Study On Wear Mappping And Wear Transition Mechansim Of CL60 Wheel Material

Railway transportation is of great significance to the improvement of our country's economy and society.High-speed and heavy-haul railways are two main directions for today's railway development.The service conditions of a train are quite complicated and the operating parameters,environmental conditions and the third mediums all have an effect on the operation safety of the train.As a basic component,the wheel-rail may suffer many kinds of damages during the service period.With the development of railway,the requirements for the service performances of wheel-rail become increasingly strict.Therefore,it is very important to study the wear and damage behavior of wheel and rail materials under various service conditions.The wheel/rail rolling wear and contact fatigue test machine of MJP-30A was used to perform the tests of wheel materials under dry and water conditions.The effect of slip ratio and contact pressure on the wheel wear and damage performance was studied in this paper,and the wear maps for dry and water conditions were plotted.Furthermore,the wear transition mechanisms of wheel material under the dry and water conditions were also discussed.The main conclusions of this paper are as follows.?1?With the increase of slip ratio,the wear rate of wheel material can be divided into three regions:linear wear region,nonlinear wear region and uncertain wear region under the dry condition.Under the low slip ratio condition???18%?,the wear rate rises with the contact pressure increasing,while it increases first and then decreases under the high slip ratio conditions??=25%?.?2?The wear rate of the wheel material generally increases with the increase of slip ratio under the water condition.Furthermore,the wear rate also shows an increasing trend with the increase of contact pressure.?3?Under the dry condition,with the increase of slip ratio,the surface damage of wheel material is gradually transformed from the mechanical damages?such as pitting,peeling and spalling?into the thermal damages?such as plowing,peeling and partial oxidation?,and with the increase of contact pressure,the surface damage becomes more serious.But under the water condition,with the increase of slip ratio,the surface damage is gradually changed from the pitting to the slight plowing and spalling,and with the increases of contact pressure,the surface damage becomes increasingly serious.?4?The wear rates of CL60 and AAR-D materials first decrease and then increase with the increase of slip ratios under nonlinear wear region?6%???18%?.It is because the Fe₃O₄appeared on the worn surface achieves the highest relative content under the slip ratio of12%,and it has a lubricating action.Under the undefined wear region??>18%?,the wear rate of AAR-D material decreases again with the increase of slip ratio,which attributes to the WEL formation on the surface of AAR-D under the slip ratio of 25%.?5?With the increases of slip ratio,the wear rate of wheel material increases first and then decreased under the water conditions,and finally increased again.It is probably due to the reason that a water film forms on wheel-rail contact interface under water conditions,and the film thickness increases with the increase of slip ratio,which reduces the interaction between the specimens,and further reduces the wear rate.However,with the slip ratio increases further,the damage mechanism of wheel specimen changes and the effect of water film decreases gradually,so the wear rate increases again.