Adding N to Enhance Low-Cycle Fatigue Properties of High-Mn Austenitic Steel

This study comparatively investigated the low-cycle fatigue properties and microstructure of two high-Mn austenitic steels, Fe- 18.5Mn-7Cr- 0.6C and Fe- 18.5Mn-7Cr- 0.6C- 0.21 N. The results revealed that adding N promoted the dislocation planar slip during cyclic deformation in high-Mn austenitic steel, due to the presence of Cr-N short -range ordering (SRO) and the decrease of stacking fault energy (SFE). With an increased number of cycles, the planar slip characteristics of the N -containing high-Mn austenitic steel led to a rapid decrease in effective stress, which promoted cyclic softening. Moreover, adding N increased the fatigue life of high-Mn austenitic steel, by enhancing the fatigue strength, reducing the plastic damage accumulation, and inhibiting the fatigue crack propagation. This study provided a valuable reference for the practical applications of N -alloyed high-Mn austenitic steel.