Effect of atomization pressure on the breakup of TA15 titanium alloy powder prepared by EIGA method for laser 3D printing

Abstract

TA15 titanium alloy powder was prepared by Electrode Induction Melting Gas Atomization (EIGA) method at different gas pressure. The breakup behavior of molten droplet in the primary and secondary breakup process was analyzed. Also, the properties of TA15 fine powder prepared at optimized gas pressure were tested. Results shown that gas pressure played a positive role on the transformation between large size oval metal flake and regular molten stick in primary breakup process. After then, the molten stick followed three kinds of breakup modes and turned to disparate shape powders in secondary breakup process, which were normal necking down breakup mode, interfere breakup mode and impact breakup mode. At 6MPa pressure, simulation shown that the back-flow area had the largest volume and the average velocity on the flow field axis reached to 260 m/s. The preparation rate of fine TA15 powder was 82% and had the narrow particle size distribution. The phase of fine powder prepared at 6MPa was all the α-Ti phase. Flow ability and apparent density were 22.1s/50 g and 2.82 g/cm3 respectively, which was conformed to the ASTM test standard and was in line with the requirement for Laser 3D printing.