Effect Of Temperature And Curvature Of Counter Pair On Tangential Fretting Wear Behavior Of 15-5PH Stainless Steel

In recent years,with the development of science and technology and the continuous improvement of economic and military strength,the research and manufacturing of various military products,large aircraft and precision instruments are also in full swing,and the application demand for high-strength stainless steel is also greatly improved.As one of the most widely used high-strength stainless steel in China,15-5PH stainless steel is widely used to produce aircraft parts,valve parts,gear,transmission shaft and other vital parts with its excellent hardness,toughness and corrosion resistance.During the operation of the device,fretting wear will occur between these"approximate fastening"parts,which will cause loosening of components,power loss,increase of noise,decrease of service life,and eventually lead to failure of parts,resulting in a lot of economic losses and even casualties.Therefore,the research on fretting wear of 15-5PH steel plays an important role in exploring the damage mechanism of materials and strengthening the protection of critical parts in the future.The tangential fretting wear test in this thesis is carried out on a self-developed full-mode fretting test machine,and the fretting wear tests of 15-5PH stainless steel were carried out by ball/plane contact method with Si C ceramic ball,GCr15 steel ball as ball samples and 15-5PH stainless steel as plane samples under different temperature and the curvature of counter pair.Combined with the white light interferometer,scanning electron microscope(SEM),energy dispersive spectrometer(EDS),electron probe microanalysis(EPMA)and other analytical equipment,the surface morphology and microchemical analysis of 15-5PH stainless steel were carried out,and the fretting damage mechanism was discussed.The conclusions are as follows:(1)Using Si C ceramic ball as counter pair,the fretting wear characteristics of the material at room temperature under different normal loads and displacement amplitudes were studied.The research shows that the transformation of fretting operation regime is greatly affected by displacement amplitude and normal load.According to the shape change rule of the F_t-D curve under different parameters,the fretting operation characteristics can be divided into three fretting regimes:partial slip regime,mixed regime and slip regime.The friction coefficient first increases and then decreases with the increase of displacement amplitude or normal load.Among them,the maximum friction coefficient appears in the mixed regime.In the partial slip regime,the surface damage of the material is slight,and the elastic deformation is mainly coordinated.In the mixed regime,the damage of the material surface is complex,and the wear mechanisms are mainly adhesive wear,abrasive wear and oxidation wear.In the slip regime,the material surface is seriously damaged,and the wear mechanisms are mainly abrasive wear,delamination and oxidation wear.In the same fretting regime,the wear volume of the material gradually increases with the increase of displacement amplitude or normal load.(2)Using Si C ceramic ball as counter pair,the fretting wear characteristics of the material at different temperatures were studied.The research shows that the temperature has little effect on the transformation of fretting regime of the material when the test temperature is from room temperature to 300?.When the slip regime is taken as the research object,the normal load is 40 N,and the displacement amplitude is 50?m,the friction coefficient increases with the increase of test temperature.At the same time,affected by the increase of temperature,the content of the O element on the surface of the grinding mark increases,and the oxidation degree increases.As the test temperature increases,the critical time for the test to reach the stable stage becomes shorter,and the wear volume of the material decreases gradually due to the protection of the third layer,and the material shows better wear resistance.(3)Using GCr15 steel balls with different diameters as counter pairs,the fretting wear characteristics of the material under different curvature of counter pair are studied.The research shows that the curvature of counter pair has little effect on the transformation of fretting regime of the material.When the slip regime is taken as the research object,the normal load is 40 N,and the displacement amplitude is 50?m,the friction coefficient decreases with the increase of the diameter and the decrease of the curvature of the counter pair.The distribution of O element content on the surface of the wear scar was observed.It was found that the content of the O element in the center of the wear scar and the accumulation of the wear debris was higher,and it showed a circular decrease along the edge of the wear area.With the increase of the diameter and the decrease of the curvature of the counter pair,the O element content in the center of the wear scar and the accumulation of the wear debris decrease gradually,and the O element content in the edge of the wear area increases gradually.Simultaneously,with the increase of the diameter and the decrease of the curvature of the counter pair,the wear volume of the material decreases gradually and the wear resistance of the material increases.