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 degrees C. Room temperature hardness and tensile properties at four different temperatures (25, 150, 300 and 450 degrees 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 beta grains leading to higher hardness, tensile. strength and ductility of weldments in the as-welded condition. The post-weld heat treatment at 900 degrees C resulted in improvement in ductility and reduction in strength of weldments (both unpulsed and pulsed) owing to more coarsening of alpha, reduction in defect density and decomposition of martensite to equilibrium alpha and beta. Both pulsed and unpulsed weldments after PWMT exhibited almost the same values of strength and ductility. This may be attributed to the width of the a plates being almost the same in both welds. (C) 2006 Elsevier Inc. All rights reserved.