关键词: 激光熔丝增材;残余应力;顺序热结构耦合;超声微锻造;工艺参数

Abstract: In the laser fuse additive manufacturing process， the residual stress of the cladding layer is disadvantageous to the surface strength because of the rapid heating and cooling of the material， and the additive manufacturing-micro-forging processing technology can improve the processing quality of laser fuse additives， mechanical properties and microstructures. TC4 is taken as the research object， and the material surface is improved and strengthened by high frequency impact and rolling on the surface of the cladding layer through the feeding movement of the ultrasonic micro-forging tool head and molten pool at a certain relative distance. A model is established to conduct the numerical simulation study on the sequential thermal structure coupling of the additive and micro-forging process， and analyze the variation of the stress field of the cladding layer during the processing. The results show that the residual tensile stress of the cladding layer due to heat source loading is transformed into beneficial residual compressive stress by ultrasonic micro-forging on the surface of the uncooled cladding layer， and the probability of surface defects is reduced. The parameters of ultrasonic amplitude， feed rate and forging temperature have great influence on the residual compressive stress and normal deformation.

Key words: laser fuse additive manufacturing; residual stress; sequential thermal structure coupling; ultrasonic micro-forging; technical parameter