Surface Characteristics and Roughness of Laser Powder Bed Fusion Processed Parts

Although the laser powder bed fusion (LPBF) technology has incomparable advantages over traditional manufacturing technology in manufacturing complex parts, the LPBF formed parts have a poor surface roughness. The poor surface roughness of LPBFed parts can be due to the surface defects such as balling, powder adhesion, connection of coarse particles and discontinuity of melting tracks. In view of the fact that each surface of the part is formed by overlapping continuous melting tracks, the shape of melting track is an important factor affecting the surface roughness. Therefore, to deeply understand the surface roughness of LPBFed parts, in this section the surface (divided into upper surface and side surface) roughness of LPBFed parts was theoretically studied from the microscopic forming angle of laser melting powder to form melting track and body, that is from one dimension to two dimensions and three dimensions. The evaluation parameters of surface roughness include the arithmetic mean deviation Ra of contour and the evaluation width Rsm of contour element. Since the surface is formed through the overlap of the melting track during the LPBF forming process, the surface will form an undulating surface shape. The surface quality of the LPBFed parts can be comprehensively reflected by using the arithmetic mean deviation Ra and the maximum contour height Rz. Thus Ra and Rz are selected as the evaluation parameters of the surface roughness in this study.