40B alloy structural steel technical parameters

40B alloy structural steel, unified digital code: A70402; executive standard: GB/T 3077. 40B steel can replace 40Cr steel to produce small-sized parts with low performance requirements.

40B alloy structural steel chemical composition (mass fraction) (%)
C: 0.37-0.44
Si: 0.17-0.37
Mn: 0.60-0.90
B: 0.0005-0.0035

Mechanical properties of 40B alloy structural steel:
Tensile strength (σb/MPa): ≥785
Yield point (σs/MPa): ≥635
Elongation after breaking (δ5/%): ≥12
Reduction of area (ψ/%): ≥45
Impact absorption (Aku2/J): ≥55

40B alloy structural steel is usually used in quenched and tempered state to manufacture parts with larger cross-section and higher performance requirements than 40 steel, such as gears, steering rods, shafts, camshafts, tractor crankshaft handles and other parts.