Micro-and meso-structures of Ti–6Al–4V formed by SLM process and its formation mechanism

In order to regulate the multi-scale structure of Ti–6Al–4V formed by the SLM (selective laser melting) process, this study uses the method of combining numerical simulations with experiments to investigate the effects of SLM process parameters on the phase composition, micro- and meso-structures, and their distribution of Ti–6Al–4V. The study shows that the SLM-formed Ti–6Al–4V is mainly composed of α/α′ phases. Horizontally, the specimens at a 0° phase angle mainly show a striped pattern, while the specimens at 67° and 90° phase angles will show a tessellated pattern. Vertically, the specimens at 0°, 67°, and 90° phase angles exhibit columnar crystal structures, and these micro- and meso-structural differences are mainly caused by the size, orientation, and distribution of martensite. Furthermore, with the increase in energy density, the percentage of tessellated pattern area decreases while the martensite size increases. The complex thermal history under different process parameters is the main reason for the formation of different micro- and meso-structures. The results of this study provide a basis for SLM to regulate the process parameters.