The Olson-Cohen model for strain-induced deformation, further developed by Stringfellow and others, has been calibrated together with a flow stress model for the plastic deformation of metastable stainless steel. Special validation tests for checking one of the limitations of the model have also been carried out. The model has been implemented into a commercial finite element code using a staggered approach for integrating the stress-strain relations with the microstructure model. Results from a thermo-mechanical coupled simulation of hydroforming of a tube have been compared with corresponding experiments. The agreement between experimental results of radial expansion and martensite fraction and the corresponding computed results is good.