[RedIron881]

I've gotten into this debate many times with younger welders right out of school all the way up to welders twice my age and experience. The debate about TIG welding Aluminum on DC. They all say you Can't do it! One thing I've learned in my 15 years in welding is there no such thing as Can't in this industry, you just don't know how. So, figured I'd post something about it and see what all you welders around the world have to say.

Here is the recipe I like to use...

Set machine for welding Steel no more than 190-210 amps regardless of thickness, need a foot pedal for this
Standard or gas lens set up (Gas lens is a bit cleaner but not needed)
2% tungsten works fine 3/32-1/8 sharpened
4043 rod 3/32 (depending on thickness of course)
25-30 psi of Helium (use the helium to bump up the heat not the amps)
5 psi Argon (helps clean up the weld a bit but also not always needed)

A few Pros and Cons

Pros...

-Don't have AC and need to weld aluminum!
-No Preheat for thick parts
-Makes for a great small root pass (preheats for the cap) or one large pass
-Burns much hotter so you can get in and out with minimum warpage but still getting good penetration

Cons...

-Dirty looking weld (until you figure out the right angles). If the material is dirty it really shows in the top and bottom of the weld (as in the photo) but comes right off with a wire brush. This was just handles for a base plate so didn't need to clean up nice.
-Wire will ball up very easy if not added properly. It's not forgiving so add it in the right spot
-Uses a lot of Helium which isn't cheap but if you're welding of a machined billet plate that can't warp too much...


Anyone else ever try this? If not give it a try.

[CoreyMac]

I guess if you found a procedure that (gets you by) then more power to you. But you NEED AC to do a proper weld because one cycle digs and one CLEANS. If you take the cleaning cycle out the weld will be dirty (to say the least) and won't pass any inspections (if needed). If your just sticking 2 pieces of aluminum together fine but I'll stick to AC.

IMO

[ajlskater1]

I guess if you found a procedure that (gets you by) then more power to you. But you NEED AC to do a proper weld because one cycle digs and one CLEANS. If you take the cleaning cycle out the weld will be dirty (to say the least) and won't pass any inspections (if needed). If your just sticking 2 pieces of aluminum together fine but I'll stick to AC.

IMO

ya i agree. I have done some welding aluminum on dc before as kinda of quick get by type of deal for a couple buddies when my syncowave broke down at the shop at the house a couple years ago. But I definetly would not want to do it on some critical and it also kinda took the fun out of welding aluminum for me because I was not able to get that nice stacked dimes look.

[RedIron881]

IMO,

I have to disagree with you about passing inspections using DC. I have passed many NDT tests using this process (Penetrant and X-Ray), so it can do much more than just get you by. Yes, AC is preferred 98% of the time but just wanted to share with others looking for that 2%. When it is called out on the print it's handy to know how to do.

[rahtreelimbs]

You seemed to have proven your point to yourself. But I have to ask..............can you weld aluminum on AC ??? If so, why not stick to AC ???

[RedIron881]

You seemed to have proven your point to yourself. But I have to ask..............can you weld aluminum on AC ??? If so, why not stick to AC ???

Yes, I can weld aluminum on AC. I learned it just the same as everyone else that welds aluminum. Where DC comes in handy is in that photo the base plate has a vacuum sealing surface on the other side, so with DC you can get in and get out with very minimal warping. On AC with those thicknesses you have to linger around a lot longer putting more heat into the part which could warp the plate out of tolerance. Could you put the parts in a oven heating everything evenly, weld it on AC and let it cool to get less warping, absolutely. DC is just another option and in some cases with thicker parts a faster one. Which is why I wanted to share this Tip on the Tips and Tricks forum for other welders that might not have ever known how or tried it. Use it or not is solely up to the welder with the torch in their hand (and there employer...)

[bryce39]

Sorry, I had to register to comment on this. Yes, aluminum can be welded with DC and pass whatever tests given all day long! The preferred method is AC because people do not know what they are doing when it comes to aluminum DC plain and simple. If you brush the material with a stainless brush, clean with acetone, machine settings, torch angle, etc the weld will be just as pretty as AC and have deep penetration as well. The sooty layer will be present in the weld but very minimal, just lightly brush it off and you are good to go.

[rahtreelimbs]

Sorry, I had to register to comment on this. Yes, aluminum can be welded with DC and pass whatever tests given all day long! The preferred method is AC because people do not know what they are doing when it comes to aluminum DC plain and simple. If you brush the material with a stainless brush, clean with acetone, machine settings, torch angle, etc the weld will be just as pretty as AC and have deep penetration as well. The sooty layer will be present in the weld but very minimal, just lightly brush it off and you are good to go.

I would really like to see some examples on DC welded aluminum !!!

[bryce39]

If I can remember, I will take some pictures of welds on a 1/4 t joint and upload them. If everything is correct, people cannot tell the difference between DC and AC aluminum. I will take a picture of the weld before I brush it off so you know that I am not bullshitting you

[Otto Nobedder]

Bryce,

Don't be "sorry" that you had to register. All input is welcome here. I have no doubt on the DC Al. Though I've never had to do it myself, the logic is sound. The pre-clean is the key, as you don't have the electrode-positive phase to do that work for you.

I look forward to seeing the pictures, and since I love to learn new things, I may have a question or two for you and RedIron. I have a great deal of autonomy at work, so I can experiment with this there. There is an application that comes to mind where the penetration is more important than the appearance (as I assume, like most things, I won't master it in the first go )

Steve S.

[bryce39]

That's just a figure of speech, I am glad I stumbled upon this site as there are all kinds of tips and tricks to learn in this trade. I will do my best to upload some pictures as soon as my company lets me get back to welding (what I was hired for). I had the luxury of working with some pretty sharp NDT guys over the years in the space program and experimented with a lot of aluminum finding that DC is the way to go for thick to thin transitions

[Otto Nobedder]

Aerospace background explains a lot. I've known a couple of people who worked at the Micoud facility in New Orleans East, at the fuel tank assembly plant.

I absorbed anything I could from them.

Steve S.

[Otto Nobedder]

I currently work in the hydrogen chain, diagnosing, repairing, rehabbing and retesting LHY tanker trailers for APCI.

Steve S.

[bryce39]

[attachment=0]20121008_082206.jpg

[Otto Nobedder]

Ain't nothin' wrong with that!

I see in the second pic, it seemed you didn't have enough heat-soak yet to get as consistent a bead in that first inch as in the rest of the weld. Is that effect from advancing slower at the start? I have similar on welds I don't preheat (or don't preheat enough), even with He added. When I advance and feed at a very slow rate at the start of a weld, it just doesn't look as smooth as when the heat spreads out, and I can back off the pedal a bit and move with a rythym.

Steve S.

[Otto Nobedder]

BTW, Bryce,

Are you a southpaw? Or is that camera perspective?

[bryce39]

Yes, I am left handed. I picked the plate up and tried to turn it to show the best lighting scenario. Sometimes I will "pedal" the bead in by short bursts of increased amperage while adding the filler material to make the weld perfectly even from start to finish. I know it is unconventional to some people that solely believe in AC aluminum but then again, most welders are unconventional to begin with. The only time I perfer AC is when the material is ultra thin such as .040 and smaller because of the heat intensity welding with helium.

[bryce39]

Oh, yes that was the initial one inch or so because I did not preheat the plate before I welded it. Good catch man, its nice when people know what they are looking at!

[rahtreelimbs]

Impressive Bryce !!!

[RedIron881]

Thanks for the extra information Bryce! I had posted this a while back and just noticed that there were more comments, ha ha! Not sure if Bryce has answered your questions yet Steve but ask away!

[Otto Nobedder]

Thanks, RedIron,

I haven't any questions yet, because I've not had the opportunity to try it yet. 99% of the time I spend welding (which is maybe 10% of my work hours, these days), is on 304 SS, sch.10 down to .049 wall tubing. Because of an odd set of circumstances, and my odd combination of skills and experience, I've become the de-facto first-line supervisor, lead vacuum tech, lead ASME vessel retest mechanic, and the list goes on. I'm only called on to weld for critical repairs, and complicated valve change-outs. This actually means I'm usually "out of practice" when I'm called on to weld.

I WILL find some free time or a good excuse to try my hand at this, though. The logic is sound, the results are clearly sound, and I love adding another skill to my resume'.

Steve S.

[nova_70_383]

this is very interesting! do any of you think the same results could be had by running AC 99% electrode negative?? many of the new inverters can go 90% or higher like the dynasty 700 i use at my work place.

[Ballinator]

Hi Bryce,

It's refreshing to hear open minds thinking outside the box.
Would you tell us what your machine settings are?
Especially polarity, gas etc..

Thanks,
Don

[bryce39]

Sure, this setup for 1/4 aluminum plate was run with DCEN with a gas lense, 3/32 2% thorated tungsten sharpened to a point.
I like the gas lense for the even flow characteristics of the gas, minimal turbulence.
Straight Helium was used at about 15-20psi
Machine was set at about 180 amps as I like to have the option for more heat control in the pedal but actually 150 will do just fine
The machine was a miller 300 and gave you the option for clean, penetration or balance----------set it too balanced
Clean the material including your rod with acetone, brush material throughly with a stainless steel brush and then wipe again with a clean low lint wipe
Preheating the material is recommended, but I did not do that in the joint in the picture

The thing is when you clean aluminum this good, you dont need any AC for cleaning ability. Whatever you weld in life no matter what it is, it will always, always be a better weld with proper preparation including cleaning. I cannot stress this enough, the cleaner the better.

This old man I worked with years ago used to tell me that if you start with a turd you will end with a turd. Polish it all that you want but the end result is going to still be a turd, lol
Welding was created for people by people that think outside the box!

[Otto Nobedder]

I had assumed the "very clean, and right now" part.

You specify 100% helium (available to me, no issue), but at a PSI, rather than a CFH. Are you using a dry rig with a gas valve?

I've used helium as a percentage of my gas with excellent results.