Effect of Laser Bulk Energy Density on Densification Behavior of TC4 Titanium Alloy by SLM

The TC4 titanium alloy was prepared by selective laser melted (SLM) technique, and the effect of laser bulk energy density on surface quality and densification behavior of the alloy was studied. The results show that when the laser bulk energy density increased from 33 J·mm^-3 to 80 J·mm^-3), the surface roughness of the alloy decreased, indicating the surface quality was improved; the surface balling effect was improved significantly. With the increase of the laser bulk energy density, the amount of voids inside the alloy decreased and the relative density increased from 90.5% to 99.3%; but excessive flow of the melt at an over high laser bulk energy density affected the dimensional accuracy and properties of the formed parts. The optimum parameter for preparing the alloy was the laser bulk energy density of laser 66 J·mm^-3, namely the laser effect of 250 W and scanning velocity of 500 mm·s^-1, and the alloy had good surface quality and densification.