Charpy v Notch Impact Test

CHARPY V NOTCH IMPACT TEST Objective:

To determine the amount of energy absorbed in fracturing a standardized test piece at a specified temperature.

Method:

A machined, notched specimen is broken by one blow from a pendulum. Because scatter occurs in the results, at least three specimens are used to assess the joint represented. Testing is carried out at a temperature specified in the appropriate application standard. (BS EN 875:1995)

Dial calibrated in joules

P- point reach after fracture A

B Hammer Anvil

Energy absorbed during fracture is proportional to A-B after hammer hit the specimen. The Charpy impact test, measured in joules, is an assessment of TOUGHNESS or energy absorption

TEST PIECE

3 pieces sample are required for each weld place (BG-50) and (BG35). Each specimen with dimension 55mm (L) x 10mm (W) x 10mm (T) and root radius prepared.

55mm

10 mm

10 mm

To show the boundary line, fusion zone and HAZ, the specimen was immerged in the nitro acid for a minutes. Then dry with the blower,

Reporting Results: 1. Location and orientation of the notch. -The fusion zone is the area of highest dilution between filler metal and parent plate. -Adjacent to the fusion boundary is the heat affected zone (HAZ), in which the plate material has had its metallurgical structure modified by the heat of welding. Hammer blow from this side Fusion zone Fusion Boundary/ line

HAZ

2. Testing temperature. Dry ice- Solid carbon dioxide that sublimates at -78.5=C (-110=F) and is used primarily as a coolant.

Digital Thermometer Specimen Solid carbon dioxide

3. Energy absorbed in joules.

Energy absorbed during fracture is proportional to A-B after hammer hit the specimen PRINCIPLE A charpy V-notch test specimen is placed on an anvil in the path of a pendulum. When the pendulum hits the specimen, the material is subjected to elastic deformation, plastic deformation, and finally, fracture is rapid succession. The pendulum transform its potential energy to kinetic energy and back to potential energy again while swinging back and forth. Its energy is only potential when it is at its highest point, h1, before it is released. At its highest point the potential energy is Ep = mgh1 Where m is the mass of the hammer at the end of the pendulum, g is the acceleration due to gravitation and h is the vertical distance between the highest and the lowest position of the pendulum. When the pendulum swings through and breaks the specimen it will lose part of its energy, and consequently swing up to a lesser height, h2. The energy E, used to fracture the specimen is therefore E = mg (h1-h2)

4. Description of fracture appearance. 5. Location of any defects.

The surface change from dull for ductile fracture, to shiny for brittle fracture V notch position / location of facture at weld metal.