Microstructural Changes, Tensile, and Hardness Behaviour of Welded Ti-6Al-4V Plates

Abstract

In this work, Ti-6Al-4V alloy was joined by tungsten inert gas (TIG) welding and the plates were undergone through optical microscopy test, elemental study, tensile test, hardness test, and fractographic observation. Plate-A, with low value of current input, possesses α + β bimodal structure at BM, acicular martensite at HAZ, and Widmanstätten structure with a low amount of martensite at the WZ. Plate-B, with comparatively higher value of current during welding, possesses similar structure at the BM. The HAZ area was comparatively lesser with significant martensite formation, and the WZ contains considerable formation of Widmanstätten structure. The elemental composition of BM and WZ was established by EDS. The stress-strain curves for both plates show that plate-B has almost 3%, 8%, and 7% greater UTS, YS, and elongation, respectively, than plate-A. The significant formation of Widmanstätten structure has made the WZ of plate-B more ductile and tough, although the fractography analysis of both the plates has shown macrodimples and flowing sign of metal as indicators of good ductility.