ASTM4340 

 Alloy Steel: 4340 Executive Standard: ASTM A29/A29M-04 ● Chemical Composition: C: 0.38 ~ 0.43 Si Si: 0.15 ~ 0.35 Manganese Mn: 0.60 ~ 0.90 S S: to allow the residual phosphorus content ≤ 0.040 P: allow the residual content ≤ 0.035 Chromium Cr: 0.60 ~ 0.90 Ni-Ni: 1.65 ~ 2.00 Copper Cu: Mo allow the residual content ≤ 0.025 Mo: 0.20 ~ 0.30 ● Mechanical Properties: Tensile σb (MPa): ≥ 980 (100) yield strength σs (MPa ): ≥ 835 (85) Elongation δ5 (%): ≥ 12 Reduction of area ψ (%): ≥ 55 Impact energy Akv (J): ≥ 78 impact toughness αkv (J/cm2): ≥ 98 (10 ) Hardness: ≤ 269HB sample size: the sample blank standard size 25mm ● Heat treatment and microstructure: heat treatment specifications: quenching 850 ℃, oil-cooling; tempering 600 ℃, water-cooled, oil-cooling. ● Delivery status: to heat treatment (normalizing, annealing, or tempering) or heat treatment delivery, delivery status should be indicated in the contract.