Vil,

Your trying to get fusion at the root with Zero burn through on your Ti Tee fillets?


You must construct an argon backup/heat sink.

Here is how. (at least one way, there are others, hopefully more folks will share.)

Take 0.063 copper sheet. Layout a checkerboard pattern lines every 1/4 inch and drill holes at all line intersections (less than 1/16 hole dia). Shear sheet into pieces that are 2 inches longer than your welds and at least an inch wide. (for instance 1x4 inch strips pre drilled.) Weld them together at an exact 90 degree angle and use 304 stainless for the other two sides. 347 or Hastelloy W make good filler rods. Blend excess weld metal on outside corners to a sharp true edge.

Make baffles inside the backup or diffuse with steel wool. Cap the ends and add a copper or stainless tube to attach to your backup source.

The backup must supply argon to the full heat affected zone and have total contact to the back side of the weld. Fit this behind the fillet and clamp the bottom of the Tee to a flat backup of similar design.

Soon you will have a toolbox full of custom backups that will fit in crazy part geometries. The tight fit behind the weld is important or you will go crazy with melt thru.

The idea behind this is nothing new. The same goes for stainless. Ti is just more sensitive.