metal alloys ( 금속 합금 )

Metal AlloysMetal AlloysManufacturing ProcessesManufacturing Processes© 2013 Su-Jin Kim, GNU© 2013 Su-Jin Kim, GNU

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Metal Alloys ( 금속 합금 )

Associate Professor Su-Jin Kim

School of Mechanical EngineeringGyeongsang National University

http://ma.gnu.ac.kr/

http://engine.gnu.ac.kr/

http://www.gnu.ac.kr/


Metal Alloys( 금속 )

Metal Alloy( 금속합금 )

Ferrous( 철 )

Nonferrous( 비철금속 )

Steels( 강 )

C<1.4%

Cast Irons( 주철 )

3.0~4.5%

Copperalloy

Aluminumalloy

…alloy


Ferrous Alloys ( 철 )

• Ferrous alloys are useful metals in terms of mechanical, physical and chemical properties.

• Alloys contain iron Fe (density 7.9 g/cm3) as their base metal.

• Carbon steels (700W/kg) are least expensive of all metals while stainless steels (7,000W/kg) is costly.


Steels ( 강 )

Composition and processing are controlled in a manner that is suitable for different applications.

Several elements are added to steels for Strength( 강도 ), Hardness( 경도 ), Toughness( 인성 )Hardenability( 경화성 ), Wear resistance( 내마모성 )Workability( 가공성 ), Weldability( 용접성 ), Machinability( 절삭성 )


SteelsCarbon steel

( 탄소강 )High alloy steel

( 고합급강 )

Low carbon( 저탄소강 )

C < .25 %

Med carbon( 중탄소강 )

.25-.60%

High carbon( 고탄소강 ).60-1.40%

Plain HSLA( 고강도 )

PlainHeat

Treatable( 열처리 )

Plain Tool( 공구 )

Stainless( 스테인리스 )

auto struc. sheet

bridges towers press. vessels

crank shafts bolts hammers

pistons gears wear applic.

wear applic.

drills saws dies

high T turbines furnaces corrosion resistant

strength, hardenability, costductility

1010S10C

4310SNCM10

1040S40C

4340SNCM40

1095 4190KD11

304, 409SUS304


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Steels

AISI/SAE JIS/KS Nomenclature( 조성 ) for steels

10xx SxxC Plain Carbon Steels ( 탄소강 )40xx SMoxx Mo (.2 ~ .3%)41xx SCMxx Cr (.80~1.1), Mo (.15~.25)43xx SNCMxx Ni (1.65 ~ 2.0), Cr (.4 ~ .9), Mo (.2~.3)

where xx is % C x 100Ex) 1045 S45C – Plain Carbon Steel with 0.45 % C

Stainless Steel 304 SUS304 Cr (11%~)


Carbon steels ( 탄소강 )

• Classified as low, medium and high:1. Low-carbon steel or mild steel, C< 0.25%, bolts, nuts

and sheet plates.2. Medium-carbon steel, 0.25% ~ 0.60%, machinery,

automotive and agricultural equipment.3. High-carbon steel, C > 0.60%, springs, cutlery, cable.

• Ex) S10C S45C


Alloy steels ( 합금강 )

• Steels containing significant amounts of alloying elements.

• Structural-grade alloy steels used for construction industries due to high strength.

• Other alloy steels are used for its strength, hardness, resistance to creep and fatigue, and toughness.

• It may heat treated to obtain the desired properties.


HSLA

High-strength low-alloy steels ( 고강도 저합금강 )• Improved strength-to-weight ratio.• Used in automobile bodies to reduce weight and in

structural plate.


Tool & Die steels ( 공구강 금형강 )

• Designed for high strength, impact toughness, and wear resistance at a range of temperatures.

Ex) SKD11 SKD61 NAK80


Stainless steels

• Characterized by their corrosion resistance, high strength and ductility, and high chromium content( Cr >11%).

• Stainless as a film of chromium oxide protects the metal from corrosion.

• It resist oxidization and maintain mechanical integrity at high temperature (1000°C).JIS/KS Cr(%) Heat

treatCor. Res.

Magnetic

Application

SUS304 austenite 19 X OO X Automotive exhaust

SUS409 ferrite 11 X O O Chem. proc. equip.

SUS410 martensitic 12.5 O O O Knifes


Posco• Hot rolled steel, Steel plate, Wire rod, Cold rolled steel,

Electric steel, Stainless steel, Galvanized steel, Titanium

Posco http://www.posco.co.kr

http://www.posco.co.kr/


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Cast Irons ( 주철 )• Ferrous alloys with 3.0 ~4.5% C• Low melting point relatively easy to cast• Generally brittle

• Cementite decomposes to ferrite + graphiteFe3C 3 Fe () + C (graphite) : slow process


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Cast IronsGray iron( 회주철 )• graphite flakes• weak & brittle in tension• stronger in compression• excellent vibrational dampening• wear resistant

Ductile iron( 연주철 )• add Mg and/or Ce• graphite as nodules not flakes• matrix often pearlite – stronger but less

ductile


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Cast IronsWhite iron( 백주철 )• < 1 wt% Si• pearlite + cementite• very hard and brittle

Malleable iron( 가단주철 )• heat treat white iron at 800-900ºC• graphite in rosettes• reasonably strong and ductile


Cast Irons

급랭 서랭

가열

가단주철 백주철 회주철 연주철

metal alloys ( 금속 합금 )

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