EFFECT OF PRE-WELD AND POST-WELD HEAT-TREATMENTS ON THE MECHANICAL-PROPERTIES OF ELECTRON-BEAM WELDED TI-6AL-4V ALLOY

This paper represents a summary of experimental work carried out to fi nd the effect of various pre- and post-weld heat treatments on Ti-6Al- 4V alloy. In the as-welded state the samples exhibit about 80% of the tensile ductility and about 90-95% of the impact/fracture toughness of the base metal. Low temperature stress relieving or ageing carried ou t subsequent to the welding operation improves the tensile properties but decreases the toughness at the fusion zone. Solution treatment fol lowed by-welding and ageing or the post-weld solution treatment and ag eing treatment leads to only a marginal increase in tensile strength a t the expense of toughness at the fusion zone. High temperature anneal ing of the welded samples does not increase the tensile ductility but improves the toughness at both the fusion zone and the heat affected z one. The above facts and a special burst-pressure test conducted on a gas bottle in the as-EB welded state show that Ti-6Al-4V components ca n be used without subjecting them to any post-weld heat treatments.