Study On The Shot Peening Process Of TA15 Titanium Alloy Profile

TA15 titanium alloy is widely used in aerospace bearing structural components due to its high specific strength,easy welding,good thermal stability and good creep resistance.With the rapid development of domesticaerospace industry,higher requirements have been imposed on the service performance of titanium alloy components.The enhancement of fatigue resistance is of vital importance.Shot peening is one of the most useful surface strengthening technology that effectively improves the surface integrity of materials.It can significantly increase the fatigue life of parts.However the strengthening effect varies depending on the material properties and process parameters.Therefore,it is necessary to conduct research on the shot peening process of TA15 titanium alloy in-depth.In this paper,a quasi-static tensile and dynamic compressive experiment of TA15 titanium alloy was carried out with the electronic universal testing machine and the Split Hopkinson Pressure Bar at room temperature.The true stress-strain curve of TA15 titanium alloy under different strain rate was analyzed.It was found that TA15 titanium alloy show significantly strain rate strengthening effect and plasticizing effect under high strain rate.Based on the Johnson-Cook constitutive equation,an adiabatic temperature rise was introduced,and the strain rate strengthening coefficient was modified to obtain a dynamic plastic constitutive model that can accurately describe the flow stress characteristics of TA15 titanium alloy under high strain rate.The modified Johnson-Cook constitutive model was used to define the material properties of the target.Single-shot and random multi-shot finite element model were established in the ABAQUS finite element software.Numerical analysis of shot peening of TA15 titanium alloy was performed.Studies have shown that when the shot diameter and shot peening velocity increase within a certain range,TA15 titanium alloy exhibits better residual stress distribution.When the shot diameter and shot peening velocity exceed 0.425 mm and 50m/s,the residual stress field approaches saturated,but the surface roughness continues to increase;when the shot peening angle range of 60～90 °,the residual stress distribution is better and the surface roughness does not increase greatly;when the shot peening coverage increases from 200% to 400%,the change of the residual stress was not obvious,but the roughness increased significantly.After calculating the shot peening intensity under different process parameters.It was found that when the shot peening intensity increases from 0.106 mmA to 0.218 mmA,the surface compressive residual stress increases first and then decreases,and there is a maximum at0.192 mmA.The depth of the compressive stress layer,the maximum compressive residual stress and the location have increased to varying degrees,and the surface roughness has also increased.The shot peening experiments of TA15 titanium alloy with different shot peening intensity and shot peening coverage were performed.The changes in the residual stress distribution and surface roughness with the shot peening intensity and shot peening coverage are consistent with the results of numerical analysis.When the shot peening intensity reaches 0.188 mmA and the shot peening coverage reaches 200%,the compressive residual stress and surface microhardness no longer increase significantly,while the surface roughness continues to deteriorate,and the surface integrity of the material becomes worse,which has a bad influence to fatigue resistance.When the shot peening intensity reaches about 0.19 mmA and the shot peening coverage is between100% and 200%,the surface compressive residual compressive stress,maximum compressive residual stress,and compressive stress layer depth of TA15 titanium alloy are about 650 MPa,740MPa,and150 um,respectively,the roughness Rz does not exceed 17.5um,which can obtain better strengthening effect.