Study On The Properties Of Shot Peened Nickel-based Superalloy GH4169 And Parameter Optimization

The nickel-based superalloy GH4169,which has many advantages such as high strength,good hot workability,fatigue resistance and fracture toughness,is widely used in aerospace,aviation and other industrial fields.The industrial field has a high demand for the strength,hardness and fatigue resistance of the parts,and it is a very effective method to strengthen the parts by shot peening surface treatment.In this paper,the kinematic simulation and strengthening experiment of the nickel-based superalloy GH4169 were carried out by computer simulation technology and experimental method.In the first place,a representative volume element(RVE)model which can be related to the actual shot peening parameters was established,based on ABAQUS software and PYTHON script language.The residual stress profile simulated by the present model is in good agreement with the experimental data obtained from literature.Based on the RVE model,the influence of the typical process parameters on the shot peening effect was studied by selecting the radius of the projectile and the incident speed of the projectile as the independent variable.The results show that when the size of projectile increases,the depth of the residual compressive stress will also increase,but the surface roughness increases rapidly.Although high velocity produces a good residual stress distribution,it will also make excessive demands on the shot peening test equipment,which might cause unnecessary waste.Afterwards,the GH4169 specimens were subjected to shot peening under different parameters and residual stresses at different depths from the surface were measured.The surface roughness,surface morphology and surface microstructure were measured and analyzed by optical microscopy and electron microscopy.The experimental results show that when the shot peening strength is constant,the shot peening coverage has little effect on the surface residual stress and surface roughness of GH4169.With the increase of shot peening coverage,the deformation degree of the plastic deformation layer will increase.When the coverage keeps unchanged,the effect of shot-peening strength on the residual stress field and surface roughness is significant.The maximum residual compressive stress increases slightly with the increasing intensity,but the residual stress on the surface remains almost the same.Furthermore,the depth of the plastic deformation layer of the surface micro-structure remains almost unchanged.Finally,based on fast non-dominated sorting algorithm(NSGA-II)and the single shot peening finite element model,the optimal process of parameters are carried out,and the maximum residual compressive stress,residual compressive stress layer depth and maximum residual tensile stress were taken as optimization targets.