Welding Ti-6Al-4V

 

Welding Ti-6Al-4V

 

Having mastered welding of commercially pure titanium we decided to continue our work on Ti-6Al-4V alloy of titanium which is called the work horse alloy in defence and aerospace industries.

This alloy has the following mechanical properties:

Ultimate tensile strength: 950MPa or 138kpsi

Yield strength: 880MPa or 128kpsi

Elongation: 10 to 14 percent.

These are typical values. Since Ti-6Al-4V is a heat treatable alloy the above strengths can be increased by suitable heat treatment.

For aerospace applications, the above alloy containing very low oxygen and nitrogen designated as ELI grade(Extra low interstitial) is used.

The welding of Ti-6Al-4V is not different from that of commercially pure titanium except that we used ultra pure argon gas to keep the interstitial low. Ti-6Al-4V is welded by TIG welding using commercially pure titanium filler wire or by matching composition filler wire or by the so called half alloy which is Ti-3Al-2V filler wire. The selection of wire depends upon the final property desired in the final weld.

We welded Ti-6Al-4V in annealed condition, solution annealed and solution annealed and aged condition. We also used commercially pure filler wire, matching composition filler wire and also half alloy wire. Welded test coupons were subjected to extensive testing. Test results were tabulated so that we have data bank select what type of filler wire to use for a specific application.

 

The data so collected by us was used for defence application about which I will later.