This study characterizes the microstructure changes of Inconel 718 (IN718) by laser cladding (LC). Well-bonded pore-free, crack-free, single-layer, and multi-layer (overlapped) LC was done on IN718 with the same powder. The basic microstructure illustrates the presence of $\gamma$, $\delta$, and ${\gamma }^{\prime \prime }$ -phases. The precipitation of an irregularly shaped laves phase was observed with dendritic grains in the top and bottom regions of the single-track LC. Further, the epitaxial grain growth of columnar dendrites was observed in the interdendritic region along the laves phase. High leveraging of quick-dissolving behaviors of the laves phase in multi-track LC enhances the high-temperature mechanical performance. Modified grain morphology of the multi-track LC in terms of size, shape, and orientation is reported. Columnar dendrites (short and long) are the most common grains, with varied sizes and orientations reported in line with the Marangoni effect. The microhardness at the top layer of single and multi-track exhibited a higher value of 490.6$$HV and 500.7$$HV, respectively, which is comparatively lower than the bottom layer of single and multi-track samples. The influencing process parameter over clad width is scan speed, and over clad height is powder feed. The nonlinear mathematical model is proposed with a reliability of 99.22% and 99.52% for clad width and height, respectively.

本研究通过激光熔覆 (LC) 表征了 Inconel 718 (IN718) 的微观结构变化。使用相同的粉末在 IN718 上完成了粘合良好的无孔、无裂纹、单层和多层（重叠）LC。基本微观结构说明了存在$\gamma$,$\delta$， 和${\gamma }^{\prime \prime }$-阶段。在单轨液晶的顶部和底部区域观察到不规则形状的莱夫相的沉淀和树枝状晶粒。此外，在枝晶间区域沿着Laves相观察到柱状枝晶的外延晶粒生长。在多道液相色谱中充分利用拉夫相的快速溶解行为可增强高温机械性能。报告了多轨液晶在尺寸、形状和方向方面的改进晶粒形态。柱状枝晶（短和长）是最常见的晶粒，具有不同的尺寸和方向，与马兰戈尼效应一致。单道和多道顶层的显微硬度表现出较高的值，达到490.6$$高压和500.7$$HV 分别低于单轨和多轨样本的底层。影响包覆宽度的工艺参数是扫描速度，影响包覆高度的工艺参数是送粉量。提出的非线性数学模型对于包层宽度和高度的可靠性分别为99.22%和99.52%。