Research On Influence Of Shot Peening Pretreatment On Wear Resistance Of Medium Manganese Steel Containing Ti

Wear is one of the primary forms of mechanical parts failure,widely exists in the mining machinery,construction machinery and railway transportation departments of steel materials,resulting in substantial economic losses and material consumption;the fundamental reason is that the intense friction between parts leads to the damage of the material surface.Wear will not only reduce production efficiency,but excessive wear will also even cause serious accidents.Therefore,the research on high-performance steels helps improve the service life of construction machinery,and it is significant to improve high-quality development of our society and economy.In this paper,medium manganese steel 1C-8Mn is used as comparison steel and 1C-8Mn-0.1Ti as test steel.The effect of Ti(C,N)particles on the microstructure of medium manganese steel was studied by adjusting the characteristics of the precipitated phase,and the synergistic strengthening effect of refined strengthening and precipitation strengthening on mechanical properties was discussed.In addition,the mechanism of Ti(C,N)precipitation relative work hardening was studied by shot peening to strengthen the surface of the test steel,and the wear behavior and strengthening mechanism of medium manganese steel were analysed,which provided the basis for the popularization and application of manganese steel.The main conclusions were obtained as follows:(1)The microstructure of two steels are composed of austenite and precipitated phase.The contrast steel’s precipitated phase is(Fe,V,Mo,Cr)C alloy cementite,and the precipitated phase of the test steel is Ti(C,N)particle.The grain of test steel is refined because the Ti element can refine effectively.In addition,under the same conditions,the hardness of test steel is higher than that of the comparison steel due to the refined strengthening and the precipitation strengthening of Ti(C,N)particles.Meanwhile,the impact energy of the comparison steel is significantly reduced due to the precipitation of large alloy cementite and Mn element at the austenitic grain boundary.(2)The work-hardening performance of test steel depends on the synergistic interaction between its fault energy and Ti(C,N)precipitated phase.The as-hot rolled and solution test steel with lower fault energy(about 13mJ/m2)show a thicker hardening layer due to the interaction between martensitic phase transformation and dislocation.The ageing test steel with high fault energy(about 17mJ/m2)shows a smaller hardened layer due to the interaction between twins and dislocation.Still,the Ti(C,N)precipitated phase helps improve the hardness of the hardened layer of ageing test steel,however,stress concentration is easily caused by Ti(C,N)precipitated phase in the process of shot peening,which also leads to the initiation and propagation of micro-cracks in the subsurface of the ageing steel.(3)The dry sliding wear test after shot peening did not lead to further work hardening effect,and the fundamental reason for the difference in wear resistance was attributed to the characteristics of the hardened layer produced by shot peening.As-hot rolled and solution test steels’ wear resistance increases with the shot peening time.The thicker hardening layer effectively alleviates the stress concentration and has fewer defects in the subsurface.The wear resistance of ageing test steel decreases with the increase of shot peening time,which is attributed to the Ti(C,N)particles in the process of shot peening leading to the initiation and expansion of micro-cracks in the subsurface microstructure,embrittlement of the material surface,and thus reduce the wear resistance of ageing test steel.In addition,surface roughness also significantly affects the wear resistance of the test steel by influencing the run-in stage.(4)After shot peening,the wear mechanism of the impact wear test mainly depends on the work-hardening effect of the material.The wear resistance of the three kinds of test steels increases with the peening time because the hardening layer is produced,significantly reducing the wear loss caused by the initial stage of impact wear.Among them,the ageing test steel with the highest surface hardness shows the best wear resistance due to the high hardness of the shotpeening hardened layer’s excellent resistance to external impact deformation ability.(5)The wear mechanisms of the two steels are intently associated with the microstructure and mechanical properties.For the dry sliding wear test,the wear mechanism of as-hot rolled test steel is commonly abrasive wear,the wear mechanism of solution test steel is dominated by fatigue and abrasive wear,and the ageing test steel’s wear mechanism is primary fatigue wear.For the impact wear test,the wear mechanism is primarily abrasive wear,accompanied by a small amount of fatigue and adhesive wear.