A model for TRIP steel constitutive behavior

A constitutive model is developed for TRIP steel. This is a type of steel which contains three or four different phases in its microstructure. One of the phases in TRIP steels is metastable austenite (Retained Austenite) which transforms to martensite upon deformation. The accompanying transformation strain and the increase in hardness provide excellent formability characteristics. The phase transformation depends on the stress in the austenite, which is not equal to the overall stress. An estimate of the local stress in the austenite is obtained by homogenization of the response of the phases using a Mean-Field homogenization method. Overall stress strain results as well as stress strain results for individual phases are compared to measurements found in literature. The model can be used in finite element simulations of forming processes