Effect Of Carburizing Strengthening Unit On The Fatigue Wear Of U71Mn Steel

Railway rails are an important component of rail transport,and their quality and performance directly affect the safety and efficiency of rail transport.With the rapid development of C hina's passenger high-speed rail and the increase of freight traffic,the fatigue wear of railway rail is becoming more and more serious,which leads to the shortening of service time.In order to ensure the safety of railway transportation and minimize the cost of railway operation,we need to improve the rolling contact fatigue wear resistance of railway rails as much as possible to extend the service time.According to the previous research,a high-hardness bionic unit is prepared on the surface of the matrix material by laser remelting.The high-hardness units and the low-hardness matrix material form a kind of special structure of interlaced hardness distribution similar to the biological carrier.It can effectively improve the rolling contact fatigue wear resistance of the matrix material surface.If the hardness of the bionic unit is further improved,it is possible to further improve the rolling contact fatigue wear resistance of the surface.In this paper,the U71 Mn steel is treated by laser carburizing to prepare the laser carburizing unit with higher hardness than the laser remelting unit,which is subjected to greater stress in rolling wear experiment,so as to further improve the rolling contact fatigue wear resistance of the wear samples.The results show that the bionic samples processed by laser processing have excellent rolling contact fatigue wear resistance than untreated samples.Compared with the laser remelting of bionic samples,the rolling contact fatigue wear resistance of the laser carburizing samples has better.Based on the simplification and re-design of the biological model,it can be found that the biomimetic specimen with the grid unit treated by laser carburizing has the best rolling contact fatigue wear resistance,and the weight loss is 82% lower than that of the untreated specimen.Due to laser carburizing,the external carbon element into the unit,making the overall carbon content of the unit to enhance,resulting in lattice distortion.Compared with the laser remelting unit,the carbon co ntent of the laser carburizing unit is high,and it is easy to form high-carbon martensite,which has higher microhardness and stronger resistance to plastic deformation,and has been further strengthened.In the wear test,the high hardness of the laser carburizing unit can withstand more stress,so that the matrix part of the stress to bear,to improve the rolling contact fatigue wear resistance.When the thickness of the coated carbon layer is constant and the laser parameters are gradually increased,the rolling contact fatigue wear resistance of the biomimetic specimen will be parabolic.At the same time,the decrease in the thickness of the coated carbon layer will result that,in the same laser parameters,the rolling contact fatigue wear resistance of the bionic samples is improved.