Study On Surface Integrity In Ultrasonic Assisted Grinding Of GH4169 Superalloy

GH4169 superalloy is an important aviation material with excellent corrosion resistance,oxidation resistance and good fatigue resistance.However,GH4169 superalloy has large plastic deformation coefficient,high strength,low thermal conductivity,high chemical activity,and large work hardening,which make it difficult to ensure the surface quality,use performance and processing efficiency of parts during processing.Grinding is a commonly used processing method for aerospace materials,but the grinding of GH4169 superalloy has a large grinding force,high grinding temperature.And grinding wheel is easy to wear.Therefore,further research on ultrasonic assisted grinding of GH4169 superalloy was carried out to solve the above problems.Ultrasonic assisted grinding is an efficient machining method for aerospace materials.In the grinding process,ultrasonic vibration with a certain amplitude is applied to the grinding wheel or workpiece.Now ultrasonic assisted grinding is more and more widely used.Surface integrity affects the performance of the parts,and has a certain impact on the fatigue resistance,stress resistance and corrosion resistance of the material.It is an important evaluation index for material processing.Therefore,it is necessary to study and control the surface integrity index in ultrasonic assisted grinding of GH4169 superalloy to achieve the goal of improving the performance and fatigue life of the parts.This paper takes GH4169 superalloy as the research object,carries out ultrasonic assisted grinding and conventional grinding GH4169 superalloy machining experiments,and studies the generation mechanism and influence law of GH4169 superalloy grinding surface layer microstructure,work hardening and dislocation density,and residual stress.The main research content includes:(1)Study the microstructure after GH4169 superalloy ultrasonic assisted grinding.The microstructure of the grinding surface layer was detected by Optical Microscope(OM),Scanning Electron Microscope(SEM),Transmission Electron Microscope(TEM),Electron Backscatter Diffraction(EBSD)methods,and the formation mechanisms of the microstructure of the grinding surface layer were analyzed.The effects of ultrasonic vibration and grinding parameters on the microstructure were explored.(2)The work hardening and dislocation density of the grinding surface layer after ultrasonic assisted machining GH4169 superalloy were studied.The effects of ultrasonic vibration and grinding parameters on work hardening were discussed and analyzed.The dislocation density was calculated by EBSD and XRD methods,respectively,and the experimental value of dislocation density was verified,and the influence mechanism of work hardening was obtained.(3)Study the surface residual stress after GH4169 superalloy ultrasonic assisted grinding.The surface residual stress after grinding were measured by XRD method,and the influence law and influence mechanism of ultrasonic vibration and grinding parameters on the residual stress were explored.