Influence of rescanning parameters on selective laser melting of Ti6Al4V

Rescanning is an effective modification technique in selective laser melting (SLM). However, the results about the effect of the rescanning have been indicated to be contrary from different researchers. In this study, the influence of the rescanning parameters on the surface roughness, relative density, residual stress and microhardness of SLMed Ti6Al4V were systematically investigated. The surface roughness decreases and the relative density improves only when the appropriate rescanning process parameters are adopted. When the sample is nearly full density, there is a negative correlation between the surface roughness and the relative density. According to the finite element model, the stress evolution experience three stages due to the thermal cycles during remelting processes, which makes the relationship between the residual stress and the rescanning parameters complicated. For the micro-hardness, it is positively correlated with the residual stress.