Constitutive modeling of trip steel and its application to the improvement of mechanical properties

Abstract

The transformation-induced plasticity (TRIP) steel possesses such favorable mechanical properties as high work-hardening characteristics, tenacity and strength. The strain-induced martensitic transformation, however, strongly depends on the temperature and strain rate imposed, and an appropriate improvement of mechanical properties is realized under quite restricted circumstances. To obtain the required mechanical properties, a constitutive model which can suitably predict the deformation behavior including transformation under a wide range of deformation rate and temperature has been developed by employing Olson and Cohen's model for strain-induced martensitic transformation kinetics. Then, the deformation behavior of a SUS304 (18-8) cylinder has been simulated under different environmental temperature with different strain rates by the thermocoupled finite-element method accounting for the latent heat induced by martensitic transformation. The possibility of the improvement of such mechanical properties of the material as strength, ductility and toughness has been individually discussed.