GAS or MIG welding on 4130 tube?

pbc76049 wrote:
Hi Ron.
I wouldn't say the standard is OA. That would mean there IS a standard, and
there isn't one.
The entire center wing box of the B1 is welded Titanium, and not a gas weld
to be seen.
Light alloy steel tubular structures are almost universally welded with an
electric process with the
exception of low dollar lugged bicycle frames which are brazed. Nascar Roll
Cage rules
prohibit TIG welded joints due to some history of brittle failures in what
should be a
deformable structure. Their preferred process is MIG. Very few aluminum
fabricators
use torches anymore, their preferred process is TIG. Homebuilders use OA
gear
because it is cheap to use, requires a low degree of skill to get acceptable
results, and is portable.

You might wish to go to the welding specs and do a bit of review.
The SAE and AWS do not require/recommend PWHT of 4130 welds on material less
than
1/2 inch thick. PWHT of 4130 only adds to its ability to move to somewhere
you don't want it .
Post weld heat treatment can do more harm thru distortion than any small
benefit you MIGHT
get reheating things.


Some further information...

Bud Davisson's How To Get Started in Homebuilding articles:
http://www.airbum.com/articles.html#How

Zen and the Weld Puddle:
http://www.airbum.com/articles/ArticleZenWelding.html

Richard