Comprehensive analysis on the effects of different stress states on the bainitic transformation

The bainitic transformation with various stress states was investigated by thermal simulation, scanning electron microscope and X-ray diffraction. The results show that as the stress increases, the promotion degree of stress on bainitic transformation increases fast firstly, then increases slowly and finally decreases. There are two critical stress values. The first one corresponds to the yield strength of parent austenite and the second one corresponds to the maximum promotion degree of stress. A simple model is proposed to describe this phenomenon. In addition, the effects of compressive stress and tensile stress on microstructure and the kinetics of bainitic transformation are similar. Moreover, even a small stress such as 30 MPa can slightly promote bainitic transformation. Finally, like bainitic transformation without stress, bainitic transformation with stress is an incomplete-reaction.