Tig welding question

[Lucky R A]

      While TIG welding the breech of a first model Brown Bess in a re-conversion to flint, we ran into a problem with bubbles forming in the weld.  In use was a Lincoln Precision TIG 275 Argon gas, 1/8 tungsten tip using an INWELD Mild/Low alloy steel 705-2  1/16 rod.  Gas pressure was initially set at 50.  First thought was that air was getting to the weld, but the same thing happened when the pressure was bumped up to 75.  The weld area was thoroughly sand blasted prior to welding, so there should have been no contaminants.  We were building up a very eroded area where the drum had been installed in the percussion conversion.   We had a similar problem on a lock some time ago.  What are we  missing or doing wrong?  We have had a lot of good welds, but now and then bubble problem. 

Thanks

Ron 

[JCKelly]

This is theory only, I have no practical experience TIG welding wrought iron - but it is fact that wrought iron contains a certain amount of iron oxide. Suspect your bubbles coming from that oxide breaking up into gas and iron.

Anyway, I am sorry to hear you are degrading an historic item.

[ironwolf]

  When you say breach are you refering to the barrel?  If you'r trying to weld up the flash hole you would need to purge the barrel withwelding gas.  Run a Y-conector from the flow meter on the gas bottle into the barrel.  While tig welding, pressure is not the concern, but volume is.  35cu. ft/min should do it.  It could also be caused by weld inclusions in the old forge welded material.  If thats the case, stick welding would be the best bet.

  Kevin

[Bentflint]

2 things, sand blasting will leave shatered particals imbedded in the metal. If you turn the gas up too much it will suck air in with it.

Try turning your gas down to 30 or 35 as Kevin said.

[JTR]

Ron,
I've tried TIG welding several times with various settings/materials, and it just doesn't work reliably. I think it's from impurities in the iron, and sometimes you get bubbles, sometime small explosions, but whatever, it ruins the weld.
Now I either arc weld with something like 7018, or most of the time, gas weld using cheap tie-wire (thanks LP) for the filler.

If anyone has the secret for tig welding old iron, I'd sure like to hear it!

John

[Lucky R A]

      Thanks for all the responses.  It is nice to hear that I am not the "Lone Ranger" experiencing this problem.  There are many variables as well as other methods so the learning curve continues with some new avenues to try ...Now I shall have to address "Degradation of Historic items" in another post...

Ron

[D. Taylor Sapergia]

Cody, this is your cue...

[louieparker]

A tig welder is a wonderful thing on modern metal ..On old barrels and locks it can be a nightmare ..I was told just grind out the bubbles and redo it ..On occasion this works ..But for me its rare ..I usually get  worse bubbles and  end up going to a gas welder to flow it all together ..I use a tig to tack parts together and flow brass together, and that is about all.... I really think a gas welder with soft wire gives the best end result .But getting to the end is far more work, because of scale , heating a large area and sometimes warpage .
Right now I have two acetylene welders ,one of which is a miniature by Tescom, ( I think out of business now )   a tig and a mig ..If I was forced to do without one it would probably be the tig ......Louie  

[Rasch Chronicles]

Now I shall have to address "Degradation of Historic items" in another post...

Even I knew that one was coming...

Best regards,
Albert “Afghanus” Rasch
Mama Domicenti’s Kitchen: Albert Tries Market Hunting

[T*O*F]

Ron,
Not that I know anything about TIG welding, but I used to have a friend who repaired iron machinery.  He said the standard repair was brazing for these items but he welded everything.  He said that iron had to be welded hot.  He would bring the item up to temperature with a rosebud and then weld it.

Perhaps if you are trying to TIG a cold item, that could be the problem.  Something to experiment with anyway.

[ramserl]

needs to be hot! that is why stick and mig works better. you have lots of old junk and carbon hanging around in there. try to heat to 350 and turn heat up a little try to burn the junk out it may work. with stick you have flux on rod to help with the junk with mig you may have flux core wire or not. i have run into the same problem with mig without flux core wire. yes somtimes you can grind out the bad weld and do it again because you burnt out the junk. if barrel is thin then i would purge the barrel with argon to keep it from burning through and looking like sugar.   please remember that there is more than one way to skin a cat. just my two cents
good luck
Ray

[louieparker]

I failed to mention that I had also used an argon box . A metal box with argon flowing through ..a metal cover with an opening just big enough to weld through , The part competely surrounded with argon ..All I can say for sure  , it made welding more difficult ..This would no doubt be good for clean metal, but not a solution for me on old gun parts ...Louie

[tim crowe]

Ron,
Fl -flinter has welded just about everything possible , he is a well of knowledge with welding. You may drop him aline, I know he had computer problems awhile back but could answer email.

Cheers

Tim

[Eric Krewson]

A friend tried to arc weld up a crack a very large cast iron cooking pot with very poor results. His brother is a master welder and told him to heat the pot to red hot with a torch and and weld it while it was hot. My friend got a flawless weld by following his brothers advice.

[KNeilson]

Ron, "bubbles" that form in a weld deposit are called porosity, more likely than not caused by oxidation of the weld puddle. Now how this oxidation happens can be the question. The first post stated

Gas pressure was initially set at 50.  First thought was that air was getting to the weld, but the same thing happened when the pressure was bumped up to 75.

Hopefully you were meaning cfm or cubic feet per minute, but if you are talking PSI you will need to get a flow meter and not a regulator to meter your shielding gas. If you do have a flowmeter, 50 cfm is a very high setting, and in certain torch set-ups could contribute to air contamination. What I mean is... with a small gas nozzle, a large tungsten(1/8 in.), and no gas lens, high argon flow rates can "pull" air over the edges when exiting the nozzle causing your problem. Normal flow rates are about 20-25 cfm for a 3/8 to 1/2 in. nozzle. Now, once porosity is encountered, it has to be removed before proceeding with the welding. If you do not remove it, and attempt to re-melt the deposit to remove it ( the porosity) 99 time out of a hundred you`ll just create more of a mess. The last 20 years as a TIG welder has taught me this.

We were building up a very eroded area where the drum had been installed in the percussion conversion.

  Did you remove the eroded (oxidised) material completely? This could be one of the sources of oxidation.

INWELD Mild/Low alloy steel 705-2  1/16 rod.

  This filler rod,  70 S-2 is what most "normal" carbon steel welding uses. If you suspect these kind of problems I would suggest a rod with a higher amount of de-oxidizing ability like 70 S-6. This may help... 
Also

I really think a gas welder with soft wire gives the best end result

  This holds true in my experience also. Does not create the intense heat that TIG does, also a bigger shield (flame envelope) than TIG. But other problems  occur as has been stated.

A friend tried to arc weld up a crack a very large cast iron cooking pot with very poor results

Cast iron is a whole different animal, totally different than steel when talking about welding.........   hope this is of some help.......    Kerry

[ironwolf]

 Cast iron cookware is "pigiron".  Whole different story.  Pre-heating most likely would though.

  KW

[JCKelly]

Finally got brain in gear.
Problem (technical) is the slag in your wrought iron

Inert gas shielded processes like TIG & MIG do not work well for base metal full of oxides. That argon or helium) is meant to prevent the weld from oxidizing but it does absolutely nothing for metal that is already oxidized. And wrought iron is full of oxides & stuff.

You need something with flux.

Like a good old flux coated "stick" electrode. Probably an AC/DC rod run on Direct Current (if you think AC/DC is a rock 'n roll group, or a sexual matter - best have someone else do this job). I'd have to actually study up on it to know which is best, Straight Polarity (less penetration) or Reverse Polarity (the normal way to weld steel or nickel alloy).

In Ancient Times people acetylene welded even nickel alloy using flux - if such flux is still available, you could acetylene weld with some decent iron/steel TIG wire + flux

I believe you will need the flux to deal with the slag in the iron.

I base this on Zero experience welding wrought iron but decades with situations where one must weld used heat resistant alloy full of internal oxidation.

Yes, cast iron is a different animal. You do NOT have to get that wrought iron hot before you weld it.

But you gotta have flux. In which case you should be successful in degrading that historical object.

[JTR]

But you gotta have flux. In which case you should be successful in degrading that historical object.

Spoken like a true believer! But one mans degradation can be another mans salvation!

John

[Dphariss]

Finally got brain in gear.
Problem (technical) is the slag in your wrought iron

Inert gas shielded processes like TIG & MIG do not work well for base metal full of oxides. That argon or helium) is meant to prevent the weld from oxidizing but it does absolutely nothing for metal that is already oxidized. And wrought iron is full of oxides & stuff.

You need something with flux.

Like a good old flux coated "stick" electrode. Probably an AC/DC rod run on Direct Current (if you think AC/DC is a rock 'n roll group, or a sexual matter - best have someone else do this job). I'd have to actually study up on it to know which is best, Straight Polarity (less penetration) or Reverse Polarity (the normal way to weld steel or nickel alloy).

In Ancient Times people acetylene welded even nickel alloy using flux - if such flux is still available, you could acetylene weld with some decent iron/steel TIG wire + flux

I believe you will need the flux to deal with the slag in the iron.

I base this on Zero experience welding wrought iron but decades with situations where one must weld used heat resistant alloy full of internal oxidation.

Yes, cast iron is a different animal. You do NOT have to get that wrought iron hot before you weld it.

But you gotta have flux. In which case you should be successful in degrading that historical object.

The key is not getting it too hot.
This will work for filling pits not so good when doing structural work.
When heated to really melt the metal it will bubble and fizz like Alka-Seltzer.
So drill/grind, reweld. Drill grind/reweld. I am told that yes a good torch welder may have better luck. This from a gunsmith who does torch weld.
But the gas pits are often very numerous and ugly with electric.
With structural work done, the pits can then be welded using just enough heat to bond the plug to the pit. Virtually pit by pit in some cases. But the end result can be excellent with patience. But its much better if its possible to sucker some unsuspecting welder to do this. But he will likely refuse once he strikes an arc... Even experienced firearms restorers may not do this for other people's projects.
My experience with flux and arc welding has not been clean enough for gun work. End up with a lot of splatter stuck where its not wanted. So flux wire mig welding is a no-no for guns IMO.

Dan

[FL-Flintlock]

Given the right machine, skilled operator and quality flux-core wire, it's more than capable of producing a good clean bead.

[rick landes]

Ron, "bubbles" that form in a weld deposit are called porosity, more likely than not caused by oxidation of the weld puddle. Now how this oxidation happens can be the question. The first post stated

Gas pressure was initially set at 50.  First thought was that air was getting to the weld, but the same thing happened when the pressure was bumped up to 75.

Hopefully you were meaning cfm or cubic feet per minute, but if you are talking PSI you will need to get a flow meter and not a regulator to meter your shielding gas. If you do have a flowmeter, 50 cfm is a very high setting, and in certain torch set-ups could contribute to air contamination. What I mean is... with a small gas nozzle, a large tungsten(1/8 in.), and no gas lens, high argon flow rates can "pull" air over the edges when exiting the nozzle causing your problem. Normal flow rates are about 20-25 cfm for a 3/8 to 1/2 in. nozzle. Now, once porosity is encountered, it has to be removed before proceeding with the welding. If you do not remove it, and attempt to re-melt the deposit to remove it ( the porosity) 99 time out of a hundred you`ll just create more of a mess. The last 20 years as a TIG welder has taught me this.

We were building up a very eroded area where the drum had been installed in the percussion conversion.

  Did you remove the eroded (oxidised) material completely? This could be one of the sources of oxidation.

INWELD Mild/Low alloy steel 705-2  1/16 rod.

  This filler rod,  70 S-2 is what most "normal" carbon steel welding uses. If you suspect these kind of problems I would suggest a rod with a higher amount of de-oxidizing ability like 70 S-6. This may help... 
Also

I really think a gas welder with soft wire gives the best end result

  This holds true in my experience also. Does not create the intense heat that TIG does, also a bigger shield (flame envelope) than TIG. But other problems  occur as has been stated.

A friend tried to arc weld up a crack a very large cast iron cooking pot with very poor results

Cast iron is a whole different animal, totally different than steel when talking about welding.........   hope this is of some help.......    Kerry

I AGREE WITH THIS ANAYSIS AND WOULD ADD TO KEEP THE PRESSURE AT 20 CF. THE SAND BLASTING MAY HAVE PUSHED THE CONTAINATION INTO THE METAL. SOME MATERIAL HAS LEAD IN IT FOR VARIOUS REASONS AND WILL NOT WELD NO MATTER WHAT. AND THE HIGH CARBON FILLER may HELP THE PROBLEM. THE BARREL WAS MADE A TIME BACK WITH UNKNOWN MATERIAL. IT IS WITHOUT A METALS TEST IMPOSSIBLE TO DIRECT YOU IN WHAT IS TH EBEST COURSE. i AM MOST WARY THAT A GREAT LOOKING WELD ON TH EBARREL MAY IN FACT BE ONLY THAT AND IT WILL not PERFORM UNDER PRESSURE. you MAY HAVE A POTENTIAL BOMB IN THE MAKING.

DANG PLEASE FOR GIVE THE CAPS...NOT TO FLAME ANYONE, JUST DID NOT LOOK UP AS I WAS TYPING

Richard L. Landes
President/Owner
High Tech Welding, Inc.