Contact Fatigue Properties Of Textured Tpray Coating

With the rapid development of China’s railway network and the continuous increase in the mileage and speed of train operations,the service life of train wheels and rails will face enormous challenges.When accidents occur due to wheel-rail damage,it will cause great distress to people’s lives and property.Therefore,it is imperative to solve the problem of wheel-rail damage.Rolling contact between the track and the wheel is prone to cracks and other defects.When the cracks expand to the surface and form a fracture,it will lead to serious derailment accidents and affect people’s lives and property safety.Therefore,how to improve the rolling contact fatigue life of the track i s the key to sol ving the problem.This paper first analyzes the causes of the contact fatigue failure of the track.Then the development of contact fatigue failure theory is summarized.Finally,the necessity of,improving the contact fatigue performance of rails is proposed.In this experiment,a method of texturing the sprayed layer was used to find ways to improve the contact fatigue life of the workpiece.This article introduced the optical,physica,chemical texture processing technology and compared the advantages and disadvantages of each processing technology.Finally,a convenient and fast laser surface processing technique was selected for the test.The laser surface texture technology was used to process the sprayed layer samples.The three-dimensional morphology and microstructure of the sample were characterized and the surface integrity of the material was measured.The results show that the surface texture can significantly increase the hardness of the c.oating around the surface pit;the hardness value between adjacent two pits presents a "W" type distribution;the hardness of the lower section of the pit shows a phase change.The roughness of the textured surface is greatly affected by the density,and the higher the density,the greater the roughness.The observation,of surface morphology under different fatigue tests found that the fatigue damage of the textured surface is a cumulative process:it gradually develops from pitting and spalling failure to layer failure.In this paper,the influence of the texture parameters on the contact fatigue performance of the workpiece surface is studied.It is found that the surface texturing can significantly improve the contact fatigue performance of the sprayed layer surface.With the increase of diameter and decreases.The lubricating effect of lubricating oil increases first and then decreases.In this paper,the influence of load conditions on the contact fatigue performance of the workpiece surface is studied.It is found that as the speed and load increase,the fatigue life is gradually reduced;when the surface is subjected to fatigue failure at different speeds and loads,there will be three typical fatigue failure phenomenon;The vibration amplitude gradually increases with the increase of the rotation speed and the load,and it is easy to reach a preset threshold value,and the shutdown is realized,and the vibration signal is shortened.