If you are new to TIG welding Titanium, you might want to watch my 3 biggest mistakes for tig welding titanium video..you can see it right here ...
Like most welding tests, a 3g test on titanium involves a few key things to increase your chances of passing.
Since most tests like these are x ray tested, cleaning the metal thoroughly and properly is one of the key factors in preventing porosity.
There are many ways to clean titanium prior to welding but here is what I have found to work well.
First, wipe test plates with acetone and clean lint free cloth to remove any oils or debris
Fixtures are all slightly different so if possible, run a practice plate to determine the right argon purge flow rate for fixture and also flow rate for the cup used.