AISI 4140

AISI 4140

Category	Steel
Class	Alloy steel
Type	Standard
Common Names	Chromium-molybdenum steel
Designations	France: AFNOR 40 CD 4 , AFNOR 42 CD 4 Germany: DIN 1.7225 Italy: UNI 38 CrMo 4 KB , UNI 40 CrMo 4 , UNI G 4O CrMo 4 Japan: JIS SCM 4 , JIS SCM 4 H Sweden: SS 2244 United Kingdom: B.S. 708 A 42 , B.S. 708 M 40 , B.S. 709 M 40 United States: AMS 6378 , AMS 6379 , AMS 6381B , AMS 6382 , AMS 6382G , AMS 6390 , AMS 6390A , AMS 6395 , ASTM A322 , ASTM A331 , ASTM A505 , ASTM A519 , ASTM A547 , ASTM A646 , MIL SPEC MIL-S-16974 , SAE J404 , SAE J412 , SAE J770 , UNS G41400

Composition

Element Weight % C 0.38-0.43 Mn 0.75-1.00 P 0.035 (max) S 0.04 (max) Si 0.15-0.30 Cr 0.80-1.10 Mo 0.15-0.25

Mechanical Properties

Properties		Conditions
		T (°C)	Treatment
Density (×1000 kg/m3)	7.7-8.03	25
Poisson's Ratio	0.27-0.30	25
Elastic Modulus (GPa)	190-210	25
Tensile Strength (Mpa)	655.0	25	annealed at 815°C more
Yield Strength (Mpa)	417.1
Elongation (%)	25.7
Reduction in Area (%)	56.9
Hardness (HB)	197	25	annealed at 815°C more
Impact Strength (J) (Izod)	54.5	25	annealed at 815°C more

Thermal Properties

Properties		Conditions
		T (°C)	Treatment
Thermal Expansion (10-6/ºC)	12.3	20-100 more	oil hardened, tempered 600°C
Thermal Conductivity (W/m-K)	42.7	100 more
Specific Heat (J/kg-K)	473	150-200 more

Electric Properties

Properties		Conditions
		T (°C)	Treatment
Electric Resistivity (10-9W-m)	222	20 more

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