Thermo-Mechanical Constitutive Equation of 22MnB5 Steel Sheet for Hot Press Forming Process

Abstract

The 22MnB5 steel sheet is applied to the hot press forming process to enhance the strength of the final product with guaranteeing sufficient formability. Since it undergoes the austenitizing process up to 850 degrees C and is quenched down to room temperature, it does not only occur large plastic deformation, but also induce the phase transformation. It is substantially difficult to take into consideration of the flow stress variations with respect to the temperature and strain rate associated with the phases such as the austenite, ferrite/pearlite, bainite, and martensite in the numerical simulation for the HPF process. This paper mainly proposes a generalized form of thermo-mechanical constitutive equation which is able to capture the experimental flow curves, precisely, in terms of the strain and strain rate hardening including the temperature softening, simultaneously.