DMA2022-Martensite transformation and its microscopic mechanism of TRIP duplex stainless steel under cyclic loading

Abstract Because of the features of high strength and high plasticity, TRIP duplex stainless steels can achieve the purpose of lightweight and reduce fuel consumption and emissions. In order to further develop and apply the lightweight metastable duplex stainless steel, the martensite transformation and the microscopic mechanism of Mn-N alloyed TRIP duplex stainless steel under the cyclic loading were studied. The in-situ measurement platform of martensite transformation under the cyclic loading was built by the INSTRON 8801 series servohydraulic testing machine and FMP30 ferrite measuring instrument. The volume fraction of martensite transformation under symmetrical cyclic loading of different cycles with strain amplitudes of 0.5%, 0.7%, 0.9%, 1.1% and 1.3% were measured. The transformation law of martensite under the cyclic loading was analyzed, and the kinetics model of martensite transformation under the cyclic loading was established; The martensite transformation law, the effect of austenite grain orientation on martensite transformation and the microscopic mechanism of martensite transformation under the cyclic loading were analyzed by the electron backscattering diffraction(EBSD) and the transmission electron microscope(TEM).