Parametric study of surface morphology for selective laser melting on Ti6Al4V powder bed with numerical and experimental methods

Abstract

A three-dimensional (3D) selective laser melting (SLM) model comprising coupled heat transfer and flow behavior is proposed. The free surface of the melt pool is calculated by the volume-of-fluid (VOF) method, which is a means of acquiring the surface morphology. In this research, laser powers and laser scanning speeds were normalized to characterize the influence on the surface morphology. Results showed that when the scanning speed was increased, the surface morphology initially became flatter, but then roughness developed again at high speed case. Further, as the laser power was increased, the surface morphology gradually roughened. To better describe the surface-morphology phenomenon according to different laser parameters, the melt pool volume and melt pool lifetime were also investigated. With these two factors constrained, a fine surface could be obtained with a low melt pool volume and proper lifetime (approximately 100 to 130 μs). The surface morphology and the width of the melt track were experimentally acquired, and are in a good agreement with the results predicted by simulation.