Aluminum TIG AC vs DC w/Argon

[pulser]

This is a comparison of TIG AC versus DCEN, on 1/16" aluminum.
60 amps, 10 cfh argon with gas lens, 3/32" 2% thoriated sharp, arc gap approx. 1/16", torch angle approx. 10 deg. push, travel speed approx. 6 ipm. Lincoln Invertec 205, AC balance 85%, AC frequency 150 Hz.
Bead on plate, no filler added. Cleaned front and back with SS wire brush by hand. Type of Aluminum unknown.

Front side, DCEN on top.
http://i56.photobucket.com/albums/g166/stanwp/DSCN1168.jpg

Back side, DCEN on top, no penetration on AC.
http://i56.photobucket.com/albums/g166/stanwp/DSCN1169.jpg

DCEN TIG with argon on thin aluminum, not bad, just need clean base metal.

[David R]

Nice stuff Pulser. Thank you :)

David

[Jolly Roger]

Looks just like it should, and proof that AL can be and is welded with dc. You just have to work fast when using dc to avoid the way AL oxidizes, and like you said make sure it's really clean.

[hotrodder]

Demonstrates the differences in heat input well but an autogenous bead on a piece of plate doesn't compare to a real world joint.

[aczeller]

very nice stuff pulser... thanks. was that done with one of your spiffy little CNC machines?

Later,
Andy

[pulser]

Andy,
thanks. No CNC, just me trying to be steady like a machine. I think I maintained the arc gap, the travel speed was the most difficult to try to make the same for both welds. That's what I love about a machine, everything is so repeatable, you can compare welds at different amperage, travel, gap, whatever, and be confident that you are only seeing the effect of that one variable. :drinkup:

[turboguy]

Pulser, thank you very much for drawing this thread to my attention.

I LOVE the look of that DC weld bead, although it looks like there is quite a bit of penetration.


Any chance we can see a few different joints welded (and maybe fused?) using the DC/Argon process on 16 or 14 gauge Aluminum sheet?

I'm new to welding so I'm not sure what all the joint types are called, but a "T" joint and what you'd see on the outside corners of a box made from sheet metal would be great if you're taking requests :D :D

[Jolly Roger]

It works real well on real world joints hotrodder. I used to use dcen w/helium (I prefer argon but my boss would only buy helium) on 1/2" regularly. We were having problems with the welds cracking out over time using ac. I tried the dc and it cured the problem and went a whole lot faster.

[David R]

OK, I tried it. I had these "cupons" of unknown make up. I wire wheeled them and spaced them out a little. I used pure argon, DCEN. It was quiet for welding aluminum. You can see from the beads it took me a while to learn KEEP THE ROD IN THE PUDDLE. The oxidation gets in the way. Amps I don't know. I set it on 185 and used the foot pedal. Getting towards the end, I had to back off a lot.

22256

22257

22258

Back side
22259

[David R]

Then I flipped it over and ran a bead over he back side. After wire brushing the heck out of it with a SS brush.

22260

22261

22262

I picked the best spot and cut it with a hacksaw.
22263

I can see how it would work, when things are going right, It moves right along. It gives new meaning to "watch the puddle".

David :)

[Engloid]

It works better with helium....and doesn't turn out so dirty looking.

[David R]

I can see how it would work, but thin plate would be a b*tch. I have AC and a spoolgun, so I doubt I will use it in the real world. Was fun trying.

David :)

[gaustin]

On this Aluminum, Argon and DCRP can be used if the tungsten is BIG and the material is thin. The cleaning action is very good.

I have welded 1/4" thick aluminum electrical enclosures in the field using GTAW DCSP and Helium. Havent tried Argon.

The finished welds look like any others except for the black smoke. The puddle can be a little un-cooperative at times if the lleast amount of trash is in the joint.

Repaired a friends pontoon boat last year with a thunderbolt 225 AC/DC and a bottle of helium.

[pulser]

David,
interesting experiment, thanks for sharing. In the interest of "science", not to critisize your work, I think the DCEN Argon aluminum thing needs some more discussion. It seems like something went wrong with those welds, not related to DCEN or argon, that is pretty bad oxide contamination. DCEN and helium works well, we know that, so there is no reason that argon should not also work well, just not as much heat transfer for a given amperage. I think that if the shielding is sufficient, and the oxide on the base metal is removed, you will get welds much "cleaner" than what happened with these welds.

Just for the sake of discussion, assume you look at the most extreme "clean" conditions, you put the aluminum plate in an inert glovebox with oxygen and moisture levels below 10 ppm. You remove the surface oxide by brushing it inside the box, so new oxide does not form, because there is no oxygen. You weld in the inert atmosphere and the weld is pristine, no oxidation.

Now look at the real world again, cleaning and welding out on the work bench. You do the best you can to remove the oxide and provide the best shielding, and I think it is possible to get better results than what you got.

One thing that may have hurt you is the power wire wheel. This can be too aggressive, actually causing increased oxidation due to friction heating in air. Then, the other thing is shielding, did you use a big ole gas lens?
I'll see if I can try some welds, heavier aluminum with filler wire, DCEN and argon. I'm sure it's not as easy as I think it should be.

[longevity-inc.com]

David,

I may have misunderstood. Did you weld the aluminum with helium in DC mode with your lincoln?

Thanks

[pulser]

David,
I tried some DCEN argon with filler on aluminum today, pictures to follow later, and it is very difficult to get everything oxide free enough to make a smooth weld. I had pretty good luck with some thin sheet, it looked like the sheet oxide was not too bad, but I could actually see the oxide from the wire being deposited into the puddle with ever dip, and I was careful not to pull back too far out of the shield. Each dip of filler left a crusty dark patch of oxide on the weld surface. I guess a person could figure out the right kind of "sand" paper to use on the wire, probably not alumina oxide, then acetone wipe, right before making the weld.

Anyway, with really tedious cleaning/oxide removal, the DCEN with argon is possible, but AC wets out and flows so much better it is the way to go on thin aluminum.

[gaustin]

I would suggest clean unused steel wool followed by a wipe with a clean cloth. Still not as nice as AC, but it may help. I have used DCRP to clean surfaces difficult to reach.

While repairing a piece of cast aluminum that I had preheated and was starting to clean using DCRP, it puddled up nicely and I made the weld on DCRP with Argon. It was a boat prop tip and welded up nicely. I may have had 75/25 Ar/He.

[Burnit]

David,
It seems like something went wrong with those welds, not related to DCEN or argon, that is pretty bad oxide contamination..............

Just for the sake of discussion, assume you look at the most extreme "clean" conditions, you put the aluminum plate in an inert glovebox with oxygen and moisture levels below 10 ppm. You remove the surface oxide by brushing it inside the box, so new oxide does not form, because there is no oxygen. You weld in the inert atmosphere and the weld is pristine, no oxidation.

Now look at the real world again, cleaning and welding out on the work bench. You do the best you can to remove the oxide and provide the best shielding, and I think it is possible to get better results than what you got.

One thing that may have hurt you is the power wire wheel. This can be too aggressive, actually causing increased oxidation due to friction heating in air.


Its funny this thread came back, I was working with aluminum all day and was wondering about DC.

I agree with pulser on those welds, that doesnt look like a DC problem, but I have never tried it.

Today I was thinking about getting the oxide off and trying to keep it off, from what I have read/heard it starts forming immediatly. I wonder if the wire wheel not only compounded the problem like pulser said with heat/air but when finished it had scoured the surface of the plate increasing its surface area quite a bit I would imagine, even more oxide.

We have what we call the "titanium tent" at work, I wonder what would happen if I prepped a coupon in that? That was a neat idea pulser.

[hotrodder]

Jolly Roger,
I know DCEN works well, the point i was making is that running an arc over a piece of metal does not compare to a real joint- no disrespect to Pulser but anyone capable of holding a torch could achieve that

I haven't used DCEN and He on Al for a good few years, never did a lot anyway but we only switched to DCEN above 6mm

Gave it a little go today with argon on some 1mm sheet. Oxide was removed from the base with a SS brush, edges scrapped too. Filler was cleaned with scotchbrite, both were then solvent wiped until the cloth remained clean- took around twice as long as it would to clean off the etched zone after welding with AC :rolleyes:, obviously the welding itself was faster

I haven't bothered with pics as although i got a full pen weld they were very ugly and dirty never any sign of a puddle (had to use 'the force' :p). I won't be bothering again

[David R]

Like I said, I can see how it would work, just not in my world.

Its nice to see more trying it.

David :)

[Engloid]

I would suggest clean unused steel wool followed by a wipe with a clean cloth.
STEEL wool can make aluminum rust.

[gaustin]

STEEL wool can make aluminum rust.

I would have to disagree but only based on my limited experience and the fact that steel is harder than aluminum. Clean, new steel wool is pretty much free of any loose particles. Forit to become embedded in the aluminum, the aluminum would have to have the ability to remove the iron.

Steel wool on aluminum is similar to using a NEW clean carbon steel file on stainless. The file will not cause the stainless to "rust".

My 1st aluminum GTAW was in highschool many years ago and that was all I used, from the beginning of the year, to the end of the year, the pieces never showed any signs on contamination. From then on I have used whatever type of new brush I could get. The steel wool seemed to be MUCH cleaner than a wire brush even if both were new.

I still use a new steel wire brush on aluminum or steel wool if I can get it.

I will concede that its possible I have not seen the same service conditions of as-welded aluminum as you.

Just because I have never seen "rust" on the aluminum I have welded does not mean it doesn't happen. I very well may not have welded as much as you as far as aluminum goes.

You seeing aluminum "rust" one time from using new clean steel wool can disprove my 20 or 30 times (probably more counting scrap pieces I have welded) of not seeing it.

Scotchbright may be the thing .

It is possible all of the times I had "steel wool" it was stainless. It looked like the same steel wool I used for refinishing stocks. I may try some on a hunk and leave it in the yard for awhile. I reckon that would straighten me out. The pontoon boat I did last year was done with a CS wire brush. I may have to go look at it. Luckily its between the pontoons and not visible on the outside.

[Engloid]

I would have to disagree but only based on my limited experience and the fact that steel is harder than aluminum. Clean, new steel wool is pretty much free of any loose particles.
Just how large a particle do you think it takes to create rust?
Forit to become embedded in the aluminum, the aluminum would have to have the ability to remove the iron.
It doesn't have to become embedded into the aluminum. Remember that EVERYTHING is magnetic to some degree. Even water molecules stick to each other.
Steel wool on aluminum is similar to using a NEW clean carbon steel file on stainless. The file will not cause the stainless to "rust".
If I had a dollar for every stainless pipe weld that somebody "ring filed" and it rusted, I'd be retired. Even a new carbon file will dull when used on stainless...and some of those particles will be in the stainless.
Scotchbright may be the thing .
I'd say it is much safer and eleminates the chances of rust.
It is possible all of the times I had "steel wool" it was stainless.
Maybe. I was wondering about that when you posted it.

It looked like the same steel wool I used for refinishing stocks. I may try some on a hunk and leave it in the yard for awhile. I reckon that would straighten me out.
Or scrub some dishes with it and let it dry. If it's carbon steel wool, it will likely be rusted within a few days, especially if you wet it each day.

[Ag Specialties]

When you guys wire alu with a spool gun, do you use AC or DC + or - ? I always use DC + with argon.

[gaustin]

Just how large a particle do you think it takes to create rust?

It doesn't have to become embedded into the aluminum. Remember that EVERYTHING is magnetic to some degree. Even water molecules stick to each other.

Hence, wiping off


If I had a dollar for every stainless pipe weld that somebody "ring filed" and it rusted, I'd be retired. Even a new carbon file will dull when used on stainless...and some of those particles will be in the stainless.


If I had a dollar for every SS pipe I hand bevelled to within +/- 2 degrees with a BRAND NEW nicholson file in accordance with the material control requirements for US Navy Nuclear Power Plant repairs id be , just like I am today- Thats about what it paid .. Files normally "dull" from the backstroke used by someone not familar with how a file (or hacksaw) should be used. The backstroke with too much pressure will deform the teeth easily (and maybe break some).


Or scrub some dishes with it and let it dry. If it's carbon steel wool, it will likely be rusted within a few days, especially if you wet it each day.

The steel wool will rust, my stainless and aluminum and various types of glassware still have yet to exhibit any rust.

Again, if you have seen it, I believe it. I have a piece of 1/4" aluminum oustide that I welded 3 or 4 years ago and precleaned and post cleaned using a new carbon steel wire brush, I am pretty sure it is unrusted. I am pretty sure it was washed when I was done with it so that may have prevented the rusting

[pulser]

Picks of 1/16" aluminum TIG with DCEN, Argon, and 1/16" 5356 filler.
1/8" 2% thoriated sharp tungsten, Argon at 20 cfh throung gas lens and #8 cup (1/2" dia.) Lincoln Invertec inverter starting amps 60, reduced to unknown amperage during weld via foot pedal.
Frontside top weld is a butt joint, bottom weld is bean on plate. I could see crusty dark oxide deposits coming from the filler metal.
http://i56.photobucket.com/albums/g166/stanwp/DSCN1296.jpg

Backside top weld shows that butt joint did not want to wet together due to oxide, thus leaving a line. Bottom weld without joint shows no line.
http://i56.photobucket.com/albums/g166/stanwp/DSCN1305.jpg

Looks like super cleaning (oxide removal) is required for both base metal and filler metal.

[David R]

Nice stuff, thanks

"Buttcheeks" I can't see how you could avoid them, there isn't even any cleaning on top. That is why I welded both sides of the one I tried.

It seems to take a lot less heat than on AC.

David :)

[hotrodder]

I got full pen without any suckback, for about an inch :blush:. Even uglier than those posted though

[RogerRoger]

So, is the bottom-line "Use AC for aluminum" still valid?

Roger

[gaustin]

DCSP Works fine. I left a manufacturer yesterday that used DCSP and Helium for parts used in the aerospace industry. DCSO with ARgon is tough but can happen. DCRP can be done with Argon.

I got to see some friction stir welds . Never got to see that before in person.

[Engloid]

So, is the bottom-line "Use AC for aluminum" still valid?

Roger

No, DCEN works fine, with helium or with he/ar mix. It's actually MUCH better for fillet welds.

[SR20steve]

Im really lost here, so its possible to weld aluminum with DCEN we just now made that clear. But looking at your beads I thought I was looking at the back side of the weld. Was this without filler? I'd like to see a DCEN aluminum weld with filler if thats the case. I really like that you are thinking out of the box though :D.

[Engloid]

Im really lost here, so its possible to weld aluminum with DCEN we just now made that clear. But looking at your beads I thought I was looking at the back side of the weld. Was this without filler? I'd like to see a DCEN aluminum weld with filler if thats the case. I really like that you are thinking out of the box though :D.

DCEN on aluminum is nothing new. I first did it about 10-13 years, and I wasn't the first to do it. Most people just assume that you have to use AC on all aluminum. It simply can't be beat for fillet welds and thick aluminum.

[David R]

Im really lost here, so its possible to weld aluminum with DCEN we just now made that clear. But looking at your beads I thought I was looking at the back side of the weld. Was this without filler? I'd like to see a DCEN aluminum weld with filler if thats the case. I really like that you are thinking out of the box though :D.

Post 9, 10 and 26 show with filler. There is no cleaning action, so its a little different.

David

[WookieWelding]

3/32 red thoriated sharp point 145ish amps 1/16 4043 filler and argon at about 18 cfh 1/8 inch aluminum with a fillet weld

[geezer]

3/32 red thoriated sharp point 145ish amps 1/16 4043 filler and argon at about 18 cfh 1/8 inch aluminum with a fillet weld

I am assuming you done these good looking welds with a transformer machine, correct? If so, was it the Precision 275? Thanks

[WookieWelding]

I am assuming you done these good looking welds with a transformer machine, correct? If so, was it the Precision 275? Thanksyup they were done with a transformer machine and it was on a Lincoln Precision tig 275

[welds4d]

When you guys wire alu with a spool gun, do you use AC or DC + or - ? I always use DC + with argon.

DCEP in argon. Helium for MIG is also an option, although I've never used it.