目的 研究基体待沉积表面粗糙度的变化对激光沉积之后沉积层质量（宏观形貌、微观组织和力学性能）的影响，从而获得形貌、组织及性能优良的沉积层。方法 采用316L不锈钢粉末，在不同表面粗糙度状态下P20钢基体表面分别进行单道单层、薄壁、多道搭接及块体沉积实验，获得测试分析所需沉积层，基于OM、SEM以及拉伸试验对沉积层组织性能进行分析。结果 单道单层时，相对于铣削基体表面沉积层，喷砂基体表面沉积层的熔高、熔深增加幅度达到了100%，而熔宽增加较平缓；单道薄壁时，在前5层的沉积中，喷砂基体表面沉积高度增长达到2.5 mm，铣削表面沉积高度仅为前者一半，喷砂基体上沉积层内部孔隙率仅为铣削基体的31%；多道搭接时，随着粗糙度的增大，沉积层截面纵向尺寸H的内部增长范围持续变大，而横向尺寸L范围保持稳定。喷砂基体表面沉积层的σb为540.93 MPa，而铣削基体上的σb为523.12 MPa。结论 随着基体表面粗糙度的增加，沉积过程中陷光效应相应增强，单道单层沉积层的宏观形貌尺寸随之增大。对于薄壁沉积，基体粗糙度对薄壁高度的影响主要集中在前5层，粗糙度的增大使得沉积高度生长加快，内部孔隙率减小。多道搭接时，粗糙度越大，熔高熔深方向的尺寸变化越大，沉积层内部枝晶更加粗大，且不均匀。沉积层内部的抗拉强度随粗糙度的增大而提升。

The work aims to study the effect of the change of surface roughness of the substrate to be deposited on the quality of the deposited layer (macroscopic morphology, microstructure and mechanical properties) by laser, so as to obtain a deposition layer with excellent morphology, texture and properties. Single-channel single-layer, thin-wall, multi-pass and block deposition experiments were carried out on the surface of P20 steel substrate under different surface roughness with 316L stainless steel powder to obtain the deposition layer required for test analysis. OM, SEM and tensile test were used to analyze the microstructure of the deposition layer. Single-channel single-layer: compared with the deposition layer on the surface of the milled substrate, the deposition layer on the surface of the sandblasted substrate had a melting height and melting depth of 100%, while the melting width increased more slowly. Single-channel thin wall: in the deposition of the first five layers, the surface deposition height of the sandblasted substrate increased to 2.5 mm. The surface deposition height of the milling surface was only half of the former, and the internal porosity of the deposition layer on the sandblasted substrate was only 31% of the milling substrate. Multi-pass: the internal growth range of the longitudinal dimension H of the deposited section continued to become larger as the roughness increased, while the lateral dimension L range remained stable. Mechanical properties: σb on the surface of the sandblasted substrate was 540.93 MPa, and σb on the milled substrate was 523.12 MPa. With the increase of the surface roughness of the substrate, the trapping effect of the deposition process is correspondingly enhanced, and the macroscopic topography of the single-channel single-layer deposition layer is increased; For thin-walled deposition, the effect of substrate roughness on thin-wall height is mainly concentrated in the first 5 layers. The increase of roughness makes the deposition height increase and the internal porosity decrease. When multi-pass is used, the greater the roughness, the larger the dimensional change in the direction of the melt penetration. The dendrites inside the deposition layer are coarser and uneven. The tensile strength inside the deposition layer increases as the roughness increases.