Microstructure Refinement and Property Improvement of Metastable Austenitic Manganese Steel Induced by Electropulsing

Grain refinement efficiency of electropulsing treatment (EPT) for metastable austenitic manganese steel was investigated. The mean grain size of original austenite is 300 μm. However, after EPT, the microstructure exhibits a bimodal grain size distribution, and nearly 70vol.% grains are less than 60 μm. The refined austenite results in ultrafine martensitic microstructure. The tensile strengths of refined austenitic and martensitic microstructures were improved from 495 to 670, and 794 to 900 MPa respectively. The fine grained materials possess better fracture toughness. The work-hardening capacity and wear resistance of the refined austenitic microstructure are improved. The reasonable mechanism of grain refinement is the combination of accelerating new phase nucleation and restraining the growth of neonatal austenitic grain during reverse transformation and rapid recrystallization induced by electropulsing.