Hot deformation behavior and microstructure evolution of a stabilized high-Cr ferritic stainless steel

The hot deformation behavior and static microstructure evolution of a 21Cr stabilized ferritic stainless steel was studied using axisymmetric hot compression tests on a Gleeble 1500 thermomechanical simulator. The deformation was carried out at 950-1050 °C to strains of 0.2 to 0.6 using strain rates of 0.01, 0.1 and 1 s−1. The compression was followed by a holding period of 0 to 180 s in order to study the static recrystallization kinetics. The electron backscatter diffraction (EBSD) technique was used in analyzing the resultant microstructures. A constitutive equation that well describes the flow stress as a function of strain, strain rate and temperature was developed. The active dynamic restoration mechanism was found to depend on the Zener-Hollomon parameter, such that continuous dynamic recrystallization was observed under low Zener-Hollomon parameter conditions but under high Zener-Hollomon parameter microstructures were dynamically recovered, and no dynamic formation of new grains occurred. Static recrystallization resulted in little or no grain refinement, and further, strain did not have an accelerating effect on the static recrystallization kinetics beyond the strain of 0.4.