Effects of Laser Power and Laser Scanning Speed on Microstructure and Property of TC4 Titanium Alloy Formed by Selective Laser Melting

TC4 titanium alloy samples were formed by selective laser melting, and the influence of laser power (50-300 W) and laser scanning speed (250-1 750 mm·s^-1) on the microstructure and properties of the samples was studied. The results show that with the decrease of the scanning speed or the increase of the laser power, the forming quality of the samples was improved, the surface roughness was reduced, and the hardness on longitudinal section increased. The needle-like α' phase and nano-β phase were found in the microstructure of the samples. The size of the α' phase was relatively small, and the content of the β phase was relatively low at the relatively high scanning speed. Changing the scanning speed or the laser power had little effect on the tensile strength of the samples, but the elongation after fracture was relatively high at relatively low laser power or relatively high scanning speeds. When the laser power was 200 W and the scanning speed was 1 150 mm·s^-1, the samples had relatively good strength and plasticity matching.