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Due to the phenomenon of deformation-induced phase transformation, the mechanical properties of TRIP steel, including the elastic modulus, undergo changes during the deformation process. This deviation from plastic theory in describing the deformation process is addressed in this study. Through tensile and cupping tests conducted at different rates, the relationship between inelastic deformation and forming time in TRIP steel is established. These tests demonstrate the presence of viscosity and the rheological behavior of solid metal materials during inelastic deformation. The experimental findings also highlight the significance of selecting an appropriate deformation rate for successful TRIP steel forming. Excessive deformation rates can result in the rapid transformation of residual austenite into martensite and increase the likelihood of material cracking. Building upon rheological theory, a constitutive equation is developed to describe the relationship between stress, strain, and strain rate for TRIP600 under creep test conditions. This constitutive model is then applied to simulate the cupping test, and by comparing the simulation results with actual test data, it is confirmed that the rheological constitutive model provides a more accurate representation of TRIP steel deformation. Furthermore, it can guide the improvement of the forming process to enhance the success rate of forming operations.
Yin et al. (Sun,) studied this question.