Effect of input energy on hardness and surface quality in Ti64 by sputter-less selective laser melting with modulated pulse

A titanium alloy (Ti64) has α + β crystal orientations, and the β phase mainly appears in the SLM process since Ti64 melts above 1600 °C by laser irradiation and then solidifies. In order to control the crystal orientation and crystal grain size, the modulated pulse of laser was employed to control the heat input energy of laser in the SLM process in this study. After fabrication, the sample was cut to measure the Vickers hardness which was compared with that of the commercial Ti and Ti64; the continuous wave (CW) laser fabricated sample had a value close to that of pure Ti, and the fabricated sample using modulated pulse of laser had a value close to Ti64. It was considered that a phase was formed by using a CW laser and the α + β phase was formed by using modulated pulse of laser, suggesting the possibility of controlling the material structure by controlling the heat input of one layer which was formed by these processes.