20 J. Johnson, Madison-Beloit — 19 K. Temme, Philadelphia — 19 V. Facchiano, Lehigh Valley — 18 R. Munns, Utah — 18 S. Lindsey, San Diego — 17 R. Richwine, Indiana — 17
J. Russell, Fox Valley — 17 M. Anderson, Indiana — 16 R. Fuller, Green & White Mts. — 16 E. Norman, Ozark — 16 A. Oberman, Ozark — 16 C. Donnell, NW Ohio — 14 J. Kline, Northern New York — 13 G. Smith, Lehigh Valley — 13 D. Schnalzer, Lehigh Valley — 13 T. Sumerix, Dayton — 12 C. Daily, Puget Sound — 12 J. Daugherty, Louisville — 12 C. Morris, Sacramento — 12 S. Robeson, Cumberland Valley — 12 J. Ciaramitaro, N. Central Florida — 11 K. Cox, Palm Beach — 11 A. Duron, Cumberland Valley — 11 J. Boyer, Lancaster Section — 10 G. Seese, Johnstown-Altoona — 10 R. Vann, South Carolina — 10 C. Schiner, Wyoming — 9 C. Galbavy, Idaho/Montana — 8 C. Gilbertson, Northern Plains — 8 J. Dawson, Pittsburgh — 7 R. Udy, Utah — 7 A. Badeaux, Washington, D.C. — 6 T. Buckler, Columbus — 6 S. Caldera, Portland — 6 J. Elliott, Houston — 6 T. Shirk, Tidewater — 6 P. Host, Chicago — 5 R. Ledford, Birmingham — 5 G. Rolla, L.A./Inland Empire — 5 G. Siepert, Kansas — 5 P. Strother, New Orleans — 5 W. Wilson, New Orleans — 5 C. Chifici, New Orleans — 4 L. Clark, Milwaukee — 4 J. Ginther, International — 4 C. Griffin, Tulsa — 4 J. Johnson, Northern Plains — 4 J. Reed, Ozark — 4 E. Shreve, Pittsburgh — 4 P. Strother, New Orleans — 4 R. Zadroga, Philadelphia — 4 J. Fitzpatrick, Arizona — 3 L. Gross, Milwaukee — 3 R. Hilty, Pittsburgh — 3 C. Hobson, Olympic — 3 S. Liu, Colorado — 3 D. McGrath, Houston — 3 J. Vincent, Kansas City — 3 G. Von Lunen, Kansas City — 3 B. Wenzel, Sacramento — 3 R. Wilsdorf, Tulsa — 3
SECTIONNEWS Manchester Community Technical College welding students and instructors are shown during the dedication of their new welding facilities attended by Boston Section members in April.
District 1
Thomas Ferri, director (508) 527-1884
[email protected]
BOSTON APRIL 23 Activity: The Section participated in the dedication of a new welding lab at Manchester Community Technical College (MCTC) in Manchester, Conn. An overhead crane was dedicated to Jack Paige, a retired welding instructor and past Section chair and technical chair. The roast pig dinner was provided by alumnus Mark Stock of Multi-Weld Services. Participating were Tony Hanna, welding instructor; Dan Chabot, faculty director; Paul Plourde, professor of welding technology; Susan Huard, MCTC president; and Section Chair Dave Paquin.
Shown (from left) are Jack Paige, Tony Hanna, Dan Chabot, Paul Plourde, Susan Huard, and Dave Paquin, Boston Section chair.
CENTRAL MASS./R.I. APRIL 9 Speaker: Stephen St. John Affiliation: St. John Fabrication & Welding Topic: Using a ring rolling machine Activity: St. John demonstrated how to use a Baileigh ring rolling machine to bend a 20-ft-long, 3- × 2-in., 0.125-in. wall rectangular tubing into an arc. The meeting was held at Old Colony Regional Technical High School in Rochester, Mass.
District 2
Harland W. Thompson, director (631) 546-2903
[email protected]
Central Mass./R.I. Section members learned how to bend rectangular tubing in April. Long Island Section judges (from left) Jim Malamon, Lou DeFulio, and Dave Terpolilli Jr. are shown at the SkillsUSA welding competition.
LONG ISLAND APRIL 20 Activity: The Section participated in the SkillsUSA welding competition held at Somerset Technical High School in Bridgewater, N.J. Judging and other duties were performed by Jim Malamon, Lou DeFulio, Dave Terpolilli Jr., Welding Instructor Don Smith, and Harland Thompson, District 2 director.
Don Smith, welding instructor, poses with ninth graders Rebecca Jackson and Joe Paolillo at the Long Island Section event. WELDING JOURNAL
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Shown at the Long Island Section program are (from left) Jesse Provler, Alex Duschere, Tom Garland, Ray O’Leary, Chair Brian Cassidy, District 2 Director Harland Thompson, and Ken Messemer.
Ray Sosko, advisor, Central Piedmont C.C. Student Chapter, is shown with his class.
Lancaster Section members (from left) Tucker Hill, Daniel Hrizhynku, Pete Bibawy, Chair Justin Heistand, Steve Mitchell, Josh Joyce, and Mike Sebergandio, are shown during the Rohrer’s Quarry tour.
Herb Browne (left), Morris County School of Technology Student Chapter advisor, works with Boy Scout Ben Smith (center) and welding student Gehring Andrew. APRIL 23 Activity: The Long Island Section held an awards-presentation program in Wantagh, N.Y. Chair Brian Cassidy and District 2 Director Harland Thompson presented Tom Garland the Private Sector Instructor Award, and the Section Meritorious Award to Ray O’Leary.
Morris County School of Technology Student Chapter
Mike Sebergandio (right) is shown with Justin Heistand, Lancaster Section chair. 70
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AWS President Nancy Cole is shown with Justin Heistand (left), Lancaster Section chair, and Ed Calaman, York Section chair.
APRIL 20 Activity: The Student Chapter, headed by Advisor Herb Browne, conducted a Boy Scout merit badge workshop at the school in Denville, N.J. The Student Chapter is affiliated with the New Jersey Section.
Florida West Coast Section board members are (from left) Robert Brewington, Charles Crumpton, Al Sedory, Bill Maknivitz, Walt Arnold, Alan Shissler, Albert Carr, and Roger Aker.
District 3
Michael Wiswesser, director (610) 820-9551
[email protected]
LANCASTER MAY 4 Activity: The Section members and guests toured Rohrer’s Quarry, Inc., in Lititz, Pa., to study the equipment and methods used for processing limestone for agricultural, construction, and road-building uses.
LANCASTER/YORK APRIL 25 Speaker: Nancy Cole, AWS president Affiliation: NCC Engineering Topic: The need for women in welding jobs Activity: Nancy Cole presented Ed Calaman a certificate for serving as York Section chair. Mike Sebergandio presented Lancaster Section chair Justin Heistand his chairman award. The event was held at Heritage Hills Golf Resort in York, Pa.
District 4
Stewart A. Harris, director (919) 824-0520
[email protected]
CHARLOTTECentral Piedmont C.C. Student Chapter MAY 3 Activity: The college hosted its 13th annual welding competition at the college in Charlotte, N.C. Student Chapter Advisor Ray Sosko and members participated, including John Grillo, Justin Shearin, Jeremiah Vernon, Justin Burgess, Paul Martin, Joseph Barnes, Dlip Tolani, Frank Turner, Jayce Kinney, Connor Pohlman, Austin Price, Ryan Moore, Trey Mitchell, Kyle Waters, Reed O’Neal, Tanner Bright, Theo VanEssendelft, Jamey Richardson, Samantha Vick, Matt Cooler, Seth Hogan, Jason Greene, Richard Grady, Chad Fox, Jason Laird, Joshua Cox, Melody Blechlin, William Daugherty, and Ryan Wilson. Student welders from ten local colleges competed with prizes donated by ESAB, Victor, Lincoln Electric, Machine and
Welding Supply, Ward Tank, Chicago Bridge and Iron, Praxair, Airgas, Martin Marietta, Liburdi Dimetrics, and Colonna’s Shipyard.
District 5 Carl Matricardi, director (770) 979-6344
[email protected]
FLORIDA WEST COAST MAY 4 Activity: The Section hosted its annual Shrimp-A-Roo outing for more than 75 members and guests at Yuengling Brewery Biergarten in Tampa, Fla. Al Sedory received the District Meritorious Award from Carl Matricardi, District 5 director, for his work at many District 5 conferences. Charles Crumpton was recognized for his services as chair. Devin Lytle received a $750 scholarship from Alan Shissler, scholarship chair.
Al Sedory (right) receives the District Meritorious Certificate Award from Carl Matricardi, District 5 director, at the Florida West Coast Section event.
District 6 Kenneth Phy, director (315) 218-5297
[email protected]
NIAGARA FRONTIER APRIL 18 Activity: The Section and Erie 1 Board of Cooperative Educational Services (BOCES) hosted a career fair at the school in West Seneca, N.Y., for about 50 job seekers.
District 7
Uwe Aschemeier, director (786) 473-9540
[email protected]
DAYTON MAY 14 Activity: The Section held its past chairmen’s night program at Asian Buffet in Dayton, Ohio. Al J. Mealey Scholarships were awarded to Robert Lacy to study at Hobart Institute of Welding Technology (HIWT), and to Wesley Hart to study at The Ohio State University. Other scholarships were presented to Lila Golly, Ben-
Wesley Hart (left) receives a scholarship from Chris Lander, Dayton Section chair. jamin Kettler, and Justin Heiland, all studying at HIWT. Chris Lander received a certificate of appreciation for his services as chair.
District 8 Joe Livesay, director (931) 484-7502, ext. 143
[email protected]
District 9
George Fairbanks Jr., director (225) 473-6362
[email protected] WELDING JOURNAL
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Southeastern Louisiana University Student Chapter members and guests are shown with speaker Nancy Cole, AWS president.
AWS President Nancy Cole is shown with some of the Birmingham Section members.
Presenter Bill Faircloth (left) is shown with Johnny Dedeaux, Mobile Section chair.
Cody Manders (right) is shown with Craig Donnell, advisor, Whitmer Career and Technical Center Student Chapter. 72
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Shown at the Pascagoula Section program are (from left) AWS President Nancy Cole, Awardee Cynthia Harris, and George Fairbanks, District 9 director.
Lawson State C.C. Student Chapter members shown at the SkillsUSA event are (from left) Corey Lehfeldt, Ramiro Lopez, and Benjamin Vining.
BIRMINGHAM
MOBILE
MAY 14 Speaker: Nancy Cole, AWS president Affiliation: NCC Engineering Topic: Careers in welding for women Activity: Myron Laurent, education speciality and Alabama SkillsUSA director, discussed the recent Alabama competition. Jim Casey was recognized for his services as chair.
APRIL 18 Activity: The Section members met at Faircloth Metallurgical Services in Mobile, Ala., for a barbecue dinner followed by a tour of the facilities. Bill Faircloth, metallurgist and owner, discussed the importance of weld procedure qualifications and weld testing then conducted the plant tour.
Lawson State C.C. Student Chapter MAY 2 Activity: Thirteen Student Chapter members and welding students from Wallace State C.C. participated in two events. Corey Lehfeldt, James Foster, Ramiro Lopez, and Ben Vining tack welded for the competitors from 8 a.m. to 3 p.m at the National Crafts Championship, sponsored by Go Build Alabama and the Associated Builders & Contractors of Alabama. At the Alabama SkillsUSA competition, Ramiro Lopez and Ben Vining competed in the SkillsUSA welding competition. Vining earned the gold medal. He will participate in the National SkillsUSA welding competition to be held in Kansas City, Mo. Both events were held at the Birmingham Jefferson Convention Complex.
PASCAGOULA FEBRUARY 28 Speaker: Nancy Cole, AWS president Affiliation: NCC Engineering Topic: Women in welding Activity: Section Vice Chair Cynthia Harris received the District Educator of the Year Award from George Fairbanks, District 9 director. Harris was recognized for her outstanding work in the Moss Point School District where she was cited for raising the standards for welding education in the district from the lowest to one of the top-rated programs in the state. She is the only woman welding instructor in the Mississippi Public School System.
SE Louisiana University Student Chapter FEBRUARY 28
Shown at the Fox Valley Section program are (from left) Bill Hanke, Al Sherrill, Randy Schmidt, Joe Hoban, Barb Schmidt, Colleen Schmidt, Steve Waldvogel, CDR William Roth, Louis Janzen, Patti Shreve, Jerry Sackman, William Shreve, Jeffery Bunker, and Kevin Werth.
Shown at the Milwaukee Section tour are (from left) Carl Senek, Karen Gilgenbach, Brian Stone, Dale Gilbertson, Chris and Anni VanDyke, Adam Thomas, and Scott Lancelle. Shown at the Lakeshore Section event are (from left) Aaron Parvechek, David Saunders, and Jimmy Dao. Speaker: Nancy Cole, AWS president Affiliation: NCC Engineering Topic: Careers in welding for women Activity: The Chapter and members of the SLU Industrial Technology department hosted a breakfast meeting for President Nancy Cole and George Fairbanks, District 9 director, at the university in Hammond, La.
District 10
Robert E. Brenner, director (330) 484-3650
[email protected]
District 11 Robert P. Wilcox, director (734) 721-8272
[email protected]
NORTHWEST OHIO APRIL 4 Speaker: Karl Hoes, instructor Affiliation: The Lincoln Electric Co. Topic: Welding competition vehicles Activity: More than 25 competition vehi-
cles were on display for study. Members also tried their skills using a VRTEX® 360 virtual reality arc welding training station. Top scorers won a welding helmet. The program was held in Perrysburg (Toledo), Ohio.
Whitmer Career and Technical Center Student Chapter APRIL 26 Activity: Cody Manders received the Student Chapter Member Award from Advisor Craig Donnell, CWI and CWE. Manders was cited for maintaining a 3.5 GPA in the welding program while working as a welder-machinist at TM Tool & Die and participating in many community service projects. He was one of four seniors who fabricated a solar-powered car frame for an engineering class project.
Topic: Passivation of carbon and stainless steels for corrosion control Activity: Colleen Schmidt received a Section scholarship to attend Hobart Institute of Welding Technology.
LAKESHORE APRIL 19 Activity: The fourth annual Lakeshore Section student career day event was held at Lakeshore Technical College, Cleveland, Wis., to promote welding as a good career choice. Section scholarships were presented to Aaron Parvechek and Jimmy Dao. David Saunders received the Madison-Beloit Section Educator of the Year Award.
MILWAUKEE
District 12
APRIL 18 Activity: Ninety-four Section members and guests toured the Caterpillar mining shovel manufacturing facility in South Milwaukee, Wis.
FOX VALLEY
RACINE-KENOSHA
APRIL 23 Speaker: CDR William Roth, CWI, corporate welding and materials engineer Affiliation: Proctor & Gamble
MARCH 7 Activity: The Section members and welding students from Gateway Technical College toured the US Tanker-Fire Appara-
Daniel J. Roland, director (715) 735-9341, ext. 6421
[email protected]
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Racine-Kenosha Section members and welding students are shown during their tour of US Tanker Fire Apparatus.
Bob Zimny (left) and Pete Host, Chicago Section chair, display the Illinois governor’s welding month proclamation.
Indiana Section officers (from left) Gary Tucker, Chair Bennie Flynn, and Gary Dugger judged the state SkillsUSA welding event. Shown at the Chicago Section board meeting are from left (seated) Craig Tichelar, Chair Pete Host, and Jeff Stanczak; (standing) Bob Zimny and Cliff Iftimie.
Dean Wilson, an AWS vice president, and Glenda Ritz spoke at the Indiana Section’s Mid-West Welding Tournament awards banquet. tus, Inc., facility in Delavan, Wis., to study the manufacture of stainless steel tankers and pumpers used in rural and suburban fire departments.
District 13 At the Mid-West Team Welding Tournament, Instructor Keith Cusey poses with his winning team Marcus Crawford, Ryan Porter, Jordan Bird, Chad Wanless, and Brandon Gibbs. 74
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John Willard, director (815) 954-4838
[email protected]
CHICAGO APRIL 17 Activity: Jeff Noruk gave a presentation on the Wiki-SCAN, a hand-held, laserbased welding inspection system for use in the field. Bob Zimny and Chair Pete Host displayed a proclamation signed by Illinois Governor Pat Quinn declaring April as welding month in the state. MAY 7 Activity: The board members met at Hog Wild Restaurant to review applications for Section scholarships. Participating were Chair Pete Host, Craig Tichelar, Jeff Stanczak, Bob Zimny, and Cliff Iftimie.
Shown at the Lexington Section program are (from left) Chair Coy Hall, Welding Instructor Sherman Cook, Eric McCracken, Kayla Lovell, and Tim Nicely.
District 14
Robert L. Richwine, director (765) 378-5378
[email protected]
INDIANA APRIL 19, 20 Activity: The Section conducted the Indiana state SkillsUSA welding contest. Serving as judges were Chair Bennie Flynn, Gary Tucker, Gary Dugger, and Tony Brosio. The teams from New Castle Area Career Programs and Ivy Tech C.C. won trips to attend the National SkillsUSA contests. APRIL 14, 25 Speaker: Dean Wilson, AWS VP Affiliation: Well-Dean Enterprises Topic: Welding as a career Activity: The Section held its 35th annual Mid-West Team Welding Tournament at J. Everett Light Career Center (JELCC). Judges included District 14 Director Bob Richwine, Chair Bennie Flynn, Gary Tucker, Gary Dugger, Tony Brosio, and Richard Alley, a past AWS president. Eric Cooper from JELCC and David Jackson from Indiana Oxygen Corp. organized the event. The top three teams represented Heartland Career Center, 4-County Career Center, and New Castle Area Career Programs. Dean Wilson, AWS vice president, and Glenda Ritz, superintendent of public instruction, spoke at the event.
LEXINGTON APRIL 25 Activity: ESAB presented a program on automated welding at Bluegrass Community and Technical College in Lexington, Ky., for 30 attendees.
ST. LOUIS MARCH 28 Activity: The Section hosted its annual mini welding show to display the latest in safety, testing, welding tools, and technology. Representatives from several companies provided demonstrations of their
St. Louis-area vendors are shown at the mini welding show in March.
Shown at the St. Louis Section event are (from left) Chair Tully Parker, Joe Grinston, Brandi Phelps, Tiffany Turnbo, Charles Siebert, Brandon Shelton, Matthew Lockhart, Wesley Johnson, Brandon Hays, David Gill, and Christopher Crain.
Students recognized by the St. Louis Section are (from left) Instructor Joe Candela, Nick Vallejo, Tyler Scott, Instructor Kevin Corgan, Mitchel McFarland, and Cameron Medley. products and technical expertise. The event was held at the Hil Bax Technical Center at Cee Kay Supply, Inc., in St. Louis, Mo. APRIL 18 Speaker: Pat Cody, welding engineer Affiliation: Ameren (ret.) Topic: The SkillsUSA welding competition Activity: Section and Hil Bax scholarships were presented to Joe Grinston, Brandi Phelps, Tiffany Turnbo, Charles Siebert, Brandon Shelton, Matthew Lockhart, Wesley Johnson, Brandon Hays, David Gill, and Christopher Crain. Student awards were presented to Nick Vallejo, Tyler Scott, Mitchel McFarland, and Cameron Medley by their instructors Joe Candela and Kevin Corgan.
Speaker Pat Cody (right) is shown with Tully Parker, St. Louis Section chair. WELDING JOURNAL
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Nebraska Section members are shown with the Boy Scouts they trained to earn their welding merit badges.
Nebraska Section members are shown at Joe’s Karting in April.
Angela Harrison from Welsco receives the Honorary Lifetime Member award from Ray Winiecki, Arkansas SkillsUSA director, at the Central Arkansas Section program. Shown at the Saskatoon Section event are (from left) Scott Krieg, Eric Krueger, Chair Ike Oguocha, and Huawei Guo.
Ike Oguocha (left) receives his chairman appreciation certificate from Huawei Guo at the Saskatoon Section program.
Shown at the Central Arkansas program are (from left) Drake Collins,Chance Johnson, Vice Chair Dennis Pickering, Kory House, Dillon Dugan, and Jimmy Allison.
Attendees are shown at the Tulsa Section-sponsored CWI training class. 76
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Scott Blom demonstrated a soldering technique at the East Texas Section program.
Some of the attendees are shown at the Alaska Section student night event.
District 15 David Lynnes, director (701) 365-0606
[email protected]
SASKATOON APRIL 25 Activity: Ike Oguocha received an appreciation award for his services as chair from Treasurer Huawei Guo. The presentation took place in Saskatoon, Saskatchewan, Canada.
District 16 Dennis Wright, director (913) 782-0635
[email protected]
NEBRASKA APRIL 19 Activity: The Section visited Joe’s Karting in Council Bluffs, Iowa, to celebrate National Welding Month. The Section, in conjunction with Metropolitan Community College and The Lincoln Electric Co. taught a group of Boy Scouts how to weld to help them earn their welding merit badges.
to Welsco, Inc., for its 27 years of service and contributions to the Arkansas SkillsUSA welding competitions.
EAST TEXAS APRIL 25 Speaker: Scott Blom, district sales manager Affiliation: The Harris Products Group Topic: Materials and techniques for soldering and brazing dissimilar metals Activity: Following the lecture, the attendees had a hands-on opportunity to braze and solder dissimilar metals. The program was held at Tyler Jr. College in Tyler, Tex.
Ernest Levert, AWS past president, addressed the North Texas Section in April.
NORTH TEXAS APRIL 16 Speaker: Ernest Levert, AWS past president Affiliation: Lockheed Martin, senior staff manufacturing engineer Topic: New trends in welding Activity: The program was held in Grand Prairie, Tex.
TULSA
District 17
MARCH 12–APRIL 11 Activity: The Section sponsored a CWI preparatory class for 27 students. Ray Wilsdorf and Ralph Johnson taught the class at Tulsa Technology Center, Lemley Campus, in Tulsa, Okla.
CENTRAL ARKANSAS
District 18
District 19
HOUSTON
ALASKA
APRIL 17 Speakers: Jean-Marc Tetevuide and John Evans, general manager and technology manager, respectively Affiliation: Plasma Technology Automation & Materials Topic: Hardfacing using lasers and plasma transferred arc welding Activity: The program was held at Brady’s Landing in Houston, Tex.
APRIL 24 Speaker: Kalen Hollinberger Affiliation: Kiewit Building Group Topic: Bridges and other projects built by Kiewit Activity: More than 60 people attended this student night event that offered information on careers in welding, advanced welding processes, and existing welding jobs in the area.
J. Jones, director (832) 506-5986
[email protected]
APRIL 10 Activity: The Section members manned a booth at the SkillsUSA event held at Hot Springs Convention Center in Hot Springs, Ark. The District Director Award was presented to Jimmy Brewer from UA Local 155. Section Meritorious Awards were presented to Matt Fair from UA Local 155, Monte Breeden from UA Local 29, and Angela Harrison from Welsco. Michael Dugan from the University of Arkansas, Ft. Smith, received the Section Educator Award, accepted in his absence by his son Dillon Dugan. Ray Winiecki, SkillsUSA director for Arkansas, presented an award
John Bray, director (281) 997-7273
[email protected]
Houston Section Vice Chair Derek Stelly (left) is shown with speaker Jean-Marc Tetevuide.
Ken Johnson, director (425) 957-3553
[email protected]
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District 19 Section officers are shown at the District 19 conference hosted by the Inland Empire Section.
Speaker Bob Heffernan (left) is shown with Ken Johnson, District 19 director, at the Puget Sound Section program.
Shown at the Puget Sound Section program are (from left) District 19 Director Ken Johnson, Steve Nielsen, Art Schnitzer, Steve Pollard, and Dave Edwards. Bien Irizarry discussed the casting process for the Central New Mexico C. C. Student Chapter members in April.
Speaker Bob Miller (left) is shown with Steve Prost, British Columbia Section chair.
Pat Newhouse presents the chairman appreciation certificate to Steve Prost at the British Columbia Section program.
The New Mexico Section members are shown at the Albuquerque Airgas facility in May. 78
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The winning team in the District 19 ‘Stump the Experts’ contest included (from left) Jared Satterlund, Mark Lynch, and Phil Zammit. Chris Lynch holds the trophy.
Long Beach/Orange County Section members are shown at their April meeting.
BRITISH COLUMBIA APRIL 17 Speaker: Bob Miller, materials engineer Affiliation: Postle Industries, Inc. Topic: Tungsten carbide hardfacing Activity: Steve Prost received a certificate of appreciation for his services as chair from Pat Newhouse. The catered dinner and program were held at UA Piping Industry College of British Columbia in Delta, B.C., Canada.
District 19 Conference MAY 3 Activity: The annual “Stump the Experts” contest was held on the eve of the District conference in Pasco, Wash. The winning team featured Phil Zammit (Spokane Section), Jared Satterlund (Puget Sound Section), and Mark Lynch (Portland Section). The conference, hosted by the Inland Empire Section, featured a tour of the Laser Inferometer Gravitational Wave Observatory (LIGO) in Richland, Wash.
Boy Scouts in Troop 895 earned their welding merit badges with the help of the Utah Section. Shown are (from left) Travis Harding, Brady Horstmann, Jesus Acosta, Rob Hansen, William Mortensen,Campbell Hall, and Bart Mortensen.
PUGET SOUND MAY 2 Speaker: Bob Heffernan, welding applications engineer Affiliation: Praxair Topic: Laser cutting using carbon dioxide Activity: The incoming slate of officers was elected: Dan Sheets, chair; Ken Johnson and Robert White, vice chairs; Dave Edwards, secretary; Steve Nielsen, treasurer, Gary Mancel, membership chair; Steve Pollard, technical and newsletter chair; and Art Schnitzer, publicity chair. The event was held at Rock Salt Steak House in Seattle, Wash.
L.A./Inland Empire officers are (from left) Tim Serviss, Tim Chubbs, Robert Doiron, Che Chancy, Ladon Gilbert, Kenny Reid, Mariana Ludmer, and George Rolla.
SPOKANE MAY 15 Activity: Forty-two Section members and guests met at Spokane Community College welding lab where Phillip Formento from ESAB demonstrated the submerged arc welding process.
Eric Budwig, chair of the Long Beach/Orange County Section, presents a certificate of appreciation to Phil Fulgenzi and his team of Lincoln Electric representatives. WELDING JOURNAL
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The San Fernando Valley Section members are shown during their Aero Bending Co. tour.
District 20
District 21
Central New Mexico C. C. Student Chapter
LONG BEACH/ ORANGE COUNTY
APRIL 6 Activity: The Chapter members visited the Shidoni Bronze Foundry in Tesque, N. Mex. Bien Irizarry led the tour and explained the steps in the casting process.
APRIL 11 Speaker: Phillip Fulgenzi, district manager Affiliation: Lincoln Electric Center Topic: Job opportunities for welders Activity: After the talk, Fulgenzi and his team conducted hands-on demonstrations of plasma cutting machines, wire feeders, and robotic welding equipment. The meeting was held at the Lincoln Electric Center in Santa Fe Springs, Calif.
William A. Komlos, director (801) 560-2353
[email protected]
NEW MEXICO APRIL 18 Activity: The Section met at MEGA Corp. in Albuquerque, N. Mex., for talks on welding plastic pipes. The presenters were Herb Smith and Dean Rogers.
Nanette Samanich, director (702) 429-5017
[email protected]
L.A./INLAND EMPIRE MAY 16 Speaker: Steve Mize Affiliation: Airgas Topic: Welding gas mixtures Activity: This New Mexico Section event was held at Airgas in Albuquerque, N. Mex.
UTAH MAY 1 Activity: The Section assisted Boy Scouts in Troop 895, West Point, Utah, to earn their welding merit badges. Travis Harding, special process engineer, headed the training program. The event was held at the Weber Applied Technology Center in Ogden, Utah. 80
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APRIL 27 Activity: The Section’s board met to discuss the upcoming District 21 conference and to introduce new board members Tim Chubbs and Ladon Gilbert. Others attending were Tim Serviss, Robert Doiron, Che Chancy, Kenny Reid, George Rolla, and Mariana Ludmer.
SAN FERNANDO VALLEY MAY 2 Speaker: Neil Chapman, lead welding engineer Affiliation: Entergy Northeast Topic: Welding repairs in nuclear power plants Activity: The dinner and meeting were
held at Aero Bending Co. in Palmdale, Calif., hosted by Robert Burns, president. Following the talk, Burns guided the members on a tour of the facility that specializes in precision tube bending for the aerospace industry.
District 22 Kerry E. Shatell, director (925) 866-5434
[email protected]
International Section GERMANY CALENDAR Essen, Germany SEPT. 11–17 66th IIW Annual Assembly 2013 Int’l Trade Fair Joining, Cutting, Surfacing SEPT. 16, 17 Int’l Conf. on Automation in Welding SEPT. 16–21 Young Welders’ Competitions www.iiw2013.com
Guide to AWS Services American Welding Society 8669 Doral Blvd., Ste. 130, Doral, FL 33166 (800/305) 443-9353; FAX (305) 443-7559; www.aws.org Staff phone extensions are shown in parentheses. AWS PRESIDENT
INTERNATIONAL SALES
TECHNICAL SERVICES
Nancy C. Cole
[email protected] NCC Engineering 2735 Robert Oliver Ave. Fernandina Beach, FL 32034
Managing Director, Global Exposition Sales Joe
[email protected] . . . . . . . . . . . . . . . .(297)
Dept. information . . . . . . . . . . . . . . . . . . . . . . .(340) Managing Director Technical Services Development & Systems Andrew R. Davis..
[email protected] . . . . . . .(466) International Standards Activities, American Council of the International Institute of Welding (IIW)
ADMINISTRATION Executive Director Ray W. Shook..
[email protected] . . . . . . . . . .(210) Sr. Associate Executive Director Cassie R. Burrell..
[email protected] . . . . . .(253) Chief Financial Officer Gesana Villegas..
[email protected] . . . . . .(252) Chief Marketing Officer Bill
[email protected] . . . . . . . . . . . . .(211) Chief Technology Officer Dennis
[email protected] . . . . . . . . .(213) Executive Assistant for Board Services Gricelda Manalich..
[email protected] . . . . .(294)
Administrative Services Managing Director Jim Lankford..
[email protected] . . . . . . . . . . . . .(214) IT Network Director Armando
[email protected] . .(296)
Corporate Director, International Sales Jeff P.
[email protected] . . . . . . .(233) Oversees international business activities involving certification, publication, and membership.
PUBLICATION SERVICES Dept. information . . . . . . . . . . . . . . . . . . . . . . .(275) Managing Director Andrew Cullison..
[email protected] . . . . . .(249)
Welding Journal Publisher Andrew Cullison..
[email protected] . . . . . .(249) Editor Mary Ruth Johnsen..
[email protected] . .(238) National Sales Director Rob Saltzstein..
[email protected] . . . . . . . . . . .(243) Society and Section News Editor Howard
[email protected] . .(244)
Welding Handbook Editor Annette O’Brien..
[email protected] . . . . . . .(303)
MARKETING COMMUNICATIONS
Director Hidail Nuñ
[email protected] . . . . . . . . . . . .(287)
Director Ross Hancock..
[email protected] . . . . . . .(226)
Director of IT Operations Natalia
[email protected] . . . . . . . . . .(245)
Public Relations Manager Cindy
[email protected] . . . . . . . . . . . .(416)
Human Resources
Webmaster Jose
[email protected] . . . . . . . . .(456)
Director, Compensation and Benefits Luisa Hernandez..
[email protected] . . . . . . . . .(266) Director, Human Resources Dora A. Shade..
[email protected] . . . . . . . . .(235)
International Institute of Welding Senior Coordinator Sissibeth Lopez . .
[email protected] . . . . . . . . .(319) Liaison services with other national and international societies and standards organizations.
GOVERNMENT LIAISON SERVICES Hugh K. Webster . . . . . . . .
[email protected] Webster, Chamberlain & Bean, Washington, D.C., (202) 785-9500; FAX (202) 835-0243. Monitors federal issues of importance to the industry.
CONVENTION and EXPOSITIONS Director, Convention and Meeting Services Matthew
[email protected] . . . . . . .(239)
ITSA — International Thermal Spray Association Senior Manager and Editor Kathy
[email protected] . . .(232)
RWMA — Resistance Welding Manufacturing Alliance Management Specialist Keila
[email protected] . . . .(444)
WEMCO — Association of Welding Manufacturers Management Specialist Keila
[email protected] . . . .(444)
Brazing and Soldering Manufacturers’ Committee Jeff Weber..
[email protected] . . . . . . . . . . . . .(246)
GAWDA — Gases and Welding Distributors Association Executive Director John Ospina..
[email protected] . . . . . . . . . .(462) Operations Manager Natasha Alexis..
[email protected] . . . . . . . . .(401)
Section Web Editor Henry
[email protected] . . . . . . . . .(452)
MEMBER SERVICES Dept. information . . . . . . . . . . . . . . . . . . . . . . .(480) Sr. Associate Executive Director Cassie R. Burrell..
[email protected] . . . . . .(253) Director Rhenda A. Kenny...
[email protected] . . . . . .(260) Serves as a liaison between Section members and AWS headquarters.
CERTIFICATION SERVICES Dept. information . . . . . . . . . . . . . . . . . . . . . . .(273) Managing Director John L. Gayler..
[email protected] . . . . . . . . . .(472) Oversees all certification activities including all international certification programs. Director, Certification Operations Terry
[email protected] . . . . . . . . . . . . .(470) Oversees application processing, renewals, and exam scoring. Director, Certification Programs Linda
[email protected] . . . . . . .(298) Oversees the development of new certification programs, as well as AWS-Accredited Test Facilities, and AWS Certified Welding Fabricators.
EDUCATION SERVICES
Director, Technical Services Operations Annette Alonso..
[email protected] . . . . . . .(299) Associate Director, Technical Services Operations Alex Diaz....
[email protected] . . . . . . . . . . . . . .(304) Welding Qualification, Sheet Metal Welding, Aircraft and Aerospace, Joining of Metals and Alloys Manager, Safety and Health Stephen P. Hedrick..
[email protected] . . . . . .(305) Metric Practice, Safety and Health, Joining of Plastics and Composites, Welding Iron Castings, Personnel and Facilities Qualification Managing Engineer, Standards Brian McGrath ....
[email protected] . . . . .(311) Structural Welding, Methods of Inspection, Mechanical Testing of Welds, Welding in Marine Construction, Piping and Tubing Senior Staff Engineer Rakesh Gupta..
[email protected] . . . . . . . . . .(301) Filler Metals and Allied Materials, International Filler Metals, UNS Numbers Assignment, Arc Welding and Cutting Processes Standards Program Managers Efram Abrams..
[email protected] . . . . . . . .(307) Thermal Spray, Automotive, Resistance Welding, Machinery and Equipment Stephen Borrero...
[email protected] . . . . .(334) Brazing and Soldering, Brazing Filler Metals and Fluxes, Brazing Handbook, Soldering Handbook, Railroad Welding, Definitions and Symbols Patrick Henry..
[email protected] . . . . . . . . . .(215) Friction Welding, Oxyfuel Gas Welding and Cutting, High-Energy Beam Welding, Robotics Welding, Welding in Sanitary Applications
Note: Official interpretations of AWS standards may be obtained only by sending a request in writing to Andrew R. Davis, managing director, Technical Services,
[email protected]. Oral opinions on AWS standards may be rendered, however, oral opinions do not constitute official or unofficial opinions or interpretations of AWS. In addition, oral opinions are informal and should not be used as a substitute for an official interpretation.
AWS FOUNDATION, Inc. www.aws.org/w/a/foundation General Information (800/305) 443-9353, ext. 212,
[email protected] Chairman, Board of Trustees Gerald D. Uttrachi Executive Director, Foundation Sam Gentry..
[email protected]. . . . . . . . . . . . . . . (331)
Director, Operations Martica Ventura..
[email protected] . . . . . .(224)
Corporate Director, Workforce Development Monica Pfarr..
[email protected]. . . . . . . . . . . . . . . . (461)
Director, Education Development David Hernandez..
[email protected] . . .(219)
The AWS Foundation is a not-for-profit corporation established to provide support for the educational and scientific endeavors of the American Welding Society.
AWS AWARDS, FELLOWS, COUNSELORS Senior Manager Wendy S. Reeve..
[email protected] . . . . . . . .(293) Coordinates AWS awards, Fellow, Counselor nominees.
Promote the Foundation’s work with your financial support. For information, call Vicki Pinsky, (800/305) 443-9353, ext. 212; e-mail
[email protected].
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PERSONNEL
Lincoln Promotes Two to Fill Key Sales Posts Lincoln Electric Holdings, Inc., Cleveland, Ohio, has promoted Michael S. Mintun to VP sales and marketing — North America, and Phil Bouchard to U.S. sales manager. Previously, Mintun served as VP of sales — North America and Bouchard was north central regional manager.
MSCI Elects Chair The Metals Service Center Institute (MSCI), Rolling Meadows, Ill., has elected David H. Hannah, previously vice chair, to chairman of the board. He succeeds Michael H. Hoffman, vice chair of Kloeckner Metals, who served in the post for two years. Hannah is chairman and CEO of Reliance Steel & Aluminum Co. in Los Angeles, Calif. Brian R. Hedges was named a new vice chair. He is president and CEO of Russel Metals, Inc., Mississauga, Ont., Canada.
V. Nakonechnyy
Kevin Barton
Fronius Fills Three Sales Positions
Michael Mintun
Phil Bouchard
Fronius USA, LLC, Portage, Ind., a manufacturer of welding equipment, has promoted Vadim Nakonechnyy to area sales manager for its southeast region,
Matthew Chynoweth
responsible for Georgia, Florida, the Carolinas, Virginia, and West Virginia. Kevin Barton was hired as sales/application engineer for its Chattanooga, Tenn., office, filling Nakonechnyy’s former position. Barton has nine years’ experience as a CNC machinist and robot programmer. Matthew Chynoweth, a recent Ferris State University welding technology graduate, was hired as a sales/system engineer, based in the Portage office.
Mazak Optonics Names Southwest Sales Manager Mazak Optonics Corp, Elgin, Ill., a provider of laser cutting systems, has named David Widlund regional sales manager for its southwest territory, including Arizona, New Mexico, David Widlund Texas, Oklahoma, Kansas, Missouri, Arkansas, and Louisiana. Widlund has 12 years’ experience in the sheet metal fabrication industry, laser production management, direct sales, and most recently as a regional sales manager. For info go to www.aws.org/ad-index
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Member Milestones Edward N. C. Dalder
Ernest D. Levert Sr.
Edward N. C. Dalder, an AWS Gold Member, affiliated with the San Francisco Section, has been recognized by Continental Who’s Who as a Pinnacle Professional in the field of engineering. He was cited for his achievements as vice president of Dalder Materials Consulting, Inc., in the areas of welding engineering, failure analysis, metallurgy and process selection, and accident reconstruction. His papers have been published in the Welding Journal, Materials Transactions, and Cryogenic Engineering Conference Proceedings. Dalder earned his PhD in welding engineering from The Ohio State University.
Ernest D. Levert Sr., an AWS past president and member of the North Texas Section, has been named one of “180 of the nation’s top African American scientists” by The HistoryMakers. Levert was chosen as “a positive role model whose life story will be used to encourage others to enter scientific professions.” His biography is posted online at www.thehistorymakers.com/makers/sciencemakers. Levert is a senior staff manufacturing engineer at Lockheed Martin Missiles, Fire Control Div., Dallas, Tex., where he received its NOVA Award for Outstanding Leadership. He has worked on the Space Shuttle, International Space Station,
Multiple Launch Rocket System, and the Army Tactical Missile System. He chaired IIW Commission IV, Power Beam Processes, and was 2007 president of the Federation of Material Societies. He has contributed to the AWS Ernest Levert Sr. Welding Handbook and Boy Scouts of America Welding Merit Badge Book. The Ohio State University School of Engineering awarded him its Outstanding and Distinguished Alumni Awards.
For info go to www.aws.org/ad-index
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Obituaries
Robert J. Dybas
William Thomas Phillips
Robert J. Dybas, an AWS Gold Member, died March 19 in Niskayuna, N.Y. He served as chair of the AWS Northern New York Section where he received the Meritorious Certificate Award. At GE, he reRobert Dybas ceived its Industrial and Power Systems Engineering Award.
William Thomas Phillips, 79, died May 9. A long-time resident of Northville, Mich., he was founder and chairman of the board of Phillips Service Industries, Inc., Livonia, Mich., the $130-million parent company of POWERTHRU™, Beaver Aerospace & Defense, Sciaky, Inc., Evana Automation Specialists, Mountain Secure Systems, and Skytronics, Inc. During the Korean War, he served as a hydraulic technician and line chief in the U.S. Air Force, based in Newfoundland, Canada. William Phillips
Gordon Eugene Smith Gordon Eugene Smith, 65, died March 21 in Columbus, Ohio. In 1977, he became one of the first ASNT Certified NDT Level III engineers. He worked for Marion Power Shovel, GE Plastics, ASNT in the area of personnel certification and qualification, and H.C.Nutting Co. as design consultant. Most recently,
Smith was senior engineer with JonesStuckey, Ltd., Inc., a civil engineering firm. He has authored numerous publications on inspection and the prevention of cracking in bridge structures.
Randal Keith Easterwood Randal Keith Easterwood, 58, died March 30 in Mesa, Ariz. In the U.S. Air Force he trained welders. Later, he joined Honeywell Aerospace where he worked his entire career, serving as an engineer in the Material and Process R. K. Easterwood Engineering department and conducting training worldwide. Easterwood was active with SkillsUSA at the state and national levels, where he participated in welding contests for more than 25 years.◆
$ $6450.3&13*/54 6450.3&13*/54
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[email protected] For info go to www.aws.org/ad-index
86
JULY 2013
The Emmet A. Craig
RESISTANCE WELDING SCHOOL
November 19-20,, 2013 2013 McCormick Place, Chicago, IL
To T o register go to www www.fabtechexpo.com w.fabtec .fabtechexpo.com . Space is limited
An Association of Welding Manufacturers
Pictured at the 2012 Image of Welding Welding e A Awards wards
(from left) are Ernest D. Levert (Individual); David Parker (Educator); Allie Reynolds (Distributor, (Distributorr, WELSCO); WEL David Corbin (Large Business, V Vermeer ermeer Corp.); and Glenn Kay (Educational ducational Facility, Facilityy, Washtenaw Washtenaw Community College). (Not shown are the Small Business, A AWS WS Section, and Media winners.)
A AWS WS Houston Section 2012 A AWS WS IOW Section A Award ward Winner
Know an individual, company, educator, or educational facility that exemplifies what welding is all about?
Nominate them! Thee Image of Welding Weld e ding Awards Aw wards Program recognizes recognizees outstanding achievement hievement in the following categories:
Individual
Section
Large Busin Business
(you or other individual)
(AWS (A AWS W local chapter)
WELSCO 2012 IOW Distributor Award Award ard Winn Winner
Small Business Busin (less than 200 employees)
Educator
(welding teacher at an institution, facility facility,, etc.)
Educational Facility
(any organization that conducts welding education or training)
(200 or more employees)
Distributor
(welding products)
Media
(imagpromoting (imagpromoting article or news broadcast)
Entry deadline is July 31, 2013
Vermeer Manufacturing Vermeer 2012 IOW Large Business Award Award Winner
For more information and to submit a nomination form online, visit www www.aws.org/awards/image.html .aws.org/awards/image.html or call 800-443-9353.
BRAZIL WELDING SHOW OCT. 1 – 4, 2013 São Paulo Trade Show and Congress Essen Trade Shows Karen Vogelsang Tel. +1. 9 14. 9 62-13 10
[email protected] www.schweissen-schneiden.com
In cooperation with:
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SEPT. 16– 21, 2013 ESSEN RUSSIA
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CHINA
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JUNE 25–28, 2013 MOSCOW ARABIA
JAN. 10–13, 2015 DUBAI
19,500-sq-ft facility near Pittsburgh, Pa. It supports global orders with regional manufacturing and instrument repair.
NEWS OF THE INDUSTRY — continued from page 12
• ILMO Products Co., Jacksonville, Ill., an industrial gases distributor, is celebrating its 100th anniversary in 2013. It surprised all 97 employees with $100 on the 100th day of the year.
• Iron Man 3 features Lincoln Electric welding equipment used by actor Robert Downey Jr.’s character, Tony Stark/Iron Man, to fabricate his armored suit, various tools, and weapons.
• Hyundai Heavy Industries has developed mini welding robots
• PFERD, Leominster, Mass., has a new tool mobile program in North America. Application specialists have the resources to instantly address and troubleshoot challenges on-site.
• Workshops for Warriors, San Diego, Calif., a metalworking training facility for veterans, has earned accreditation from the National Institute for Metalworking Skills®.
• Freudenberg Sealing Technologies’ laser welding process has won a Manufacturing Leadership 100 Sustainability Award from Frost & Sullivan’s Manufacturing Leadership Council.
for building ships. The design measures 50 × 30 × 15 cm when its welding arm is retracted. The robot has six joints as well.
• SMS Meer, Germany, has received an order from California
• ESAB Cutting Systems, Florence, S.C., has been awarded the
Steel Industries for delivering a 24-in., high-frequency tube welding line. It will be brought into service in 2014.
2013 Gold Stevie Award for sales and customer service, recognized as the “Sales Turnaround of the Year.” ESAB Welding & Cutting Products has also launched a blog that will feature posts on CNC cutting systems and various processes.
• USA Tank has expanded its manufacturing capabilities to in-
• Lucas-Milhaupt, Inc., has acquired the assets of Wolverine
• Great Falls College Montana State University recently an-
Joining Technologies, Warwick, R.I. It will operate as LucasMilhaupt Warwick LLC and provide the company with a primary domestic mill for brazing consumables.
nounced a $30,000 donation from General Distributing Co. to be used, in part, for supporting the welding program’s needs.
clude shop welded tanks. This division will be located in Goodman, Mo., in the 100,000-sq-ft manufacturing facility.
• Many robotic welding enhancements, including new fixtures • More than 1400 experts recently gathered in Livonia, Mich., at
and add-ons, have been made to Gilchrist Metal Fabricating Co.’s 70,000-sq-ft metal fabrication facility in Hudson, N.H.
the Great Designs in Steel seminar. More than 35 presentations on all aspects of advanced high-strength steel design, development, and use showed the future for these materials.
• Tom Spika and Spika Welding, a small, family enterprise, re-
• Operations have gone live at Industrial Scientific’s newly leased
ceived the first Manufacturer of the Year award in Helena presented by the Montana Manufacturing Council.◆
For info go to www.aws.org/ad-index
WELDING JOURNAL
91
PRODUCT & PRINT SPOTLIGHT — continued from page 26
color images, a broad range of accessories to enhance materials testing systems. The 420-page catalog features detailed product information on grips, extensometers, fixtures, environmental chambers, load cells, furnaces, and other materials testing accessories. Many items in the catalog can be adapted to suit testing equipment from other manufacturers. Highlighted is the new AutoX 750 automatic extensometer and Bluehill® TrendTracker™ used for managing and analyzing test results.
zirconia sensor. Designed for personnel in welding and quality departments, this monitor is suitable for weld purging of all stainless, duplex, and superduplex steels, as well as titanium, zirconium, and nickel alloys. It has many applications for weld purging tube and pipe joints, either with manual or orbital welding techniques, and welding chambers, boxes, and enclosures to ensure the internal atmosphere is reduced to 10 parts/million of oxygen or less. Huntingdon Fusion Techniques Ltd. www.huntingdonfusion.com (800) 431-1311
Power Units Useful for Many Electronic Devices
Instron based analyzer, as well as the S1 TitanSP, Si-PIN based analyzer. This optional accessory can be ordered with either model when buying a new unit.
www.instron.com (800) 564-8378
Weld Shaver Features Adjustable Depth of Cut
Bruker Corp. www.bruker.com/shield (509) 783-9850
Downdraft Tables Contain Flame-Retardant Filters
The WS90 weld shaver is hand-held, operates at 2.3 hp, and weighs 12 lb. It uses indexable carbide inserts in a milling cutting tool to remove weld beads from both flat butt-joint welds and inside 90 deg fillet welds. The new model also features an adjustable depth of cut and an adjustable fence, making it easy to remove only a weld bead and not the surrounding primary materials. Heck Industries www.heckind.net (810) 632-5400
Monitor Measures Oxygen down to 1 Part/Million
The Power Swap System allows the company’s NB Series workstations to operate 24 h a day with no recharging break. The workstations, which can run computers, printers, scales, testers, scanners, and other electronic hardware, provide AC power without extension cords or ceiling drops. The system is useful for facilities with multiple work shifts or applications that draw enough power to shorten typical battery life. The power units are on swivel casters, and their connectors work with the workstation’s ports. They include a UL- and CSA-approved inverter/ charger package and digital remote meter with a color-coded LED display. Newcastle Systems www.newcastlesys.com (781) 935-3450
Shield Protects Analyzer’s Detector Window
The PurgEye® 300 Nano Weld Purge MonitorTM has been updated to read down to 1 part/million using a new-style
The Titan Detector Shield™, a patent pending accessory, protects the detector window from being punctured by sharp objects like scrap shavings and wires, while allowing analysis of almost any material. It also minimizes the chance that the detector will be damaged. This does not sacrifice the instrument’s analytical performance, even for light elements like magnesium, aluminum, and silicon. The shield is available for both the S1 TitanLE, SDD
The company’s downdraft tables protect workers from smoke, fumes, and particles generated during grinding, welding, or sanding. They are designed to pass pollutants and sparks over water pans to protect the filters and reduce fire risk. Flameretardant cartridge filters are standard. They are made of 100% spunbond polyester and remove particulates down to 0.5 micron with a 99.95% efficiency rate. A jet pulse system cleans the filters using compressed air. The standard table top is a 1⁄4-in. steel plate. Holes around the top’s perimeter create a higher air flow near the spark shield and work area. The tables are available from 26 × 35 in. for small or single work cells to a large 48 × 96 in. table. Denray Machine, Inc. www.denray.com (800) 766-8263
WELDING JOURNAL
93
pp Excellent Feedability Premium Copper Coating
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FOR DETAILS CALL OR E-MAIL: (800) 489-2890
[email protected] Also offering: 9–Year CWI Recertification, RT Film Interpretation, MT/PT/UT Thickness, Welding Procedure Fundamentals, CWS, SCWI, Advanced Inspection Courses
SERVICES
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JOE FULLER LLC We manufacture tank turning rolls 3-ton through 120-ton rolls www.joefuller.com
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[email protected] Phone: (979) 277-8343 Fax: (281) 290-6184 Our products are made in the USA
(800) 443-9353, ext. 465
[email protected] WELDING JOURNAL
97
ADVERTISER INDEX ALM Materials Handling Positioners . . . . . . . . . . . . . . . . . . . .11 www.almmh.com . . . . . . . . . . . . . . . . . . . . . . . . . . .(815) 673-5546
Lincoln Electric Co. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .OBC www.lincolnelectric.com . . . . . . . . . . . . . . . . . . . . .(216) 481-8100
Arc Machines, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 www.arcmachines.com . . . . . . . . . . . . . . . . . . . . . .(818) 896-9556
Magnatech, LLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 www.MagnatechLLC.com . . . . . . . . . . . . . . . . . . . .(860) 653-2573
Arcos Industries, LLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .IBC www.arcos.us . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(800) 233-8460
Mathey Dearman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 www.matheycnc.com . . . . . . . . . . . . . . . . . . . . . . . .(918) 447-1288
AWS Education Services . . . . . . . . . . . . . . . . . . . . . . . . .62, 92, 96 www.aws.org/education/ . . . . . . . . . . . . . . . . . . . . .(800) 443-9353
Mercer Abrasives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59 www.mercerabrasives.com . . . . . . . . . . . . . . . . . . .(631) 243-3900
AWS Membership Services . . . . . . . . . . . . . . . . . . . . . . . . . .90, 94 www.aws.org/membership/ . . . . . . . . . . . . . . . . . . .(800) 443-9353
Micro Air Clean Air Systems . . . . . . . . . . . . . . . . . . . . . . . . . . .19 www.microaironline.com . . . . . . . . . . . . . . . . . . . .(866) 566-4276
Bonal Technologies, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 www.Meta-Lax.com . . . . . . . . . . . . . . . . . . . . . . . . .(800) 638-2529
Midalloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 www.midalloy.com . . . . . . . . . . . . . . . . . . . . . . . . . .(800) 776-3300
Camfil Air Pollution Control . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 www.camfilapc.com . . . . . . . . . . . . . . . . . . . . . . . . .(800) 479-6801
National Bronze & Metals, Inc. . . . . . . . . . . . . . . . . . . . . . . . . .84 www.nbmmetals.com . . . . . . . . . . . . . . . . . . . . . . . .(713) 869-9600
Champion Welding Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86 www.championwelding.com . . . . . . . . . . . . . . . . . .(800) 321-9353
National Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 www.NationalStandard.com . . . . . . . . . . . . . . . . . .(800) 777-1618
CM Industries, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 www.cmindustries.com . . . . . . . . . . . . . . . . . . . . . .(847) 550-0033
Netbraze LLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53 www.netbraze.com . . . . . . . . . . . . . . . . . . . . . . . . . .(855) 444-1440
Commercial Diving Academy . . . . . . . . . . . . . . . . . . . . . . . . . . .17 www.commercialdivingacademy.com . . . . . . . . . . .(888) 974-2232
OTC Daihen, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51 www.daihen-usa.com . . . . . . . . . . . . . . . . . . . . . . . .(888) 682-7626
Cor-Met . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 www.cor-met.com . . . . . . . . . . . . . . . . . . . . . . . . . . .(800) 848-2719
Red-D-Arc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 www.reddarc.com . . . . . . . . . . . . . . . . . . . . . . . . . . .(866) 733-3272
Diamond Ground Products, Inc. . . . . . . . . . . . . . . . . . . . . . . . .91 www.diamondground.com . . . . . . . . . . . . . . . . . . .(805) 498-3837
Revco Industries, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 www.bsxgear.com . . . . . . . . . . . . . . . . . . . . . . . . . . .(800) 527-3826
ESAB Welding and Cutting . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 www.esabna.com . . . . . . . . . . . . . . . . . . . . . . . . . . .(800) 372-2123
RWMA/Resistance Welding Manufacturing Alliance . . . . . . . .87 www.aws.org/rwma . . . . . . . . . . . . . . . . . .(800) 443-9353, ext. 444
ESSEN Welding Show/Brazil . . . . . . . . . . . . . . . . . . . . . . . . . . .89 www.schweissen-schneiden.com . . . . . . . . . . . .001-914-962-1310
Schaefer Ventilation Equipment . . . . . . . . . . . . . . . . . . . . . . . . .12 www.schaeferfan.com . . . . . . . . . . . . . . . . . . . . . . .(800) 779-3267
FABTECH 2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61 www.fabtechexpo.com . . . . . . . . . . . . . . .(800) 443-9353, ext. 297
Select Arc, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .IFC www.select-arc.com . . . . . . . . . . . . . . . . . . . . . . . . .(937) 295-5215
Fischer Engineering Co. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86 www.fischerengr.com . . . . . . . . . . . . . . . . . . . . . . . .(937) 754-1750
Sumner Manufacturing Co., Inc. . . . . . . . . . . . . . . . . . . . . . . . .10 www.sumner.com . . . . . . . . . . . . . . . . . . . . . . . . . . .(888) 999-6910
Fronius USA, LLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 www.fronius-usa.com . . . . . . . . . . . . . . . . . . . . . . .(877) 376-6487
Tianjin Leigong Welding Alloys . . . . . . . . . . . . . . . . . . . . . . . . .52 www.hardfacing.en.alibaba.com . . . . . . . . . . . .+86-13752201959
Gedik Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85 www.gedikwelding.com . . . . . . . . . . . . . . . . . . .+90 216 378 50 00
Tip Tig USA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26, 43, 50 www.tiptigusa.com . . . . . . . . . . . . . . . . . . . . . . . . . .(856) 312-8164
Greiner Industries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 www.greinerindustries.com . . . . . . . . . . . . . . . . . .(800) 782-2110
TRUMPF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 www.us.trumpf.com . . . . . . . . . . . . . . . . . . . . . . .web contact only
Gullco International, Inc. - U.S.A. . . . . . . . . . . . . . . . . . . . . . . .53 www.gullco.com . . . . . . . . . . . . . . . . . . . . . . . . . . . .(440) 439-8333
Weld Aid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55 www.weldaid.com . . . . . . . . . . . . . . . . . . . . . . . . . . .(800) 935-3243
Harris Products Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57 www.harrisproductsgroup.com . . . . . . . . . . . . . . .(800) 733-4043
Weld Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47 www.weldengineering.com . . . . . . . . . . . . . . . . . . .(508) 842-2224
Hobart Inst. of Welding Technology . . . . . . . . . . . . . . . . . . . . . .12 www.welding.org . . . . . . . . . . . . . . . . . . . . . . . . . . .(800) 332-9448
Weld Hugger, LLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 www.weldhugger.com . . . . . . . . . . . . . . . . . . . . . . . .(877) 935-3447
Image of Welding/WEMCO . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88 www.aws.org . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(800) 443-9353 K.I.W.O.T.O., Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54 www.rodguard.net . . . . . . . . . . . . . . . . . . . . . . . . . .(269) 944-1552 Koike Aronson, Inc./Ransome . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 www.koike.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(800) 621-4025 98
JULY 2013
IFC = Inside Front Cover IBC = Inside Back Cover OBC = Outside Back Cover
Visit the AWS Interactive Ad Index: www.aws.org/ad-index
SUPPLEMENT TO THE WELDING JOURNAL, JULY 2013 Sponsored by the American Welding Society and the Welding Research Council
Vacuum-Assisted Laser Welding of Zinc-Coated Steels in a Gap-Free Lap Joint Configuration High-quality welds were produced with a new laser process that stabilized the keyhole to allow the zinc vapors to escape
ABSTRACT Zinc-coated steels are increasingly used in the automotive industry due to their excellent corrosion resistance and long-term mechanical performance. However, it is still a great challenge to weld zinc-coated steels in a gap-free lap joint configuration. When zinc vaporizes at 906°C, which is much lower than the melting temperature of steel (1300°C), a high-pressure vapor will be generated at the faying interface of the steel sheets. If the zinc vapor is not appropriately vented out, a weld discontinuity such as porosity is usually produced in the weld and spatter is expelled from the weld. In this paper, a new laser welding process is proposed to join zinc-coated steels in a gap-free lap joint configuration. The new process uses a suction device to create a negative pressure zone (relative to ambient) directly above the molten pool. The purpose of this negative pressure zone is two-fold. First, a drag force is generated due to the external suction device, which can counterbalance the shear force induced by the erupting zinc vapor. Secondly, the negative pressure zone facilitates the zinc vapor to escape along the suction direction. As a result, the molten pool becomes more stable and the keyhole will remain open to allow the escape of zinc vapor. With vacuum assist, welds free of spatter and porosity can be obtained. In addition, mechanical properties of the welds are evaluated by tensile shear test and microhardness measurements.
Introduction To reduce vehicle weight and improve fuel efficiency, high-strength steels are increasingly used in the automotive industry. These steels are usually coated with zinc, which provides an excellent corrosion resistance for a typical guarantee of up to ten years’ corrosion protection for automotive body panels. However, the presence of zinc coating in the metal sheets poses several severe issues for welding. When welding the zinc-coated steels in a gap-free lap joint configuration, a highlypressurized zinc vapor is readily produced at the interface of two coated metal sheets because of the lower boiling point of zinc (906°C) compared to the melting point of steel (above 1300°C). If the generation of zinc vapor at the interface of the metal S. YANG (
[email protected]), J. WANG, , AND J. ZHANG are with GM China Science Lab, Pudong, Shanghai, China. B. E. CARLSON is with General Motors R & D Center, Warren, Mich.
sheets is not suppressed, various weld discrepancies such as spatter and porosity will be produced during welding. Consequently, the resultant mechanical properties are degraded, and repair is usually required after the welding process. With respect to high welding speeds and low heat input, various laser welding techniques have attracted tremendous attention from industry. In the past several decades, many efforts were made around the world in order to achieve a sound weld in zinc-coated steels. The American Welding Society set a standard of removing the
KEYWORDS Zinc-Coated Steels Gap-Free Lap Joint Single Laser Beam Weld Dicontinuities Negative Pressure Zone Suction Device
zinc coating layer at the interface of metal sheets completely, prior to welding zinccoated steels (Refs. 1, 2). A common way for industries to weld zinc-coated steels is to include a spacer with the thickness of about 0.1–0.2 mm at the interface of metal sheets. The gap created by the spacer facilitates the zinc vapor escape from the interface of metal sheets resulting in high-quality welds (Ref. 3). Alloying the zinc with copper is another way to weld zinc-coated steels (Ref. 4). Before the steel is melted, a zinc-copper compound is formed, which has a higher melting point (1083°C) than the boiling point of zinc. Hence, the formation of highly pressurized zinc vapor is avoided. Similarly, a thin aluminum alloy foil was set along the weld line at the interface of metal sheets in order to alloy the zinc. Under the heat from the laser, an Al-Zn compound was formed, resulting in a reduced pressure level of zinc vapor (Refs. 5, 6). One potential issue for using this method was that the mechanical properties of welds could be degraded by excessive dissolution of aluminum into the welds (Refs. 5, 6). In addition, methods of depositing a nickel coating having a high melting point along the weld line at the interface of metal sheets (Refs. 7, 8), using dual beam or two lasers (Refs. 9–13), pulsed laser (Ref. 14), and hybrid laser welding (Refs. 14–19), have been proposed to weld zinc-coated steels. Wang et al. (Ref. 20) proposed a method of using a laser to cut a slot for the zinc vapor to escape from the interface of the metal sheets and using the second laser to weld the metal sheets. Speranza et al. (Ref. 21) suggested a method of introducing a metal powder, which can alloy with the zinc, into the molten pool produced by the laser beam, thereby reducing the weld porosity and spatter. Recently, Yang et al. (Ref. 22) developed a hybrid laser arc welding process that employed a gas tungsten arc welding
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BY S. YANG, J. WANG, B. E. CARLSON, AND J. ZHANG
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Fig. 2 — Typical laser welds in zinc-coated steels. A — Top view; B — bottom view. (Laser power 3.4 kW; welding speed 1.8 m/min).
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Fig. 1 — Experimental setup of vacuum-assisted (welding direction: right to left).
(GTAW) preheating technique to weld zinc-coated, high-strength, dual-phase steels in a gap-free lap joint configuration where GTAW preheating leads the laser beam and simultaneously moves with the laser beam. With the GTAW preheating, a portion of the zinc along the weld line at the interface of metal sheets is vaporized and part of the zinc is transformed into zinc oxide, which has a melting point (above 1900°C) greater than that of steel. Under these welding conditions, a completely defect-free weld in the zinc-coated steels was achieved. Furthermore, Yang et al. (Ref. 23) optimized the shielding conditions to stabilize the molten pool, thus achieving a constantly open stable keyhole. The stable keyhole provides a channel that allows the zinc vapor to escape from the interface of the metal sheets. Consequently, the molten pool is not disturbed by the zinc vapor and the formation of spatter and porosity in the welds is eliminated. Gu et al. (Ref. 25) utilized a remote laser welding technique with a high scanning speed called laser dimpling to create a dimple prior to welding, which provides a gap for the subsequent laser welding of the zinc-coated steels. Sound welds were obtained with this laser dimpling technology. In addition, Kim et al. (Ref. 24) developed a CO2 laser microplasma arc hybrid welding to weld zinccoated steels. Although the aforementioned methods can address the issues arising from the welding of the zinc-coated steels in a lap joint configuration, there exist some limitations, such as high cost for implementation in the automotive industry. In order 198-s JULY 2013, VOL. 92
to reduce the cost and cycle time, the automotive industry looks for simple and flexible laser welding techniques, using a single laser beam to weld the zinccoated steels in a gap-free laser welding lap joint configuration. Therefore, it becomes necessary to develop a new laser welding technique which can flexibly weld zinc-coated steels in a gapfree lap joint. In this study, a 4-kW fiber laser was used to weld the zinc-coated steels. A suction device was developed to create a negative pressure zone directly above the molten pool. The presence of the negative pressure zone had two effects: The first was to help the generated zinc vapor to escape along the suction direction, and the second was to maintain the molten pool stability. In addition, tensile shear and microhardness tests were carried out to assess the weld mechanical properties.
Experimental Setup The materials used in this study were zinc-coated dual-phase (DP590) steels. The zinc coating was hot dipped at a level of 60 g/m2 per side. The tested coupons had the following dimensions: 120 × 85 × 1 mm. The two metal sheets were then tightly clamped together during the laser welding process so that there was no joint clearance. The overlap length between the two metal sheets was 25 mm, and the laser beam was located at the center of overlap. The lap-shear samples did not contain the start and stop of the welds. The laser welding process was performed with a 4-kW fiber laser. A multimode laser beam was brought into the laser welding head by an optical fiber and focused on the top surface of the workpiece. The laser spot diameter at focus was 0.3 mm. A high-speed camera with a frame rate of 4000 fps was used to record images of the laser-induced plasma in order to study its dynamic be-
havior. During the laser welding process, the laser beam was focused on the top surface of the two-sheet stack up. The experimental setup is shown in Fig. 1. The suction device used in this study was an AirStar vacuum cleaner with bag made by Philips (Model: HomeCare-FC8224), which has an input power of 1400 W and a maximum vacuum level of 29 kPa. A copper tube of 8 mm in diameter was connected to the cleaner to provide a negative pressure zone above the welding pool. It was positioned 3 mm in front of the laser beam and 6 mm from the top surface of the workpiece. In addition, the lap joint coupons were sectioned, ground, polished, and etched for hardness measurements and examination using an optical microscope. Vickers microhardness tests were conducted using a load of 100 g and a dwell time of 10 s.
Results and Discussion Issues from laser welding of zinccoated steels in a gap-free lap joint configuration are below. Figure 2 shows the characteristics of typical laser welds in zinc-coated steels. As shown, a large amount of spatter and porosity are produced in the welds. It is well known that the highly pressurized zinc vapor is the root cause of these weld defects. When spatter is produced and expelled along the laser beam propagation direction, coupling of the laser beam energy to the workpiece is impeded resulting in only partial penetration (Fig. 2B) being achieved, even at high power levels. In addition, a turbulent molten pool is always observed due to the large difference in the velocity and pressure between the zinc vapor and the liquid melt. The instability of the molten pool manifests itself in the form of waves, which are generated on the molten pool with the associated swelling and troughs. Under these welding conditions, the laser beam is projected onto the uneven surface of the molten pool. This phenomenon is equivalent to changing the
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position of focus, the spot size, and the focus location of the laser beam, i.e., the laser beam intensity will be distributed unevenly at the spatial and temporal dimensions. Figure 3A and B schematically demonstrates the different mechanisms of the absorption of the laser beam when the keyhole is unstable and stable, respectively. The absorption of the laser beam for the case of a stable keyhole is dramatically improved through multireflection within the keyhole. In contrast, the uneven surface of the turbulent molten pool causes a majority of the laser beam energy to be reflected. When the laser beam is projected onto the surface of the zinccoated steel, the zinc is immediately vaporized as a result of the low boiling point of zinc. Furthermore, a large amount of time varying laser-induced plasma and plume is always produced during the laser welding process (Ref. 25). Previous studies have found that the laser-induced plasma and plume fluctuates in a high frequency and changes its shape and size over time during the welding process (Refs. 11, 25). The uneven surface of the molten pool along with the fluctuating laser-induced plasma and plume deteriorates the coupling efficiency of the laser beam energy into the welded materials. Consequently, the keyhole size and depth changes during the laser welding process and is forced to collapse due to an insufficient power density of the incident laser beam into the workpiece. When the keyhole collapses or the keyhole depth can’t reach the faying interface, the zinc vapor is entrapped and expands inside the molten pool. Once the zinc vapor pressure is beyond the threshold, the vapor bubble and associated liquid metal are ejected out of the molten pool, scattering drops of molten metal in different directions, which deposit onto the surrounding top surface of the workpiece. As a consequence, spatter and porosity are formed. As mentioned
previously, the spatter scattered along the laser beam propagation direction blocks a portion of the incident laser beam energy into the workpiece to be welded. In order to study the real-time dynamic liquid metal behavior, high-speed cameras were used to monitor the welding process. Using a 5-W green laser as an illumination light to suppress the strong laser light enabled the dynamic behavior of the molten pool and the keyhole to be clearly observed. Figure 4 shows ten successive photos taken in the middle of the welding process, which indicate the transformation of a relatively stable molten pool into a turbulent molten pool due to the eruption of zinc vapor. A relatively stable molten pool and a stable keyhole are shown in Fig. 4A where a white spot represents the keyhole and the area inside the blue line represents the molten pool. As shown in Fig. 3B, a stable molten pool has a relatively flat surface with a circular shape of the keyhole as seen from a top view. Evolution of the zinc vapor through the keyhole causes the molten metal behind the keyhole to be pushed back opposite to the welding direction, as shown in Fig. 4B. A trough and a swelling featured as indicated by the yellow line in Fig. 4B are also observed in the molten pool. This phenomenon suggests that the molten pool has become unstable and is fluctuating at some frequency. Additionally, the keyhole begins to disappear in Fig. 4B. By the analysis of the recorded images and direct observation of the laser welding process, it was found that the formation of spatter is associated with some sort of molten pool fluctuation frequency and amplitude of the swelling. Further studies are needed to clarify this relationship. From Fig. 4B to J, the shape of the swelling and troughs vary over time as do the size and shape of the keyhole and the inclined angle of the keyhole with respect to the workpiece. Note that after the molten pool experiences a significant fluc-
tuation and a given volume of liquid melt is ejected out of the molten pool, the molten pool begins to stabilize, as shown in Fig. 4J. It is theorized that the reason for the molten pool to resume a relatively stable condition following a period of turbulence is that the zinc vapor pressure at the faying interface becomes lower than the threshold value after the zinc vapor is released during the turbulent period. Then as the pressure builds up over time to a point where the vapor is emitted from the molten pool, the cyclic nature of the molten pool turbulence is explained. This area of study requires further research. Vacuum-Assisted Laser Welding of Zinc-Coated Steels
In the current body of work, a new method, vacuum-assisted laser welding, is proposed and developed for the welding of zinc-coated steels in a gap-free lap joint configuration where a vacuum system is integrated with the laser system. As shown in Fig. 1, a copper tube connected to the vacuum system is positioned directly in front of the laser focal point. During the laser welding process, the drag force produced by the vacuum system can be adjusted with a change in the pressure level within the vacuum system. Figure 5 shows the initial experimental results, which exhibit neither spatter nor porosity in addition to full penetration. The main reason for achieving sound welds by the vacuum-assisted laser welding process is that a stable and open keyhole can be consistently created, which in turn, provides a stable channel for the zinc vapor to escape. For the conventional single laser beam welding of zinc-coated steels, a large shear force is always present and acts upon the molten pool resulting from the competing forces induced by the upward and lateral moving, unstable zinc vapor and the downward acting laser-induced plasma. Under this large fluctuat-
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Fig. 3 — Effect of keyhole shape on coupling efficiency of laser beam energy. A — Unstable keyhole reflecting a majority of the laser beam; B — stable keyhole coupling where most of the laser beam energy is transferred into the workpiece through multireflection within the keyhole.
B A
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Fig. 4 — Sequenced images of molten pool turbulence during laser welding (power 3.4 kW; welding speed 1.8 m/min) taken at different times. A — t = 1.00000 s; B — t = 1.00025 s; C — t = 1.00050 s; D — t = 1.00075 s; E — t= 1.00100 s; F — t = 1.00125 s; G — t = 1.00150 s; H — t=1.00175 s; I — t = 1.00200 s; J — t = 1.00225 s.
ing shear force as the zinc vapor pressure builds, and subsequently releases, the molten pool becomes dramatically unstable and the keyhole tends to collapse. With the vacuum-assisted laser welding of zinc-
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coated steels, the leading vacuum system guides the laser-induced plasma and plume toward the welding direction, which provides an external force, i.e., a drag force, to counter-balance the shear
force acting on the molten pool surface resulting from the zinc vapor. Figures 6 and 7 illustrate this mechanism. The removal of the laser-induced plasma and plume enhances the coupling
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efficiency of the laser power into the weld. Furthermore, a negative pressure zone is created directly on the top of the molten pool when a vacuum system is used during the laser welding process. This suggests that the pressure level in front of the laser beam is always the lowest. The difference in the pressure level of the highly pressurized zinc vapor and that around the copper tube facilitates the zinc vapor to escape toward the lower pressure zone, i.e., the suction direction. Thus, the applied force on the surface of the molten pool from the zinc vapor and laser-induced plasma is reduced. Under these welding conditions, the molten pool remains stable and the coupling of laser power into the workpiece is consistent. As a consequence, the keyhole is stable and remains open during welding for the zinc vapor to escape. Real-Time Monitoring of Laser-Induced Plasma and Plume
A high-speed camera was used to study the dynamic behavior of the laser-induced plasma. In this case, the illuminating green laser light was not used. Figure 8 presents successive top view images of the laser-induced plasma and plume taken by the high-speed camera. Figure 8A–F indicate the typical characteristics of the laser-induced plasma plume including weld spatter for conventional laser welding and Fig. 8G–M demonstrate the typical characteristics of laser-induced plasma plume with no weld spatter for vacuum-assisted laser welding. As shown in Fig. 8A–F, the laserinduced plasma and plume are highly dynamic and demonstrate rapid change in their shape and size over a short time. Because of the strong force the plasma and plume induce on the molten pool, the molten pool is severely disturbed and becomes very unstable when the laserinduced plasma and plume fluctuates in a large angle with respect to the top surface of the workpiece. Furthermore, changes in the shape and size of the laser-induced plasma and plume influences the coupling efficiency of the laser beam energy into
the workpiece. As a consequence, the keyhole is unstable, and its depth and shape are changed. When the keyhole depth does not reach the faying interface of the two metal sheets or is collapsed, the highly-pressurized zinc vapor can’t find a channel to escape, and it expands inside the molten pool. Consequently, a large amount of liquid metal is expelled from the molten pool and spatter is observed, as shown in Fig. 8A. In contrast, the size and shape of the laser-induced plasma and plume are very stable when the vacuum system is applied. As can be seen in Fig. 8 G–M, the laser-induced plasma and plume are guided by the vacuum system toward the direction of suction, and their shape and size exhibit little change over time. The stability of the laser-induced plasma and plume facilitates coupling of the laser beam energy uniformly into the welded materials. Thus, the keyhole depth and shape do not vary dramatically, which helps the zinc vapor to escape from the interface. It is observed that when the vacuum system is applied, the weld penetration is nearly the same at different locations of the weld. Figure 9 presents a set of six sequenced images of the keyhole and molten pool recorded by a high-speed camera using an illumination light during the vacuum-assisted laser welding. These images clearly show that the shape and size of the keyhole vary within a small range, and the keyhole is maintained open during the entire sequence. The improved stability achieved by vacuum-assisted laser welding can be explained from an energy point of view, by the fact that the suction device improves the molten pool/keyhole stability thereby reducing the effects of defocusing and absorption of laser-induced plasma and plume on the laser beam energy. Figure 10 schematically shows the improved laser beam transmission to the workpiece. According to the Beer-Lambert Law, I(Z)=I0e–αZ
(1)
Fig. 7 — Schematic of the negative pressure zone above the molten pool.
where I is the laser beam energy absorbed by the workpiece, I0 is the incident laser beam energy, α is the absorption coefficient of laser-induced plasma and plume, and Z is the height of the laser-induced plasma and plume. From Equation 1, it is found that changes in the height of the laser-induced plasma and plume are associated with changes in the shape and size of the laser-induced plasma and plume, which alters the amount of laser beam energy transferred to the workpiece. As shown in Fig. 10, the vacuum-assisted laser welding process has a lower height of laser-induced plasma and plume of Z2 than that of Z1 produced in the conventional laser welding process. Previous studies have found that the absorption coefficient of laser-induced plasma and plume is relative to the temperature and electron density. The higher the temperature and electron density, the higher the absorption coefficient and refraction index of the laser-induced plasma and plume (Refs. 27, 28). When using the suction device, the plume is quickly diluted and removed, i.e., the electron density is reduced and the value of laser-induced plasma and plume absorption is reduced. As a consequence, the vacuum-assisted laser welding process has a lower value of Z than that in conventional laser welding. Based on Equation 1 and considering the constant incident laser beam energy, the laser beam energy absorbed by the WELDING JOURNAL 201-s
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Fig. 5 — Welds obtained by vacuum-assisted laser welding. A — Top view; B — bottom view (laser power 3.2 kW; welding speed 3 m/min).
Fig. 6 — Schematic of the stabilizing mechanism in vacuum-assisted laser welding of zinc-coated steels in a gap-free lap joint.
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Fig. 8 — Sequenced images of the molten pool during laser welding.(laser power 3.4 kW; welding speed 1.8 m/min) exhibiting dynamic behavior of laser-induced plasma plume when suction is turned off. A — t = 0.500 s; B — t = 0.501 s; C — t = 0.502 s; D — t = 0.503 s; E — t = 0.504 s; F — t = 505 s (arrows point to spatter); suction turned on; G — t = 1.000 s; H — t = 1.002 s; I — t = 1.003 s; J — t = 1.004 s; K — t = 1.005 s; L — t = 1.006 s. Welding direction is from right to left for each image.
laser-induced plasma and plume during vacuum-assisted laser welding process is lower than that produced in conventional 202-s JULY 2013, VOL. 92
laser welding process. In addition, the laser beam could be defocused by the laser-induced plasma and plume during
the laser welding process. As shown in Fig. 10A, the incident laser beam spot is enlarged due to the refractive effect of the
Tensile Tests
Tensile shear testing was carried out to determine the peak load, which is used as a measure of strength for base and weld metals. Three tensile test specimens were machined from the same weld for both the vacuum-assisted and without applied vacuum conditions, both of which were welded under the same conditions. The average value was used to compare the vacuum-assisted laser weld strength to that of the single laser weld strength. The loadbearing area of the weld was assumed to be the weld length at the faying interface as measured on polished cross sections. For the base metal, its tensile strength is 0.78 kN/mm, as calculated from the peak load divided by sample width. All of the vacuum-assisted laser welds fractured in the heat-affected zone (HAZ) adjacent to the base metal. Figure 11B shows the characteristics of a typical fracture in a sample produced by vacuum-assisted laser welding. The average maximum tensile strength of the vacuum-assisted laser weld was 0.77 kN/mm. Similar to the previous studies (Refs. 22, 23), the weld strength achieved by the vacuum-assisted laser welding process approaches that of the base metal. However, the laser welds obtained by regular laser welding fractured in the weld zone under tensile loading resulting in an average strength of 0.51 kN/mm. The formation of weld defects such as the porosity degraded the weld strength. Figure 11C shows that when deep porosity was present in the weld, cracking first initiated along its edge and then propagated into the base material. Microhardness Tests
Microhardness tests were also conducted across the weld using a 100-g load and 10 s holding time. Figure 12 shows 1) the relative position of the hardness measurements, and 2) the microhardness distribution profile for a typical vacuum-assisted weld. As is typical for steel, the highest hardness value is within the weld zone due to a quenching effect following the laser welding process. The hardness value in the weld zone was relatively uniform. Furthermore, the hardness values decreased from the weld zone,
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Fig. 9 — Top view images of the stable keyhole achieved by vacuum-assisted laser welding (laser power 3.4 kW; welding speed 1.8 m/min). A — t = 1.000 s; B — t = 1.002 s; C — t = 1.003 s; D — t = 1.004 s; E — t = 1.005 s; F — t = 1.006 s. The welding direction for all images is from right to left.
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Fig. 10 — Schematic of the laser-induced plasma and plume above the molten pool during welding. A — Baseline without suction; B — improved laser beam energy transmission resulting in larger keyhole diameter with application of a suction device. Welding direction is from right to left. Z1 and Z2 are laser-induced plume heights without/with suction device turning off/on respectively. r1 and r3 are the laser focus spot sizes. r2 and r4 are the real laser spot sizes without/with suction device turned off/on, respectively.
through the HAZ and to the base metal. The lowest hardness value was located in the region close to the base metal. No internal porosity was found in the welds, which is similar to the results obtained by the previous studies (Refs. 22, 23).
Conclusions Experiments for zinc-coated steels were conducted by vacuum-assisted laser welding. The conclusions of this study can be summarized as follows: High-quality, gap-free lap joints in zinc-coated steels can be obtained by using a vacuum-assisted laser welding process. This is achieved because a stable and open keyhole can always be produced when the
suction is turned on. Therefore, the highly pressurized zinc vapor can be vented out through the open keyhole. Aside from the zinc vapor itself, the laser-induced plasma and plume are key factors that influence the stability of the laser welding process. When using a single laser beam, the shape and size of the laser-induced plasma and plume fluctuate at a high frequency. This imposes a large force on the molten pool and results in a turbulent molten pool. A large amount of liquid metal is squeezed out of the molten pool and spatter is observed when laser-induced plasma and plume vibrate at a large angle. The laser-induced plasma and plume are guided by the vacuum system and move
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laser-induced plasma during the conventional laser welding process. However, the defocusing effect of the laser-induced plasma and plume is reduced during the vacuum-assisted laser welding process, as shown in Fig. 10B. Based on the above analysis, the coupling efficiency of the laser beam energy is improved by vacuum assisted laser welding in comparison to conventional laser welding.
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Fig. 11 — Fracture under tensile shear loading. A — Schematic representation of lap-shear sample; B — fracture at HAZ for the vacuum-assisted weld; C — fracture in the weld zone for a conventional laser weld.
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Fig. 12 — Microhardness profile of welds obtained by vacuum-assisted laser welding. A — Position of hardness measurements; B — microhardness distribution profile.
along the suction direction, which also helps to stabilize the molten pool. Vacuum-assisted laser welding can also have a higher coupling efficiency of the laser beam than that of the conventional laser welding. Acknowledgments The authors would like to thank Professor Chunming Wang from the Huazhong University of Science and Technology for providing a fiber laser system for concept validation. The authors would also like to thank Shichun Chen, Xiyuan Hu, and Jun Wang for preparing the tensile shear test coupons. References 1. Akhter, R., Steen, W. M., and Watkins, K. G. 1991. Welding zinc-coated steel with a laser and the properties of the weldment. Journal of Laser Applications 3(2): 9–20. 2. American Welding Society. 1972. Welding Zinc-Coated Steels, AWS WZC/D19.0-72. 3. Graham, M. P., Hirak, D. M., Kerr, H. W., and Weckman, D. C. 1994. Nd:YAG laser weld-
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ing of coated sheet steel. Journal of Laser Applications 6(4): 212–222. 4. Dasgupta, A., Mazumder, J., and Bembenek, M. 2000. Alloying based laser welding of galvanized steel. Proceedings of 19th International Conference on Applications of Lasers and Electro-Optics, ICALEO, Laser Institute of America, Dearborn, Mich. 5. Li, X. G., Lawson, S., and Zhou, Y. 2008. Lap welding of steel articles having a corrosion resisting metallic coating. United States Patent Application US 2008/0035615 A1. 6. Li, X., Lawson, S., and Zhou, Y. 2007. Novel technique for laser lap welding of zinccoated sheet steels. Journal of Laser Applications 19(4): 259–264. 7. Pennington, E. J. 1987. Laser welding of galvanized steel. United States Patent US 4, 642,446. 8. Williams, S. W., Salter, P. L., Scott, G., and Harris, S. J. 1993. New welding process for galvanized steel. Proceedings of 26th International Symposium Automotive Technology and Automation. pp. 49–56, Aachen, Germany. 9. Forrest, M. G., and Lu, F. 2005. Development of an advanced dual beam head for laser lap joining of zinc-coated steel sheet without gap at the interface. Proceedings of 24th International Congress on Applications of Lasers and Electro-Optics. ICALEO: pp. 1069–1074. 10. Chen, W., Ackerson, P., and Molian, P.
2009. CO2 laser welding of galvanized steel sheets using vent holes. Material and Design 30(2): 245–251. 11. Xie, J. 2002. Dual beam laser welding. Welding Journal 81(10): 223-s to 230-s. 12. Gualini, M. M. S., Iqbal, S., and Grassi, F. 2006. Modified dual-beam method for welding galvanized steel sheets in lap configuration. Journal of Laser Applications 18(3): 185–191. 13. Milberg, J., and Trautmann, A. 2009. Defect-free joining of zinc-coated steels by bifocal hybrid laser welding Production Engineering Research Development 3: 9–15. 14. Tzeng, Y. F. 1999. Pulsed Nd:YAG laser seam welding of zinc-coated steel. Welding Journal 78(7): 238-s to 244-s. 15. Choi, H. W., Farson, D. F., and Cho, M. H. 2006. Using a hybrid laser plus GMAW process for controlling the bead humping defect. Welding Journal 85(8): 174-s to 179-s. 16. Mueller, G. H. 2004. Hybrid welding of galvanized steel sheet. European Patent EP 1454701. 17. Kusch, M., and Thurner, S. 2008. Application of the plasma-MIG technology for the joining of galvanized steel materials. Welding and Cutting 7(1): 54–59. 18. Kim, C., Choi, W., Kim, J., and Rhee, S. 2008. Relationship between the weldability and the process parameters for laser-TIG hybrid welding of galvanized steel sheets. Materials Transactions 49(1): 179–186. 19. Gu, H., and Mueller, R. 2001. Hybrid welding of galvanized steel sheet. Proceeding of 20th International Congress on Applications of Lasers and Electro-Optics, ICALEO, pp. 13–19. 20. Wang, P. C., and Hou, W. K. 2003. Method of joining galvanized steel parts using lasers. United States Patent US 6,646,225. 21. Speranza, J. J, and Wang, P. C. 2003. Joining workpieces by laser welding with powder injection. United States Patent US 6,797,914. 22. Yang, S. L., and Kovacevic, R. 2009. Laser welding of galvanized DP980 steel assisted by the GTAW preheating in a gap-free lap joint configuration. Journal of Laser Application 21(3): 139–148. 23. Yang, S. L., Carlson, B. E., and Kovacevic, R. 2011. Laser welding of high-strength galvanized steels in a gap-free lap joint configuration under different shielding conditions. Welding Journal 90(1): 8-s to 18-s. 24. Kim, C. H., Ahn, Y. N., and Kim, J. H. 2011. CO2 laser-micro plasma arc hybrid welding for galvanized steel sheets. Transactions of Nonferrous Metals Society of China 21: 47/s–53/s. 25. Gu, H. P. 2010. Laser lap welding of zinccoated steel sheet with laser-dimple technology. Journal of Laser Applications 22(3): 87–91. 26. Yang, S. L. 2009. Hybrid laser-arc welding of galvanized high strength steels in a gap free lap joint configuration. PhD dissertation. Southern Methodist University. 27. Mazumder, J., and Steen, W. 2011. Heat transfer model for cw laser material processing. Journal of Applied Physics 211: 668–674. 28. Beck, M., Berger, P., and Hugel, H. 1995. The effect of plasma formation on beam focusing in deep penetration welding CO2 lasers. Journal of Physics D: Applied Physics 28: 2430–2442.
Active Droplet Oscillation Excited by Optimized Waveform Experiments reveal the effects of waveform parameters on the excited droplet oscillation, plus the optimal range of current waveform parameters is determined
ABSTRACT The active droplet oscillation method is an approach previously proposed to detach the droplet at currents below the transition current. In this method, a droplet oscillation is first excited by intentionally switching the current from the peak to base level; the downward momentum of the oscillating droplet is then utilized to enhance the droplet detachment such that the droplet can be detached at reduced peak currents lower than the transition current. In the present work, this method is systematically studied to initiate stronger oscillations with lower average currents. To this end, the current waveform is modified by differentiating the exciting current from the growing current. This differentiation enables the growing current (heat input) be reduced without affecting the oscillation excitation. The current waveform is then further modified by adding a base period before the exciting pulse to maximize the oscillation, resulting in an optimized waveform. A series of experiments has been conducted to correlate the droplet oscillation to the parameters in the optimized waveform. The optimal ranges for the waveform parameters are experimentally determined. The active droplet oscillation method is improved at a fundamental level, and its mechanism is also better understood.
Introduction Gas metal arc welding (GMAW) is currently the most widely used arc welding method in the manufacturing industry due to its high productivity by using a consumable wire and its good compatibility to automatic welding. The formation and detachment of the metal droplet is generally referred to as the metal transfer process, which plays a critical role in determining the arc stability and welding quality; therefore, effective control of the metal transfer helps improve the GMAW process for better stability and weld quality (Refs. 1, 2). The metal transfer is typically classified into three modes — short circuiting transJ. XIAO is with the National Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, China, and the Institute for Sustainable Manufacturing, University of Kentucky, Lexington, Ky. G. J. ZHANG and L. WU are with the National Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, China. S. J. CHEN is with the Welding Research Institute, Beijing University of Technology, China. Y. M. ZHANG (
[email protected]) is with the Institute for Sustainable Manufacturing and Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Ky.
fer, globular transfer, and spray transfer. Spray transfer can be further classified into drop (projected) spray and streaming spray (Ref. 3). With relatively low welding currents, the transfer mode is expected to be short circuiting or globular transfer, which both often produce unstable arc and significant spatters unless appropriate controls such as surface tension transfer (STT) and cold metal transfer (CMT) (Refs. 4–6) are applied. When the welding current increases to be higher than the transition current (Ref. 3), the transfer mode changes into the spray transfer in which the droplet is detached at a diameter similar to that of the wire. A further increase in the current would result in the
KEYWORDS Droplet Oscillation Waveform Metal Transfer Transition Current Spray Transfer
streaming spray where the impact from high-speed small particles on the weld pool may produce undesirable fingershaped penetration (Refs. 7–10). While drop spray, which is generally associated with good stability and low spatter, is often the preferred transfer mode, its required amperage — higher than the transition current, resulting in increased heat input, metal vapors, and arc pressures — may not always be preferred. Welding researchers are motivated to develop methods that use currents lower than the transition currents to produce drop spray transfer. According to the dynamic force model balance (DFMB) theory on metal transfer (Ref. 11), the electromagnetic force determined by the welding current is the primary detaching force, and the gravitational force, plasma gas drag force, and momentum force also contribute to droplet detachment. The major retaining force that resists the droplet detachment is the surface tension. When the detaching force is greater than the retaining force, the droplet is detached from the wire tip. Based on this theory, the approaches developed to achieve spray transfer have focused on changing the forces on the droplet using electrical and mechanical ways (Refs. 12–17). Pulsed gas metal arc welding (GMAWP) is a widely used electrical way to produce the desired drop spray transfer at a wide range of average current (Refs. 14, 18). In GMAW-P, the desired one droplet per pulse (ODPP) transfer is achieved by selecting an appropriate combination of the duration and amplitude of the peak current. Basically, the amplitude of the peak current still needs to be higher than the transition current to avoid one droplet multiple pulses (ODMP) while its duration needs to be appropriately short to avoid multiple droplets per pulse (Refs. 19, 20) and appropriately long to ensure the detachment for ODMP. Achieving the desired droplet ODPP transfer using GMAW-P through optimizing parameters may not be robust enough while a peak WELDING JOURNAL 205-s
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BY J. XIAO, G. J. ZHANG, S. J. CHEN, L. WU, AND Y. M. ZHANG
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Fig. 1 — Active metal transfer by monitoring the excited droplet oscillation.
Fig. 2 — Schematic of the experimental system.
Fig. 3 — Sketch of the droplet oscillation.
Fig. 4 — Simple current waveform for the separation-based modification.
current higher than the transition current is still needed. A method has been proposed to achieve a robust control for repeatable and controllable metal transfer in GMAW-P with reduced peak current amperage, referred to as active control of metal transfer, by using an excited droplet oscillation (Refs. 21–23). The droplet is actively oscillated to generate a downward momentum that will significantly enhance the droplet detachment. As shown in Fig. 1, during the exciting pulse, the droplet grows gradually at the same amperage as the exciting current and is dragged into an elongated shape with initial amplitude in the weld pool direction by the electromagnetic force. Then the current is switched from the exciting level to the base level, so the electromagnetic force decreases, and the droplet springs back to the wire tip and starts oscillating due to the surface tension.
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When the downward motion of the droplet is first detected, the current is increased to the detaching level. With the assistance of the downward momentum, the droplet detachment is ensured with a detaching current lower than the spray transition current, which is essential in conventional GMAW-P. The synchronization of the detaching current and downward momentum of the droplet is referred to as phase match. In Ref. 24, this method has been modified to suit for metal transfer control for titanium by applying appropriate current levels, but the current waveform is unchanged. In the dynamic force balance model (DFBM), a mass-spring system is used to model the droplet oscillation (Ref. 11). The dynamic droplet motion is described as a second-order system varying with time as follows: m(t)ẍ + c(t)ẋ + k(t)x = F(t)
where x represents the mass center displacement in the axial direction, F is the axial force exerted on the droplet, and m, c, and k are the mass, damping coefficient, and spring constant of the droplet, respectively. The surface tension acts as a spring force. In literature (Ref. 11), the droplet oscillation under continuous current is numerically analyzed. The droplet oscillation under the pulsed current condition is studied in literature (Ref. 25). The numerical computation results in Refs. 11 and 25 both demonstrate that the droplet oscillation frequency is mainly determined by the droplet mass. With respect to the active droplet oscillation, the previous research focused on introducing its novel principle. However, the associated oscillation was not fully studied. In particular, the exciting pulse current was fixed at a high level (220 A for a 1.2-mm-diameter wire) to ensure that the droplet could be elongated and oscil-
A
B
lated consequently. The droplet growing period was coupled within the exciting period. Only the base current and duration were adjusted to analyze the droplet oscillating frequency and amplitude (Ref. 21). Its further analysis may result in improvements and optimization for much enhanced metal transfer control abilities. In particular, the excited droplet oscillation is a damping process. The initial displacement of the droplet that determines the initial oscillating energy increases with the exciting peak current. However, in the original active oscillation method, this exciting peak current is the same with the current that grows the droplet. If a lower and adjustable growing current is used to form the droplet as determined by the application, and then a shorter exciting pulse is applied to excite the droplet oscillation, the growing and exciting processes can be separately controlled. The metal transfer control achieved by the active oscillation method may be improved. Active droplet oscillation can be considered as an electrical control strategy for metal transfer. This active control technology can be applied not only in GMAWP as a modified GMAW-P process, but also can be coupled with other control methods to improve the original process such as laser-enhanced GMAW, a method recently developed to actively control the metal transfer at given arc variables (Ref. 26). In such a process, a laser beam irradiating on the droplet is applied to vaporize the droplet partially. A recoil force is generated as an additional detaching force to enhance droplet detachment. As a result, short circuiting transfer under a range of welding currents becomes controlled globular transfer or even drop spray transfer. Therefore, the metal transfer and heat input, respectively, can be freely controlled. Welding spatter is also reduced significantly, and the arc stability is improved (Refs. 27, 28). However, the requirement on the laser power restricts its application in industry. If the active droplet oscillation technology is combined
into laser-enhanced GMAW, a reduction in the required laser power may be expected, just as the reduction of the detaching peak curC rent in GMAW-P. In this paper, the active droplet oscillation process is further analyzed and optimized. A modified current waveform is proposed in which the droplet growing and oscillation exciting are decoupled and become separately controllable. The growing current can be set no longer as high as the exciting peak
current. The average welding current decreases. On the other hand, the exciting peak duration can be set very narrow, which is expected to generate enough electromagnetic force to elongate the droplet prominently but not melt the wire significantly. Based on the observation and analysis of the preliminary results, the
Table 1 — Definitions of Variables in Oscillation Description
Symbol
Definition
Lint
Initial droplet length measured at the end of the growing period
A(i)
Droplet oscillation amplitude of cycle i: A(i) = Lmax (i) – Lmin (i)
T(i)
Measured droplet oscillation period of cycle i: T(i) = ts(i) – te(i)
Aint
Initial amplitude of the whole droplet oscillation duration: Aint = Lmax(0) – Lint
Aavg
Average oscillation amplitude of N droplet oscillating cycles:
A
avg
Tavg
=
1
N
N
∑ A( i ) i =0
Average droplet oscillation period under certain waveform parameters:
T
avg
=
1
N
N
∑T ( i ) i =0
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Fig. 5 — Current waveform and droplet oscillation with a 1-ms interval per frame. A — Experiment 1; B — experiment 2; C — experiment 3.
B
A
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C Fig. 7 — Optimized welding current waveform.
Fig. 6 — Dynamic curves of the droplet oscillation. A — Experiment 1; B — experiment 2; C — experiment 3.
Table 2 — Growing Parameters in Experiments 1–3
Table 3 — Growing Parameters in Experiments 4, 5
No.
Ig (A)
Tg (ms)
Waveform
No.
Ig (A)
Tg (ms)
Waveform
1 2 3
150 80 40
11 20 40
Original Modified Modified
4 5
80 150
20 11
Optimized Optimized
current waveform is further optimized to maximize the droplet oscillation energy despite the actual growing current level. The key factors that characterize the dynamic droplet oscillation, such as the amplitude, frequency, and rate of decay under different exciting parameters, are calculated to measure the droplet oscillation magnitude. By selecting an optimal combination of the exciting parameters, a much stronger droplet oscillation with significantly lower heat input are achieved. In this sense, the study improves the active oscillation method and furthers the un-
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derstanding on the dynamic droplet oscillation behavior and mechanism.
Experimental System and Approach Experimental Setup
The experimental setup is shown in Fig. 2. An inverter power source was used to conduct the welding experiments. It can be used for either constant current (CC) or constant voltage (CV) mode. In this work, the CC mode was selected to
achieve the desired welding current waveform. The arc length was controlled to be stable by adjusting the wire feeding speed based on arc voltage feedback. The power supply and wire feeder can both be controlled by analog input signals. A singleboard computer-based controller was established to compute the output waveform of the welding current and wire feed speed. A data-acquisition set was established to record the actual welding current and arc voltage waveform during the welding experiments, and an Olympus iSpeed2 high-speed camera was used to observe and record the droplet oscillation. The data-acquisition board and high-speed camera both can be triggered to work by a 5-V TTL signal such that recording the arc variables and metal transfer is synchronized; therefore, the arc voltage signal can be further processed to analyze the droplet oscillation process. To view the highly dynamic characteristics of the droplet oscillation, the recording fre-
B
A
Fig. 9 — Dynamic curve of the droplet oscillation in experiment 4.
quency was set at 5000 hz. All the welding experiments were conducted as bead-on-plate welding with a travel speed of 3 mm/s; the base metal was mild steel; the wire was ER70S-6 with 0.8 mm diameter; and the distance from the contact tip to workpiece was set at 12 mm. Experimental Study Steps
As mentioned earlier, the major modification introduced from this study is that the droplet growing and exciting are intentionally separated as two actions. That is, a lower growing current with a specified duration is applied to form the droplet. When the droplet reaches the desired size, the welding current is increased to the exciting peak level. This peak current is maintained for several milliseconds. During this exciting peak period, the droplet is elongated by the increased electromagnetic force. Due to this elongation, the droplet springs back to start oscillating when the current is switched to the base level. As can be seen, this modification involves a number of parameters that char-
Fig. 10 — Droplet oscillation amplitudes measured from experiments 1–4.
acterize the current waveform and may affect the effectiveness of the proposed modification. To optimize the modification, the experimental studies will follow pursuing three steps. Feasibility Verification. The experiments in this step will be designed and used as examples to verify that the modification characterized by the separation of the exciting current from the growing current can help increase the initial energy of the oscillation. The average droplet diameter will be controlled to be slightly larger than the wire diameter to avoid the effect from the droplet mass. Waveform Optimization. The separation of the exciting current from the growing current provides a modification to increase the oscillation. However, the separation method (current waveform) used above for the feasibility verification is a relatively simple one. To further take advantage of the separation, the effect of the separation is maximized by reducing the current from the growing current to the possible minimal level allowed, i.e., the base current, before the exciting pulse
is applied. The waveform is further modified to maximize the oscillation. Parameter Optimization. While the optimized waveform provides a type of current waveform that can further increase the oscillation using the separation principle, there are still parameters depicting the actual waveform and that can be optimized to maximize the oscillation. In this step, experiments are designed/conducted and the experimental data are analyzed to optimize these parameters. Analysis Approach
High-speed droplet image sequences and actual arc variable waveforms are synchronously recorded by using the same trigger signal to analyze the oscillation. For quantitative analysis of the oscillation, the vertical coordinates of the droplet top and bottom are measured in pixels (11.25 pixels = 1 mm) from the recorded images. The droplet length can be calculated to describe the droplet oscillation behavior. The fluctuation of the measured droplet WELDING JOURNAL 209-s
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Fig. 8 — Droplet oscillation using the optimized current waveform with a 1-ms interval per frame. A — Experiment 4; B — experiment 5.
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A
B
C
D
E
F
Fig. 11 — Droplet oscillation with different exciting peak durations. A — Te = 2 ms; B — Te = 3 ms; C — Te = 4 ms; D — Te = 5 ms; E — Te = 6 ms; F — Te = 7 ms.
Fig. 12 — Droplet oscillation energy with different exciting peak durations.
Fig. 13 — Droplet motion during the exciting period for experiment 11 with a 0.4-ms interval per frame.
length curve gives the droplet oscillation magnitude. However, in previous work (Ref. 21), only the coordinates of the droplet bottom position were measured to describe the oscillation. The top and bottom coordinates of the droplet can apparently be used to better describe and analyze the oscillation. A standard damping oscillation is used to model the droplet oscillation in this study as shown in Fig. 3. The parameters in this model are self defined in Fig. 3 and explained in Table 1. In Table 1, N denotes the total oscillation cycles the droplet experiences from the end of the exciting pulse to the application of the detaching pulse. In particular, at the end of the exciting pulse, the droplet oscillation starts. The initial amplitude Aint is used to represent the initial droplet oscillation energy for a
given mass droplet. Because of possible errors in image measurement, the average amplitude of the droplet oscillation Aavg is defined to better quantify the droplet oscillation energy during the whole oscillating period. What should be pointed out is that each oscillating cycle is not isochronous because the droplet mass is still slowly increasing during the oscillation. Therefore, the droplet oscillation period and frequency cited in this paper are actually the average period and frequency. Also, in this paper, the oscillation of the droplet is quantitatively analyzed using the model and parameters together with high-speed images.
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Simple Current Waveform for Separation The effectiveness of separation as a
modification to the active oscillation method is first verified using a simple current waveform as shown in Fig. 4. In this case, the whole metal transfer cycle is divided into four periods as follows: growing, exciting, oscillating, and detaching. The droplet grows gradually during the growing period at a relatively low current Ig. The initial droplet length Lint is controlled by adjusting the growing duration Tg. Then the current is increased to the exciting peak level Ie. The exciting peak duration Te is expected to be as short as several milliseconds. The difference between the exciting peak current and growing current is defined as the exciting rising level IR: Ie – Ig. Then the current is reduced to the exciting base level Ib, and this stepdown level is defined as the exciting falling level IF: Ie – Ib. The base duration Tb is set to be long enough to provide adequate
A
B
Fig. 14 — Droplet oscillation with different exciting base currents. A — Ib2 = 10 A; B — Ib2 = 50 A.
Fig. 15 — Droplet oscillation amplitude with different exciting base currents.
Fig. 16 — Droplet oscillation with 70-A exciting peak current.
three experiments were measured at approximately 1.2 mm. The droplet oscillation frequencies in experiments 1–3 were all measured to be approximately 166 Hz. The oscillation periods Tavg were approximately 6 ms in these experiments. The equivalence of the oscillation frequency observed from these experiments is supported by the previous theoretical work that the droplet oscillation frequency is mainly determined by the droplet mass (Refs. 11, 25). The initial droplet oscillation energy should have been believed to be mainly determined by the exciting peak current level when the droplet mass is given. This would suggest that the initial amplitude in all these three experiments should be similar as their exciting peak current and droplet mass are the same. However, this prediction is not supported by the experimental results. Each frame 6 in Fig. 5A–C shows the elongation of the droplet at the falling edge of the exciting pulse. As aforementioned, this elongation represents the initial energy of the active oscillation. As can be seen, despite the same droplet mass and application of the same exciting current, the droplet is more elongated when applying the lower growing current. In particular, the difference among these three experiments is the exciting rising level IR, defined as Ie – Ig, which is 0 A in
experiment 1, but 70 and 110 A for experiments 2 and 3. The dynamic droplet length curves of the whole metal transfer cycle in experiments 1–3 are measured to demonstrate the droplet oscillations and perform a further quantitative comparison, as shown in Fig. 6A–C. It can be seen that the fluctuation of the droplet length in experiment 3 is prominently more significant, implying that its droplet oscillation energy is significantly larger than those in experiments 1 and 2. It is now clear that the exciting peak current is not the only parameter determining the initial oscillation energy when the droplet mass is given. Instead, the initial oscillation energy is determined by the exciting raising level. In the original active oscillation method, the exciting current equals the growing current, resulting in a zero exciting raising level. The separationbased modification specifies an effective direction to increase the oscillation.
Current Waveform Optimization Rising Level Maximization
Although the droplet oscillation can be enhanced by applying a lower growing current to enlarge the exciting rising level, the droplet growth also slows down, resulting in reduced metal transfer frequency. The current waveform should maximize the
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time for the droplet to oscillate. At the end of the base duration, the detaching current Id is applied to guarantee the droplet detachment. Hence, the whole growing, exciting, oscillating, and detaching periods are periodically repeatable and controllable. Experiments 1–3 were conducted to examine the droplet oscillation under the simple waveform modification. The growing parameters of the current waveform used in these three experiments are listed in Table 2. The growing period Tg has been intentionally changed with the growing current Ig to control the droplet diameter to be slightly greater than that of the wire. The droplet mass in these three experiments were controlled approximately the same such that the effect of the droplet mass on the oscillation can be excluded in the verification experiments. The remaining waveform parameters in these experiments are fixed to be the same: Ie = 150 A, Te = 4 ms; Ib = 30 A, Tb = 30 ms; and Id = 165 A, Td = 5 ms. It is apparent the oscillation in experiment 1, where the growing current equals the exciting current, is actually the oscillation excited using the original method. Its comparison with those in experiments 2 and 3 will be used to verify the effectiveness of the separation-based modification. In particular, the exciting peak current Ie was set at 150 A based on that the actual transition current was experimentally measured to be 165 A under the aforementioned welding condition (wire diameter, shielding gas, etc.). The exciting peak duration Te was 4 ms. The growing currents Ig were set at 150, 80, and 40 A for experiments 1–3, respectively. The growing durations Tg were correspondingly set at 11, 20, and 40 ms to keep the initial droplet size approximately even in the three experiments. The average current in experiments 1–3 — 79.5, 66.5, and 49.7 A, respectively — can be easily calculated. It is quite clear that the heat input can be effectively reduced by using the modified current waveform. The droplet oscillations in these three experiments were analyzed from the obtained image sequences. A typical cycle of measured current waveforms and images of droplet oscillation are shown in Fig. 5A–C in which the time interval for each frame is 1 ms. Due to the rapid damping of the droplet oscillation, only the droplet images during the exciting period and first oscillating cycle are presented for a quick visual verification. As can be seen from the recorded current waveform, the dynamic response time of the selected power source to a step control signal is approximately 1 ms. Consequently, the exciting peak duration should be no less than 2 ms. The initial droplet lengths Lint in the
A
B
C
Fig. 17 — Droplet oscillation with Ie = 140 A. A — Te = 2 ms; B — Te= 3 ms; C — Te = 4 ms.
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A
B
C
Fig. 18 — Droplet oscillation with Ie = 130 A. A — Te = 2 ms; B — Te = 3 ms; C — Te = 4 ms.
A
B
C
Fig. 19 — Droplet oscillation with Ie = 120 A. A — Te = 2 ms; B — Te = 3 ms; C — Te = 4 ms.
rising level of the exciting pulse despite the growing current. To this end, the further optimized waveform shown in Fig. 7 is proposed. In this waveform, at the end of the growing duration, the current is first switched to the base level, and then increased to the exciting peak level. Two new parameters are introduced: the base current Ib1 and its duration Tb1 before exciting. The exciting rising level IR becomes Ie – Ib1. Since the base current is approximately the lowest amperage allowed, the exciting rising level is maximized. Preoscillation
While the intentional decrease of the
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current before exciting maximizes the exciting rising level to enhance the droplet oscillation, it introduces a possible need for phase match such that the base duration Tb1 should be determined based on the growing current level. That is, when the growing current amperage is high enough, for example, 150 A, the droplet is expected to have been pre-elongated during the growing duration. As a result, when the current is changed to the first base level Ib1, the droplet oscillation should have been excited. This oscillation that occurs before the exciting pulse is referred to as the preoscillation in this study. In this case, the droplet downward momentum during the first base period Tb1
can be utilized to further enhance the droplet oscillation during the second base duration Tb2. However, this enhancement occurs only when the exciting pulse matches the preoscillation in phase, i.e., the exciting pulse that is supposed to elongate the droplet should be applied when the droplet moves down toward the workpiece during the preoscillation. The first base duration Tb1 should be half of the droplet oscillation period to synchronize the droplet downward motion and exciting pulse. However, if the growing current is not high enough to pre-elongate the droplet significantly, the phase match condition is not required. Hence, the first base current period in the optimized current
A
B
C
A
B
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Fig. 20 — Droplet oscillation with Ie = 110 A. A — Te = 2 ms; B — Te = 3 ms; C — Te = 4 ms.
C
Fig. 21 — Droplet oscillation with Ie = 100 A. A — Te = 2 ms; B — Te = 3 ms; C — Te = 4 ms.
A
B
C
Fig. 22 — Droplet oscillation with Ie = 90 A. A — Te = 2 ms; B — Te = 3 ms; C — Te = 4 ms.
waveform needs to be determined based on the growing current. Verification of Optimization Effect
To verify the effect of the optimized waveform, which is characterized by the first base period before the exciting pulse, experiments 4 and 5 were conducted using the optimized waveform with different growing parameters listed in Table 3. The remaining waveform parameters in these two experiments were fixed: Ib1 = 30 A, Tb1 = 3 ms; Ie = 150 A, Te = 4 ms; Ib2 = 30 A, Tb2 = 30 ms; and Id = 165 A, Td = 5 ms. The initial droplet mass in the two experiments were also approximately the
same. To utilize the possible preoscillation to enhance the final droplet oscillation, the first base time Tb1 was set at 3 ms to match the phase because the droplet oscillation period was approximately 6 ms for the given droplet mass in experiments 4 and 5. The recorded current waveforms and droplet oscillation images from experiments 4 and 5 are shown in Fig. 8A, B. The time interval for each frame is also 1 ms. The measured droplet length curve of experiment 4 is shown in Fig. 9. The result from experiment 4 (using the optimized waveform for separationbased modification) is first compared with that from experiment 2 (using the simple waveform for separation-based modifica-
tion). The growing and exciting parameters in the two experiments are the same. The only difference is that the exciting rising level IR has been maximized to 120 A in experiment 4 for the exciting current and base current used while it is 70 A in experiment 2 due to the simple waveform. It can be clearly seen from corresponding frame 6 in Figs. 5B and 8A that the droplet is apparently more elongated during the exciting period in experiment 4. From Figs. 6B and 9, it also can be seen that the droplet length fluctuation in experiment 4 using the optimized waveform is much more intensive than that in experiment 2 using the simple waveform. The droplet oscillation energy in experiment 4 is sigWELDING JOURNAL 213-s
A
B
C
Fig. 23 — Droplet oscillation with Ie = 80 A. A — Te = 2 ms; B — Te = 3 ms; C — Te = 4 ms.
Table 4 — Waveform Parameters in Experiments 6–11
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No.
Te (ms)
6 7 8 9 10 11
2 3 4 5 6 7
nificantly higher than that in experiment 2. The effect of the optimized waveform characterized by the first base period before the exciting pulse is experimentally demonstrated. Secondly, the results of experiments 4 and 5 can be compared to demonstrate the effect of the growing current (preoscillation) on the droplet oscillation. In these two experiments, the exciting rising level IR is 120 A in both experiments. However, the growing current is different although the droplet mass is approximately the same. In experiment 5, the growing current (150 A) is high enough to pre-elongate the droplet. In experiment 4, the growing current (80 A) is relatively low; the droplet is not significantly pre-elongated during the growing period such that the preoscillation during the first base period is quite weak. It can be seen from Fig. 8B the droplet is detached by the exciting pulse of 150 A current with only 4 ms duration due to the preoscillation in experiment 5. However, in Fig. 8A for experiment 4 where the preoscillation is insignificant, the droplet is not detached. The oscillation in experiment 5 (with preoscillation) is stronger. The effect of the preoscillation in enhancing the oscillation is demonstrated, and it is apparently an additional advantage of the optimized waveform. To further perform a global quantitative analysis of the current waveform (original, simple, and optimized) effect on the droplet oscillation, the initial ampli-
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tude Aint and average amplitude Aavg for experiments 1–4 are measured and calculated. The results are shown in Fig. 10. In addition, the following can be seen: 1. For experiments 1–3, in which the simple current waveform was used, the exciting rising level is 0, 70, and 110 A, respectively. From Fig. 10, the droplet oscillation amplitude increases with the increased exciting rising level. The average amplitude in experiment 2 is 42.8% higher than that in experiment 1, and the average amplitude in experiment 3 is, respectively, 171 and 90% higher than that in experiments 1 and 2. Much stronger droplet oscillation is achieved by using the simple waveform for separation-based modification with a reduced growing current when the exiting current is given. 2. In comparison with experiment 3, the magnitude of the droplet oscillation in experiment 4 is improved. As can be seen from Fig. 10, the initial amplitude of experiment 4 is 25% higher than that in experiment 3, and the average amplitude is increased by 7.9%. This improvement is achieved because the exciting rising level IR is 9.09% higher than that in experiment 3. This increase in the exciting rising level IR is the result of the first base period that characterizes the optimized waveform, which decouples the exciting rising level IR from the growing current. The growing current can be freely selected to grow the droplet and control the metal transfer frequency. It is apparent that the optimized waveform is responsible for the improvement. In summary, it has been found that a larger exciting rising level produces a stronger droplet oscillation. The optimized waveform proposed provides a method to maximize the exciting rising level by adding a base period before the exciting pulse. This addition of additional base period also introduces a possible preoscillation, and this preoscillation may further enhance the oscillation if the duration of the added base period facilitates a phase match with the exciting pulse.
Optimization of Waveform Parameters Although the optimized waveform provides a method to maximize the exciting rising level, there are still other parameters which specify the actual waveform and can be optimized to maximize the oscillation. These parameters include the exciting peak duration, exciting peak/base current, and growing duration. A series of experiments was designed and conducted in this section to analyze the effects on the droplet oscillation and determine the optimal selection of these parameters. Exciting Peak Duration
In this subsection, the exciting peak duration Te was set into several different levels to analyze its influence on the droplet oscillation. If the exciting peak duration is too long, the droplet may grow to a relatively large size and then get detached by the gravity such that the desired droplet oscillation cannot be observed. On the other hand, if the peak duration is too narrow, the droplet probably could not be elongated enough, and the droplet oscillation would be too weak to be observed. In this sense, an appropriate range for the exciting peak duration is needed. Based on the results from experiments 3 and 4, it has been confirmed that the droplet oscillation is reasonably strong by using 4 ms exciting peak duration. Furthermore, the droplet oscillations with other different exciting peak duration levels also need to be studied to lead a deeper comprehension on the droplet oscillation behavior. Hence, experiments 6–11 were conducted in which the exciting peak duration Te was the only varying variable. As can be seen from Table 4, the exciting peak duration was changed from 2 to 7 ms in experiments 6–11. The other waveform parameters in this group of experiments were fixed: Ig = 80 A, Tg = 20 ms; Ib1 = 30 A, Tb1 = 3 ms; Ie = 150 A; Ib2 = 30 A, Tb2 = 30 ms; and
Id = 165 A, Td = 5 ms. The dynamic droplet length curves are measured, as shown in Fig. 11A–F, for experiments 6–11, respectively. The initial amplitude Aint and average amplitude Aavg in this group of experiments are also measured to demonstrate how the exciting peak duration influences the droplet oscillation magnitude, as shown in Fig. 12. As can be seen from Fig. 11A–C, the droplet length keeps increasing during the whole exciting peak period when the exciting peak duration is 2–4 ms. When the exciting peak duration is 5–7 ms, as shown in Fig. 11D–F, the droplet is elongated to its maximum displacement in approximately 3 ms from the start of the exciting pulse. In the rest of the exciting peak period, the droplet length is no longer increased and even slightly reduced. The fluctuations of the droplet length curve with the exciting duration of 3 and 4 ms are approximately in the same level. The fluctuation in experiment 6 with the exciting duration of 2 ms is significantly weaker. This result agrees with the logical prediction that weaker droplet oscillation is associated with shorter exciting duration. However, the unexpected result is that the droplet oscillation also got weaker when the exciting peak duration exceeded 4 ms. As can be seen from Fig. 11C–F, the fluctuation of the droplet length gets weaker with the increased exciting peak duration (from 4 to 7 ms). As can be calculated from Fig. 12, the average amplitude of the droplet oscillation with 5 ms exciting peak duration is approximately 36.6% lower than that with 4 ms exciting peak duration, even 13.3% lower than that with 2 ms exciting duration. Take experiment 11 using 7 ms exciting peak duration as an example to analyze the dynamic motion of the droplet during
Fig. 25 — Droplet oscillation with different growing durations.
the entire exciting peak period, as shown in Fig. 13, with the time interval for each image being 0.4 ms. During the period as frames 1–8 show (3.2 ms), the droplet length keeps increasing until it reaches the maximum displacement, and the arc length is stable. After that, the droplet length stops increasing, while the droplet starts to move upward and the arc length is slightly increased by 0.6 mm, as shown in frames 9–16 of Fig. 13. Such a fluctuation level of the arc length is absolutely acceptable in the GMAW process. It can be seen that the droplet is getting slightly less elongated during its upward moving period. A qualitative analysis of this phenomenon is performed based on the dynamic force balance model (DFBM) of metal transfer (Ref. 11), in which droplet momentum is considered. The droplet momentum contributes to attaching or detaching the droplet, depending on the droplet moving directions. During the exciting peak period, the wire melting rate is significantly increased because the current is increased. Meanwhile, the wire feed speed can be considered constant during this several-millisecond short period, because the adjustment on the wire feed speed is much slower. As a result, the wire melting rate exceeds the wire feed speed during the exciting peak period. The wire is burned back toward the contact tip, and the droplet moves upward. It is the upward momentum of the droplet that partly counteracts the electromagnetic force. Therefore, the droplet gets less elongated, and the droplet oscillation is weakened. The dynamic motion of the droplet during the whole exciting peak period clearly reveals two effects of the current increase (from the base level to exciting peak level) on the droplet:
1. Force Effect. The high electromagnetic force generated by the exciting peak current drags the droplet into an elongated shape. Based on the experimental results, we can see that this effect takes place instantly once the current is switched to the exciting peak level. 2. Thermal Effect. Because the current is increased, the wire melting rate increases to exceed the wire feed speed. The wire is burned back slightly, in other words, the arc length increases slightly, and the droplet moves upward to the wire tip during the dynamic process. The upward momentum is produced, and it weakens the droplet oscillation. However, the so-called thermal effect demonstrates a slight delay to the current increase, which is approximately 3 ms measured from the experimental results. In summary, it is the upward momentum of the droplet during the exciting period that weakens the droplet oscillation, but the delay of its occurrence to the current increase determines that there is a threshold of exciting peak duration for the droplet oscillation to get weaker. Based on the results as Figs. 11 and 12 show, the threshold level is 4 ms, and the optimal selection of the exciting peak duration is confirmed to be 3 to 4 ms. An exciting peak duration of 2 ms is also acceptable. However, the exciting peak duration exceeding 4 ms is not recommended. Exciting Base Current
As mentioned above, the droplet oscillation is a damping process. When the exciting peak current is switched to the base level, the electromagnetic force is reduced but not eliminated, and it contributes to decay of the droplet oscillation. In this sense, an applicable exciting base current WELDING JOURNAL 215-s
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Fig. 24 — Average amplitude with different exciting peak currents.
Table 5 — Exciting Parameters of Experiments 14–34
Table 6 — Growing Duration of Experiments 35–37
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No.
Ie(A)
Te (ms)
No.
Tg (ms)
14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
140 140 140 130 130 130 120 120 120 110 110 110 100 100 100 90 90 90 80 80 80
2 3 4 2 3 4 2 3 4 2 3 4 2 3 4 2 3 4 2 3 4
35 36 37
10 20 40
should be determined. The criteria should be that the droplet oscillation will not decay too fast to weaken the beneficial downward momentum significantly and that the arc would still burn stably. To this end, the exciting base current Ib2 is set to be 10 and 50 A in experiments 12 and 13, respectively, to verify its effect on the droplet oscillation. The other current waveform parameters in the two experiments were fixed to be Ig = 80 A, Tg = 20 ms; Ib1 = 30 A, Tb1 = 3 ms; Ie = 150 A, Te = 4 ms; Tb2 = 30 ms; and Id = 165 A, Td = 5 ms. The result of experiment 8 is referred to as a comparison, in which the exciting base current Ib2 is 30 A, and the other parameters are the same with those in experiments 12 and 13. The measured droplet oscillation from experiments 12 and 13 are shown in Fig. 14A and B, respectively. It can be seen that the fluctuation of droplet length in experiment 13 is weaker than that in experiment 12. The initial amplitude Aint and average amplitude Aavg in experiments 8, 12, and 13 are calculated correspondingly, as shown in Fig. 15. It can be seen that the initial amplitudes in the three experiments are quite similar, because the same growing and exciting parameters were used in the three experiments. However, the average amplitude demonstrates a down trend with the increased exciting base current. As shown in Fig. 15, the average amplitude with the base current of 10 and 30 A are measured being similar, but that with the exciting base current of 50 A is approximately 24% weaker. Furthermore, with respect to the fact that the arc burning at 30 A is more stable than that burn216-s JULY 2013, VOL. 92
ing at 10 A, the exciting base current was fixed at 30 A in the following experiments as an optimal selection. Exciting Peak Current
The droplet oscillation behavior is further analyzed by changing the exciting peak current in this subsection. The exciting peak current certainly cannot be higher than the transition current. However, it is also doubtless that the exciting peak current cannot be lower than a specific level. Otherwise, the droplet will not be elongated and then oscillated effectively. This minimum exciting peak current level is defined as the oscillating transition current in this paper. Based on the study above, the selections of the current waveform and exciting peak duration are optimized. An exciting peak current, Ie of 150 A, is used to elongate the droplet according to the transition current of 165 A. The optimal range of the exciting peak duration is also confirmed to be 2–4 ms. In this subsection, the oscillating transition current is first verified by experiments, then a group of experiments with a different combination of exciting peak current Ie and duration Te are conducted. The droplet oscillations are recorded and analyzed. The oscillating transition current was tested to be 70 A by the experiments in which the exciting peak current is stepping down, while the exciting peak duration Te was fixed at 4 ms. The droplet length curve with the exciting peak current of 70 A is shown in Fig. 16. It can be seen from the figure that the droplet is almost not oscillated at all. Based on this result, the selected exciting peak current Ie changes from 140 to 80 A, stepped down by 10 A each time, as shown in Table 5; plus, the exciting peak duration ranges from 2 to 4 ms for each selected exciting peak current level. The other waveform parameters are fixed to be the same: Ig = 80 A, Tg = 20 ms; Ib1 = 30 A, Tb1 = 3 ms; Ib2 = 30 A, Tb2 = 30 ms; and Id = 165 A, Td = 5 ms. The droplet length was measured to demonstrate the dynamic droplet oscillation in experiments 14–34, as shown in Figs. 17 to 23, respectively. The average amplitude Aavg was also calculated to quantitatively reveal the relationship between the droplet oscillation energy and
exciting current, which is shown in Fig. 24. It can be seen that the average amplitude of the droplet oscillation presents a parabolic growth approximately with the increased exciting peak current. As calculated before, the average amplitude of the droplet oscillation in experiment 1, applying the original waveform and 150 A exciting peak current, is approximately 0.124 mm. By comparing this result with those in experiments 32–34, it is found that the same or even stronger droplet oscillation is achieved with only 80 A exciting peak current by applying the optimized current waveform. In this sense, the enhancement of the optimized current waveform on the droplet oscillation is further ensured. Meanwhile, the average current is 79.5 A in experiment 1, but only approximately 58 A in experiment 32 and 60 A in experiment 34. The heat input is significantly reduced by applying the optimized current waveform. Growing Duration
As introduced previously, the initial droplet size/mass can be controlled by adjusting the growing duration. In this subsection, the growing duration Tg is set at three different levels, and the remaining waveform parameters are fixed: Ig = 80 A; Ib1 = 30 A, Tb1 = 3 ms; Ie = 140 A, Te = 3 ms; Ib2 = 30 A, Tb2 = 30 ms; and Id = 165 A, Td = 5 ms. As shown in Table 6, the growing duration is double increased from 10 to 40 ms in experiments 35 to 37, so the initial droplet mass is also approximately doubled. The droplet oscillations in these three experiments were measured and shown in Fig. 25. It demonstrates that the initial droplet size is 0.98, 1.16, and 1.42 mm for experiment 35–37, respectively. The droplet oscillation frequencies were measured to be 216, 183, and 133 Hz, respectively. This result agrees with the theoretical calculation result that the droplet oscillation frequency changes along with the droplet mass (Refs. 11, 25).
Conclusions and Future Work The dynamic droplet oscillation behavior was systematically studied in this work. Stronger droplet oscillation and lower heat input were achieved by applying the optimized current waveform. The effects of the waveform parameters on the excited droplet oscillation were revealed by a number of experiments. The optimal range of current waveform parameters was determined. 1. The current waveform applied to excite the droplet oscillation is modified. The critical modification is that the droplet growing and exciting periods are separated. It is found that the droplet oscillation can be significantly enhanced by
This work is supported by the State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, China, and the National Science Foundation under grant CMMI-0825956. Jun Xiao greatly appreciates the scholarship from the China Scholarship Council that funds his visit to the University of Kentucky. References 1. Sadler, H. 1999. A look at the fundamentals of gas metal arc welding. Welding Journal 78(5): 45–50.
2. The Procedure Handbook of Arc Welding. 1994. The Lincoln Electric Co., Cleveland, Ohio. ISBN 99949-25-2-2. 3. O’Brien, R. L. 1991. Welding Handbook. Vol. 2: Welding Processes. 8th edition, American Welding Society, Miami, Fla. 4. Stava, E. K. 1993. A new, low-spatter arc welding machine. Welding Journal 72(1): 25–29. 5. Stava, E. K. 1992. System and method of short circuiting arc welding. U.S. Patent #5,148,001. 6. Himmelbauer, K. 2005. The CMTProcess — A revolution in welding technology. IIW Doc XII-1875-05, 20-27. 7. Kim, Y.-S., and Eagar, T. W. 1993. Analysis of metal transfer in gas metal arc welding. Welding Journal 72(6): 269-s to 278-s. 8. Lancaster, J. F. 1984. The Physics of Welding. Pergamon Press, Oxford, England. 9. Iszink, J. H., and Piena, M. J. 1986. Experimental investigation of drop detachment and drop velocity in GMAW. Welding Journal 65(11): 289-s to 298-s. 10. Essers, W. G., and Walter, R. 1981. Heat transfer and penetration mechanisms with GMA and plasma-GMA welding. Welding Journal 60(2): 37-s to 42-s. 11. Choi, J. H., Lee, J., and Yoo, C. D. 2001. Dynamic force balance model for metal transfer analysis in arc welding. Journal of Physics D: Applied Physics 34: 2658–2664. 12. Shi, Y., Liu, X., Zhang, Y. M., and Johnson, M. 2008. Analysis of metal transfer and correlated influences in dual-bypass GMAW of aluminum. Welding Journal 87(9): 229-s to 236-s. 13. Li, K., and Zhang, Y. M. 2007. Metal transfer in double-electrode gas metal arc welding. Journal of Manufacturing Science and Engineering — Transactions of the ASME 129(6): 991–999. 14. Thomsen, J. S. 2006. Control of pulsed gas metal arc welding. International Journal of Modelling, Identification, and Control 1(2): 115–125. 15. Zheng, B., and Kovacevic, R. 2001. A novel control approach for the droplet detachment in rapid prototyping by 3D welding. Journal of Manufacturing Science and Engineering 123: 348–355. 16. Wu, Y., and Kovacevic, R. 2002. Mechanically assisted droplet transfer process in gas metal arc welding. Journal of Engineering Manufacturing 216: 555–564. 17. Yang, S. Y. 1998. Projected droplet transfer control with additional mechanical forces (AMF) in MIG/MAG welding process. PhD dissertation, Harbin Institute of Technology. 18. Allum, C. J. 1985. Welding technology data: pulsed MIG welding. Welding and Metal Fabrication 53: 24–30. 19. Kim, Y. S., and Eagar, T. W. 1993. Metal transfer in pulsed current gas metal arc welding. Welding Journal 72(7): 279-s to 287-s. 20. Amin, M. 1983. Pulse current parameters for arc stability and controlled metal transfer in arc welding. Metal Construction 15: 272–278. 21. Zhang, Y. M., Liguo, E., and Kovacevic, R. 1998. Active metal transfer control by monitoring excited droplet oscillation. Welding Journal 77(9): 388-s to 395-s. 22. Zhang, Y. M., and Liguo, E. 1999. Method and system for gas metal arc welding. U.S. Patent #6,008,470. 23. Wang, G., Huang, P. G., and Zhang, Y. M. 2004. Numerical analysis of metal transfer in gas metal arc welding under modified pulsed
current conditions. Metallurgical and Materials Transactions B 35(5): 857–866. 24. Zhang, Y. M., and Li, P. J. 2001. Modified active control of metal transfer and pulsed GMAW of titanium. Welding Journal 80(2): 54-s to 61-s. 25. Li, S. K. 2004. Numerical analysis of droplet transfer in active control mode of the pulsed GMAW. Master’s dissertation. Shandong University. 26. Huang, Y., and Zhang, Y. M. 2010. Laser-enhanced GMAW. Welding Journal 89(9): 181-s to 188-s. 27. Huang, Y., and Zhang, Y. M. 2011. Laser-enhanced metal transfer — Part 1: System and observations. Welding Journal 90(10): 183-s to 190-s. 28. Huang, Y., and Zhang, Y. M. 2011. Laser-enhanced metal transfer — Part 2: Analysis and influence factors. Welding Journal 90(11): 206-s to 210-s.
Welding Journal Becomes Digital and Mobile The Welding Journal can now be enjoyed by AWS members for free using their computers or Internet-ready mobile phones or tablets, including iOS (iPad® and iPhone®), Android®, Windows 7®, and HP Web OS® devices. Presented below are three key areas with details for reading the magazine in various ways. • For desktops/laptops, the Welding Journal can be read online, or downloaded for offline reading and archiving. You can also do custom searches within a single issue or throughout all the issues in the archive (dating back to December 2011), and print individual pages or whole issues. Active links add convenience. • For mobile devices, the Welding Journal can be used on Internetcapable tablets or phones. A Web app runs in your mobile browser and automatically recognizes the device, optimizing presentation and functionality. It is the best choice for those who prefer reading content online vs. downloading to their mobile device. • For iPad and iPhone users, go to iTunes, type in “Welding Journal” in the search window, and download the app to retrieve the magazine online or download for immediate access. This is the best choice for those who prefer to store issues in their iOS devices for offline reading. In addition, build your Welding Journal catalog with all the available issues in the archive. The digital edition will be sent to you automatically every month, but make sure your e-mail address is up to date by logging in at www.aws.org.
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enlarging the exciting rising level. The average current is meanwhile reduced. Based on this result, the modified current waveform is further optimized to obtain maximized droplet oscillation energy with any level of growing current. 2. The influence of the exciting parameters on the droplet oscillation was analyzed. It was found that the exciting peak duration is a key parameter determining the droplet oscillation. Its optimal range was confirmed in experiments to be 3–4 ms while 2 ms is also acceptable. The droplet oscillation with a different exciting base current and peak current was also studied. The optimal base current is considered to be 30 A according to the experimental results. The exciting transition current was defined and tested to be 70 A. The droplet oscillations using the exciting peak current ranged in 80–140 A were measured. The results demonstrate that the droplet oscillation energy increased approximately in a parabolical way when the exciting peak current was stepping up. 3. The growing duration was set in a group of values to verify its influence on the droplet oscillation. It is demonstrated that the droplet oscillation frequency changes significantly with the growing duration. The droplet mass gets larger with increased growing duration, so the droplet frequency is decreased. As future work, the correlation of the droplet oscillation with the arc voltage needs to be analyzed such that the droplet motion can be monitored by sensing the arc voltage signal. Furthermore, a closedloop control of the phase match based on the feedback of arc voltage is expected to maximize the enhancement on metal transfer during the droplet oscillation. Based on this work, the minimum detaching current utilizing the active droplet oscillation will be tested with a different combination of the exciting peak current (80–150 A) and duration (2–4 ms). In addition, such closed-loop controlled active droplet oscillation technology may be further applied into the laser-enhanced GMAW process to reduce the required laser power. Acknowledgments
High-Temperature Corrosion Behavior of Alloy 600 and 622 Weld Claddings and Coextruded Coatings Thermogravimetric and solid-state corrosion testing techniques were used to evaluate the corrosion behavior of nickel-based alloys BY J. N. DUPONT, A. W. STOCKDALE, A. CAIZZA, AND A. ESPOSITO ABSTRACT
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Weld claddings are often used for corrosion protection for waterwalls in coal-fired power plants. Although these coatings provide good resistance to general corrosion, recent industry experience has shown they are susceptible to premature failure due to corrosion-fatigue cracking. The failure has been attributed, in part, to microsegregation and dilution of the weld cladding that compromise the corrosion resistance. Coextruded coatings may provide improved resistance to this type of failure due to elimination of microsegregation and dilution. In this work, the high-temperature gaseous and solid-state corrosion behavior of Alloys 600 and 622 weld claddings, and coextruded coatings were evaluated using thermogravimetric and solid-state corrosion testing techniques. The results demonstrate that Alloy 622 exhibits better corrosion resistance than Alloy 600 under the simulated combustion gases of interest, and coextruded coatings provide corrosion resistance that is significantly better than the weld claddings. The improved corrosion resistance of Alloy 622 is attributed to the higher Cr and Mo concentrations, while the better corrosion resistance of the coextruded coatings is attributed to elimination of dilution and microsegregation. Additional benefits of the coextruded coatings in terms of service performance are also likely, and include better control over coating thickness and surface finish and reduced residual stresses.
Introduction Many coal-fired power plant operators have moved toward a staged combustion process in order to reduce boiler emissions as required by recently implemented environmental regulations. By delaying the mixing of fuel and oxygen, and thereby creating a reducing environment in the boiler, the amount of nitrous oxides (NOx) that are released as a byproduct of coal combustion is reduced (Refs. 1, 2). The use of this staged combustion process has been found by many power plant operators to be the most cost- and time-effective method for decreasing NOx emissions. Prior to implementation of staged combustion, most boiler atmospheres were oxidizing, allowing for formation of protective metal oxides on waterwall tubes made out of carbon or low-alloy steels (Refs. 1, 3). Under those conditions, failure of waterJ. N. DUPONT and A. W. STOCKDALE (
[email protected]) are with the Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pa. A. CAIZZA and A. ESPOSITO are with Plymouth Engineered Shapes, Hopkinsville, Ky.
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walls due to accelerated corrosion was generally not a major problem. Staged combustion boilers, on the other hand, create a reducing atmosphere in the boiler due to the lack of oxygen. Sulfur compounds from the coal are transformed into highly corrosive H2S gas (Ref. 4). Subsequent reaction with the steel waterwall tubes leads to the formation of metal sulfides or mixed sulfides and oxides on the tube surfaces. Additionally, corrosive deposits may form on the waterwall tubes due to the accumulation of solid particles in the combustion environment, such as ash and unburnt coal. As a result of these changes, the low-alloy steel tubes are often susceptible to accelerated corrosion and unsatisfactory service lifetimes (Refs. 1, 4).
KEYWORDS Corrosion Weld Overlay Coating Coextruded Coating Ni-Based Alloys Dilution Microsegregation
The current industry solution to accelerated waterwall corrosion is to deposit a weld cladding of a more corrosion-resistant alloy on the tube. Commercially available nickel-based alloys have been used for weld claddings (Refs. 5–7). These alloys generally provide good resistance to general corrosion for this application. However, weld claddings have recently been shown to be susceptible to corrosionfatigue cracking in many boiler environments (Ref. 6). The primary features associated with corrosion-fatigue cracking are summarized in Fig. 1 (Ref. 6). Figure 1A is a photograph of a weld cladding with extensive corrosion-fatigue cracks that were observed after approximately 18 months of service (Ref. 6). Figure 1B shows a scanning electron photomicrograph of several small cracks that were examined early in the cracking stage, and Fig. 1C shows the distribution of alloying elements across the dendritic substructure of the overlay. Figure 1D provides a lowermagnification view that demonstrates the cracks initiate at the valley of the weld ripple. The dendrite cores in the cladding exhibit a minimum in alloy concentration due to the relatively rapid solidification conditions associated with welding (Ref. 7). As a result, the corrosion rate is accelerated in these regions and localized attack occurs at the dendrite cores. These localized penetrations form stress concentrations that eventually grow into full-size corrosion-fatigue cracks under the influence of service-applied stresses. As shown in Fig. 1D, most cracks initiate in the valley of surface weld ripples where an additional stress concentration exists. The high residual stress that results from welding also probably contributes to the cracking problem. In addition, dilution from the underlying tube substrate, which results in reduced alloy content of the cladding, compromises the corrosion resistance of the cladding. It is important to note that the primary factors that contribute to corrosionfatigue cracking (weld ripple, microsegregation, high residual stresses, and dilution) are all associated with the localized
C
B
D
Fig. 1 — A — Photograph of an IN625 weld cladding with extensive circumferential cracks; B — crosssectional scanning electron photomicrograph of several small cracks early in the cracking stage; C — distribution of alloying elements across the dendritic substructure of the IN625 weld cladding; D — photograph showing crack initiation at the valley of the weld ripple.
heating, melting, and solidification of the welding process. As such, use of a coating that can be applied uniformly on the substrate surface in the solid state (i.e., without the need for localized heating) should help mitigate these problems and improve the cracking resistance of the coating. Thus, there is a need to develop alternative coating technologies that avoid these drawbacks. Coextruded coatings provide a potential alternative because they are produced completely in the solid state and therefore require no melting and resolidification. In this work, the high-temperature corrosion resistance of two nickelbased alloys (600 and 622) were investigated in the form of both coextruded coatings and weld claddings. The counterpart wrought product form was also tested for Alloy 600 for comparison.
Experimental Procedure Three types of samples were corrosion tested: coextruded coating, wrought alloy (for Alloy 600 only), and weld cladding. Coextruded tubes were manufactured at Plymouth Engineered Shapes using an outer layer of either Alloy 600 or 622 and
a 1.25Cr-0.5Mo (SA213-T11) steel substrate. The composition of the Ni-based alloys and the steel are provided in Table 1. The steel substrate and nickel alloy outer layer were joined by an explosion welding process prior to coextrusion. As shown in Fig. 2, the substrate and outer layer had a starting diameter of 6 in. and length of about 2 ft. The bimetallic billet was heated to 1040°C prior to coextrusion, and the coextrusion occurred in approximately 5 s. Figure 3 shows an example of the final bimetallic tube produced after coextrusion that has an outside diameter of 2.5 in. with a 0.250-in. wall thickness and a coating thickness of 0.085 in. The final tube length was approximately 20 ft. Simulated weld claddings were fabricated by mixing (by weight) 10% of an Alloy 285 Grade C steel substrate (this alloy is similar to those typically used for waterwall tubes) with 90% of Alloy 600 or 622. The 10% steel was added to simulate a typical dilution level of a commercial weld cladding. (It is recognized that Alloy 600 is not available in wire form for use as a weld cladding. However, the weld cladding samples were prepared and tested here to provide a direct comparison to the coex-
Fig. 2 — Photograph of starting bimetallic billet showing the inner steel substrate and outer nickel alloy layer prior to coextrusion. The starting billet had a diameter of approximately 6 in. and a length of about 2 ft.
truded coating of the same composition.) The mixture was then melted and resolidified in an arc button melter, which essentially duplicates the chemical composition and thermal conditions used to make weld claddings. This process has been used extensively for preparing and corrosion testing weld cladding samples (Ref. 8). Gaseous corrosion testing was carried out at 600°C for 100 h in a Netzsch thermogravimetric balance. The gas used for the corrosion tests was modeled after a typical low-NOx environment and consisted of the following mixture (Ref. 8): 10%CO5%CO2-2%H2O-0.12%H2S-N2 (vol-%). Corrosion samples were acquired from the coating of the bimetallic tube by completely machining away the underlying steel substrate. The Alloy 622 weld cladding and coextruded samples were also tested under solid-state corrosion conditions. (Alloy 600 was not evaluated under solid-state conditions, since the gaseous corrosion results demonstrated that Alloy 622 had superior corrosion resistance.) Samples that were ¾ × ¾ × 5⁄16 in. were machined from the coextruded tube and the weld cladding. A quartz ring was placed on top
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A
A
Fig. 3 — A section of the final bimetallic tube produced after coextrusion. The tube has an outside diameter of 2.5 in. with a 0.250-in. wall thickness and a coating thickness of 0.085 in. The final tube length was approximately 20 ft.
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of the samples, and 1680 mg of FeS2 powder was poured into the quartz ring. The FeS2 powder simulates the iron sulfide that is often deposited on waterwall surfaces in the form of coal particles that are not completely combusted. The iron sulfide will oxidize at high temperature and subsequently release sulfur gas that corrodes the underlying coating (Refs. 9, 10). The samples were placed in a furnace and heated to 600°C for 50, 150, and 300 h (separate samples were used for each exposure time). The samples were then examined in cross section to reveal the depth of attack and corrosion morphology after each exposure time. This test has been shown (Ref. 8) to simulate the solid-state corrosion that occurs when deposits form on the waterwall tubes in service. Corrosion test coupons from the gaseous and solid-state tests were mounted under vacuum in cold setting epoxy and ground through 600 grit with a SiC abrasive. The samples were then polished to a 0.05-μm surface finish. Post-test imaging of corrosion scales was conducted via light optical microscopy and scanning electron microscopy on a Hitachi 4300 scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer.
Results Figure 4 shows photographs that compare the coating surface finish and thickness uniformity of the coextruded coating (Fig. 4A, B) and a weld cladding typically used for this application (Fig. 4C, D). The weld cladding exhibits the typical surface ripples associated with solidification and a relatively uneven coating thickness. The coextrusion process provides a relatively smooth surface finish and more uniform coating thickness. Elimination of the weld ripple is significant, since the valleys of the weld ripple present stress concentrations that exacerbate corrosion-fatigue crack initiation (Ref. 6). The more uniform coating thickness and improved surface finish associated 220-s JULY 2013, VOL. 92
B
D
C
Fig. 4 — Comparison of coating surface finish and thickness uniformity of the following: A, B — Coextruded coating; C, D — a weld cladding typically used for this application.
with the coextruded coating eliminates this form of stress concentration and should therefore be more resistant to initiation of corrosion-fatigue cracks. Figure 5 shows the thermogravimetric analysis results from the gaseous corrosion testing. These results compare the normalized weight gain of the weld cladding and coextruded coating. Corrosion results from the alloy in the wrought condition are also shown for Alloy 600 for comparison. Good corrosion results are indicated by relatively low weight gains, and the slopes of the lines are an indication of the corrosion rates. The coextruded coating clearly shows improved corrosion resistance over the weld cladding, and the corrosion resistance of the wrought alloy and coextruded coating for Alloy 600 is comparable. Also note that Alloy 622 demonstrates better corrosion resistance (i.e., lower weight gains) than Alloy 600. Figure 6 shows SEM cross-sectional photomicrographs of the corrosion coupons from the gaseous corrosion tests. These samples reveal an outer scale in addition to an inner corrosion scale that formed adjacent to the coating surface during corrosion testing. It is important to note that, due to the large differences in corrosion scale thickness, the photomicrographs
acquired from the coextruded coating (Fig. 6A, B) are generally taken at a higher magnification than those of the weld cladding (Fig. 6C, D). The inner corrosion scale that formed on the coextruded sample is signifi-
Table 1 — Composition of the Ni-Based Alloys and Steel Used to Make the Coextruded Tubes (all values are given in wt-%)
C Co Cr Fe Mn Mo Ni P S Si V W Nb Ta Ti Al Cu Cs N Sn
622 0.002 0.81 21.3 3.7 0.25 13.1 Bal 0.012 0.002 0.03 0.02 2.8 — — — — —
600 0.06 0.06 16 7.47 0.36 — Bal — 0 0.34 0.04 — 0.01 0.01 0.22 0.2 0.03
T11 0.12 — 1.22 — 0.52 0.52 0.02 0.009 0.026 0.62 0.006 — — — — 0.029 0.02 0.002 0.005 0.002
B
A
A
B
C
D
Fig. 6 — SEM cross-sectional photomicrographs of the corrosion coupons from the gaseous corrosion tests of Alloy 600 for the coextruded coating (Fig. 6A, B) and weld cladding (Fig. 6C, D).
cantly thinner than the inner scale that formed on the weld cladding. Figure 6A, which was acquired from the coextruded sample, was taken at the same magnification as Fig. 6D acquired from the weld cladding, and the differences in scale thickness are readily apparent when these two images are compared. Also note that corrosion has occurred more uniformly on the co-
extruded coating compared to the weld cladding. The differences in scale thickness are consistent with the differences in the weight gain results shown in Fig. 5, where the weld cladding exhibited a higher weight gain (due to the higher corrosion rate and concomitantly larger scale thickness). A thinner inner corrosion scale is preferred, as this indicates that the scale provides better
protection between the corrosion environment and underlying coating surface. Figure 7 shows EDS spectra collected from the corrosion scales that formed on the gaseous corrosion samples. The locations that the EDS scans were acquired from are shown as white boxes in Fig. 6B, D. (In each case, EDS spectra acquired from the area between the inner and outer WELDING JOURNAL 221-s
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Fig. 5 — Thermogravimetric results from the gaseous corrosion testing. A — Alloy 600; B — Alloy 622.
A
B
C
D
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Fig. 7 — EDS spectra acquired from gaseous corrosion samples of Alloy 600. A — Top surface scale of the coextruded coating; B — inner surface scale of coextruded coating; C — top surface scale of the weld cladding; D — inner surface scale of weld cladding.
scales were observed to reveal the presence of carbon and oxygen, indicating that it is merely the mounting material used to prepare the samples. This occurs when the inner and outer scales separate during preparation.) For each coating type, the outer scales are rich in nickel and sulfur. The inner scales of each sample are also similar and reveal the presence of a chromium-rich mixed oxygen-sulfur scale. Figure 8 shows the extent of corrosion that occurred during the solid-state corrosion testing for the Alloy 622 weld cladding and coextruded coatings. A significant amount of corrosion scale can be observed on the surface of each sample. The amount of scale on the surface is indicative of the severity of the corrosive attack. The corrosion resistance of the weld cladding and coextruded coatings are somewhat similar up to 50 h of exposure. However, at 150 and 300 h, the depth of attack is greater on the weld cladding. Also note that the weld cladding exhibits localized corrosion penetrations (arrows in Fig. 8F) while corrosion on the coextruded coating is uniform. Figure 9 shows the 300-h corrosion sample of the weld cladding after it was etched to reveal the dendritic substructure. Note that preferential corrosion has occurred at the dendrite cores (arrows). Figure 10 provides an EDS line scan that was acquired across the dendritic substructure of the weld cladding. As expected (Refs. 6, 7), the dendrite cores are
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depleted in Mo, with Mo concentration levels down to ~ 11 wt-% (the nominal Mo concentration of the filler metal is ~ 13 wt-%). Note that the Ni segregates in the opposite direction compared to Mo (i.e., to the dendrite cores). The particularly high Mo level of ~ 38 wt-% (at a position of ~ 3 μm) is coincident with Ni depletion down to ~ 28 wt-% and is associated with the electron beam interacting with Mo-rich interdendritic phase. Figure 11 shows the microstructure of the coextruded coating, and an EDS line scan acquired across several grains of the coating is shown in Fig. 12. The coextruded coating exhibits a uniform, equiaxed grain structure and a uniform distribution of alloying elements. Discussion The corrosion results demonstrate the effect of the coating process on the resultant corrosion resistance. For each alloy, the coextruded coatings provide significantly better corrosion resistance than the weld claddings. Since the alloy is the same in each case, the reduced corrosion resistance of the weld cladding must be attributed to differences in processing that affect the microstructure. This is confirmed by the results shown for Alloy 600 in which a wrought alloy was also tested for comparison — Fig. 5A. Note that the wrought alloy and coextruded coating exhibit essentially identical corrosion rates. This in-
dicates the coextrusion process has no detrimental effect on the inherent corrosion resistance of the wrought alloy. This is consistent with the observed microstructure (Fig. 11) and distribution of alloying elements (Fig. 12) observed for the coextruded coating. The equiaxed grain structure and uniform distribution of alloying elements is similar to that observed for a wrought alloy, so the corrosion resistance is also expected to be similar, as observed in Fig. 5A. The differences in corrosion resistance among the two alloys and coating types evaluated here can be understood by considering differences in their composition. It is well known that Cr and Mo additions significantly improve the sulfidation resistance of Ni-based alloys (Refs. 11, 12). For example, Chen and Douglass (Refs. 11, 13) evaluated the effect of Mo additions on the sulfidation resistance of NiMo alloys at 600°C at a sulfur partial pressure of 0.01 atm PS2. Five alloys were evaluated, including Ni, Ni-10wt-%Mo, Ni-20wt-%Mo, Ni-30wt-%Mo, and Ni40wt-%Mo. The parabolic rate constant decreased by four orders of magnitude as the Mo content was increased to 40 wt-% Mo. Similar reductions in the parabolic rate constant were also observed for Ni-Cr alloys tested by Mrowec et al. (Refs. 12, 14). The sulfidation behavior of Ni with up to 82 at-% Cr was evaluated in a sulfur partial pressure of 1 atm PS2 at 600°C. The parabolic rate constant decreased by three orders of magnitude as the chromium content was increased up to 82 at.-% Cr. These results demonstrate that the corrosion resistance of Ni-based materials is improved by alloying additions of Cr and Mo. Thus, the improved corrosion resistance of Alloy 622 over Alloy 600 is attributed to the higher Cr and Mo concentration of Alloy 622. The improved corrosion resistance of the coextruded coatings can be attributed to two factors. First, the weld cladding exhibits a 10% reduction in key alloying elements (e.g., Cr and Mo) due to 10% dilution with the steel substrate, and a reduction in the concentration of these elements will produce an increase in the corrosion rate. The 10% dilution value used for these tests represents a lower limit on the dilution level for commercially applied weld claddings. The dilution level in fieldapplied weld claddings can often be higher than this, and the corrosion resistance can be reduced even further as a result. Such dilution effects do not occur with the coextruded coating because there is no melting and mixing associated with this process. Although there is localized solidstate diffusion across the coating/substrate interface during processing, there is no bulk change in coating composition. Second, the weld cladding exhibits mi-
D
B
E
C
F
Fig. 8 — Light optical photomicrographs showing the extent of corrosion that occurred during solid-state corrosion testing for the following: A, B, C — Alloy 622 coextruded; D, E, F — weld cladding coatings.
A
B
Fig. 10 — A — EDS line scan acquired across the dendritic substructure of the weld cladding showing the composition profiles for Fe, Ni, and Cr; B — EDS line scan acquired across the dendritic substructure of the weld cladding showing Mo depletion at the dendrite cores.
Fig. 9 — Light optical photomicrographs of the 300-h corrosion sample of the weld cladding after it was etched to reveal the dendritic substructure. Note that preferential corrosion has occurred at the dendrite cores (arrows).
crosegregation in which the dendrite cores are depleted in alloying elements (particularly of Mo) that are important for corrosion protection (Ref. 15). As a result, corrosion occurs more rapidly at the alloydepleted cores, thus leading to the preferential corrosive attack at the dendrite cores observed in Figs. 6C, 6D, and 9. It is worth noting that the coextruded (and wrought) Alloy 600 provides corro-
sion resistance that is nearly comparable to the Alloy 622 weld cladding, suggesting that Alloy 600 may be useful as a coextruded coating. However, the objective here is to develop a coating/process combination that provides performance better than the current industry standard (622 weld cladding). Thus, the use of Alloy 600 as a coextruded coating does not appear warranted based on this consideration. These results indicate that coextruded coatings should provide significant benefits over weld claddings for corrosion protection in fossil-fired boilers. (It should be recognized that weld claddings can be applied in the field or the shop, while coextruded coatings can only be applied in the shop.) Reduction or elimination of failures due to corrosion-fatigue cracking will require the development of coatings with improved resistance to both general corrosion and localized corrosion that occurs due to microsegregation. Other factors that promote corrosion-fatigue crack initiation should
also be avoided, such as surface irregularities and high residual stresses. Coextruded coatings provide several advantages over the weld claddings in these regards. First, the coextruded coatings will not exhibit dilution and microsegregation that compromise corrosion resistance. The weld claddings also exhibit surface ripples associated with the solidification process, and the valleys of these ripples are sources of stress concentration that can contribute to corrosion-fatigue cracking (Ref. 6). In contrast, the coextruded coatings have a uniform coating thickness and smooth surface finish that should help eliminate localized stress concentrations that initiate corrosion-fatigue cracks. Weld claddings also develop very high levels of residual stress that are associated with localized heating and cooling. The residual stress level is generally on the order of the yield strength of the alloy (Ref. 16), and this may also be a contributing factor to the corrosion-fatigue problem. In contrast, the heating and cool-
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A
Fig. 11 — Light optical photomicrograph showing the microstructure of the coextruded coating.
WELDING RESEARCH
ing cycles experienced during coextrusion are less severe and more uniform. As a result, the residual stresses should be significantly reduced. Corrosion-fatigue testing and field tests are currently in progress to verify this expected level of improvement and will be reported in the future.
Summary The high-temperature corrosion resistance of Alloys 600 and 622 weld claddings and coextruded coatings was evaluated in this work. A wrought sample of Alloy 600 was also corrosion tested for comparison. The results demonstrate: 1) Alloy 622 exhibits better corrosion resistance than Alloy 600; and 2) coextruded coatings provide corrosion resistance that is significantly better than the weld claddings. The improved corrosion resistance of Alloy 622 is attributed to the higher Cr and Mo concentrations. The improved corrosion resistance of the coextruded coatings relative to the weld cladding is attributed to elimination of dilution and microsegregation in the coextruded coating. Additional benefits of the coextruded coating in terms of service performance are also likely, and include better control over
12 — EDS line scan acquired across several grains of the coating.
coating thickness/surface finish and reduced residual stresses. Acknowledgments
The authors gratefully acknowledge financial support through the National Science Foundation Center for Integrated Materials Joining Science for Energy Applications, Grant IIP-1034703, and PPL Corp., Contract 00474836. Useful technical discussions with Ruben Choug and Robert Schneider of PPL Corp. are also gratefully appreciated. References 1. Jones, C. 1997. Power January/February, pp. 54–60. 2. Whitaker, R. 1982. EPRI Journal, pp. 18–25. 3. Urich, J. A., and Kramer, E. 1996. FACT (American Society of Mechanical Engineers), Vol. 21, pp. 25–29. 4. Kung, S. C., and Bakker, W. T. 1997. Mater. High Temp. 14: 175–182. 5. Smith, G. D., and Tassen, C. S. 1989. Mater. Perf. 28: 41–43. 6. Luer, K., DuPont, J. N., Marder, A. R., and Skelonis, C. 2001. Mater. High Temp. 18: 11–19. 7. DuPont, J., Lippold, J., and Kiser, S. 2009. Welding Metallurgy and Weldability of Nickel-
base Alloys. p. 440, Hoboken, N.J.: John Wiley & Sons. 8. Regina, J. R., DuPont, J. N., and Marder, A. R. 2004. Corrosion behavior of Fe-Al-Cr alloys in sulfur- and oxygen-rich environments in the presence of pyrite. Corrosion. pp. 501–509. 9. Bakker, W. 1998. Waterwall Wastage in Low Nox Boilers: Root Cause and Remedies. TR111155. 10. Kung, S., and Bakker, W. 2000. Waterwall corrosion in coal-fired boilers a new culprit: FeS. Corrosion 2000. pp. 26–31. NACE International. 11. Chen, M. F., and Douglass, D. L. 1989. The effect of molybdenum on the high-temperature sulfidation of nickel. Oxid. Met. 32: 185–206. 12. Mrowec, S., Werber, T., and Zastawnik, M. 1966. The mechanism of high temperature sulfur corrosion of nickel-chromium alloys. Corros. Sci. 6: 47–68. 13. Gleeson, B., Douglass, D. L., and Gesmundo, F. Effect of niobium on the high-temperature sulfidation behavior of cobalt. Oxid. Met. 31: 209–236. 14. Czerski, L., Mrowec, S., and Werber, T. 1962. Kinetics and mechanism of nickel-sulfur reaction. Journal of the Electrochemical Society 109: 273–278. 15. Deacon, R. M., DuPont, J. N., and Marder, A. R. 2007. Materials Science & Engineering A Vol. 460–461, pp. 392–402. 16. Kou, S. 2002. Welding Metallurgy. p. 461, Hoboken, N.J.: John Wiley & Sons.
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