SCr440 is an alloy structural steel, is the most commonly used alloy structural steel, tensile strength, yield strength and hardenability are higher than 40 steel.
Characteristics and scope of application
The most commonly used alloy structural steel has higher tensile strength, yield strength and hardenability than No. 40 steel, but its weldability is limited and it has a tendency to form cracks. For more important tempering parts, such as parts working under alternating loads, medium speed and medium load parts. After surface quenching, it can be used for parts with high load and wear resistance without great impact, such as gears, sleeves, shafts, crankshafts, and dowels.
Chemical composition：
Carbon C: 0.38 ~ 0.43
Silicon Si: 0.15 ~ 0.35
Manganese Mn: 0.60 ~ 0.90
Sulfur S: Allowable residual content ≤0.030
Phosphorus P: allowable residual content ≤0.030
Chromium Cr: 0.90-1.20
Nickel Ni: allowable residual content ≤0.25
Copper Cu: Allowable residual content ≤0.030
Mechanical property：
Tensile strength σb (MPa) : ≥980(100)
Yield strength σs (MPa) : ≥785(80)
elongation δ5 (%) : ≥9
Section shrinkage ψ (%) : ≥45
impact work Akv (J) : ≥47
impact toughness value αkv (J/cm²) : ≥59(6)
Hardness: ≤207HB
Sample size: sample blank size is 25mm
Heat treatment specification: quench 850℃, oil cold; Tempering 520℃, water cooling, oil cooling.
