Study on the Subcritical Quenching Process of High-Chromium Cast Iron Prepared by Squeeze Casting

Abstract

In this study, the heat treatment process of a high-chromium cast iron (HCCI) alloy prepared via 128 MPa squeeze casting at different subcritical quenching temperatures was investigated. The results showed that subcritical heat treatment can change the martensite content, the carbide type and size of the squeeze casting HCCI microstructure. Furthermore, it was revealed that the subcritical quenching heat treatment can improve the hardness of the liquid-forged HCCIs. When the quenching temperature increased from 500 °C to 530 °C, the hardness of the alloy increased significantly, reaching a maximum value of 57 HRC. Thereafter, if the temperature continued to rise to 630 °C, the hardness decreased rapidly. For impact toughness, when the quenching temperature was 500 °C, the toughness of alloy increased by 0.9 J/cm2 than that of the no heat treatment group. If the quenching temperature continued to increase, the toughness was reduced. Taking hardness and toughness into account, the microstructure evolution diagram of the optimal process-500 °C subcritical quenching process was established, various characterisation techniques were used to gain insights into the optimal heat treatment process. Compared with high temperature heat treatment, subcritical heat treatment can improve the performance of the HCCI alloy and reduce costs.