The Influence Of C And Mn Elements On The Microstructure And Mechanical Properties Of Austenite Manganese Steel

High manganese steel is widely used in mines,railways and other industries due to its excellent work hardening properties.At present,China's railway frog steel is mainly based on high manganese steel.In order to meet today's railway development towards high-speed,heavy-duty,and inter-zone seamless development,higher requirements have been placed on new materials for high-manganese steel frogs.The basic elements of traditional high-manganese steel are C,Mn,Si,P,S.Among them,C and Mn elements are required as alloying elements,which are important elements for ensuring high manganese steel to obtain single-phase austenite microstructure and obtaining excellent work hardening performance.Therefore,this paper systematically studies the effect mechanism of carbon and manganese on the performance of high manganese steel.The mechanical testing results showed that the strength and plasticity of austenitic manganese steel increased with the increase of carbon content.Due to the combined effect of twin density and dislocation density,the work hardening index is hardly affected by changes in carbon content.The work hardening rate curve shows that as the carbon content increases,the second stage of the work hardening rate curve becomes later.In the early stage of the second stage,the austenite manganese steel with high carbon content has a lower work hardening rate than the austenite manganese steel with low carbon content.With the increase of the strain,the austenite manganese steel with high carbon content is processed.Hardening rate higher than austenite manganese steel with low carbon content.This is related to the fact that carbon increases stacking fault energy and affects the formation of twins.The increase of manganese content increases the strength,ductility and toughness of austenitic manganese steel,and the work hardening index and work hardening rate increase with the increase of manganese content.This is due to the fact that manganese promotes twin formation and increases dislocation density.For the same manganese content of austenitic manganese steel,the deformation twins can be refined due to the improvement of strain rate.Besides which is conductive to the formation of deformation twins.The formation of deformation twins further refined the austenite grain and hindered the dislocation motion.On the other hand,it can be coordinate plastic deformation.Therefore,the strength and plasticity of austenitic manganese steel with four kinds of manganese content increased with the strain rate.The deformation twins in 120Mn19 steel at lower strain rate were much more than 120Mn15 steel.However,at the high strain rate,the deformation twin of 120Mn19 steel and 120Mn15 steel was not much different.Therefore,under the condition of low strain rate,the performance of two kinds of steel is quite different,however the difference between them is small at high strain rate.The results of low cycle fatigue testing showed that The fatigue life of 130Mn11 steel is higher than that of 80Mn11 steel,This is because the strength of 80Mn11 steel is lower than 130Mn11 steel and Strength can affect the expansion of fatigue cracks.There is a large difference between the dislocation density and dislocation structure in the matrix after cyclic deformation of the two kinds of steel,thus the cyclic hardening rate of 130Mn11 steel under each strain amplitude was higher than that of 80Mn11 steel.