A hybrid fabrication method combining additive manufacturing (AM) and ultrasonic impact treatment (UIT) techniques was developed to improve the microstructure and mechanical properties of additive manufactured metal parts. Experimental and numerical methods were conducted to analyze the stress and strain fields of ultrasonic impact on additive manufactured parts. Laser metal deposition (LMD) technique was applied to prepare the 304 stainless steel (SS) samples and then the samples were post-treated by UIT. Considering high strain rate effect of metallic materials in the UIT process, the dynamic hardening properties of the as-deposited 304 SS sample were experimentally measured using a split Hopkinson pressure bar (SHPB) technique. The strain rate controlling factors and stress-strain relationship of the as-deposited sample in the SHPB tests were theoretically analyzed. The dynamic and high transient impact-rebound-impact process of UIT including the pin velocity, stress field and plastic strain field were investigated numerically via a three-dimensional finite element model. The impact stress field parameters such as the magnitudes and directions of principal stress and principal shear stress were investigated to further analyze the plastic deformation behavior of the deposited sample. The experimental results of plastic deformation zone obtained from optical microscopy, electron backscatter diffraction (EBSD) and microhardness testing are in good agreement with the numerical results. Both the experimental and numerical results confirm that UIT can effectively improve the performance of additive manufactured metal parts.

开发了一种将增材制造（AM）和超声冲击处理（UIT）技术相结合的混合制造方法，以改善增材制造的金属零件的微观结构和机械性能。进行了实验和数值方法，以分析超声冲击对增材制造零件的应力和应变场。应用激光金属沉积（LMD）技术制备304不锈钢（SS）样品，然后通过UIT对样品进行后处理。考虑到UIT工艺中金属材料的高应变速率效应，使用裂开式霍普金森压力棒（SHPB）技术通过实验测量了沉积的304 SS样品的动态硬化性能。从理论上分析了SHPB测试中沉积样品的应变速率控制因素和应力-应变关系。通过三维有限元模型，对UIT的动态和高瞬态冲击回弹冲击过程进行了数值研究，包括销速度，应力场和塑性应变场。研究了冲击应力场参数，例如主应力和主剪应力的大小和方向，以进一步分析沉积样品的塑性变形行为。由光学显微镜，电子背散射衍射（EBSD）和显微硬度测试获得的塑性变形区的实验结果与数值结果吻合良好。