Design of V+N Micro-alloyed High Manganese Steel Used for Railway Frogs and Its Strengthening Toughening Mechanism

High manganese steel with its excellent work hardening properties and wear resistance is widely used in the field of railway frogs. However, the low yield strength of high manganese steel results in a relatively short service life.Therefore, enhancing the strength and toughness of high manganese steel is significant for extending the service life of railway frogs. V+N microalloying approach was employed to promote the precipitation of a large number of V（C, N） nanoscale precipitates in the high manganese steel matrix, thus significantly increasing the yield strength and hardness of the material.The results show that compared to the traditional Mn13 steel, the yield strength of V+N micro-alloyed high manganese steel is increased by 39%, reaching 535 MPa, the elongation rate is slightly reduced, which is 44.3%. The nanoscale precipitates, on the one hand, enhance the material’s yield strength by hindering the movement of dislocations, and on the other hand, they suppress the formation of twins, raise the critical stress required for twinning. This encourages the occurrence of twins at higher strains, which make the twinning-induced plasticity effect（TWIP） to continue to higher strain stages, thereby endowing the material with better plasticity.