Abstract:

In view of the complex temperature changes in metal additive manufacturing that lead to residual stress in the parts and then form holes，cracks and other defects，TC4 titanium alloy parts with circular tracks were taken as the research object，and ultrasonic micro-forging technology was used to apply high-frequency micro-vibration on the surface of the workpiece，so as to achieve the effect of refining the grains and reducing the residual stress. By studying the thermal stress changes of different characteristic points of the single-layer laser-cladding layer，the thermal stress field results were obtained and imported into the ultrasonic rotaty micro-forging system， and then the effects of the diameter of the micro-forging head，the rotating speed of the tool head，the amplitude and the forging temperature on the residual stress of the cladding layer were studied. The results showed that laser fuse additive manufacturing has the characteristics of“fast cooling and fast heating”. In the forging system，different forging parameters have different effects on improving the performance of additive parts.

Key words: metal additive manufacturing, residual stress, ultrasonic rotary micro-forging, TC4 titanium alloy, thermal stress