| Aiming at the difficulties in controlling the surface finishing of thin-walled compressor blade of aero-engine,the abrasion of the blade surface by atmospheric particles in the process of use and the corrosion of the blade surface by atmospheric environment,this paper polishes the surface of Ti6Al4 V workpiece with high roughness after milling by using nanosecond pulsed laser under argon and air atmosphere respectively.The results of the study are as follows:(1)The optimal parameters of laser polishing were obtained by orthogonal test method under argon atmosphere,which resulted in the minimum surface roughness of Sa=2.94μm after polishing,with a reduction of surface roughness of 56.12%;while the roughness of the surface after polishing in air atmosphere was reduced by 51.89%.And on this basis,the effects of four factors,namely,laser lap rate,laser pulse width,laser average power gas and gas atmosphere,on the roughness and morphology of laser polished Ti6Al4 V workpiece surface were analyzed by single-factor test,respectively.(2)After the metallographic and EDS elemental analysis of the surface XRD and cross-section of Ti6Al4 V workpiece,it was found that α’-Ti martensite was obtained on the polished surface under argon atmosphere,which increased its surface hardness by21.94%,while titanium nitride was obtained under air atmosphere,which increased its surface hardness by 176.79%.(3)The wear resistance of the polished Ti6Al4 V workpiece surface under argon and air atmosphere was investigated,and the friction wear test results showed that both the original workpiece surface and the workpiece surface polished under argon atmosphere were dominated by abrasive wear,in which the workpiece polished under argon atmosphere had a narrower width of abrasion marks due to the higher hardnessα’-Ti martensite obtained during the polishing process,while the workpiece polished under air atmosphere had a narrower width of abrasion marks due to the remelting ofα’-Ti martensite.In the air atmosphere,the high hardness titanium nitride obtained from the remelted layer reduced the average dynamic friction coefficient of the workpiece surface from 0.46 to 0.16,which significantly improved the wear resistance of the workpiece surface and significantly reduced the width of the abrasion marks,and the workpiece surface mainly showed adhesive wear in the process of grinding with GCr15 ceramic balls.(4)Electrochemical tests were conducted on the surface of Ti6Al4 V workpiece after polishing under argon and air atmosphere.The obtained impedance patterns and Tafel curves showed that the α’-Ti martensite and titanium nitride obtained from the laser polished surface could improve the corrosion resistance of the Ti6Al4 V workpiece surface.In argon atmosphere,the increase of laser polishing average power will make the workpiece corrosion potential shift positively and the corrosion current density decrease;while in air atmosphere,the increase of laser average power will also make the workpiece corrosion current density decrease,but due to the appearance of cracks on the surface during the polishing process,its corrosion potential shifts negatively,and the corrosion resistance of the workpiece surface is lower than the initial workpiece when the cracks are too large. |
