Effect of Heat Treatment Process on Mechanical Properties and Microstructure of S280

Abstract

The effect of solution temperature and aging temperature on mechanical properties and microstructure of the new ultrahigh strength stainless steel S280 was investigated by heat treatment process experiment. The results showed that the optimal heat treatment process was as follows: heating to 1080 °C，holding for a hour, and quenching in oil; cooling to -73 °C, holding for 2 hour, and warming in air to room temperature; heating to 540~550 °C, holding for 4 hour, and cooling in air. Choosing this heat treatment process, the steel can get good coordination between strength and toughness. Analyzed by HREM, the steel had desirable microstructures, which were fine lath martensite matrix with high density dislocation and finely dispersed precipitate strengthening phase, and film-like reversed austenite precipitated from the boundary of martensite.