Laser Surface Modification Of 32CrNi3MoVE Steel

In this paper,the 32CrNi3MoVE steel was used as the research object,and used laser to modify the chromium plated steel and non chromium plated steel.The laser surface modification technological parameters,microstructure,hardness distribution,element and phase,wear mark,friction coefficient and wear volume of the treated32CrNi3MoVE steel with chromium coating and non chromium coating were studied by the means of optical microscope,scanning electron microscope,microhardness tester,X-ray diffractometer and reciprocating friction and wear tester.Summarized the influence of process parameters on microstructure,hardness and wear resistance.The laser surface modification process parameters were 1400W,scanning speed15mm/s and defocusing amount 304mm.After laser surface modification,the surface of 32CrNi3MoVE steel was hardened.The maximum hardening depth was 0.55mm,and the maximum surface hardness was 647HV.The calculation formula of laser surface modification index was derived,which could effectively predict the process parameters.The microstructure after modification was mainly cryptocrystalline martensite,fine strip martensite and retained austenite.There was no significant change in the elements except Fe in EDS,and C_0.08Fe_1.92,C_0.09Fe_1.91,and C_0.05Fe_1.945 were generated in the modified layer.After texting by the friction experiment,it was found that the friction coefficient was lower,the friction coefficient curve was more stable,the wear volume was reduced,and the wear furrow was obviously smaller.The laser surface modification process was executed on the chromium plated32CrNi3MoVE steel.When the process parameters were 1800W,13mm/s scanning speed and 304mm defocus,the harden effect of the material was the best.When the process parameter was power 2000W,scanning speed 13mm/s,it was found that the surface of the material is melted and the Cr layer falls off.After laser treatment,the average hardness of chromium layer was 7.73GPa,the surface hardness of steel was578HV,and the hardening depth is 0.36mm.The distribution of Cr layer on the surface of the material was uniform after laser surface modification.The hardness was the highest on the hardened surface,and decreased gradually from surface to inside.Because Cr₂O₃ was formed after laser strengthening of Cr layer.After XRD scanning,Cr₂O₃,C_0.055Fe_1.945 and C_0.08Fe_1.92 were found.After laser treatment,the friction coefficient curve of the sample was more stable than before,the friction coefficient was lower,the wear volume was reduced,and the furrow was obviously smaller.