● Chemical Composition:
Carbon C: 0.22 ~ 0.29
Si Si: 0.17 ~ 0.37
Manganese Mn: 0.50 ~ 0.80
Sulfur S: allow the residual content ≤ 0.025
Phosphorus P: allow the residual content ≤ 0.025
Chromium Cr: 2.10 ~ 2.50
Ni: to allow the residual content of ≤ 0.030
Copper Cu: allow the residual content ≤ 0.025
Vanadium V: 0.30 ~ 0.50
Mo Mo: 0.90 ~ 1.10
● Mechanical Properties:
Tensile strength σb (MPa): ≥ 735 (75)
Yield strength σs (MPa): ≥ 590 (60)
Elongation δ5 (%): ≥ 16
Reduction of area ψ (%): ≥ 50
Impact energy Akv (J): ≥ 47
Impact toughness αkv (J/cm2): ≥ 59 (6)
Hardness: ≤ 241HB
Sample size: Sample size is 25mm rough
● Heat treatment and microstructure specifications:
Standard heat treatment: quenching 1040 ℃, air-cooled; tempering 700 ℃, air-cooled.