服役温度影响的 DD6 单晶高温合金磨削/喷丸加工表面完整性演化规律研究

DD6 single crystal super alloy is an important material for turbine blades of aero engines because of its excellent high temperature resistance and creep resistance. Shot peening is an important process for surface strengthening of super alloys, which can effectively remove machining tool marks, increase the surface tissue hardness and improve the fatigue properties of the material. To improve the surface integrity of DD6 after grinding and shot peening, an experimental study on the effect of temperature loading is carried out. The influence law of service temperature on the surface condition of DD6 grinding and shot peening is investigated. It is found that with the increase of temperature, the surface material remelting phenomenon, resulting in the reduction of surface morphology consistency, surface roughness increases, the surface microstructure recrystallization layer thickened. The surface morphology and microstructure changes are significantly affected by temperature, and are more obvious after shot peening. The surface morphology and microstructure at different temperatures are analyzed by SEM and EDS. It was determined that the factors affecting the surface morphology and roughness are mainly surface oxidation phenomenon and surface tissue recrystallization. Surface oxidation is found to cause loss of surface elements and recrystallization of the surface microstructure results in recrystallized grain boundaries, leading to modification of the surface material. Therefore, the influence of temperature on the surface integrity of the material should be considered during processing, and then the grinding and shot peening process parameters should be reasonably controlled to reduce microstructure damage. The research results provide a theoretical basis for the fatigue-resistant fabrication of nickel-based single-crystal super alloys.