Deformation-induced martensite formation is a thermo-mechanical phenomenon whereby the transformation of the austenite phase into martensite occurs above the martensite start temperature due to deformation assistance. A large number of parameters have great influence on the martensite formation, such as steel composition, applied stress, plastic strain and temperature. The deformation induced by the applied load can supply the necessary strain energy to assist martensite formation, and also by introducing defects to promote the nucleation of martensitic grains. Further reduction of temperature provides a large chemical driving force that promotes martensite formation. In this project, we propose to investigate the influences of the appearance of martensite due to deformation and temperature using neutron diffraction