40CrMn, is China's national standard [1] of an alloy steel grades. Unified digital code: A22402.

Standard: GB / T 3077-1988

Chemical composition
Mass fraction (%):

Carbon C: 0.37 ~ 0.45

Si Si: 0.17 ~ 0.37

Manganese Mn: 0.90 ~ 1.20

Sulfur S: to allow the residual content of ≤ 0.035

Phosphorus P: allow the residual content ≤ 0.035

Chromium Cr: 0.90 ~ 1.20

Ni: to allow the residual content of ≤ 0.030

Copper Cu: to allow the residual content ≤ 0.030

Mechanical properties
Sample size [blank]

25mm

[Heat]

Quenching temperature (℃): 840; Coolant: Oil

Tempering heating temperature (℃): 550; coolant: water, oil

[Mechanical properties]

Tensile strength σb (MPa): ≥ 980 (100)

Yield strength σs (MPa): ≥ 835 (85)

Elongation δ5 (%): ≥ 9

Reduction of area ψ (%): ≥ 45

Impact energy Akv (J): ≥ 47

Impact toughness αkv (J/cm2): ≥ 59 (6)

Brinell hardness (HBS100/3000) (annealing or tempering condition): ≦ 229

Key Features
Hardenability, high strength. Alternative 42CrMo and 40CrNi.