TIG Welding .032" 6061-T6

[Didier Beaudoin]

Hello,

Since the ceiling has fell on our working place (litterally), and we are not supposed to weld at school, we asked a tech to weld our 1/32" thick gas tank.

He told us it is impossible to do with a TIG welder and that we would have to find a place where they have plasma welders.

I have myself welded 1/32" steel and 1/64" aluminum before without any problem. I have also read before about teams that have 1/32" aluminum tanks.

So, has anybody done it before - welding 1/32" 6061 that is?

[Didier Beaudoin]

Hello,

Since the ceiling has fell on our working place (litterally), and we are not supposed to weld at school, we asked a tech to weld our 1/32" thick gas tank.

He told us it is impossible to do with a TIG welder and that we would have to find a place where they have plasma welders.

I have myself welded 1/32" steel and 1/64" aluminum before without any problem. I have also read before about teams that have 1/32" aluminum tanks.

So, has anybody done it before - welding 1/32" 6061 that is?

[Jersey Tom]

I've only gone down to .049, but a buddy of mine does .035 aluminum on a regular transformer TIG.

An inverter TIG with the frequency up to 120-150 Hz I think would be best bet for a little more arc focus. Regardless, I really like using 2% Lanthanated (blue) electrodes ground to a blunt tip and with the balance turned up. Much more focused arc. With an inverter I've seen guys TIG aluminum cans together.

You've welded 1/64" Aluminum????????? You are a pimp.

[Didier Beaudoin]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Jersey Tom:
I've only gone down to .049, but a buddy of mine does .035 aluminum on a regular transformer TIG.

An inverter TIG with the frequency up to 120-150 Hz I think would be best bet for a little more arc focus. Regardless, I really like using 2% Lanthanated (blue) electrodes ground to a blunt tip and with the balance turned up. Much more focused arc. With an inverter I've seen guys TIG aluminum cans together.

You've welded 1/64" Aluminum????????? You are a pimp. </div></BLOCKQUOTE>

Ooops.

I of course meant 1/16".

Thanks for your imput.

[mtg]

I've welded a couple fuel tanks from 0.040" 6061(we'll call that close enough to 0.035"). It is difficult for sure, but if the welder says it is impossible, I'd find a better welder. Plan on using some tank sealant afterwards so the welds don't have to be completely liquid proof and you'll be fine.

I used a 3/32" tungsten (forgot the alloy) and sharpened it like what you'd use for welding steel.

And like Tom said, there's people welding beer cans together, and that's a whole lot thinner than 0.035".

[John Stimpson]

Our fuel tank this year was .032" 6061-T6. I like to think I'm a pretty good TIG welder, been doing it for about 10 years, and .032 sheet is tough. If you weld two coupons of .032 that are laying on the bench, its pretty easy, but then, you have heat-sink action with the bench. A tank is another story. Here are a few tips:

1. Design your tank to have as FEW weld joints as possible!

2. Flange your joints, and then rivet the tank together using either 5052 or 6061 rives every inch. The aluminum moves all over the place with the heat. Also, the flanges allwo most of your welds to be lap-joints, instead of butt joints. WAY, WAY easier. Of course, fill the rivets and burn them in to ensure a seal.

3. This one is IMPORTANT... NO GAPS WHATSOEVER. Filling gaps between sheets of .032 Al is f'n tough. The aforementioned flanges and rivets will take care of this.

4. If you can adjust your AC balance, set it at about 25-35% penetration (more cleaning). I've found its pretty hard to keep the aluminum clean at the low current needed for .032. Basically, you don't have enough "back current" in the cleaning portion of the waveform to actually seek out and destroy the Al2O3 on the surface of the aluminum.

5. Use a 1/16" green tungsten. I used to be a big advocate of red tungstens on aluminum, but I'm now a convert back to the green. Use at least a #8 gas cup, Argon flow at around 20CFH. I would actually recommend use of a gas lens. Use at least a #5, but as always, the bigger the cup, the better the coverage, so use the biggest one you can get away with.

6. If you dip the tungsten, you have destroyed the first .5-1cm of the tungsten. Notice that when you try to regrind after an Al dip, the structure of the tungsten is different. As engineers, we all know that metals can diffuse into other metals. Consider that tungsten melts at something like 5000ºF, and that dAB (diffusion coeff) is very largely based on heat. The tungsten balls, meaning it melts some, so the Al gets into the tungsten. After an Al dip, take your tungsten out of the torch, and smack the end against the bench, and note how the end snaps off really easily. The Al diffused into the tungsten WILL contaminate your weldment. So, after even 1 dip, break off the end of the electrode and regrind.

7. Speaking of regrind... We all have our favorite grind technique. I like to grind for Al by making a fairly blunt point, like a crayon. Then I like to "nip the tip", by truncating the tungsten down a little, leaving a flat tip. When welding on thicker Al, its cool to just let the tungsten ball up by itself while welding, but for the thin stuff, I advocate setting the machine back to DCEN and balling on the bench. Being that you'll pull so little current on the .032, you don't need a very big ball at all. Play with it so you form the minimum required size ball for the current you'll pull. LOL - make sure to set the machine back to AC after balling the electrode. Its easy to forget, and if you do, you're in for a bunch more cleaning and prep of the work before you can continue.

8. Cleanliness: Can't say enough about it. Simply CAN NOT say enough about it. Let me reiterate: CLEAN, CLEAN, CLEAN! You MUST have a dedicated 304, 321 or 347 stainless wire wheel for your bench grinder. It MUST, MUST, MUST be dedicated to Al ONLY. I normally wash my hands thoroughly, then wash the aluminum with soap and water. Dry carefully, any trace of water will screw you over bigtime. After drying, I wire wheel at least a FULL 1" around anything that will be welded. BOTH SIDES! Anywhere you'll be aiming that torch even close to, MUST BE WHEELED. If there is a spot you can't get the wheel on, some maroon 3M scotchbrite works pretty damn well. Its nylon fiber embedded with aluminum oxide, so it does a pretty nice job at getting the AL2O3 off the work. Note you should only rub one direction. The whole one-direction thing is not nearly as critical on thicker aluminum weldments. All the nitty-gritty details of aluminum prep become super critical on the thin stuff. After wheeling and scotchbriting, prep it with acetone. Use a LINT FREE cloth. The crappy industrial brown paper towels are decent at this, but they'll start shedding paper if you rub hard or for a while, so avoid this. Any lint or paper or debris or really foreign material of any kind will hurt the welding and get it dirty. Keep your hands clean throughout the cleaning process. Wipe your tungsten with acetone, wipe your torch, wipe your gas cup, clean your bench, wipe your filler... Again: CLEAN CLEAN CLEAN, I just can't stress this enough.

9. If your machine has an anti-crater feature, use it. Its really easy to get a lot of leaking craters on .032 weldments. If you don't have it, practice your foot technique on the pedal to anti-crater manually. If you leave craters, there is a huge chance they'll leak.

10. Back purge the tank while welding on it, particularly if you don't have an opening bigger than an inch. If you've ever tried to weld something shut, you know the heat of weld expands the air inside, and as you try to seal it shut, air will try to blow out through the last little hole, and of course, air has oxygen in it - a big problem for welding.

11. Aluminum is welded hot and fast, thats kinda just the way it goes. While you can dilly dally with steel, forming just the right weld puddle, neatly adding filler, pulsing your current down, moving forward.... That just doesn't work on thin aluminum. You have to know what you're doing and flat out go for it. Be ready to really get the rod into the puddle, and at times, keep it moving into the puddle at all times, particularly when you've got a gap... Think MIG! I sorta mentioned this before - the low current with thin Al doesn't allow for really great cleaning action, so its very easy to get the work dirty, especially on start-up of the weld. Use the "minimum current" setting on your machine if you've got it, if not, practice stomping the throttle open right away, don't work up to the current you want, or it'll get dirty. You basically want a trace of your current to be a step function, so as to avoid the low current/low cleaning zone on startup. I hope this makes sense.

Thats all I can think of now. Hope it helps. You will invest a shit-ton of time into a .032 tank. I'd strongly advise you to consider a differnt kind of tank!

[Didier Beaudoin]

Thanks a lot John for the extensive reply!

I think we're gonna go for our backup plan: a .063 al tank.

[R/TErnie]

for really nice lenses... I use CK Worldwide's "Gas Saver Lense"...clear pyrex cups...simply amazing.