Laser direct deposition (LDD) is widely used to repair and manufacture high-value industrial components. However, it faces various defects, such as porosity, cracks, non-uniform microstructure, lack of fusion, keyhole phenomenon, element segregation, and undesirable secondary phases. A method to manage these defects is to concurrently apply ultrasonic vibrations (USV) during the LDD process. This study investigates the effect of USV on the mass efficiency and microstructure of LDD Inconel 718 superalloy to understand how incorporating USV can change the performance and structural integrity of single passes produced using the LDD process. For this purpose, USV is applied to a substrate during the LDD process. The resulting samples are characterized and analyzed using optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results indicate that applying USV below a threshold power value increases mass deposition by over 25%, while exceeding this threshold reduces it. Attention to this threshold power value is crucial for determining the process parameters, including laser power and speed. Additionally, USV transforms the microstructure from columnar to equiaxed and increases subgrain formation. This implementation also enhances the cooling rate, significantly decreasing the Laves phase by over 30% in all process parameters.

中文翻译：

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超声振动对激光直接沉积 Inconel 718 高温合金质量效率和微观组织的影响


激光直接沉积 （LDD） 广泛用于修复和制造高价值的工业部件。然而，它面临着各种缺陷，如孔隙率、裂纹、不均匀的微观结构、缺乏熔合、锁孔现象、元素偏析和不需要的二次相。管理这些缺陷的一种方法是在 LDD 过程中同时应用超声波振动 （USV）。本研究调查了 USV 对 LDD Inconel 718 高温合金的质量效率和微观结构的影响，以了解加入 USV 如何改变使用 LDD 工艺生产的单道次的性能和结构完整性。为此，在 LDD 过程中将 USV 应用于基材。使用光学显微镜、扫描电子显微镜和能量色散 X 射线光谱对所得样品进行表征和分析。结果表明，将 USV 应用于低于阈值功率值会增加 25% 以上的质量沉积，而超过此阈值会减少质量沉积。注意此阈值功率值对于确定工艺参数（包括激光功率和速度）至关重要。此外，USV 将微观结构从柱状转变为等轴状，并增加了亚晶粒的形成。这种实施还提高了冷却速率，在所有工艺参数中将 Laves 相显著降低了 30% 以上。