Tempering with oil quenching

Standard – UNI 10990
Typical Materials – Quenching and tempering steels such as 42CrMo4, 39NiCrMo3, etc.
Achievable Metallurgical Characteristics – Surface hardness of 260 – 350HB, with a sorbitic-bainitic microstructure.

The quenching and tempering process is typically applied to raw parts after forging to standardize the hardness and microstructure of the components. It can also be applied to semi-finished materials, though careful consideration must be given to the potential deformations this process may induce.

The process involves heating the material to austenitizing temperatures, typically between 850-950°C, with holding times sufficient to ensure thorough heating of the sections. Austenitization is followed by quenching through rapid cooling in oil to achieve microstructural stability. After quenching, tempering is carried out at temperatures ranging from 500-680°C, depending on the desired hardness levels.

This process can also be applied to lower alloy steels such as C40, C45, etc., where lower hardness levels and partially transformed microstructures (typically composed of ferrite and pearlite) can be achieved.