Hot Compression Behavior of As-Cast Precipitation-Hardening Stainless Steel

High temperature deformation characteristics of a semiaustenitic grade of precipitation-hardening stainless steels were investigated by conducting hot compression tests at temperatures of 900—1 100 °C and strain rates of 0. 001—1 s−1. Flow behavior of this alloy was investigated and it was realized that dynamic recrystallization (DRX) was responsible for flow softening. The correlation between critical strain for initiation of DRX and deformation parameters including temperature and strain rate, and therefore, Zener-Hollomon parameter (Z) was studied. Metallographic observation was performed to determine the as-deformed microstructure. Microstructural observation shows that recrystallized grain size increases with increasing the temperature and decreasing the strain rate. The activation energy required for DRX of the investigated steel was determined using correlations of flow stress versus temperature and strain rate. The calculated value of activation energy, 460 kJ/mol, is in accordance with other studies on stainless steels. The relationship between peak strain and Z parameter is proposed.