40Cr steel is a kind of Chinese GB standard alloy steel for engineering and machinery purpose, and one of the most widely used steel grades. For 40Cr material hardness, specifications and equivalent, please see the table below.
After quenching and tempering treatment, 40Cr steel has good comprehensive mechanical properties, low temperature impact toughness, low notch sensitivity, good hardenability, and high fatigue strength in cold oil. When water cooling, the complicated shape of the parts is prone to cracks, the cold bending plasticity is medium, and the cutting workability after normalizing is good, but the weldability is poor, should be preheated before welding, and is generally used in the state of quenching and tempering..
Mechanical Properties of 40Cr Alloy Steel
- Tensile strength: ≥810 N/mm2 (When actual hardness 25 HRC)
- Yield strength: ≥785 N/mm2
- Elongation after break: ≥9%
- Rate of reduction in area: ≥45%
- Impact absorbing energy: ≥47 J
- Material Brinell hardness: ≤207 (annealing or high temperature tempering state)
- Sample size: 25mm
Heat treatment specification
- First quenching heating temperature: 850 °C (Cooling: oil)
- Tempering heating temperature: 520 °C
Applications of 40Cr material
After 40Cr alloy steel quenching and tempering treatment, it is used to manufacture medium-speed, medium-load parts such as machine gears, shafts, worms, spline shafts, thimble sleeves, etc.
After quenching and tempering and high-frequency surface quenching, it is used to manufacture high-hardness, wear-resistant parts such as gears, shafts, spindles, crankshafts, sleeves, pins, connecting rods, screws, nuts, intake valves, etc.
After quenching and medium temperature tempering, it is used to manufacture heavy-duty, medium-speed impact parts such as oil pump rotors, sliders, gears, spindles, collars, etc.
After quenching and low temperature tempering, it is used to manufacture heavy-duty, low-impact, wear-resistant parts such as worms, spindles, shafts and collars.
After carbonitriding treatment, it is used to manufacture transmission parts with large size and high low temperature impact toughness, such as shafts and gears.
Equivalent Grades of 40Cr Material
40Cr steel equivalent to US ASTM AISI, European Germany DIN EN, British BS EN, France NF EN, Japanese JIS and ISO standard.