42CrMo Alloy Steel

42CrMo is a high-strength chromium-molybdenum alloy steel offering high strength, good toughness, hardenability, and wear resistance. After quenching and tempering, it provides excellent overall mechanical properties and is suitable for components subjected to high loads, impact, and cyclic stresses. Its performance and applications are broadly comparable to AISI 4140, although their chemical composition limits and standard requirements are not identical.

Appearance & Properties

Color: Silver-gray to dark gray

Density: Approx. 7.85 g/cm³

Tensile Strength: Typically ≥1,080 MPa in a common quenched-and-tempered condition, depending on standard, section size, and heat treatment

Corrosion Resistance: Poor

Machinability: Good

Weldability: Moderate

Wear Resistance: Good

Toughness: Good

Magnetism: Magnetic

Heat Treatment: Hardening, tempering, normalizing, quenching and tempering, etc.

Surface Treatments: Black oxide, phosphating, nickel plating, zinc plating, nitriding, painting, etc.

Typical Applications

42CrMo Alloy Steel is widely used in automotive, construction machinery, energy equipment, oil and gas, industrial machinery, and high-load transmission systems.

Typical parts include drive shafts, gears, spindles, connecting rods, couplings, high-strength bolts, hydraulic components, flanges, pins, and high-load precision CNC parts.

Advantages

• High strength with good toughness

• Good hardenability and heat-treatment capability

• Good wear and fatigue resistance

• Suitable for high-load and impact applications

• Well suited for shafts, gears, and transmission components

Limitations

• Poor corrosion resistance and usually requires surface protection

• Welding generally requires careful process control

• CNC machining becomes more difficult after heat treatment

• Improper heat treatment may cause distortion or inconsistent properties