Study on Selective Laser Melting Forming of Tungsten Powder Prepared by Radio Frequency Plasma Spheroidization

Using irregular tungsten powder as the raw material, spherical tungsten powder was prepared by radio frequency (RF) plasma spheroidization technique. The pure tungsten parts fabricated by selective laser melting was studied. The effects of process parameters (including laser power and scanning speed) on the densification, microstructure, microhardness and compressive properties of the pure tungsten samples were studied. The results show that after spheroidization, the tungsten powder has regular shape and its spheroidization rate reaches more than 98%. Besides, the tap density and loose density of the tungsten powder increase and its flowability is also improved. Meanwhile, the spheroidized tungsten powder is well-adapted to selective laser melting, and the density of printed samples is between 84.15% to 95.65%. The study also finds that with the increase of laser power, the density, microhardness and compressive strength of printed samples increase first and then decrease, while the cracks and holes decrease. Furthermore, with the increase of the scanning speed, the density and hardness of the printed samples reduce while the amount of cracks increase. Therefore, it is of great significance for the selective laser melting of tungsten powder to explore the appropriate printing parameters.