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AISI 4340H
Category Steel
Class Alloy steel
Type H-steel
Common Names Nickel-chromium-molybdenum steel
Designations  Germany: DIN 1.6565
Japan: JIS SNCM 8
United Kingdom: B.S. 2 S 119 , B.S. 3 S 95 , B.S. 3111 Type 6 , B.S. 817 M 40
United States: ASTM A304 , SAE J1268 , UNS H43400

ElementWeight %
C  0.37-0.44 
Mn  0.55-0.90 
Cr  0.65-0.95 
Ni  1.55-2.00 
Mo  0.20-0.30 
P  0.035 
S  0.040 
Si  0.15-0.30 

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) 745  25  annealed at 810°C  more
Yield Strength (Mpa) 475 
Elongation (%) 22 
Reduction in Area (%) 50 
Hardness (HB) 217  25  annealed at 810°C more

Thermal Properties
Properties Conditions 
T (°C)Treatment
Thermal Expansion (10-6/ºC) 9.7  -130-21 more  

Electric Properties
Properties Conditions 
T (°C)Treatment
Electric Resistivity (10-9W-m) 248  20 more