Javad Rasti - Department of Mechanical Engineering, Qom University of Technology (QUT), Qom,, Iran
A.Abbas Najafizadeh - Department of Materials Engineering, Isfahan University of Technology, Isfahan, Iran
Saeed Jafari - Department of Mechanical Engineering, Qom University of Technology (QUT), Qom, Iran
Behnam Khodabandehloo - Department of Mechanical Engineering, Qom University of Technology (QUT), Qom, Iran

The present study aimed to present a phenomenological and empirically-based constitutive model to predict flow behavior of a ۳۰۴ stainless steel. Hot compression tests performed at temperatures of ۹۵۰۱۱۰۰ °C and strain rates of ۰.۰۰۵۰.۵ s−۱ up to the strain of ۱. Classical hyperbolic sine equations with different parameters were used to derive functions for the yield stress and critical stress at the onset of dynamic recrystallization as well as the saturation stress of dynamic recovery as functions of the Zener-Hollomon parameter. Three regimes were considered to develop flow curves comprising the linear trend up to yield stress, recovery-dominant region based on the Estrin and Mecking model, and the recovery-recrystallization zone from the critical stress extends toward the steady state stress. Avrami-type equation was supposed for the kinetics of recrystallization and validated by the evolved microstructures at strain ۱. Results comprised the Arrhenius expressions for the yield, saturation, and the steady state stresses, in addition of the equations for the critical and inflection strains as well as the exponent of Avrami-type kinetics for the recrystallization, the six parameters that the model is based on those relations via strain, strain rate, and temperature. Finally, the flow curves predicted by the model satisfactorily coincided with the experimental ones, confirmed that the proposed model can give an almost accurate estimation of the flow stress of ۳۰۴ stainless steel.

Hot deformation, ۳۰۴ stainless steel, constitutive equation, Dynamic recrystallization, Arrhenius equation, Zener-Hollomon parameter