| According to the decarburization of high manganese steels wear-resistant casting in Guangxi Great Wall Machinery Co.,Ltd.,the surface decarburization law of high manganese steels during heat treatment was studied.A new type of red mud anti decarburization coating was prepared with Bayer red mud as the main raw material,and the protective ability of the coating was verified.Aiming at the problem of dehydrogenation in high manganese steels casting process,hydrogen diffusion behavior in steel was studied.In view of the high content of impurities in high manganese steels,the types and causes of impurities in steel were studied.A kind of red mud refining slag was prepared by using the reduction slag obtained from Bayer process red mud carbothermal reduction as raw material,and the impurity removal ability of refining slag was explored.At the same time,the properties of three kinds of high manganese steels produced by the enterprise were tested.Through these studies,the purpose is to provide solutions to problems and certain theoretical basis and data reference for the production of enterprises,and provide some new ideas for the resource utilization of Bayer process red mud in Guangxi.The results are as follows:(1)The decarburization of ZGMn13Cr2 steel under different heat treatment parameters was studied.It was found that there were serious decarburization and oxidation scaling loss in high manganese steels during heat treatment.The decarburization and oxidation scaling loss increased with the increase of holding temperature and time.Moreover,the traditional decarburization kinetic model is no longer applicable due to the oxidation and burning loss.The modified decarburization calculation model can accurately predict the decarburization law of high manganese steels during heat treatment.(2)An anti decarburization coating was prepared from red mud produced by Bayer process.The coating performance under different powder liquid ratio was studied.When the powder liquid ratio was 2.4 g/ml,the coating could be completely and evenly coated on the surface of steel parts.After coating,ZGMn13Cr2 steel was heat treated at 1100 ℃ for 90 min without obvious decarburization,and the oxidation loss rate of the sample was reduced by 47.4%.(3)By studying the influence of environmental relative humidity on hydrogen content of high manganese steels melt,it is found that the main reason for the increase of hydrogen content in steel during smelting is the partial pressure of water vapor in the air.When the relative humidity is high,the partial pressure of water vapor is larger,the solubility of hydrogen in steel is increased,and the hydrogen content in steel is increasing.(4)The reaction between the molten steel and refractory will increase the number of inclusions in the steel.The inclusions are mainly oxide inclusions,sulfide inclusions and some large particle composite inclusions.The red mud refining slag prepared by reducing slag has good impurity removal effect.By slag washing,when the amount of slag is sufficient,the number of inclusions in steel decreases by 86%,the oxygen content decreases by 50%,and the hydrogen content decreases by 45%.(5)The properties of ZGMn13Cr2,ZGMn18Cr2 and ZGMn21Cr2 after heat treatment are greatly improved.Due to the existence of dispersed small particles of carbide in the heat-treated microstructure of ZGMn18Cr2,ZGMn18Cr2 has the best tensile strength and wear properties.The microstructure of ZGMn21Cr2 heat treatment is uniform,it has the best plasticity and impact toughness.The thermal expansion coefficient and thermal diffusion coefficient of the three kinds of high manganese steels increase with the increase of temperature,so it is necessary to consider the influence of different steel types on the thermal physical properties when formulating the heat treatment process. |
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