4140 hot rolled bar is a medium carbon alloy steel renowned for its excellent fatigue and impact resistance after heat treatment, making it a versatile material for numerous applications, such as drill collars, chain pins, bolts, and sprockets. As a chromium-molybdenum alloy steel, 4140 HRA can be oil hardened to achieve a high level of hardenability. The presence of chromium ensures deep hardness penetration, while molybdenum contributes to the uniformity of hardness and enhances strength. The flexibility of heat treatment processes for 4140 allows for a broad spectrum of properties, making it highly adaptable to specific needs. In addition to its notable wear resistance, 4140 boasts superior toughness and excellent ductility in the quenched and tempered state. It can achieve impressive mechanical properties, with tensile strengths up to 260,000 psi and yield strengths reaching 235,000 psi, in conditions as hardened as 500 Brinell. This combination of qualities ensures 4140’s place as a highly sought-after steel for demanding applications.

Applications

Typical applications for this grade include drill collars, pins, axles, bolts, and shafts.

4140 Chemical Properties