The changing of properties of HMnS by alloy elements addition and heat treatment was presented. Studying about the hardness of HMnS were increased when the Mn contents increased. On the other hand, the Cr content has effective on the hardness and microstructure of this steel also, but with the Cr content was increased from 2% to 2,5%, the hardness of high Manganese steel was not much changed. With the research about HMnS, it was added the Cr and applied the advanced heat treatment process, the

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... icrostructure of this steel was formed the chrome carbide particles with grain fine which dispersed in the matrix with the formation of these dispersed carbide particles will contribute to increasing the alloy's abrasion resistance. With the difference in heat treatment processes, the microstructure and hardness were also changed. When the sample was heat-treated according to the model heat treating; the particle size of the sample is also significantly reduced. This explains why the hardness value of the sample increases significantly. Also, under the impact load, on the surface layer of this steel, the microstructure does not appear the martensite structure form but only see the twinning on the surface. These are new findings on the mechanism transformation of high manganese austenite steel when working under the impact of the impact force. The mechanism of transformation is quite different from the previous view of phase transformation under the impact force of high manganese austenitic steel.