Research On Wear Resistance Of Surface Microstructure Of GCR15 Bearing Steel Based On Strengthened Grinding Processing

GCr15 bearing steel is a kind of high carbon steel with few alloying elements and good performance,which is widely used in the manufacture of bearing and other mechanical parts.Because the working environment of bearing parts is relatively harsh,it is affected by periodic alternating loads for a long time in the service process,and sometimes it cannot be well lubricated,which leads to surface failure easily and reduces the service life of bearing parts.Therefore,the surface of GCr15 bearing steel material is strengthened through strengthened grinding processing technology to improve its wear resistance,so as to achieve the purpose of prolonging the service life of bearings and other parts.In this paper,the theoretical analysis of the strengthened grinding process and wear experiment is carried out,and the relationship between the parameters of the strengthened grinding process and the pressure and deformation of the impact deformation zone on the bearing steel surface is obtained.DOE test design method was used to design the strengthened grinding processing experimental scheme.Then,according to the DOE test scheme,the hardened GCr15 bearing steel plate was strengthened grinding processing.Optical microscope(OM),scanning electron microscope(SEM),X-ray diffraction and microhardness tester were used to test the thickness of the strengthened layer,surface microstructure,surface microstructure and phase distribution of the abrasive group and the blank group,as well as the microhardness distribution of the section.Comparative blank group and strengthen the reciprocating friction and wear testing machine grinding samples respectively in 40N,60N and80N load under dry friction and lubrication wear-resisting performance,in the final analysis the friction coefficient and wear volume of the sample,the surface grinding crack morphology was observed and analyzed the wear mechanism,explore the surface of samples after the strengthened grinding the influence law of microstructure and wear resistance.The main conclusions of this paper are as follows:(1)The greater the injection pressure,the longer the injection time and the greater the injection angle,the greater the thickness of the reinforced layer on the surface of the samples.The thickness of the reinforced layer of the samples in the strengthened grinding processing group was between 30 and 100?m,and the thickness of the reinforced layer of the samples in group H was the largest(93?m).According to the analysis of surface microstructure,the smaller the injection pressure,the longer the injection time and the larger the injection Angle,the less obvious the plastic deformation and micro-cutting effect of the abrasive on the steel plate,and the better the flatness of the sample.(2)The martensite content on the surface of the strengthened grinding samples was increased compared with that of the blank group.The effect of injection pressure and injection time on martensite content was greater than that of injection angle.The martensite content increased,grain size decreased,and dislocation density increased from 1.954×10¹⁴m^-2(blank group)to 1.8632×10¹⁶m^-2.The maximum microhardness of the samples in group H is 864.3HV.With the increase of the depth from the surface,the microhardness value gradually decreases to the same as that of the matrix.(3)Strengthened grinding can reduce the friction coefficient and wear of GCr15 bearing steel.In the dry friction and oil lubrication friction and wear test,the friction coefficient of samples in group H is the lowest.Compared with the blank group,the friction coefficient under dry friction 40N,60N and 80N load is reduced by 12.46%,16.04%and 16.42%,respectively,and the wear amount is 1.2mg,3.8mg and 4.6mg,respectively.For oil-lubrication friction and wear tests,compared with blank group,the friction coefficient of samples in group H under40N,60N and 80N load decreased by 24.95%,17.88%and 22.22%,respectively,and the wear amount was 0.2mg,0.4mg and 0.6mg,respectively.This is related to the higher martensite content and smaller grain size of the samples in the strengthened grinding process.The maximum martensite content of the samples(group H)is 81.43%,and the grain size is 8?m,which shows the best wear resistance.