Study on hot workability and optimization of process parameters of a modified 310 austenitic stainless steel using processing maps

To investigate the optimized hot deformation parameters of a modified 310 austenitic stainless steel, the hot compression tests were performed using a Gleeble 3500 thermal simulator. The hot deformation behavior and hot workability characteristics were investigated in a temperature range of 800-1100 °C and a strain rate range of 0.1-10 s−1. The hot processing maps of the tested steel were developed based on the dynamic material model (DMM), from which the safe deformation regions and instable deformation regions were determined. The corresponding microstructural and hardness evolutions during deformation were analyzed in detail. It was found that the deformation in the safe regions was beneficial to dynamic recovery (DRY) and dynamic recrystallization (DRX), while the deformation in unstable region would lead to flow instability, kink boundaries and grain growth. Near 950 °C, the energy dissipation rates were unusually lower, and the hardness of the deformed sample exhibited a significant increase, as a result of strain-induced precipitation. Coupled with the microstructure analysis and processing map technology, the workability map was schematically plotted and the optimal working conditions were determined. Such conditions were: temperatures in the range of 1075-1100 °C and strain rates in the range of 0.5-1.7 s−1. These conditions are critical to attain an excellent homogeneous microstructure with fine grains after deformation for the modified 310 austenitic stainless steel.