为了改善成型件表面质量，从微观上研究了决定选区激光熔化成型金属零件的上表面粗糙度的主要因素，通过研究单熔道成型，从熔道搭接的角度理论分析了成型件的上表面粗糙度，基于自主研发的成型设备Dimetal-280加工实体零件进行了实际测量对比，获得表面粗糙度的轮廓算术平均偏差Ra的理论值为3.21μm，微观不平度十点高度Rz的理论值为12.79μm，其实测值Ra=7.36μm，Rz=40.01μm；进行喷砂和电解抛光处理后，表面粗糙度减小，即Ra=2.34μm，Rz=10.86。结果表明，成型件的上表面粗糙度主要受熔道宽度、扫描间距和铺粉层厚3个因素的共同影响；粗糙度实测值与理论值有偏差，主要是由于熔道不稳定、表面出现球化、粉末粘附等缺陷造成；成型件经过电化学处理后表面质量有较大的改善。选区激光熔化成型金属零件可达到良好的表面粗糙度，此项研究为进一步提高表面质量和应用于生产加工提供了参考依据。

In order to provide the theory basis to improve the surface quality, the main factors affecting the upper surface roughness of metal parts fabricated by selective laser melting(SLM)were studied. By studying the single track melting, the upper surface roughness of SLM parts was analyzed from the view of melting track lapping. The metal parts were fabricated by using the self-developed fabrication equipment Dimetal-280 and the measure roughness parameters were compared with the theoretical value. The theoretical value of arithmetical mean deviation of the profile Ra was 3.21μm and the theoretical value of ten-point height of irregulartlies Rz was 12.79μm. The actual value was Ra=7.36μm and Rz=40.01μm. After electrochemical polishing, the surface roughness was reduced to Ra=2.34μm and Rz=10.86μm. The results prove that upper surface roughness of the metal part was influenced by melting track width, scanning space and layer thickness altogether. The reason of the discrepancy between theoretical value and actual value was some defects such as instability in melting track, spheroidization on the surface and dust adhesiveness. The quality of surface roughness was greatly improved after electrochemical polishing. The metal parts processed by selective laser melting could obtain satisfied surface roughness in this experiment. The results provide guidance to surface research and industrial application in the future.