Influence of the protective atmosphere on the structure and properties parts from titanium alloy Ti-6Al-4V produced by direct laser deposition

Abstract

This work is devoted to the microstructure, tensile deformation and microhardness behaviour of Ti-6Al-4V alloy fabricated using direct laser deposition additive manufacturing with using different oxygen concentration in protected chamber. The results show that the microstructure consists of coarse columnar prior-β grains and α-laths, with decreasing of oxygen concentration a β-phase amount is reduce. Ti-6Al-4V alloy has a basket-weave microstructure in the atmosphere with concentration of oxygen up to 0,25%, also it has higher concentration martensitic structure. Using local protection it is impossible to achieve the necessary mechanical characteristics. The required properties for Ti-6Al-4V are achieved with an oxygen content in the chamber in the range of [0,02-0.25]%, further reduction of the content is meaningless, since the mechanical properties vary slightly and higher 0,5 mechanical properties of samples is decreased.