An Overview of Densification, Microstructure and Mechanical Property of Additively Manufactured Ti-6Al-4V — Comparison among Selective Laser Melting, Electron Beam Melting, Laser Metal Deposition and Selective Laser Sintering, and with Conventional Powder Metallurgy

This chapter begins with an introduction of the fundamental properties of Ti-6Al-4V, and its densification mechanism, typical microstructure and mechanical property achievable by conventional PM routes. This functions as a point of reference for the following discussion of the AM Ti-6Al-4V in terms of densification, microstructure, and mechanical property. The mostly popular laser-based AM techniques, namely selective laser melting (SLM), electron beam melting (EBM), laser metal deposition (LMD) and selective laser sintering (SLS), for the fabrication of Ti-6Al-4V have been overviewed based on an analysis of over 100 individual studies. Heat treatment is essential to most of the AM Ti-6Al-4V. Principles for selecting appropriate heat treatment for the AM Ti-6Al-4V are proposed based on martensite phase transformation and optimisation of mechanical properties. Oxygen impurity is an issue to most Ti materials and it is addressed in this chapter as well; counter measurements to mitigate oxygen have been suggested which involves the use of rare earth based materials.