Correlation of microstructure with mechanical properties of TIG weldments of Ti-6Al-4V made with and without current pulsing

This paper deals with the influence of direct current pulsing on the microstructure, room temperature hardness and tensile properties at four different temperatures of tungsten inert gas (TIG) weldments of Ti-6Al-4V. Autogenous full-penetration bead-on-plate TIG welds were made with and without direct current pulsing. A few coupons were subjected to a post-weld heat treatment (PWHT) at 900 °C. Room temperature hardness and tensile properties at four different temperatures (25, 150, 300 and 450 °C) of the weldments in both as-welded and PWHT conditions were studied and correlated with the microstructure. Current pulsing resulted in slight refinement of prior β grains leading to higher hardness, tensile strength and ductility of weldments in the as-welded condition. The post-weld heat treatment at 900 °C resulted in improvement in ductility and reduction in strength of weldments (both unpulsed and pulsed) owing to more coarsening of α, reduction in defect density and decomposition of martensite to equilibrium α and β. Both pulsed and unpulsed weldments after PWHT exhibited almost the same values of strength and ductility. This may be attributed to the width of the α plates being almost the same in both welds.