Laser powder bed fusion (LPBF) has been extensively investigated owing to its high geometry formation accuracy and excellent mechanical properties. However, the LPBFed Haynes 230 parts typically display poor tensile and wear properties due to internal porosity. In this work, the ultrasonic impact treatment (UIT) was applied as a post-treatment to the LPBFed Haynes 230 alloy, and porosity and microstructure modulation were performed to improve the strength properties and wear resistance. The pore closure and microstructure were studied by numerical simulations and experiments, and the mechanisms of increasing densification and strength were discussed. Results show that UIT can effectively close pores and reduce porosity, the internal porosity of the ultrasonic impacted layer for one, two, and three times decreases by 63.64%, 71.25%, and 81.97%, respectively. Pore closure is attributed to the residual compressive stress and shear stress introduced by UIT. Besides, the UIT weakened texture strength and refined grains, especially promoting the formation of fine grains. Meanwhile, it also promotes the formation of a high dislocation density and improves the phase structure distribution. Furthermore, the ultimate tensile and yield strengths of the optimal impact process increased by 9.63% and 34.56%, respectively. The improvement in strength was attributed to dislocation, grain boundary, and promoting densification strengthening. The average friction coefficient reduces by 4.90%–14.59% by refining the surface grains and increasing dislocation density. This work has verified the feasibility of improving the mechanical properties and pore closure of the LPBFed Haynes 230 alloy by UIT.

激光粉末床熔融（LPBF）由于其高几何形成精度和优异的机械性能而得到了广泛的研究。然而，由于内部孔隙率，LPBFed Haynes 230 零件通常表现出较差的拉伸和磨损性能。在这项工作中，超声波冲击处理（UIT）被用作LPBFed Haynes 230合金的后处理，并进行孔隙率和微观结构调节，以提高强度性能和耐磨性。通过数值模拟和实验研究了孔隙闭合和微观结构，并讨论了增加致密化和强度的机制。结果表明，UIT能有效封闭孔隙，降低孔隙率，超声冲击层1次、2次、3次内部孔隙率分别下降63.64%、71.25%、81.97%。孔隙闭合归因于 UIT 引入的残余压应力和剪应力。此外，UIT还削弱织构强度，细化晶粒，特别是促进细晶粒的形成。同时，也促进了高位错密度的形成，改善了相结构分布。此外，最佳冲击工艺的极限拉伸强度和屈服强度分别提高了9.63%和34.56%。强度的提高归因于位错、晶界和促进致密化强化。通过细化表面晶粒和增加位错密度，平均摩擦系数降低4.90%~14.59%。这项工作验证了UIT提高LPBFed Haynes 230合金力学性能和闭孔性能的可行性。