New Constitutive Model for Hot Working

Abstract

Based on plane regressions of a set of key points in the flow curves without using Sellars–Tegart (ST) assumptions, a new approach to determine parameters in classical two-stage constitutive equations in hot working was presented. All the parameters in constitutive equations can be obtained at different temperatures and strain rates. The flow stress and recrystallized volume fraction can be predicted when workpieces undergo different conditions during plastic deformation. Experiment data of 12 pctCr was used to verify the model. The results show that when using ST model, some bounces occurred near the critical points, while using the proposed model, the results show better precision especially in determining the characteristic points such as critical strain, peak strain, and steady stress.