Microstructures and mechanical properties of Ti6Al4V alloy fabricated by multi-laser beam selective laser melting

A self-developed four-laser beam selective laser melting (SLM) system was used to fabricate Ti6Al4V alloy samples in this study. The relative density, micro-hardness and mechanical properties of all isolated processing areas were compared under optimized processing parameters to ensure the consistency of this system. The samples built across overlap area show obvious raised platform due to the repeated laser scanning when relative hatch angle (θr) is 0°. This phenomenon can be greatly improved by adjusting θr to 90°. Microstructures and mechanical properties are not affected by the method of overlap conditions (θr and overlap width). Microstructures in overlap areas are dominated by columnar grains along the building direction and martensitic needles α′ inclined at about ±45° to the building direction, which are similar with those in isolated areas. Mechanical properties in overlap areas are also not inferior to those in isolated areas. The results prove the feasibility to fabricate large-scale components with a uniform microstructure and mechanical property by this SLM system.