Abstract: Ulta-high strength heat treatment process test consisting of quenching and low-temperature tempering was carried out on the 30CrMnSi steel. The results show that the higher the quenching temperature, the higher the strength is. Both the conventional temperature and intercritical quenching can't meet the requirements of product performance, the dual-heat treatment process of quasi-intercritical quenching at below the conventional quenching temperature and above the intercritical quenching temperature and low-temperature tempering can make the tensile strength of 30CrMnSi steel reach more than 1520 MPa and has good toughness, which can meet the requirements of high-speed impact resistance of products.

Key words: heat treatment, 30CrMnSi steel, quasi-intercritical quenching, ultra-high strength, strength and toughening