Deformation behavior of the constituent phases for cold-rolled TRIP-assisted steels during uniaxial tension

Due to the fact that retained austenite is metastable and easily transforms to martensite during forming, TRIP-assisted steels consist of ferrite, bainite, retained austenite and martensite. In this paper, a deformation model for multiphase TRIP-assisted steels is proposed on the basis of a continuum mechanical model; the deformation behavior of the constitute phases is then analyzed. The contribution of different constituent phases to overall flow stress is discussed in detail. SEM monitoring of the point near the fracture region during uniaxial tension testing was carried out and experimental results demonstrated that the constituent phases deformed according to the five stages proposed in the paper. The flow stress calculated by the proposed model was compared with experimental values; agreement between them is satisfactory.