TIG, stress relieving

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Turd Ferguson

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I feel like TFF did a good job of answering your question. I HAVE heard (from a race car fabricator) though that TIG/MIG stress relieves on 4130 a lot cooler than cherry red. 250F was mentioned. And many do NOT bother, and seem to get along OK.
Maule aircraft use MIG welding now exclusively and they don't stress relieve anything. The process is FAA approved.
 

TFF

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But like Champion, they had to write a manual for the joints and amps required. AND practice. Champion had problems originally with cracks as did Kitfox with MIG. All solvable but they found they could not attack the problem in the same way as torch or TIG. Maule probably knew from others, figure it out before sending one out.

I know of three landing gear collapses from repairs made with a MiG. Spezio, Skybolt, and Marquette Charger. The simplicity of the MIG can also give false security. Welds can look pretty and be no good. That is very common with MIG beginners.
 

wktaylor

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LS... Videos not working for me at moment.

You have really thrown me off my M&P game. TIG = tungsten inert gas... hence I'd expected an electric arc from the tungsten anode melting the braze alloy... which would destroy everything alloy and base metal.

SO I poured-thru the AWS brazing handbook and finally came to the conclusion… 'TIG brazing' makes no sense... unless You are really 'just' using the inert gas from a TIG welder torch combined with a conventional brazing torch/rod set-up. IF this really is the case this is simply torch brazing within an inert-gas [argon?] atmosphere... provided by from the TIG welder-head [no weld current].
 

Geraldc

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LS... Videos not working for me at moment.

You have really thrown me off my M&P game. TIG = tungsten inert gas... hence I'd expected an electric arc from the tungsten anode melting the braze alloy... which would destroy everything alloy and base metal.

SO I poured-thru the AWS brazing handbook and finally came to the conclusion… 'TIG brazing' makes no sense... unless You are really 'just' using the inert gas from a TIG welder torch combined with a conventional brazing torch/rod set-up. IF this really is the case this is simply torch brazing within an inert-gas [argon?] atmosphere... provided by from the TIG welder-head [no weld current].
I had a play yesterday with my TIG and a bronze rod and it worked well.
For sheet metal butt joint I used a larger gap than with steel rod.
 

dog

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I havnt tried tig brazing,yet, and it occurs to me it might be just the thing for fiddly little jobs.
For non fiddly jobs I have an ancient set up for turning an ac buzz box into a brazing machine,
big handle thing with holders for some carbons,
makes the heat,and light,and noise
 

BBerson

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Why? Brass is harder than aluminum. Should push through the liner better than that soft aluminum wire that keeps sticking on me. I gave up on aluminum welding. It works but too soft welds.
 

dog

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Why? Brass is harder than aluminum. Should push through the liner better than that soft aluminum wire that keeps sticking on me. I gave up on aluminum welding. It works but too soft welds.
Brass is an aloy with a lot of tin which I think will
oxidize spectacularly when vaporized with the copper, enough shield ing gas could make it work
but Im thinking no.
If it does work,we will of course hear about it now.
 

PMD

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I think there is a need to set some things straight. "Brazing" simply means making a joint with a filler metal that melts below the point of the base metal. The common copper/zinc flux coated rod we normally encounter is but one of literally hundreds (if not thousands) of brazing alloys. The most common of these are CuNi alloys once common in fabricating motorcycle frames in furnace brazed and torch brazed joints. Those alloys are stronger than mild steel and (because of the nickel) wet out beautifully.

The component we see fuming out of low strength Cu/Zn (brass) alloys is the zinc. It oxidizes quite easily and when it is gone, the resulting alloy filler is garbage. That is why you need to do all such work with a reducing flame (lack of oxygen in the outer "feather" region of secondary cone). That is why one assumption above about TIG (GTA or Gas Tungsten Arc is correct term) brazing would be correct. The alloys that CAN work with GTA brazing are mostly eutectic alloys of Ni or Fe base. Aerospace engines are FULL of such brazed joints. Obviously, the big advantage is being able to make a high strength joint without destroying the properties or grain structure of the substrate.

(on edit) just noticed the video link to SiB alloy GTA brazing above. Note how the operator keeps his arc on the weld puddle, not the steel. Another brazing alloy that is not brass.
 
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dog

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I think there is a need to set some things straight. "Brazing" simply means making a joint with a filler metal that melts below the point of the base metal. The common copper/zinc flux coated rod we normally encounter is but one of literally hundreds (if not thousands) of brazing alloys. The most common of these are CuNi alloys once common in fabricating motorcycle frames in furnace brazed and torch brazed joints. Those alloys are stronger than mild steel and (because of the nickel) wet out beautifully.

The component we see fuming out of low strength Cu/Zn (brass) alloys is the zinc. It oxidizes quite easily and when it is gone, the resulting alloy filler is garbage. That is why you need to do all such work with a reducing flame (lack of oxygen in the outer "feather" region of secondary cone). That is why one assumption above about TIG (GTA or Gas Tungsten Arc is correct term) brazing would be correct. The alloys that CAN work with GTA brazing are mostly eutectic alloys of Ni or Fe base. Aerospace engines are FULL of such brazed joints. Obviously, the big advantage is being able to make a high strength joint without destroying the properties or grain structure of the substrate.

(on edit) just noticed the video link to SiB alloy GTA brazing above. Note how the operator keeps his arc on the weld puddle, not the steel. Another brazing alloy that is not brass.
While apreciated,your "setting things strait" was realy just the condensed version of the introductory note on brazing, which would of course be a toe thumping volume not in general
circulation.
Brazing :if it was to fit the idea that you speak up and ask a random person to go and get some brazing rods,are going to come back with a standard yellow or green whatever brass rod.
And the thousands of other possibilities
could perhaps be better characterised as processes, where the brazing aloy actualy working would be totaly dependent on conditions beyond the small shop and or trade secrets.
What might be a good copper nickle alloy to keep around for tubing and other general work? and how is it used?Oxy/acatelene, strait acetelene
oxy propane, coal /charcoal fired forge brazing
or tungsen inert gas or gas tungsen arc and
what works as flux,sand? borax?
 

Geraldc

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Does it work for you?
I have only cut off bits of wire for TIG brazing.It works ok for that.
For mig I would have to change out my liner and setup so I have not bothered.For car restoration (my other hobby) we have to use a fusion weld of mig tig or oxyacetylene for compliance.
 
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