Deformation behavior of high-Mn TWIP steels processed by warm-to-hot working

Abstract

The deformation behavior of 18%Mn TWIP steels (upon tensile tests) subjected to warm-to-hot rolling was analyzed in terms of Ludwigson-type relationship, i.e., σ = K1·εn1 + exp(K2 − n2·ε). Parameters of Ki and ni depend on material and processing conditions and can be expressed by unique functions of inverse temperature. A decrease in the rolling temperature from 1373 K to 773 K results in a decrease in K1 concurrently with n1. Correspondingly, true stress approached a level of about 1750 MPa during tensile tests, irrespective of the previous warm-to-hot rolling conditions. On the other hand, an increase in both K2 and n2 with a decrease in the rolling temperature corresponds to an almost threefold increase in the yield strength and threefold shortening of the stage of transient plastic flow, which governs the duration of strain hardening and, therefore, manages plasticity. The change in deformation behavior with variation in the rolling temperature is associated with the effect of the processing conditions on the dislocation substructure, which, in turn, depends on the development of dynamic recovery and recrystallization during warm-to-hot rolling.