A physically based model for TRIP-aided carbon steels behaviour

A physically based model for TRIP carbon steels is developed suitable to predict the macroscopic behaviour of multi-constituent aggregates. It includes the effects of phase composition and morphology on flow stress and strain hardening. In a first part, a detailed description of the stress-assisted and strain-induced martensitic transformation kinetics is given based on a generalised form of the Olson–Cohen model. The appearance of the much harder martensitic phase during plastic straining gives rise to a strong hardening of the retained austenite islands. The matrix behaviour is described using a model previously developed for ferritic–martensitic steels. A quite simple but accurate homogenisation approach is used to determine the TRIP steel behaviour. The predicted evolution of strain-induced martensite volume fraction, flow stress and incremental work hardening is in good agreement with experimental data and illustrates the critical importance of the retained austenite stability on the formability of TRIP steels.