Effect of process parameters on morphology, sectional characteristics and crack sensitivity of Ti-40Al-9V-0.5Y alloy single tracks produced by selective laser melting

Abstract

Selective laser melting (SLM) has been used to fabricate a Ti-40Al-9V-0.5Y alloy with high crack sensitivity, the effect of SLM process parameters on morphology, sectional characteristics and crack sensitivity of the as-deposited single tracks are investigated. It is found that the balling effect arises on single tracks with the increase of scanning velocity when other parameters are fixed, due to the significant Marangoni convection and liquid capillary instability. With the increase of scanning velocity, width, depth and aspect ratio of molten pools decrease while contact angle increases. With the increase of defocusing distance, width increases while depth and aspect ratio decrease. Layer thickness has little effect on the width, depth and aspect ratio as well as has a positive correlation with contact angle. The effect of process parameters on crack sensitivity of single tracks strongly depends on the laser volume energy density. Cracks can be suppressed by optimizing SLM process parameters to enhance laser volume energy density. Finally, the optimized process window of Ti-40Al-9V-0.5Y single tracks produced by SLM is determined, providing a valuable reference for the formation of bulk samples without cracks. Keywords: Selective laser melting, Titanium aluminide alloy, Process parameter, Crack sensitivity, Single track