Stainless Tig issues

I'm welding up an exhaust down pipe for a friend out of stainless and I'm
having a hard time getting nice golden brown welds. Most of the time their
dark grey or black and appear to be scaling. I'm purging the pipe and the
back side looks good. I think my problem is heat. The pipe is 14 gauge and
the plate is 3/8" so I'm having to put a lot of heat into the weld to get
good penetration on the 3/8". I've turned up the gas flow and I'm still
seeing the scaling.
Any suggestions.
Reply to
Kevin Y.
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Good penetration is easy. 14ga is around 0.075". Standard amperage for 14 ga SS would be about 50 amps. (1 amp per 0.001" - 1/3 for SS = 50) To weld it in a fillet weld would be 75 amps. (add 1/3 for inside fillets) To fillet weld it to 3/8" I would move up to 100 amps max and cheat more of the heat to the 3/8" flange. 0.045" filler would be plenty.
Use a gas lens for better shielding. Run about 10-12 CFH gas for a gas lens, 20-25 CFH gas for a standard collet body.
Hopefully you have the SS flange bolted to a big steel plate to help prevent warpage or it is going to warp all over the place. The other option is to fly-cut it flat on a mill, after welding, heat treat and passivation.
321 SS is the best material for standard exhaust pipes. 304L SS is a poor replacement, but will work, kind of.
Reply to
Ernie Leimkuhler

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