Tribocorrosion And Corrosion Performance Of Medium Manganese Autensitic Steel Under Mining Condition

Corrosion is the main cause of failure of mining machinery.Due to the darkness and damp of coal exploiting environment,the humidity of air in mines can reach more than 90%.Besides,the actual corrosion process can be quite complicated because of some complex factors,such as the interaction of alternating stress and corrosion medium.In this paper,the uniform corrosion and electrochemical corrosion test of medium manganese autensitic steel and matensitic wear-resistant steel were investigated to analysis the anti-corrosion propertiies under mining water.Meanwhile,the sliding friction and sliding tribocorrosion of two wear-resistant steels were studied to explore the effects of corrosion media,corrosion period and friction medium on tribocorrosion resistance of two wear resistant steels.The results are as follows:Both two wear-resistant steels can serve well under neutral mining condition.In comparison to matensitic wear-resistant steel,medium manganese autensitic steel is more suitable for alkaline mining condition.The XPS analyses show austenitic steel and martensitic steel have similar erosion mechanism in the three simulated mining solutions.The corrosion products are mainly Fe₂O₃,FeSO₄ and Fe?HCO₃?₃.In the three testing mediums,the corrosion mechanism of two steels transform gradually from non-uniform corrosion to uniform corrosion.The character of non-uniform corrosion is with pits in and outside the grain boundary,while uniform corrosion has bigger and deeper pits,parallel grooves and corrosion products.The polarization curve of two steels under acidic mining water turns most negative,which means corrosion current density increases and corrosion is more likely to happen.The open circuit potential of medium manganese autensitic steel is lower than that of matensitic wear-resistant steel,which reveals the latter eroded seriously.The passivation zone of medium manganese autensitic steel was obvious under three mining water.However,the passivation zone under acidic condition is narrow,while that in neutral and alkaline condition is wide.Besides,the polarization curve of two steels under acidic and alkaline mining water turns negative,corrosion current density increases and corrosion is more likely to happen.The equivalent circuit of electrochemical impedance spectra of two steels can be fitted in series with solution resistance?Rs?and the resistance-capacitance parallel?RpCp?circuit.Only one electrode reaction occurred in the electrodes.The impendence module of medium manganese autensitic steel under acidic mining water decreased significantly and the capacitive reactance arc was small,as a consequence,it was eroded seriously,as well as matensitic wear-resistant steel.Under three mining water,the wear wear loss rate of medium manganese autensitic steel is lower than matensitic wear-resistant steel,which means the former has better anti-wear properties.In this friction and corrosion system,friction plays the main role.Because of short test time,friction has little effect on the acceleration of corrosion.The hardness of the corrosive wear layer of the matrix austenitic steel is obviously improved,the microhardness of the sub-surface layer at 50 ?m under three mine water can up to 510 HV,an average of 2.1 times increase,and its depth can reach 500?m.The hardness of medium manganese autensitic steel is higher than matensitic wear-resistant steel.In the three mining water,the wear mechanism of two steels are the same.Furrow wear and fatigue cracking are the main wear mechanism.Comparison of the impact corrosion of two steels under three mining water,the friction corrosion wear loss rate under acidic mining water is slightly higher than that in the neutral and alkaline conditions.The microhardness of the sub-surface layer at 50 ?m under three mine water can up to 520 HV,an average of 2.2 times increase.The hardness of medium manganese autensitic steel is higher than matensitic wear-resistant steel.Medium manganese autensitic steel shows good work hardening ability.The deformation of corrosive wear layer of autensitic steel under three mining water induced martensitic transformation,which transformed to plate dislocation of martensite.The analysis of the strengthening mechanism of autensitic steel shows that the deformation-induced martensitic transformation,dislocation and twinning are the main mechanism of work hardening,which belongs to compound strengthening mechanism.In this impact friction and corrosion system,friction plays the main role.In addition,under three mining water,the wear mechanism of two steels are cutting wear and furrow cutting wear.