Melting, fusion and solidification behaviors of Ti-6Al-4V alloy in selective laser melting at different scanning speeds

Abstract

Purpose Melting, fusion and solidification are the principal mechanisms used in selective laser melting to produce a product. Several thermal phenomena occur during the fabrication process, such as powder melting, melt pool formation, mixing of materials (fusion), rapid solidification, re-melting, high thermal gradient, reheating and cooling. These phenomena result in several types of pores, defects, irregular surfaces, bending and residual stress. This paper aims to focus on the physical behaviors of Ti-6Al-4V alloy at several scanning speeds and their effect on porosity and metallurgical properties. Design/methodology/approach Seven scanning speeds between 150  and 1000 mm/s were chosen to observe the occurrence of different pores, defects and microstructural formations and their effect on hardness and tensile properties. Findings The various mentioned malformations occur due to the results of possible uncertainties during the melting-fusion-solidification process. Size, shape, number, location and content of the pores varied in different samples. The a cicular a' size changes with different scanning speeds. Eventually, both porosity and microstructure have shown influential consequences on the hardness and tensile properties in the samples manufactured with different scanning speeds. Originality/value This study showed the adverse effects of different physical behaviors that occurred during the fabrication process, leading to the formation of complex pores. The causations and plausible solutions of the pore formation are interpreted in this paper. The authors observe that a circular a' size differed with scanning speeds, and these influence the mechanical properties.