metals and its alloys 2

8/9/2019 Metals and Its Alloys 2

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METALS AND ITSMETALS AND ITS

ALLOYS ALLOYS 22



NONFERROUS ALLOYSNONFERROUS ALLOYS

Cu & its AlloysCu & its Alloys

Al & its AlloysAl & its Alloys

Mg & its AlloysMg & its Alloys Ti & its AlloysTi & its Alloys

The Refractory MetalsThe Refractory Metals

The SuperalloysThe Superalloys

The Noble MetalsThe Noble Metals

Miscellaneous Nonferrous AlloysMiscellaneous Nonferrous Alloys



Steel and other ferrous alloysSteel and other ferrous alloys

are consumed in exceedinglyare consumed in exceedinglylarge quantities becauselarge quantities because ««

((11) they have a wide range of ) they have a wide range of mechanical properties;mechanical properties;

((22) may be fabricated with) may be fabricated withrelative ease;relative ease;

((33) are economical to) are economical toproduce.produce.



DISTINCT LIMITATIONS OF DISTINCT LIMITATIONS OF

FERROUS ALLOYSFERROUS ALLOYS

((11) a relatively high density) a relatively high density

((22) a comparatively low electrical) a comparatively low electricalconductivityconductivity

((33) an inherent susceptibility to) an inherent susceptibility to

corrosion in some commoncorrosion in some commonenvironments.environments.



C AST VS. WROUGHT ALLOYSC AST VS. WROUGHT ALLOYS

CAST ALLOYSCAST ALLOYS

-- alloys that are so brittle thatalloys that are so brittle that

forming and shaping by appreciableforming and shaping by appreciabledeformation is not possible.deformation is not possible.

-- ³³castcast´́ meansmeans ³³moldmold´́..

WROUGHT ALLOYSWROUGHT ALLOYS-- alloys that are amenable toalloys that are amenable to

mechanical deformationmechanical deformation



³³Heat TreatableHeat Treatable´́

-- designates an alloy whosedesignates an alloy whose

mechanical strength is improved bymechanical strength is improved byprecipitation hardening or aprecipitation hardening or amartensitic transformation, both of martensitic transformation, both of which involve specific heatwhich involve specific heat--treatingtreating

procedures.procedures.



COPPER & ITS ALLOYSCOPPER & ITS ALLOYS

CopperCopper--soft and ductile; difficult to machinesoft and ductile; difficult to machine--almost unlimited capacity to be coldalmost unlimited capacity to be cold

workedworked--highly resistant to corrosion in diversehighly resistant to corrosion in diverseenvironments including the ambientenvironments including the ambientatmosphere, seawater, and someatmosphere, seawater, and someindustrial chemicals.industrial chemicals.

-- is the only element that is nowis the only element that is nowprimarily used in making the worldprimarily used in making the world¶¶sscoinage. ( Historically, its Ag, Au and Cu )coinage. ( Historically, its Ag, Au and Cu )



Copper conducts electricity at a rateCopper conducts electricity at a rate 9797%%

that of silver, and is the standard forthat of silver, and is the standard forelectrical conductivity.electrical conductivity.

High purity of High purity of 9999..99% is sought to attain% is sought to attainthe best conductivity and formability.the best conductivity and formability.

Copper provided a diverse range of Copper provided a diverse range of properties:properties:

good thermal and electricalgood thermal and electricalconductivityconductivity

corrosion resistancecorrosion resistanceease of formingease of forming

ease of joiningease of joining



COPPER ALLOYSCOPPER ALLOYS

Alloying improves mechanical andAlloying improves mechanical andcorrosion resistance properties of corrosion resistance properties of copper.copper.

CopperCopper--based alloys form protectivebased alloys form protectivefilms that will not corrode in water orfilms that will not corrode in water ornonnon--oxidizing acids.oxidizing acids.

There are approximatelyThere are approximately 370370commercial copper and coppercommercial copper and copper--alloyalloycompositions.compositions.



Most copper alloys cannot beMost copper alloys cannot behardened or strengthened by heathardened or strengthened by heat--

treating procedures;treating procedures; COLD WORKING and/or SOLIDCOLD WORKING and/or SOLID--

SOLUTION ALLOYING must beSOLUTION ALLOYING must beutilized to improve these mechanicalutilized to improve these mechanical

properties.properties.



COPPERCOPPER--BASED ALLOYS:BASED ALLOYS:

((11) Brass) Brass ( copper & zinc )( copper & zinc )((22) Bronze) Bronze ( copper & tin )( copper & tin )

((33) Cupronickel) Cupronickel ( copper & nickel )( copper & nickel )

((44) leaded copper) leaded copper((55) nickel silver ( Cu) nickel silver ( Cu--NiNi--Zn )Zn )

((66) high copper alloy) high copper alloy



BRASSESBRASSES

-- Zn is the principal alloyingZn is the principal alloyingelement.element.

((11) brass) brass ( Cu( Cu--Zn)Zn)

((22) leaded brass) leaded brass ( Cu( Cu--ZnZn--Pb )Pb )((33) Tin brass) Tin brass ( Cu( Cu--ZnZn--Sn )Sn )

((44) Silicon brass) Silicon brass ( Cu( Cu--ZnZn--Si )Si )



BRONZEBRONZE

-- tin ( Sn ) is the principal alloyingtin ( Sn ) is the principal alloyingelement.element.

((11) Tin Bronze) Tin Bronze ( Cu( Cu--Sn )Sn )

((22) Phosphor bronze) Phosphor bronze ( Cu( Cu--SnSn--P )P )

((33) Leaded Phosphor bronze) Leaded Phosphor bronze( Cu( Cu--SnSn--PbPb--P )P )

((44) Silicon bronze) Silicon bronze

((55) Aluminum bronze) Aluminum bronze

((66) Nickel) Nickel--Tin bronzeTin bronze

((77) Manganese bronze) Manganese bronze



LEADED COPPERLEADED COPPER-- Cast alloys containingCast alloys containing 2020% Pb or% Pb ormore.more.

HIGH COPPER ALLOYSHIGH COPPER ALLOYS-- contain small amounts of alloyingcontain small amounts of alloying

elements that improve its strength withelements that improve its strength withsome loss in electrical conductivity.some loss in electrical conductivity.

Ex. Adding aboutEx. Adding about 11% Cd% Cd

increases strength byincreases strength by 5050%%loss in conductivity toloss in conductivity to 8585%%



ALUMINUM ALUMINUM

The most abundant of metalsThe most abundant of metals

Excellent thermal conductivityExcellent thermal conductivity

Good strength

Good strength

Corrosion resistanceCorrosion resistance

Light weight ( Light weight ( 11 / /3 3 of steel )of steel )

Commercial purity of aluminum isCommercial purity of aluminum is9999..55% to% to 9999..7979%, but pure%, but purealuminum is too soft to be of aluminum is too soft to be of structural value.structural value.



Though light in weight, commerciallyThough light in weight, commercially

pure aluminum has a tensile strengthpure aluminum has a tensile strengthof of 1313,,000000 psi.psi.

Cold working approximately doublesCold working approximately doublesits strength.its strength.

Other ways of increasing theOther ways of increasing thestrength is by adding Mn, Si, Cu, Mgstrength is by adding Mn, Si, Cu, Mgor Zn.or Zn.

Al is stronger at subzeroAl is stronger at subzerotemperatures than at roomtemperatures than at roomtemperature.temperature.



Most Al alloys lose strength atMost Al alloys lose strength at

elevated temperatures, althoughelevated temperatures, althoughsome retain significant strength tosome retain significant strength to500500ooF.F.

Has a high strengthHas a high strength--toto--weight ratio.weight ratio. Good formabilityGood formability

Possesses its own anticorrosionPossesses its own anticorrosion

mechanism.mechanism.



Primary Reason for Alloying Aluminum:Primary Reason for Alloying Aluminum:

to increase the strength withoutto increase the strength withoutsignificantly increasing the weight.significantly increasing the weight.

Other Reasons:Other Reasons:To improveTo improve

11. machinability. machinability

22. weldability. weldability

33. surface appearance. surface appearance

44. corrosion resistance. corrosion resistance



ANTICORROSION MECHANISM OF ANTICORROSION MECHANISM OF

ALUMINUM ALUMINUM

When exposed to air, Al does notWhen exposed to air, Al does notoxidize progressively because a hard,oxidize progressively because a hard,

microscopic oxide coating forms on themicroscopic oxide coating forms on thesurface and seals the metal from thesurface and seals the metal from theenvironment.environment.

This tight chemical oxide bond is theThis tight chemical oxide bond is thereason why Al is not found in nature; onlyreason why Al is not found in nature; onlyas a compound.as a compound.



Al & its alloys numbering in theAl & its alloys numbering in the 100100s, ares, are

available in all common commercial forms.available in all common commercial forms. AlAl--alloy sheet can be:alloy sheet can be:

formedformed

drawndrawnstampedstamped

spunnedspunned

weldedwelded

brazedbrazed

solderedsoldered



Al surfaces readily accept a wideAl surfaces readily accept a wide

variety of finishes both mechanicalvariety of finishes both mechanicaland chemical.and chemical.

NonsparkingNonsparking

NonmagneticNonmagnetic



APPLIC ATIONS APPLIC ATIONS

AircraftAircraft AerospaceAerospace AutomotiveAutomotive ShipbuildingShipbuilding Household products including pots, pans andHousehold products including pots, pans and

cooking utensils.cooking utensils. Newer applications, such as shafts, radiators,Newer applications, such as shafts, radiators,

cylinder headscylinder heads

Most advantageous when dealing withMost advantageous when dealing with

weight vs. strength vs. costweight vs. strength vs. cost



MAGNESIUMMAGNESIUM

Is the lightest among the commonlyIs the lightest among the commonlyused metals.used metals.

Its versatility and abundance make itIts versatility and abundance make itone of the most popular metals.one of the most popular metals.

Too soft to be used as a structuralToo soft to be used as a structuralmaterial.material.

Low densityLow density Good mechanical strengthGood mechanical strength

High strength to weight ratioHigh strength to weight ratio



Has good fatigue resistance and performsHas good fatigue resistance and performs

well in applications involving large numberwell in applications involving large numberof cycles at relatively low stress.of cycles at relatively low stress.

Metal is sensitive to stress concentration,Metal is sensitive to stress concentration,so notches, sharp corners and abruptso notches, sharp corners and abruptsection changes should be avoided.section changes should be avoided.

Is recognized for its favorable strengthIs recognized for its favorable strength--toto--weight ratio.weight ratio.

Excellent castability.Excellent castability.

Easiest of the structural metals toEasiest of the structural metals tomachine; they can be shaped andmachine; they can be shaped andfabricated by most metal workingfabricated by most metal workingprocesses.processes.

metals and its alloys 2

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