Brief Introduce of 42CrMo4 Structural Steel Bar

42CrMo4 steel is an improved variety of American AISI standard 4140 steel. The steel has good machinability, easy polishing, biting and electroplating. It is suitable for manufacturing mechanical parts with high strength, high hardenability, good toughness, small deformation during quenching and high creep strength and endurance strength at high temperature. It can be used to manufacture forgings with higher strength and larger quenching and tempering section than 35CrMo steel, such as large gears for locomotive traction, supercharger transmission gears, rear axles, connecting rods and spring clamps with great load, and 42CrMo4 can also be used for drill pipe joints and fishing tools in deep oil wells below 2000m.

Chemical Composition of 42CrMo4:

Carbon C: 0.38-0.45

Silicon Si: 0.17-0.37

Manganese Mn: 0.50-0.80

Sulfur S: <0.035

Phosphorus P: < 0.035

Chromium Cr: 0.90-1.20

Nickel Ni: Allowable Residual Content < 0.030

Copper Co: Allowable Residual Content < 0.030

Molybdenum Mo: 0.15-0.25

3. Mechanical properties of 42CrMo4:

Density: 7.85x103kg/m3

Tensile strength_b (MPa): > 1080 (110)

Yield strength_s (MPa): > 930 (95)

Section shrinkage(%): > 45

Impact energy Akv (J): > 63

Impact toughness value alpha kV (J/cm²): > 78 (8)

Sample size: Sample blank size 25 mm

Heat treatment specification and metallographic structure:

Heat treatment specifications: quenching 850 C, oil-cooled; tempering 560 C, water-cooled, oil-cooled.

Metallographic structure: tempered sorbite.

Delivery under heat treatment (normalizing, annealing or high temperature tempering) or non-heat treatment. Delivery status shall be specified in the contract.

Specification for softening annealing of 42CrMo4

The annealing temperature is 680 ~700 C, the furnace is slowly cooled, and the hardness is less than 217HBW.

Specification for Quenching and Tempering of 42CrMo4

Quenching temperature 830 ~860 C, oil-cooled or 180 220 C salt bath cooling, hardness 52HRC, strength 1780 MPa.

Tempering temperature 100 C/200 C/300 C/400 C/500 C/600 C, hardness 50HRC/49HRC/46HRC/42HRC/36HRC/28HRC