Microstructure and Mechanical Property Improvement of Laser Additive Manufacturing Ti–6Al–4V via the Niobium Addition

Abstract

Titanium alloys with high specific strength have widespread applications within the aerospace industry. However, the direct fabrication of titanium alloys with excellent performance is very difficult using traditional manufacturing techniques. In the present work, we adopted advanced laser additive manufacturing (LAM) technology to fabricate Ti–6Al–4V titanium alloy via the addition of Niobium (Nb), which result in the improvement of mechanical properties. The effects of Nb additions on microstructure, phase composition, and mechanical properties of Ti–6Al–4V alloys were investigated. Research results showed that the addition of Nb not only significantly refined the original β-Ti and the primary acicular α-Ti structure, but also increased the content of β-Ti to some extent, which contributed to improving both the strength and plasticity of the material. The tensile strength, yield strength, the elongation, and the section shrinkage of the Ti–6Al–4V+Nb increased by 15.2%, 6.9%, 2.6%, and 7.4%, respectively, compared with Ti–6Al–4V, which exceeded the required forging standard.

Fig. 3 LAM as-deposited state SEM image (a) Ti–6Al–4V as-deposited state, (b) Ti–6Al–4V+Nb as-deposited state, (c) rectangular frame position enlarged photo in Fig. 3(a), (d) rectangular frame position enlarged photo in Fig. 3(b).