Welding 5052 .063 sheet, lap joint, new sheet, just took the plastic protector off, Cleaned with acetone.
Miller Econotig, straight argon , 4043 3/32 rod
Having a problem with contamination. Cleaning with new green scotch-brite pad, new stainless wire brush and acetone.
Cleaned tungsten, rod, sheet.
It welds fine for about an inch and then goes bad, bright green flashing in the arc and black surface on weld puddle, it's getting contamination from somewhere but I can't figure it out.
This is the second gas tank, the first one went fine and I'm not doing anything different.
More specifically a fabricated fuel tank, not referring to the shield gas here.
I thought that too. But I just ran out and got another bottle of Argon and the problem was exactly the same with the old tank and the new.
It's weird, it's intermittent, welding a 3 inch section, the first inch will be ok then the second inch is contaminated, then the final inch will be ok.
Is it better to clean with aluma-brite (acid) or something rather than the scotch pad?
It is possible that th gas is getting obstructed in your torch hose, or in the torch itself.
Is it possible to try a different torch on this machine? I have had intermittent problems like you describe because the hose was damaged, and kinked inside the main cable.
Without watching you weld I can't really diagnose if it is a operator error.
that's what I suspected, It's as clean as I can get it and yet there's this huge problem.
some things to check
a distinct possibility since I'm not that familiar with welding aluminum.
Now I'm reading a ESAB tig welding handbook and it doesn't list 4043 as being used with 5052 although the welding rod literature that comes with the rod says it's for 5052? Do you think this is going to be a problem like strength wise or something?
And how much does contaminated weld compromise a long seam on an aluminum gas tank. It's probably about 5- 1" sections in a 60" seam.
Aluminum TIGinside Fillet welds are very tricky. The arc likes to dance between the 2 pieces until you get your weld puddle started.
4043 is not as strong or as corrosion resistant as 5356, but should work. If you really want to read about aluminum TIG filler alloy compatibilty, then go here
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Check out their technical info.
tank. It's probably about 5- 1" sections in a 60" seam.
It will tend to cause small pinholes in the weld which could mean leaks.
the arc and black surface on weld puddle, it's getting contamination from somewhere but I can't figure it out.
anything different.
Hi Chris,
Use helium instead of argon when AC aluminum welding.
When in doubt, use helium when welding aluminum with AC.
Helium really improves AC welding of aluminum.
When tired, or bored of using argon when TIG welding aluminum, try using helium, a noticeable improvement in welding will be observed immediately.
You may be getting the impression that using helium as shielding gas when welding aluminum is going to have some effect.
As to the physical reasons why this is so, remember that helium has a higher ionization voltage than argon. Hence, more energy is transferred to the weld puddle.
Also, to prevent holes from forming while welding aluminum with AC, and helium shielding gas, a copper backing plate works miracles.
the arc and black surface on weld puddle, it's getting contamination from somewhere but I can't figure it out.
anything different.
Hi Chris,
It occurs to me that some added tips are useful, on top of using helium for aluminum welding. The soot you are seeing is often generated because of oxygen getting to the tungsten. It is a good idea to increase the pre and post flow on the machine. Also, gas lens collet bodies are going to prevent oxygen from generating soot on the tungsten. You are likely going to be using higher flow rates with helium.
Because of the higher heat needed for welding aluminum, the tungsten gets much, much, hotter than when welding steel. This is why soot gets generated often from the tungsten.
The scotch-brite pads have better uses. I know they are recommended in a few places, but the aluminum gets too hot, and they melt onto the surface. I haven't found any use for them near the welder.
Acetone almost always leaves a film behind that needs to be cleaned with soap and water. Plus, that stuff is nasty, you should be using a respirator, and heavy rubber gloves to prevent nerve damage, and lung-tissue damage. Acetone goes through the pores in the skin, and goes right to the nerves.
Most aluminum is pretty clean. Unless you can see, or feel that there is something actually on the aluminum, it's not worth the time and effort to do anything special to clean it before welding. Instead of acetone, try something like alcohol to clean it off. It is a much less harmful substance to work with, and will do the job for 99% of the occasionally "dirty" aluminum.
Once you start using helium when welding aluminum, your standards for cleaning aluminum will go down substantially. It is so hot (read: makes life so easy for aluminum welding) that there will be very little else that will matter. It will also become clear why zirconiated tungstens are the norm. You will also find that you can't hold the torch as close as when welding steel. I have several pairs of gloves that have shrunk from the heat exposure. Now I keep a little more distance between my hands and the arc. There is a lot of radiation coming from the AC/helium arc.
The stainless steel wire brush is by far the best tool for aluminum. It is a good idea to keep a couple of different sizes of brushes to get to the hard to reach corners, and to brush large surfaces.
Make sure you turn the shade on your visor up a few notches.
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