AISI 4140 is a 1% chromium-molybdenum medium-hard, general-purpose, high-strength steel.
Composed primarily of iron, carbon, chromium, manganese, silicon, and molybdenum, AISI 4140 steel is classified as a high-strength quenched and tempered steel according to the American Iron and Steel Institute (AISI) standard, offering high strength, wear resistance, and impact resistance. This grade corresponds to British BS 708M40/708A42/709M40, French NF 40CD4/42CD4, and Chinese GB 42CrMo. Its chemical composition includes chromium, molybdenum, and manganese, placing it in the low-alloy steel category.
Key Characteristics
Strength and Hardness: With a tensile strength of 980-1130 MPa and a hardness range of HRC32-50 after quenching and tempering, it is suitable for manufacturing parts subject to high stress, such as shafts and gears.
Wear Resistance: Suitable for high-wear applications, such as oil and gas well tools and pump shafts. Toughness: High impact toughness after heat treatment, capable of resisting impact loads.
Weldability: Moderate weldability, requiring appropriate processing to avoid cracking. Tempering is required after welding.
Typical Applications
Engineering: Used in the manufacture of high-strength components such as gears, bearings, bolts, and connecting rods.
Oil and Gas Industry: Wear-resistant components such as downhole tools, valve stem assemblies, and transfer pins.
Heat Treatment Process
Hardening: Quenching at 850-1000°C, water cooling;
Tempering: Tempering above 650°C, air cooling.
Of course, if you need large quantities of AISI 4140 forgings, you can partner with Mulan Metal. With 12 years of experience in metal forging processing, Mulan Metal has helped clients in over 30 countries complete their forging operations and has received consistent recognition. We look forward to your consultation and cooperation.
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