Weldability study of Ti-Ta-Nb alloy and pure titanium

Weldability of Ti-4.8%Ta-1.8%Nb alloy, for use in electrolytic dissolver of nuclear fuel reprocessing plant, was evaluated in autogenous bead-on-plate gas tungsten arc welds made at two different heat inputs. Pure titanium was also welded for comparison. A secondary shielding setup was employed for protection of the weldment from gaseous contamination during and after welding. In the weld and heat-affected zone (HAZ) of Ti-Ta-Nb weldments, plate-like martensite, characteristic of cooling rates during welding, was observed. Low heat input and slower welding speed resulted in greater proportion of the desirable fine equiaxed prior-β grains. Lower heat input also reduced HAZ width.