Advanced constitutive model for repeated stress relaxation accounting for transient mobile dislocation density and internal stress

Repeated stress relaxation tests are used to characterize the macroscopic time dependent behavior in metals. During stress relaxation, the mobile dislocation density and internal stress vary continuously with time. The phenomenological models available do not provide a comprehensive mathematical framework to account for transient effects during stress relaxation accurately. An advanced stress relaxation model based on the logarithmic model is proposed in the present work to overcome the limitations of existing models. The proposed model is found to fit the experimental data of SS 316 better than the available models. The proposed model in combination with Kocks–Mecking type dislocation density model is utilized to predict the rate of strain hardening during relaxation