Microstructure and mechanical properties of Ti-6Al-4V welds using α, near-α and α+β filler alloys

Effects of filler metal on the microstructure and mechanical properties of Ti-6Al-4V joints were investigated. Three specimens were prepared using α, near-α and α+β type filler materials and one specimen was welded without filler metal. The microstructural characterizations, hardness and tensile tests were applied to study the welded specimens. For the specimen welded without filler material, a coarse-grained structure of α+β was found in the microstructure of weld metal. Although this specimen showed lower hardness values compared to the base metal; the hardness of other weld metals was higher than that of the base material. The microstructure of other welds was a mixture of α, β and some amount of α´-martensite. Both acicular and basketweave morphologies of α´ were found in the weld metal. The α colonies were grown from the α lamellae which were formed at the β grain boundaries. The highest tensile strength was obtained for the specimen welded with the matching filler metal (about 91% of the base metal).