Generally, the dislocation-mechanics-based constitutive relations are applicable at high strain rates and relatively low temperatures. However, for expressing flow stress at elevated temperatures, it is required to account for the diffusion processes, namely softening effects of dynamic recovery (DRV) and dynamic recrystallization (DRX). In the current work, the Zerilli–Armstrong constitutive equation for face-centered cubic materials was appropriately modified by incorporation of peak strain and consideration of both hardening and softening phenomena. The developed constitutive relation was successfully applied to model the hot flow stress of a typical carbon steel and it was revealed that there is no need to alter the physically-based nature of the Zerilli–Armstrong constitutive equation by extensive modifications