关键词: 超声波喷丸, 表面完整性, 残余应力, 显微硬度

Abstract:

USP forming on AA2024-T351 sheet was studied. Improvement of the surface integrity of treated AA2024-T351 and the relations among several parameters (micro hardness, residual stress distribution, surface topography, surface roughness and full width half maximum(FWHM)) and different USP process parameters were analyzed. The research shows that micro hardness of treated material is improved obviously(about 20%) with influenced area of 300μm depth down. Residual compressive stress is introduced, which is higher and gradient distribution, depth of residual compressive stress field is about 500~650μm, and the maximum point is located at the 200μm layer below the surface. There are many furrows on the surface of workpices at the sametime, the roughness of surface increases slightly, the half-width of X-ray diffraction of sample is increased, the 125μm layer below the surface, which shows the cold work hardening is occurred and crystal dislocation density is considerably increased. The experiments show that the improvement of micro hardness and induced residual compressive stress by ultrasonic shot peening forming make great positive influence on
the fatigue life, wear resistance and corrosion resistance of AA2024-T351.

Key words: ultrasonic shot peening(USP), surface integrity, residual stress, micro hardness