Investigation on the Microstructure of Direct Laser Additive Manufactured Ti6Al4V Alloy

Direct laser fabrication (DLF) is one of the advanced near-net shape processing technologies. The variations of laser parameters can change the energy distribution within a laser scan, and thus affect the cooling rate, and resulting microstructure of deposited material. In this study, the effect of the laser parameters on the microstructure of additive laser fabricated Ti6Al4V alloy was investigated. It was found that huge columnar grains formed during laser fabrication of Ti6Al4V alloy for a wide range of processing conditions, and the laser power, scanning speed and duration time were had a significant effect on the refinement of the prior grains. Gradient morphologies were obtained from a complex thermal history.

Keywords:
direct laser fabrication; Ti6Al4V alloy; columnar grain; equiaxed grain; additive manufacturing