The synergistic effect of grain refinement and precipitation strengthening on mechanical properties and dry sliding wear behavior of medium manganese steels

The hot rolled medium manganese Ti-bearing and Ti-free steels were solution treated at 1000 ℃ and then aged at 500, 550 and 600 ℃, respectively. The results showed that Ti-bearing steel had refined grain size but higher hardness than Ti-free steel. Moreover, Ti-bearing steel exhibited a superior impact toughness than Ti-free steel, especially when the samples were aged at 500 ℃, which was attributed to the homogeneous distribution of Ti(C, N) precipitates and alloyed cementite in the matrix. In addition, the Ti-bearing steel aged at 500 ℃ exhibited the best wear resistance despite its lower initial hardness, which was primarily attributed to the significant work hardening achieved by ε-martensitic transformation and mechanical twins during wear deformation.