Study on Rheological Behavior and Hot Processing Maps of a Novel Ultra-Low Carbon High-Strength Stainless Steel

This study investigated the hot deformation behavior of a novel ultra-low carbon high-strength stainless steel through single-pass isothermal hot compression tests using a Gleeble-3800 thermomechanical simulator. The hot deformation behavior were examined under deformation temperatures ranging from 900 to 1150 °C, true strains of 0.2 to 0.8, and strain rates of 0.01 to 10 s^-1. The differences in recrystallization mechanisms under various strain rates were analyzed. Based on the Dynamic Materials Model (DMM) theory, hot processing maps at true strains of 0.2, 0.4, 0.6, and 0.8 were constructed. And the applicability of the Prasad and Murty instability criteria to this new steel was compared. The results indicate that different recrystallization mechanisms operate at different strain rates. Compared to the commonly used Prasad criterion, the Murty instability criterion aligns better with the experimental observations for this steel. The optimal hot processing window for this new steel is identified as a temperature range of 1100-1150 °C with strain rates of 0.1-1 s^-1 and 10 s^-1, which is consistent with the microstructure of the deformed specimens. This work offers fundamental insights into the microstructural evolution, which is essential for optimizing the hot-working properties of next-generation high-strength stainless steels.