Selective laser melting of tungsten: Effects of hatch distance and point distance on pore formation

An experimental study was conducted on the effects of point distance and hatch distance on pore formation in selective laser melting of tungsten. The Archimedes’ method was used to measure the apparent and closed porosities. Apparent (open) porosity and closed porosity were found to follow different trends: the apparent porosity increased but the closed porosity decreased as hatch distance or point distance increased. The open pores are attributed to the lack of fusion at the large hatch distance or point distance while the closed pores are attributed to the possible spattering and keyhole formation at the smaller hatch distance or point distance. The results led to understanding the effects of hatch distance and point distance on the formation of open and closed pores and provided insight on the optimization of process parameters to further increase the relative bulk density.