Hi Jim,
Sorry - I forgot about this question of yours ....
I have seen and heard of these problems, cracking during planishing, with tig welding. If the filler is the correct alloy, the metal is clean prior to welding, and the inert gas is clean one would expect no problem.
One thing remains: "Dilution."
And, according to the Aluminum Association, TIG welding offers
less dilution by its fundamental nature, than does OFW welding.
With TIG you have to stir/agitate/mix the puddle as you weld, in order to facilitate dilution - something that OFW does naturally, by its nature.
(Of course there are those welders who have no problems whatsoever with their work ...
)
I have welded old aluminum to new repair panels on many different old sports/race/touring cars from several different countries, on several different alloys,
with zero post-weld cracking problems -
while I hear about so many problems with "old metal" - and its being blamed for the problems so much that whole original bodies have been scrapped for Mr. TIG to be able to weld nice Fresh Familiar Aluminum.
(phooey on that
)
It's not about "annealing" - it's about
dilution.
Dilution is the mixing of the filler into the surrounding material enough to make a healthy workable transition from one alloy to another.
-end of lecture on that topic.
/////////////////////////////////
Next Question: [I]
What is your (the) goal when welding your panels? To weld with as little filler as possible and just planish. Or do some file work before planishing.
I assume our goal should be to use as little rod possible and planish with no filing to make the weld disappear)