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Old September 10, 2019, 23:56   #8
Old Fart
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Join Date: Jun 2013
Location: I'l know when I get there.
Posts: 8,086
Originally Posted by gunplumber View Post
No, it's because one of the welding rods I used was ER308 (stainless) instead of the ER70S (carbon steel) that I thought I was using.

Not a problem, but it can't be undone. I generally use the stainless for weld repairing hardened pieces, such as heat treated 4130 or 4140, as carbon migrates to the heat and can fracture if too hard at the joint. You will note two piece FN bolt carriers such on the M249 and and the FNC have the two parts welded with stainless.

I don't profess to be a master welder, but I do note when manufacturers choose stainless, so I copy them. I also have an example of a factory weld repair on the bridge over the chamber on an IMBEL - welded in stainless.

These two types have served me well for most jobs. It's also the reason I opted for the later black finish instead of Park.

Trust me, after 40 years of joining metal with an electric arc I still don't call myself a master welder. I've done miles of pipe, aluminum, stainless, and carbon steel. I've repaired sections on heavy equipment that were up to 4" thick and welded pipe that was only 1/16" thick.
I haven't picked up a TIG torch in nearly 5 years... You're doing well, probably take me a month of practice to get back into TIG.
"Can you lock him out of the marketplace?": My other half talking to Brunop in 2014.
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