doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Barrel Welding

After my post above I read what Toby had to say about his colleague that is an experienced tig welder of barrels and his post weld temperature to such a high temperature makes sense to me.

I learned how to make the cutting tools to join barrels for sleeving to the breech end of the original barrels without the seam showing, hence I do not have someone to weld them and have not encountered the welding problems. A successful jointing is made of barrels where one edge is 90 degrees and the other edge is about 1.5 degrees concave, or less than 90 degrees--proper making and sharpening of the concave cutting tool is critical. Gunmakers who do not have in their shop milling machines, lathes and diamond plate cutting discs (to make/sharpen machine tools) have a difficult time sleeving guns with an invisible joint and have to resort to tig welding.

I think the discussion has surfaced the issues as I had suspected, but there's also a couple other suspects that keep knawing at me.

I find that typical barrels from this era and modern barrels as well, seem to machine pretty nicely. Nothing at all like 4140 normalized (or mild steel), where you see large grain and rough machining. At least two alloying agents can facilitate free machining...sulpher and lead. Both can cause cracking in welds, if I recall correctly. Thoughts?

I am not a professional welder;however,30 years ago I learned to weld at the local community college where I taught.Two nights a week and three years later I passed their tests. The instructors were from the Norfolk Naval Shipyard and the school there was very technical(not the college one)and was upgraded by the navy after the submarine disaster in the 60's.Later, I taught Physics at the yard,but did not have the clearance to see the advanced welding school.But,I could watch welding on ships.Heater bars were placed on either side of the weld(I do not know the temperature) and low hydrogen rods were used-7018.I used 6010 for rough work and 7018 for clean steel.I then had a side business doing repair welding.From what I learned from teaching at other shipyards, hydrogen was the enemy as it will invade the crystal structure of steel and cause cracking.This is just a comment as I am not qualified in metals technology.

Chuck and others,

What is the high level parameters for annealing the barrels after welding or for pre-heating before welding?

Is it just heating the barrels to ~400F for X number of hours or do you need to just anneal the welded zone area? Does it need to be hotter? I thought the true sense of annealing was getting it up to or close to the critical temp. Are we actually just stress relieving at temps in the 400F range?

Is it just a matter of using an oven to heat the barrels either before welding or after? Or do you use a torch or something else to heat the affected area only?

From my little knothole, I've always taken the HAZ up to a dull red and cooled slowly with a torch. Not hours of heat, but just a few seconds, then played the torch on the HAZ less and less over a couple minutes, then put in a calm place to cool.

In my post of yesterday I stated that I could not remember the grade of steel used in shotgun barrels, but that I would talk to my gunmaker colleague(who began as apprentice in 1946) and ask him. Well, he does not remember either, but he remembers that actions were made from EN9 and he recalls that Webley's made their barrels from EN23 or maybe EN21. Webley supplied a good deal of barrels to the trade.

Sorry, but we older gents are recalling less each day.

Bushveld,

Interesting info on the facing for sleeving. Presumably the 90 degree face is on the breech end, the concave face on the barrels. Does this mean that when the two join there is some "mashing" of metal from the concave face against the right angle, and a raised lip which has to be filed off?

Regarding 'calm places to cool' ... one of the best is a good bed of warm ashes [not still burning, but with temps of say 100 F or so] where the object welded can be buried to normalize back to ambient temp over a long time period. It is a technique I was taught for brazing &/or welding cracks in cast iron that needed to stay repaired and not re-fail or crack near the repair. It has always served me well in that application.

It could possibly prove of value when doing bbl. welding repairs when a controled oven/furnace environment is not readily available. I dunno, never having used it for that particular application, but thot to mention it anyway as it is quite effective for ensuring any hot object cools very slowly.

Not that it will bother you on your side of the pond ,but welding a barrel will render it out of proof under Uk proof law .

Dead on right, Sir- the cracking at the edges of the HAZ on mild and mild alloyed steels is from hydrogen enbrittlement-- What makes AWS 7018 (70,000 PSI minimum tensile as stress relieved) such a fine SMAW electrode (we always used Lincoln 70 LH for code work on fab and schedule pipe steels (not on stainless of course) is that if handled properly- the flux is hydroscopic in nature, like a sponge, so it must be kept in a heated container or storage dry box- especially after you open the seal on a tin of electrodes- also it runs best with DC Reverse polarity, the same as your AWS 6010 and 7010 pipe rods- and unlike Lincoln 5P and HYP (we called it "Hippie Rod", 7018 has a heavy flux run off, and can be only run "out of position" Uphill--but as all the elements of the Lo-Hy rod are in the flux, you can't just take a stick of 7018- 3/32" is usally the smaller dia. made in 7018, scrape off the flux, and use it for TIG-- I use my Miller 250 TIG (Linde water cooled torch, soft start Hy-Freq and foot pedal rheostat for both mild, HSLA, Tool and Die (Air, Water and Oil hardened grades) and also for aluminum (AC Hy-Freq for alum.) Pre-heating and using a Tempil stick is the best way to get pre-welding temperature on your unknown alloyed gun barrels- 300 to 350 F in the adjacent areas of the HAZ- and then post heat and wrap in asbestos sacking until the entire section is cool to bare handed touch- but what the rest of the lads here have overlooked are three things, seemingly small, but crucial-- I sense a pattern of undercut as well as cracking on the edges of the weld beads- (1) the root pass is the key- you must "skip" weld or stagger the passes around the 360 degree circumference- and avoid grinding each section to a shear or sharp edge- leave a "land" where both section touch- you can't use alignment clamps and a backing ring as we do with API and ASTME code pipe welding-- (2)maintain that same 350 degree after the root pass by re-checking with the Tempilstick-- then add the fill passes, also skip weld, and in reverse rotation to the root pass- when you add the cap pass, increase slightly the gap from your tungsten in the torch, this will give the final pass a flatter "crown" and better flow to the edges, preventing undercut- with proper travel speed of course (3) One thing you all have overlooked, so far- use 100% Argon- right? Nope- more expensive, but I use a 50-Helium-50 Argon and a larger cup on the Torch- and make sure there is no debris on the inside dia. of the ceramic torch cup- that can cause turbulence and a void in the shielding gases in the molten arc/filler rod pool- also, only grind your 2% thoria tungstens on a designated clean wheen, and on the side, not the normal way- a contaminated grinding wheel will cause problems with your tungsten electrode- also make sure your filler rods are wiped clean of oil, debris- etc-- even sweat or acids from human hands can cause this- wear clean welding gloves when handling filler rods-- remember, 90 percent of a successful welding job is in the preparation-