SCM418 
 Standard: 
 China GB / T 3203-1982 Japan JIS G4053: 2003 U.S. ASTM A534: 2004 international ISO 683-17:1999 
 Chemical Composition: 
 Carbon C: 0.17 ~ 0.24 Si Si: 0.17 ~ 0.37 Manganese Mn: 0.40 ~ 0.70 S S: agreed residual phosphorus content ≤ 0.035 P: ≤ 0.035 promise residual content of chromium Cr: 0.80 ~ 1.10 Ni: to agree the residual content ≤ 0.030 Copper Cu : agreed residual content ≤ 0.030 Mo Mo: 0.15 ~ 0.25 
 Mechanical Properties: 
 Tensile strength σb (MPa): ≥ 885 (90) yield strength σs (MPa): ≥ 685 (70) Elongation δ5 (%): ≥ 12 Reduction of ψ (%): ≥ 50 Impact energy Akv (J ): ≥ 78 impact toughness αkv (J/cm2): ≥ 98 (10) Hardness: ≤ 197HB sample size: Sample size is 15mm blank 
 Heat treatment and microstructure specifications: 
 Standard heat treatment: quenching 880 ℃, water, oil cooling; tempering 500 ℃, water-cooled, oil-cooling. 
 Delivery status: 
 Heat treatment (normalizing, annealing, or tempering) or heat treatment delivery, delivery status should be indicated in the contract