Influence of pre-straining on the low-cycle fatigue performance of Fe-0.1C-5Mn medium manganese steel

The low-cycle fatigue (LCF) behavior of Fe-0.1C-5Mn medium manganese transformation-induced plasticity steel in its as-received (AR: 0% pre-strained) and 10%, 15%, and 20% pre-strained conditions was analyzed. Microstructural evolution during pre-straining and cyclic loading was characterized by X-ray diffraction, electron backscatter diffraction, and transmission electron microscopy. The LCF properties of the steel were observed to gradually improve as pre-straining increased. Moreover, during pre-straining, the blocky austenite grains were successively split into thin film-like austenite by fresh lath martensite. It refined the microstructure, delayed fatigue crack initiation, prevented crack growth, and resulted in notable improvements in the LCF performance.