Research On Work Hardening Ability And Mechanism Of High Manganese Steel By Simulating Actual Working Condition

A mass of scientific and technical literatures show small energy impact or static load compress/tension deformation is used to gain work hardening in research on work hardening ability and mechanism of high manganese steel. Small energy impact and static load compress/tension deformation are different from actual working condition, so both two methods may not show work hardening ability and mechanism of actual working condition. For this reason, this paper studied effect of impact energy , C content, Mn content, modification and heat treatment on work hardening ability and mechanism of high manganese steel by simulating actual working condition.According to the analysis of actual working condition, four 'relative impact energies' of 50, 80, 100, 200J/ cm~2 were selected in this experiment. The effect of the factors on work hardening ability of high manganese steel were studied under four 'relative impact energies' with dropping impact hammer designed on our own. The results show that the best work hardening effect could only be obtained when 'relative impact energy' exceeds the critical value; work hardening ability could benefit from the reduction of Mn content and increase of C content; RE-modification can improve work hardening velocity, but it can't improve the final work hardening effect; Proper precipitate reinforcement treatment could improve work hardening ability to some degree.Furthermore, in order to study the microstructure of high manganese steel, the samples after work hardening were investigated with optics metallographic microscope and transmission electron microscope, and also work hardening mechanism is analyzed. The research results show that the microstructure and work hardening mechanism are distinguishing under different work hardening effect; For the given specimens of high manganese steel, with the relative impact energy of 50J/cm~2 , vast dislocation , stacking fault and few twinning exist in the microstructure, therefore work hardening mechanism could be considered as dislocation hardening mechanism; With the relative impact energy more than 100 J/cm~2, dislocation and twins exist, where work hardening mechanism could be considered as twinning hardening mechanism.It's difficult to reach the best work hardening effect for high manganese steel under low and medium stress, so alloying and modification are adopted to improvethe wearing property. In this paper, we investigated the effect of SG modification on as-cast and heat-treated microstructure of high manganese steel with carbide forming element (e.g. Cr, V). The research results show SG modification could restrain the growth of columnar crystals, reduce the content of pearlite in as-cast microstructure and refine the grain and also SG modification reduces holding time or temperature of quenching.