doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com TIG Welding and Rust Blue

Do yourself a favour, find a local man who does "micro-welding". That is TIG done with extremely fine filler rod and under high magnification. Anybody in the machine shop business should be able to steer you to such a man. Make sure that you tell him that it needs to be welded with mild steel rod, otherwise he's apt to use stainless steel.The welds WILL self harden and you'll want to get some die-sinkers stones to dress them off, as files, except diamond, will just skate on them. A GOOD man will do welds so incredibly well that very little dressing off will be required. It would be $50 or so very well spent! I have a local man that I use quite often and I've never begrudged a penny that I've paid him.

Mike, the only reason I said MIG instead of TIG is because outdoorlvr said it was just some small pitting. Anything like the large job that Chuck H. did, then I would definetly say TIG. Unless the area is to be welded is spotless, and with a TIG, that means burr grinding the metal to be free of defects, (piting, rust) or else like someone said you are going to get a lot of porosity. IMOP that is why I said MIG weld.

I would never doubt that there are people who are better with a mig welder than I, but mig or tig, how do you prevent oxidation of the weld as it cools (and the subsequent porosity) without shielding gas? After all, isn't that what the "ig" stands for?

JDW,
I just prep with Birchwood (or other) blueing/rust remover, scrubbing with steelwool and a small wirebrush which gets all the oxidation off in the pits. If you have access to a fine sandblast or glassbeadblast cabinet, this will work as well. Grinding it out with a burr would be a way to go if you have trouble with finding any of the above.

I have used the Brownells 3.5% Ni. rod with a Tig rig on several guns. It has always been visible under hot bath blue. It disappears under cold rust bluing as has standard mild steel rod. I even tried Mig wire(ER70S-6 with TIG)on one job and it worked as well.

It is possible that an expert hot bluer could do a better job with covering the weldment, but the local gunsmith I used could not do it. I did the rust bluing myself using Laurel Mtn. solution and had no problems. I have often wondered if Carbonia blue would cover, but have not tried it. Turnbull's shop did not know either.

OB

I can tell you the chemical composition for several foreign steels
Krupp Special - C-0,61% Mn-0,65% Si-0,434%
Boler Antinit - C-0,117% Mn-0,49% Si-0.299 Ni-8,51%
Poldi Anticoro - C-0,145% Mn-0,50% Si-0,45% Ni-7,78%

As you can see barrel steels are very mild steels with very low carbon content. All ordinary not antirust steels are about the same in chemical composition.
The best rods for barrel TIG welding would be very very mild steel rods. The shield gas is a must. Otherwise melt steel eats oxygen and becomes porous.

I use very mild copper coated steel rods and purge the inside of the barrel with argon and use argon on my tig welder as well. I get very good results, and cold blue using a formula from one of my father in laws old books by Howe.

Geno,
That Krupp looks a little high in carbon, undoubtably enough to be quench hardenable. I welded the Galazan 4140 tubes with mild steel, but still got a hard area on the edge fo the weld from the self quenching action of the weld cooling and I think the accumulation of carbon at the edge of the weld (even with TIG).

Chuck, found some information about using high tensile strength steel 4140.
Welding
Welding of 4140 in the hardened and tempered condition (as normally supplied), is not recommended and should be avoided if at all possible, as the mechanical properties will be altered within the weld heat affected zone. It is preferred that welding be carried out on 4140 while in the annealed condition, and that the work piece, immediately on cooling to hand warm, is then stress relieved at 595 oC - 620 oC prior to hardening and tempering.
If welding in the hardened and tempered condition is really necessary, then the work piece, immediately on cooling to hand warm, should be if possible stress relieved at 15 oC below the original tempering temperature (if known).



Welding Procedure
Welding of 4140 in whatever condition should always be carried out using low hydrogen electrodes - please consult your welding consumables supplier.

JDW,
Good stuff. The Galazan barrels seem to be in the 'normalized' condition. This is just a bit harder than full anneal. This is an acceptable condition to weld without worrying too much about cracking. When annealing the welds, the temp rises high enough to stress relieve the weld and adjacent heat affected zone. Using low carbon mild steel filler rod helps keep the stresses down also, since it will yield more easily than higher alloy steel.