The Processability of Highly Spherical Gas-Atomized Ti-6Al-4V Alloy Powder in Laser Powder Bed Fusion

Abstract

The powder characteristics are one of the most important factors to affect the processability in additive manufacturing technology, especially in laser powder bed fusion. In this research, the influence of highly spherical gas-atomized Ti-6Al-4V alloy powder on the processability in laser powder bed fusion was investigated. The cubic specimens of highly spherical gas-atomized Ti-6Al-4V alloy powder were fabricated at various laser power and scan-speed using a laser powder bed fusion type machine with 1 kW fiber laser, and examined the density and surface roughness of the cubic specimens. As a result, the optimum fabrication condition was obtained using the process map evaluated by the density and surface roughness of the cubic specimen. The alloy fabricated at a laser power of 150 W and a scan speed of 700 mm/s showed the maximum relative density of 99.94% and the surface roughness, Sa, of about 5 µm. The tensile strength and elongation of the as-built alloy were more than 1300 MPa and 8%, respectively. It was thus found that the use of highly spherical gas-atomized powder greatly improves the density, surface roughness and tensile properties of the as-built alloy.