As-fabricated surface morphologies of Ti-6Al-4V samples fabricated by different laser processing parameters in selective laser melting

Abstract

The surface morphology of a product plays a crucial role under mechanical loading and chemical environment. Surfaces of Selective Laser Melting (SLM) products often contain high roughness, which varies in different planes as well. The authors have explored the surface characteristics of the SLM samples that are influenced by different combinations of laser processing parameters. The considered processing parameters were Energy Density (ED) and its technological parameters namely laser power, scanning speed and hatch spacing. Additionally, a comparison study has been executed by rescanning effects considering melting with low ED and, thereafter, rescanning by the best possible laser processing parameters. The results evidently showed that the surface morphologies differ significantly due to different laser processing parameters. Eventually, the thermal and physical behavior of materials, such as the viscosity of the melt pool, thermal and physical stability of the melt pool, solidification time, cooling time, shrinkage, capillary effect, surface tension, balling effect, and the amount of melting of a powder particle, influenced the surface properties of the samples, along with unpredictability. The results showed an interesting correlation between the processing parameters and the occurrence of microcracks on the vertical walls of the specimens caused by the partially melted adhered powder particles.