Parameter Optimization And Mechanism Exploration Of Shot Peening And Ion Implantation Of 8Cr4Mo4V Steel

8Cr4Mo4V steel is currently one of the main steels used for aero-engine bearings.The composite modification method of shot peening and ion implantation can improve the wear resistance,corrosion resistance and fatigue resistance of 8Cr4Mo4V steel,and increase the service life of the bearing.In this paper,shot peening and ion implantation are used to first explore the effects of shot peening parameters on the structure,hardness,and residual stress distribution of 8Cr4Mo4V steel,and optimize the ferrule shot peening process.For the composite modification process of shot peening and ion implantation,this article explores the effects of the composite modification parameters on the structure of the material,nano-hardness,residual stress distribution,N element content and distribution,wear resistance,and corrosion resistance,and analyzes the composite modification The mechanism of the deepening of the residual stress influencing layer due to the sexual process.Shot peening can produce work hardening effect on the surface of the material,improve the surface hardness,and form a deep residual compressive stress distribution on the surface.The higher the wind pressure is,the closer the distance is,the more the hardness of the surface layer is improved,up to 8.4%;The deeper the stress affected layer is,the deepest is 323?m;The higher the dislocation density is,the highest is2.578×10¹²cm^-2.When the wind pressure is as high as 0.55Mpa,the influence of distance and time on the distribution of stress layer decreases.When the shot peening distance is reduced to 30mm,the influence of wind pressure on the distribution of stress layer decreases.The dislocation density calculated by XRD shows that the higher the wind pressure of shot peening,the closer the distance of shot peening,and the higher the dislocation density of surface layer.The reduction of shot peening wind pressure and shot peening time can reduce the deformation of the ferrule,and also reduce the residual compressive stress value of the material near the surface.When the shot peening air pressure is 0.2MPa and the shot peening time is 4 minutes,the deformation of the ferrule is the smallest.In the research of the composite modification process,the shot peening wind pressure and shot peening distance will affect the surface layer N element content.This is because shot peening increases the dislocation density near the surface layer and provides a channel for N ion implantation.After the composite modification,the depth of the N element distribution is increased to about 850?m,which is 5 times the depth of the N distribution of the ion implanted sample.The compound modification greatly improves the hardness,wear resistance and corrosion resistance of the sample.The highest nano-hardness is 20.2GPa,which is nearly 87%higher than the original sample.The friction coefficient is reduced from 0.8 of the original sample to 0.4,and the width of the wear scar is reduced by 33.7%at most.The greater the shot peening wind pressure,the shorter the shot distance,the higher the ion implantation voltage,the longer the ion implantation time,and the better the corrosion resistance of the material.The corrosion current density of the composite treatment sample is as low as1.5993?A/cm².The original sample is reduced by 31.5%After ion implantation,the residual stress-affected layer is further improved,and the improvement of the stress-affected layer is independent of the type of implanted element and the implantation temperature.It is analyzed that the long-range effect of ion implantation affects the dislocation density near 300?m from the surface,which increases the depth of influence of the stress layer.The greater the dislocation density of the material itself,the weaker the influence of the long-range effect,and the increase of the ion implantation voltage can increase the influence of the long-range effect.