目的 为了解决选区激光熔化增材再制造时出现的首层铺粉粉层厚度不均的问题，研究首层粉层厚度为400 μm时选区激光熔化成形工艺。方法 采用倾斜基板预置楔形粉层，在粉层上进行不同激光功率的激光扫描实验，研究楔形粉层对沉积的影响规律。然后在水平放置的基板上分别预置50、100、200、300、400 μm厚度粉层，在粉层上进行激光扫描实验，研究粉层厚度对沉积的影响规律。最后做首层400 μm层厚，后续5层每层50 μm的多层沉积实验，研究厚粉层对后续SLM成形的影响规律。结果 在倾斜上表面采用选区激光熔化技术进行修复，铺粉厚度的增加会导致沉积层致密度变差且表面起伏增大。通过提高激光能量密度的方式，采用300 W、800 mm/s的工艺参数在400 μm大层厚下激光扫描，可改善沉积层与基板的结合情况并减小沉积层上表面的起伏轮廓，同时该参数也能在小层厚时得到致密的沉积层。在首层400 μm层厚的基础上进行SLM成形时，需用首层沉积的工艺沉积5层作为过渡区，后续可按正常的SLM成形工艺进行沉积。结论 用SLM技术进行零件修复时，虽然首层会出现厚度不均的楔形粉层。当粉层最厚区域不超过400 μm时，需提高激光功率密度进行沉积。在高功率密度参数下沉积5层后可以采用正常SLM工艺进行后续成形。

The work aims to study a selective laser melting forming process when the thickness of the first powder layer is 400 μm to solve the uneven thickness of the first powder layer during selective laser melting in additive remanufacturing. The wedge-shaped powder layer was preset on the inclined substrate, and laser scanning experiments with different laser powers were performed on the powder layer to study the effect of the wedge-shaped powder layer on the deposition. Then, powder layers of 50, 100, 200, 300, and 400 μm were preset on the horizontally placed substrates. Laser scanning experiments were performed on the powder layer to study the effects of the thickness of the powder layer on the deposition. Finally, a multi-layer deposition experiment with the first layer of 400 μm thick and the subsequent 5 layers of 50 μm each was done to study the effect of the thick powder layer on the subsequent SLM forming. Selective laser melting technology was used to repair the inclined upper surface. The increase in the thickness of the powder would cause the density of the deposited layer to become worse and the surface fluctuations increase. By increasing the laser energy density, using 300 W, 800 mm/s process parameters and laser scanning at a large layer thickness of 400 μm, the combination of the deposited layer and the substrate can be improved and the undulating contour of the upper surface of the deposited layer can be reduced. This parameter can also get a dense deposition layer when the layer thickness was small. When performing SLM scanning on the basis of the first layer with a thickness of 400 μm, the first layer deposition process should be used to deposit 5 layers as a transition zone, and the subsequent deposition can be carried out according to the normal SLM forming process. When repairing parts with SLM technology, a wedge-shaped powder layer with uneven thickness will appear on the first layer. When the thickest area of the powder layer does not exceed 400 μm, the laser power density needs to be increased for deposition. After 5 layers are deposited under high power density parameters, the normal SLM process can be used for subsequent forming.