Influence of induction heating conditions on quenched structure of SUJ2 steel

Abstract

When JIS-SUJ2 steel is hardened by induction heating, high-temperature austenitization is applied in order to achieve high throughput. In this case, SUJ2 is quenched from the single-phase austenite zone. As a result, the properties of SUJ2 may be different from those obtained by a conventional furnace process involving SUJ2 quenched from the two-phase austenite/cementite zone. In this study, we experimentally investigated the relationship among the amount of undissolved carbide, austenitization temperature, and holding time. Additionally, we developed a formula for predicting the amount of undissolved carbide. The formula is constructed from the Arrhenius equation and the Kolmogorov-Johnson-Mehl-Avrami equation. Subsequently, the effect of the austenitization temperature and the amount of undissolved carbide on the hardness, retained austenite content, prior-austenite grain size, and martensite block size were investigated.