Study On Laser Surface Strengthening Process And Properties Of Chromium Bronze Alloy

Chrome bronze alloys are popular in the industrial sector because of their good hardness,electrical and thermal conductivity.Such as electrode materials,mold inner sleeves,high-speed electrified railway contact lines,lead frame materials,etc.However,the surface properties of the alloy still do not fully meet the application requirements in the industrial field.This topic uses laser surface modification technology to surface-treat C18200 chrome bronze alloy to improve its surface hardness and wear resistance.Laser surface solution hardening of C18200 chrome bronze was carried out using a "LDM-4000 Laserline" laser.The effects of laser power and scanning speed on the microstructure and morphology of the quenched layer were observed and analyzed.The influence of laser power and scanning speed on the change of surface hardness was studied.The optimal laser quenching process parameters were laser power 1700 W and scanning speed 7mm / s.The defocus amount is 300 mm.Under this process parameter,the depth of the quenched layer obtained is about 40?m,and the surface hardness is110.6HV.Compared with the original substrate(100HV),the surface hardness is increased by 10.6%.The microstructure was analyzed by metallographic microscope,SEM,EDS,and XRD.The Cr phase particles in the quenched layer structure were significantly refined and dispersed.Aging treatment was performed on the laser-quenched sample.The effect of aging treatment on the change of surface hardness was studied,and the aging temperature of500 ? and aging time of 90 min were determined as the best aging process parameters.After aging treatment,the surface hardness can reach 118.9HV,which is 18.9% higher than that of the original substrate.After analysis,it is concluded that the aging treatment can precipitate the Cr phase in the supersaturated solid solution and play a role of precipitation strengthening.Friction and abrasion tests were performed on laser quenched samples and "quenched + aging" samples.The friction coefficient of the laser quenched sample was0.1771,the friction coefficient of the "quenched + aging" sample was 0.1642,and the friction coefficient of the original substrate was 0.3372.After laser quenching and aging treatment of C18200 chrome bronze alloy,the wear resistance is significantly improved.