为了获得表面平整的薄壁零件，针对DZ125L高温合金材料，采用不同工艺参数组合进行了激光金属直接成形(LMDF)单道熔覆实验，系统研究了不同工艺参数(如激光功率、扫描速度、送粉率、Z轴提升量等)对单道熔覆层高度、宽度、宽高比和成形质量的影响规律，并优化了工艺参数。提出了一种三维表征单道熔覆层能量密度的新方法，推导出了相应的计算公式,从宽高比、稀释率和能量密度3个方面阐述了获得良好熔覆层和其成形工艺参数之间的相互匹配关系，为进一步根据设计的熔覆层尺寸来确定工艺参数提供了依据。实验结果表明,采用优化后的工艺参数成形出的薄壁零件质量明显提高，表面平整，无宏观缺陷。

In order to obtain smooth surface of thin-walled parts, single-trace cladding experiments are carried out for DZ125L superalloy by laser metal direct forming (LMDF) technology using different combinations of process parameters. Influence of the process parameters (such as laser power, scanning velocity, powder mass flow rate and Z-increment ) on height, width, aspect ratio and forming quality of single-trace cladding layer is studied systematically, by which the process parameters are optimized. In order to characterize geometrical features of single-trace cladding layer, a new method of three-dimensional (3D) characterization of energy density is proposed and the corresponding formulas are derived. From aspect ratio, dilution rate and energy density, the matching relationship between good cladding layer and its process parameters is clarified, which provides the foundations for further research into determining the process parameters according to design of cladding layer size. Experimental results show that the forming quality of thin-walled parts is obviously improved with smooth surface and no macro-defect by optimizing the process parameters.