Askeland Chapter
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The Science and Engineering th of Materials, 4 ed Donald R. R . Askeland – Pradeep P. Phul
!hapter 1" – #onferrous Allo$s
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&'(ecti)es of !hapter 1"
E*plore the properties and applications of !u, Al, and Ti allo$s in load+'earing applications.
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!hapter &utline
1".1 Aluinu Allo$s 1".% Magnesiu and -er$lliu Allo$s 1"." 1".4 1". 1"./
!opper Allo$s #ickel and !o'alt Allo$s Titaniu Allo$s Refractor$ and Precious Metals Refractor$
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Section 1".1
Aluinu Allo$s
0all+0eroult process + process + An electrol$ti electrol$tic c process '$ hich aluinu is e*tracted fro its ore. Teper designation designation + + A shorthand notation using letters and nu'ers the processing of an allo$. tepers refer to to descri'e cold+orked allo$s2 T tepers refer0to age+hardening age+hardeni ng treatents.
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. e s n e c i l r e d n n i e r e h d e s k r m a e d a r t a s i ™ g n i n r a e L n o s m o h T . c n I , g n i n r a e L n s o m o h T f o n o i s i v i d a , e l o C / s k o o r B 3 0 0 2 ©
Figure 13.1 Production of aluminum in an electrolytic cell.
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Figure 13.2 (a) FeAl3 inclusions in annealed 1100 350). (b)( Mg2Si in annealed aluminum ( 5!5" aluminum alloy "5). (From (reciitates From ASM ASM #andboo$% Vol. 7, (1972), (1972 ), ASM International, Materials Park, OH 4407.) 4407 .)
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©2003 Brooks/Co le, a division of Thomson Learning, Inc. Thomson Learning ™ is a trademark sed herein nder license.
Figure 13.3 Portion of t&e t&e aluminum'magnes aluminum'magnesium ium &ase diagram.
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Figure (a)and Sand'cast !!3(b) aluminum alloy containing contain coarse 13.! silicon inclusions. Permanent'mold !!3ing alloy containing fine dendrite cells and fine silicon due to faster cooling. (c) ie'cast !!3 alloy it& a still finer microstructure ( 350). (From (From ASM ASM #andboo$% Vol. 7, (1972), ASM International,, Materials Park, OH 4407.) International 4407.)
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E*aple 1".1 Strength+to+;eight Ratio in Design A steel ca'le 6. in. in diaeter has a $ield "strength of 36,666 psi. The densit$ of steel is a'out 3.3 g7c . -ased on the data in Ta'le 1"+, deterine 8a9 the a*iu load that the steel ca'le can support, 8'9 the diaeter of a cold+orked aluinu+anganese aluinu +anganese allo$ 8"664+0 19 re:uired to support the sae load as the steel, and 8c9 the eight per foot of the steel ca'le )ersus the aluinu allo$ ca'le.
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E*aple 1".1 S&&# a. nstruent grade 'er$lliu 'er$lliu is is used in inertial guidance s$stes here the elastic deforation ust 'e inial2 structural grades are used in aerospace applications2 and nuclear applications take ad)antage of the transparenc$ of 'er$lliu to electroagnetic radiation. -er$lliu is e*pensi)e, 'rittle, reacti)e, and to*ic.
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. e s n e c i l r e d n n i e r e h d e s k r a m e
d a r t a s i ™ g n i n r a e L n o s m o h T . c n I , g n i n r a e L n o s m h o T f o n o i s i v i d a , e l o C / s k o o r B 3 0 0 2 ©
Figure 13.5 ,&e magnesium'aluminum &ase diagram.
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Section 1"."
!opper Allo$s
-lister copper + copper + An ipure for of copper o'tained during the copper refining process. Applications Applicatio ns for f or copper+'ased allo$s allo$s include include electrical coponents 8such as ire9, pups, )al)es, and plu'ing parts, here these properties are used to ad)antage. -rass + -rass + A group of copper+'ased allo$s, noral norall$ l$ containing Binc as the a(or allo$ing eleent. -ronBe + -ronBe + Cenerall$, copper allo$s containing tin, can contain other eleents.
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. e s n e c i l r e d n n i e r e h d e s k r a m d e a r t a s i ™ g n i n r a e L n o s m o h T . c n I , g n i n r a e L n o s
Figure 13. /inary &ase
o m h T f o n o i s i v i d a , e l o C / s k o o r B 3 0 0 2 ©
diagrams for t&e (a) coer'inc% (b) coer'tin% (c) coer' aluminum% and (d) coer' beryllium systems.
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E*aple 1". Design7Materials Selection for an Electrical Sitch
Design the contacts for a sitch or rela$ that opens and closes a high+current electrical circuit. E*aple 1". S&&# ;hen the sitch or rela$ opens and closes, contact 'eteen the conducti)e surfaces can cause ear and result in poor contact and arcing. Therefore, our design ust pro)ide for 'oth good electrical conducti)it$ and good ear resistance. relati)el$ pure copper allo$ dispersion strengthene strengthened d ith a A hard phase that does not distur' the copper lattice ould, perhaps, 'e allo$,, the hard ceraic+o*ide particles ideal. >n a !u+Al%&" allo$ pro)ide ear resistance 'ut do not interfere ith the electrical conducti)it$ conducti)it $ of the copper atri*.
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E*aple 1"./ Design of a 0eat Treatent for a !u+Al Cear Design the heat treatent re:uiredAllo$ to produce a high+strength aluinu+'ronBe gear containing 16 Al.
Figure 13. /inary &ase diagrams for t&e (c) coer'aluminum
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E*aple 1"./ S&&# 1. 0ea 0eatt th the e al allo lo$ $ to 56o! and hold to produce 166 β . %. uench the a allo$ llo$ to roo tepera teperature ture to cause β to transfor to artensite, β ´, hich is supersaturated in copper. ". Tepe perr 'el 'elo o / / o!2 a teperature of 466o! ight 'e suita'le. During tepering, the artensite transfors to α and γ%. The aount of the γ% that fors at 466o! is@
4. !ool rrapi apidl$ dl$ to roo tepera teperature ture so tha thatt the e:uili'riu γ does not for.
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Section 1".4 #ickel and !o'alt Allo$s
#ickel and co'alt allo$s are allo$s are used for corrosion protection and for high+teperature resistance, taking ad)antage of their high elting points and high strengths.
Superallo$s + A group of nickel, iron+nicke Superallo$s + iron+nickel, l, and co'alt+ 'ased allo$s that ha)e e*ceptional heat resistance, creep resistance, and corrosion resistance.
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. e s n e c i l r e d n n i e r e h d e s k r a m e d a r t a s i ™ g n i n r a e L n o s m o h T . c n I , g n i n r a e L n o s m o h T f o n o i s i v i d a , e l o C / s k o o r B 3 0 0 2 ©
Figure 13." ,&e effect of temerature on t&e tensile strengt& of seeral nic$el'based alloys.
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Figure 13. (a) Microstructure of a sueralloy% it& carbides at t&e grain boundaries and 4 reciitates in t&e matri- ( 15%000). (b) Microstructure of a sueralloy aged at to temeratures% roducing bot& large and small cubical 4 reciitates ( 10%000). (ASM #andboo$% Vol. #andboo$% Vol. 9, Metallo$ra%&" an' Mirostrtre (19*+), ASM International, Materials Park, OH 4407.) 4407. ) "%
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E*aple 1".3 Design7Materials Selection for a 0igh+Perforance Fet Engine Tur'ine -lade Design a nickel+'ased superallo$ for producing tur'ine 'lades for a gas tur'ine aircraft engine that ill ha)e a particularl$ o
long creep+rupture tie at teperatures approaching 1166 !.
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. e s n e c i l r e d n n i e r e h d e s k r a m e d a r t a s i ™ g n i n r a e L n o s m o h T . c n I , g n i n r a e L n o s m o h T f o n o i s i v i d a , e l o C / s k o o r B 3 0 0 2 ©
Figure 13. (a) A turbine blade designed for actie cooling by a gas. (b) ,&e &ig&'temerature &ig&'temeratu re caability of sueralloys &as increased it& imroements in manufacturing manufacturi ng met&ods (for 6-amle 13.").
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E*aple 1".3 S&&# irst, e need a )er$ sta'le icrostruct icrostructure. ure. Addition of aluinu or titaniu perits the precipitation of up to /6 )ol of the - phase phase during heat treatent and a$ perit the allo$ to operate at teperatures approaching 6. ties the a'solute elting teperature. Second, e ight produce a directionall$ solidified or e)en single+cr$stal tur'ine 'lade 8!hapter 9. >n directional solidification, onl$ colunar grains. ;e ould then heat treat the casting to assure that the car'ides and - precipitate precipitate ith the correct siBe and distri'ution. inall$, the 'lade ight contain sall cooling channels along its length. Air for co'ustion in the engine can pass through these channels, pro)iding acti)e cooling to the 'lade, 'efore reacting ith fuel in the co'ustion cha'er. "
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Section 1". Titaniu Allo$s
TitaniuGs e*cellent corrosion resistance pro)ides applications applications in in cheical processi processing ng e:uipent, arine coponents, and 'ioedical iplants such as hip prostheses. Titaniu is an iportant aerospace aterial, finding applications as airfrae and (et engine coponents. Titaniu allo$s Titaniu allo$s are considered 'iocopati'le 'iocopati'le 8i.e., 8i.e., the$ are not re(ected '$ the 'od$9. -$ de)eloping porous coatings of 'one+like ceraic copositions knon as h$dro*$apatite, it a$ 'e possi'le to ake titaniu iplants 'ioacti)e 8i.e., 'ioacti)e 8i.e., the natural 'one can gro into the h$dro*$apatite coating9.
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. e s n e c i l r e d n n i e r e h d e s k r a m e d a t r a s i ™ g n i n r a e L n o s m o h T . c n I , g n i n r a e L n o s m o h T f o n o i s i v i d a , e l o C / s k o o r B 3 0 0 2 ©
Figure 13.10 Portions of t&e &ase diagrams for (a) titanium'tin% titanium'tin% (b) titanium' titanium' aluminum% (c) titanium' molybdenum% and (d) titanium' titanium' manganese.
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. e s n e c i l r e d n n i e r e h d e s k r a m e d a r t a s i
™ g n i n r a e L n o s m o h T . c n I , g n i n r a e L n o s m o h T f o n o i s i v i d a , e l o C / s k o o r B 3 0 0 2 ©
Figure 13.11 ,&e effect of on temerature t&e yield strengt& of selected titanium alloys.
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Figure 13.12 (a) Annealing and (b) microstructure of raidly cooled al&a titanium ( 100). /ot& t&e grain boundary reciitate and t&e 7idmanst8tten lates are al&a. (From (From ASM #andboo$% Vol. 7, (1972), (197 2), ASM International, Materials Park, OH 4407.) 4407.)
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igure 1".1" Annealing of an alpha+'eta titaniu allo$. 8a9 Annealing is done (ust 'elo the 9 / / transforation teperature, 8'9 slo cooling gi)es e:uia*ed grains 8 %69, and 8c9 rapid cooling $ields acicular grains 8 %669. 8From Metals 0and'ook, Vol. 7, (1972), ASM International, Materials Park, OH 447!.9
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igure 1".14 8a9 0eat treatent and 8'9 icrostructure of the alpha+'eta titaniu allo$s. The structure contains priar$ " 8large hite grains9 and a dark # atri* ith needles of " fored during aging 8%69. From ASM Vol. 7, 80and'ook, (1972), ASM International, Materials Park, OH 447!.9
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E*aple 1". Design of a 0eat E*changer Design a +ft+diaeter, "6+ft+long heat e*changer for the petrocheic petrocheical al industr$ 8igure 1".19.
©2003 Brooks/Co le, a di division vision of Thomson Learning, Inc. Thomson Learning™ is a trademark sed herein nder license.
Figure 13.15 S$etc& of of a &eat e-c&anger using titanium titaniu m tubes (for 6-amle 13.).
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E*aple 1". S&&# Pro)ided teperature is 'e 'elo titaniu ight ight a "o! so that that the the a*iu o*ide fil operating is sta'le, titaniu good choice to pro)ide corrosion resistance at ele)ated teperatures. A coerciall$ pure titaniu pro)ides the 'est corrosion resistance. Pure titaniu also pro)ides superior foring and elding characteristics and ould, therefore, 'e our ost logical selection. >f pure titaniu does not pro)ide sufficient strength, an alternati)e is an alpha titaniu allo$,, still pro)iding good corrosion resistan allo$ resistance, ce, foring characteristics, and elda'ilit$ 'ut also soehat ipro)ed strength.
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E*aple 1".5 Design of a !onnecting Rod Design a high+perforance connecting connecting rod for the engine of a racing autoo'ile 8igure 1".1/9.
Figure 13.1 S$etc& of connecting rod (for 6-amle 13.).
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E*aple 1".5 S&&# To achie)e high strengths, e ight consider an alpha+ 'eta titaniu allo$. -ecause of its a)aila'ilit$, the Ti+/ Al+4 H allo$ is a good choice. choice. The allo$ is heated to a'out 16/o!, hich is in the all+ / / portion portion of the phase diagra. ;hen the heat treatent is perfored in the all+ / / region, the tepered artensite has an acicular structure, hich reduces the rate of groth of an$ fatigue cracks that ight de)elop.
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E*aple 1".16 Materials for 0ip Prosthesis ;hat t$pe of a aterial ould $ou choose for an iplant to 'e used for a total hip replaceent iplantI E*aple 1".16 S&&# ;e need to consider the folloing factors@ 'iocopati'ilit$, corrosion resistance, high+fracture toughness, e*cellent fatigue life, and ear resistance. resistance. These re:uireents suggest "1/ stainless steel or Ti+ / Al+4 H. H. Titaniu is 'io+copati'le and ould 'e a 'etter choice. Perhaps a coposite the ste is ade fro a Ti+/ Al+4 H aterial allo$ andina hich head that is ade fro a ear+resistant, corrosion resistant, and fractured tough ceraic, such as aluina, a$ 'e an anser. Another option is to coat the iplant ith a aterial like porous h$dro*$apatite to encourage 'one groth.
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Section 1"./ Refractor$ and Precious Metals
Refractor$ etals – etals – These include tungsten, ol$'denu, tantalu, and nio'iu 8or colu'iu9, ha)e e*ceptionall$ high+elting teperatures 8a'o)e o
15% !9 and,ser)ice. conse:uentl$, ha)e the potential for high+ teperature Applications of Refractor$ etals include etals include filaents for light 'ul's, rocket noBBles, nuclear poer generators, tantalu+ and nio'iu+'ased electronic capacitors, and cheical processing e:uipent. Precious Metals + Metals + These include gold, sil)er, palladiu, platinu, and rhodiu.ro an engineeri engineering ng ) )iepoint, iepoint, these aterials resist corrosion and ake )er$ good conductors of electricit$.
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