Constitutive description of work hardening and dynamic softening behavior under variable deformation states

By carrying out hot compression experiments for 316 L austenitic stainless steel under dynamic changes in deformation conditions, the work hardening and softening behaviors are systematically analyzed during the temperature and strain rate changing process. The response pattern of stresses to changes in temperature and strain rate during deformation is related to material properties and deformation conditions. Zener Hollomon parameters can unify the influence. The stress response pattern changes as the value of Z increases or decreases. Further a computational procedure of materials constitutive relationship suitable for the deformation process under dynamic changes in deformation conditions is proposed. The calculation procedure is based on the phenomenal model. Compared with physical-based model, the procedure shows the same accuracy for the prediction of stress and degree of recrystallization and a simple establishment process. The calculation procedure is embedded into DEFORM software. The high-temperature deformation behavior is numerically simulated under dynamic changes in deformation conditions. The dynamic changes in deformation conditions affect the center deformation resistance during the deformation process, affecting the competitive coordination of material deformation resistance and indenter-sample interfacial friction and ultimately affecting the deformation distribution. 4)The microstructure evolution during dynamic variation states is revealed by EBSD characterization. The deformation conditions variation results in the hardening and softening mechanism changing. Especially, at 1000 ℃ the strain rate changing from 0.01 s−1 to 0.001 s−1 results in the recrystallization mechanism changing from CDRX to DDRX to CDRX.