A Review of Powder Bed Fusion for Additively Manufactured Ti-6wt.%Al-4wt.%V

Selective Laser Melting (SLM) a form Powder Bed Fusion (PBF), is a type of Additive Manufacturing (AM) process which has the ability to manufacture complex geometric parts that cannot be produced by traditional means. Ti6AL4V is an α + β titanium alloy and is commonly used within the medical and aerospace industries. It is one of the few technical metal alloys that can be processed by PBF. This contribution will review the issues related to microstructure formation, residual stress, and porosity formation that can arise within Ti6Al4V parts produced by the PBF process. In particular, the influence of the manufacturing process parameters and the presence of defects on the mechanical properties will be reviewed. High thermal gradients and rapid solidification of the molten powder can lead to the development of a martensitic microstructure and other specific defects within the as-built part. Defects have a negative impact upon mechanical properties. Porosity, balling, lack of fusion and delamination are common examples of process-specific defects. The requirement for secondary processing of the additively manufactured components to improve mechanical properties will be reviewed with a particular focus on the requirement for the Hot Isostatic Pressing (HIP) processing.