Investigation of the Hot Deformation Behavior of 22Cr-25Ni Austenitic Heat-Resistant Steel by Combining Constitutive Model and Processing Map

The hot deformation behavior of 22Cr-25Ni austenitic heat-resistant steel at the temperatures of 950-1150 degrees C and strain rates of 0.01-10 s-1 is studied by isothermal compression test. It is found that the dynamic recrystallization (DRX) degree of the steel increases with the increase of temperature. The DRX degree decreases with the increase of the strain rate from 0.01 to 1 s-1, whereas the DRX degree increases with the increase of the strain rate from 1 to 10 s-1. The hot deformation activation energy is as high as 624.25 kJ mol-1 due to the addition of a large number of alloying elements. The typical strain compensation Arrhenius constitutive model established can be used to roughly predict the hot flow behavior of the steel. Furthermore, a modified model considering the influence of strain rate and deformation heat on the deformation process is proposed and showed higher accuracy (statistical parameters r = 0.994 and average absolute relative error = 4.59%). The DRX zone of the steel is determined to be 1080-1150 degrees C/0.01-0.1 s-1 through processing map analysis, representing the appropriate hot working zone. The microstructure corresponding to the instability zone in the processing map exhibits deformation concentration bands or necklace structures. The hot deformation microstructure evolution of 22Cr-25Ni austenitic heat-resistant steel is clarified. The modified Arrhenius constitutive model is proposed, which can accurately describe the hot flow behavior of the steel. The dynamic recrystallization region is determined and the microstructure corresponding to the instability region exhibits deformation concentration bands or necklace structures.image (c) 2024 WILEY-VCH GmbH