welding titanium

This goes back to 1976. When welding technologists in India were finding it difficult to weld alloy steels we were developing welding technology for commercially pure titanium.

Titanium is a highly reactive material which has great affinity for oxygen and nitrogen. Titanium cannot be welded by shielded metal arc welding. Similarly, at that time neither submerged arc welding or MIG welding. In recent times Russians have developed submerged arc welding technique. The preferred method of welding is by gas tungsten arc welding also called as TIG welding.

Welding titanium is different from welding stainless steel. While welding stainless steel by TIG welding the gas shielding is provided to the weld pool from the gas flowing through the torch and a separate gas flow is provided to the bottom side of the weld (called back purge) to prevent the weldment getting oxidized.

While welding titanium in addition to the the gas flow through the torch and back purge you have what is called a travelling shield.The travelling shield is an attachment fixed to TIG torch which blankets the molten side of the pool as the torch moves forward and also on either side of center of the weld. This is because titanium continues to absorb oxygen and nitrogen right down to temperature down to 500 deg. celsius. When nitrogen and oxygen are absorbed the weldment becomes brittle. The UTS of weldment will be high and hardness increases.

The sucecess of welding titanium depends upon the clealiness you maintain and the design of the trailing shield. We developed a method of designing the trailing shield based on calculated temperature distribution for a given welding parameter. We had developed trailing shields for butt weld, tube to sheet welding, corner welding etc. Using the technolgy developed in
R&D we manufactured titanium lined urea reactor, titanium heat exchangers, titaniun anodes and number of equipments of titanium.