The impact wear-resistance enhancement mechanism of medium manganese steel and its applications in mining machines

In order to obtain higher wear resistance steel for the application in mining machines, new modified medium manganese austenitic steel (MMAS) was developed. The impact abrasive wear properties were investigated on MLD-10 impact wear test equipment. The wear resistant and strengthening mechanisms of MMAS were analysed by SEM, TEM and XRD observation. Our research results show that the wear mass loss of MMAS decreases about 30% in comparison to that of martensitic steel, which suggests that medium manganese austenitic steel has the higher impact abrasive wear resistance than the martensitic steel. It is found that 1mm thick hardened layer is formed on the MMAS abrasive surface. In this harden layer, the highest Vickers hardness is about 531HV, and the highest Rockwell hardness is about 52HRC at the layer of 50μm from the surface. It is proved that the harden layer substantially enhances wear resistance of MMAS. The wear resistance strengthening mechanism of MMAS is found to be dependent on the impact energy. For the lower impact energy, the strengthening mechanism is controlled by the composite reinforcement of martensitic transformation, dislocation and stacking fault. For the high impact energy, the strengthening mechanism is controlled by the martensitic transformation, deformation twin and dislocation. The field wear tests of MMAS were done on the scraper conveyor machines in coal mines, the test results indicated that the wear duration of MMAS transportation slots could be double of the martensitic wear resistant steel slots.