Residual stress, porosity and surface roughness for laser powder bed fusion manufactured Ti6Al4V at high laser powers

Abstract

The use of high-powered lasers presents a unique opportunity to improve the LPBF productivity since a larger beam spot size and higher scanning speeds can be utilized to increase the process build rate. In this study, a custom-built LPBF system equipped with a 5kW fiber laser was used to investigate residual stresses, porosity, and top surface roughness using x-ray diffraction and computed micro-topography techniques. It was shown that it is possible to produce samples with low residual porosity and top surface roughness using high laser powers and build rates, and the effect of scanning speed and hatch spacing on residual stress, porosity, and surface roughness is presented and discussed. The results of this study have revealed the potential benefits of using high powered laser to increase the build rate, thus improving the LPBF productivity.