Microstructure and tensile properties of the fusion zone in Ti-6Al-4V weldments

Weldments in alpha-beta titanium alloys are characterized by low fusion-zone ductility that is usually attributed to large prior-beta grain size and an acicular martensitic microstructure. While the `standard' alloy Ti-6Al-4V exhibits a slightly better performance than other high-strength alloys, the tensile elongation even in Ti-6Al-4V welds is much poorer than in the base material. The current paper discusses the effect of weld energy input and post-weld heat treatment temperature on the structure and properties of Ti-6Al-4V welds. The tensile fracture behavior and mechanical properties are interpreted in terms of the microstructural features.