# Failed weld on aluminum tube. Why?



## Franko (Apr 13, 2020)

I had a project where I needed to weld some 1" x 2" x 1/8" aluminum rectangular tube. I utterly failed to do it.
I'm not much of a TIG welder but I can make fairly good looking welds on butt and T joints an varying thicknesses of material Using my Miller Syncrowave 210.

This is a diagram of the weld I was trying to make.




No matter how many times I tried, all could do was mess it up. I used up dozens of test pieces.
I practiced on this a day and a half and finally had to give up and make mechanical connections.

I tried everything I could think of, concentrating the arc on the horizontal part, moving faster, slower and all kinds of adjustments to my arc.
What usually happened is when I got the horizontal hot enough, the vertical would melt and I'd end up with a horrible gloppy bead.

I suspect the problem was caused by the different relative thickness of material down the middle of my bead as on the right drawing (B and C), which is an end view of the pieces.

I'd love to be able to make this weld. I'm planning something now that I need to.

Any suggestions on how to make this would be greatly appreciated.


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## Aukai (Apr 14, 2020)

Not clean enough, any type of coating, corrosion, not enough penetration???


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## Franko (Apr 14, 2020)

Aukai said:


> Not clean enough, any type of coating, corrosion, not enough penetration???



Nope, they were clean. Brushed with a clean stainless brush and wiped with acetone.
I was able to make the T welds on the narrow (1" edge) of the material.
The problem was welding the end of one tube to the edge (corner) of the other (as shown in the diagram).


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## AGCB97 (Apr 14, 2020)

You've got the right equipment and sounds like you've got enough knowledge. Hope you have enough scrap aluminum to keep trying/practicing. Main amps setting, foot pedal technique, cleaning percent EN:EP, electrode point shape etc. all can make a big difference and a few more. Don't give up till you did it!

I once made an aluminum fuel tank out of .040 3003 aluminum GAS WELDED. It took me 1-1/2 years to learn to gas weld thin aluminum. I would try and give up, try something different and give up. In the end it came down to 2 main problems: heating the flux too fast and burning it and not being able to see the puddle good enough with the lens I was using. But I finally got it and installed that tank (actually 2 of them) in a homebuilt airplane without ever a problem.

DON'T GIVE UP, and as Keith Fenner says "git er done".

Aaron


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## Cadillac (Apr 14, 2020)

first your gonna want your seams to be tight no gaps. 
Then when you first strike a arc clean/preheat the joint with your torch run it along the seam at half pedal. 
I always tack the corners so first it’s tack and second so you have material to start and stop at so you don’t have to turn the corner repositioning. 
What’s the thickness of tubing?
Idk for some reason I like welding aluminum better than steel seems to flow better for me.  
Are you doing any kind of weave pattern with your torch to disperse heat from part to part it helps with heat control. 
Those inside corner joints should be harder than the flat joints.


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## tazzat (Apr 14, 2020)

Preheat the horizontal more than the vertical..


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## BtoVin83 (Apr 14, 2020)

Practice, practice, practice. When I first started I couldn't get anything to stick together and in time I was able to weld aluminum coke cans together, heavy end though. A guy I worked with could weld the bottoms and a friend of his could according to legend weld aluminum foil together. Granted I was using a really nice Linde machine and the experts set up the machine for me. Another thing when I first started was the focus on cleanliness, no oil and only use stainless brushes.  So one time we needed to weld up a set of fork legs, the drain hole and extensions on the leg so we tool it to a local heliarc guy. Literally there was oil dripping from the drain hole and the welder said sure, took it over to the bench and welded it all up. No cleaning or anything took about 15 minutes for both legs. Did a real nice job but this welder had a lot of experience.


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## BGHansen (Apr 14, 2020)

So just a bad looking weld or no penetration?  If it's a pigeon-dropping looking weld, it's probably just practice, practice, practice.   Your tubing is 1/8" thick wall, so maybe use around 150 A in AC for starters? 

Bruce


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## rwm (Apr 14, 2020)

What type of aluminum? A lot of stuff comes with mill finish that is actually a light anodized coating. This is almost always true for extrusions. Wire brush is not enough to remove this. And it has to be removed completely from the weld area.  You may need to sand or grind off the coating and then acetone it. Go back and heavily sand the edge of the material and re-try. Also add more filler than you think you need initially. Once you get a large puddle of filler going it will proceed more easily.
Bruce is good on the number. 130-150 Amps should do it depending on how much penetration you need. 
Robert


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## Franko (Apr 14, 2020)

Thanks for the suggestions.

I'm pretty sure it was clean. I brushed it until it was shiny and scratched. It's always been good enough for other welds on the same material.
Test beads on flat material and test butt welds were average for me (pretty good).

The picture I showed isn't the position I was welding.  It was just to illustrate the shapes.
I had the pieces clamped down flat and tight together so I was welding a horizontal surface.

It is possible my arc distance was too long. I remember the arc wandering.


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## brino (Apr 14, 2020)

Franko,

Do you have AC frequency control? If so , what setting did you use?

A picture of the results may be worth 1000 words.

-brino


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## pontiac428 (Apr 14, 2020)

I think the key to all aluminum TIG welding is heat control.  If you have a big heat sink as a work piece, you've got to get your foot into the pedal a bit, but as soon as (or before) it starts really working, you need to back way off the heat.  If one piece is demanding heat and the other is blowing out, you can control the "dwell" of your weave to favor the colder side.  Alloy is tricky, makes MIG spool guns really attractive sometimes.


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## rwm (Apr 14, 2020)

I am not saying this is definitely your problem but I have seen a lot of issues with it. Just to make the point. Here is clean, shiny, brushed 6061 sheet all set to weld:




NOT! The shiny part is the polished anodized surface. This will not weld very well at all. In fact if I keep sanding, the material will actually get more gray and dull when I get through the coating. Then it will weld fine.
Maybe this is not an issue for you but hopefully it will help someone else reading this.
Robert


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## AGCB97 (Apr 14, 2020)

Franko said:


> It is possible my arc distance was too long. I remember the arc wandering.



I would start with a sharp electrode, pencil shape. If you have trouble with it not staying that sharp (like with thick 1/4" or more) then a more blunt angle but still sharp will last longer. A round or contaminated electrode will make the arc wander all over the place. Also use the shortest arc you can muster and closest to 90 degrees as posible.
Aaron


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## Franko (Apr 14, 2020)

pontiac428 said:


> I think the key to all aluminum TIG welding is heat control.  If you have a big heat sink as a work piece, you've got to get your foot into the pedal a bit, but as soon as (or before) it starts really working, you need to back way off the heat.  If one piece is demanding heat and the other is blowing out, you can control the "dwell" of your weave to favor the colder side.  Alloy is tricky, makes MIG spool guns really attractive sometimes.



I did have to get my foot into the peddle to get the thick side hot enough to shine. Then the rod would ball up and not flow into it.
(No, I didn't leave the rod in the heat while heating. Once the base metal started to glimmer, I would start dabbing, just like it ususlly works on successful welds.)

I actually did drag out the spool gun. I was able to make it work a little, but the welds were too ugly for prime time on a client project.
I was able to make a few decent welds, but the ones I messed up were terrible. The parts I was making had several pieces and one screw up would mean to scrap the whole thing, cut new pieces and start over.



AGCB97 said:


> I would start with a sharp electrode, pencil shape. If you have trouble with it not staying that sharp (like with thick 1/4" or more) then a more blunt angle but still sharp will last longer. A round or contaminated electrode will make the arc wander all over the place. Also use the shortest arc you can muster and closest to 90 degrees as posible.
> Aaron



I've gotten pretty good at sharpening my electrodes, being the beginner that I am, I tend to spoil them often. I have a wheel on one of my griders that is used for nothing but tungsten electrodes.

Brino, I took pics but they don't show much. I'll see if I can find them. It was last year. Mostly I tried to weld over the mistakes and attempted to fill holes so many times that the original problem got covered up, especially when I tried tested with the spool gun.


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## f350ca (Apr 14, 2020)

I was welding the lower unit on an outboard one time. The arc didn't sound right and I was having a devil of a time getting a smooth weld. Nothing a flap disk wouldn't fix but was a heck of a fight. Finished up, went to turn the welder off and noticed it was on DC from the last steel I'd welded. Opps

Greg


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## Franko (Apr 14, 2020)

Here are test beads I made on flat surface to get my heat right.
On the top left with TIG, not perfect, but about as good as I can do. If I could have done that on the seam, I would have been satisfied with them.
The two on the bottom right were done with the spool gun.

But, In the middle you see what happened when I tried to TIG the joint.




Inside corner welds were not beautiful but ok enough given my skill level.


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## rwm (Apr 14, 2020)

My guess on that joint is not enough heat? It looks like the filler is just piling up and not melting into a large enough puddle. Little penetration. That weld at the top is awesome! 
Robert


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## Franko (Apr 14, 2020)

rwm said:


> My guess on that joint is not enough heat? It looks like the filler is just piling up and not melting into a large enough puddle. Little penetration. That weld at the top is awesome!
> Robert



I did both welds the same. Yet, one is good and the other sucks. It drove me crazy.
Once I had enough heat to start dabbing the rod, it wouldn't join with the part. It just balled up into a glob. More heat and the thin side of the joint would burn out.


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## erikmannie (Apr 15, 2020)

Are you using 4043 filler material?


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## pontiac428 (Apr 15, 2020)

Also are you cleaning your filler rod with a piece of scotchbrite to get the oxide layer off that, too?


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## jmkasunich (Apr 15, 2020)

I would try rather heavily V'ing out the lower tube - at least half-way thru the wall thickness, maybe 3/4 of the way.  First, it guarantees that you have clean metal.  Second, it removes some of the thermal mass from the joint.  And third (most important), you can actually penetrate all the way thru rather than just laying a bead on top of the joint.


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## Franko (Apr 15, 2020)

erikmannie said:


> Are you using 4043 filler material?



Yes, 4043 rod.



jmkasunich said:


> I would try rather heavily V'ing out the lower tube - at least half-way thru the wall thickness, maybe 3/4 of the way.  First, it guarantees that you have clean metal.  Second, it removes some of the thermal mass from the joint.  And third (most important), you can actually penetrate all the way thru rather than just laying a bead on top of the joint.



Thanks, JMK. I'll try that.

I doubt my problem is about clean material material or rod. If it was that, my test weld would have been funky, too.
I don't think I've ever cleaned a rod with scotch bright. I do regularly wipe them with acetone.
I'm pretty meticulous about material cleanliness and tungsten condition.

I'd bet it has to do with the corner of the tube being a heat sink, and probably my arc was too long and wandered.

Serendipity, Miller sent an email with a link to 10 TIG welding tips right after I posted this thread.
One of them was about too long an arc and how that makes it wander. I remember it doing that.


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## General Zod (Apr 16, 2020)

Arc length and torch angle together with unsteady hands and not enough amperage are the #1 culprit for not being able to fuse aluminum butt/corner joints from what I've seen on various forums throughout the years, and trial and error on my part.  You have good gas coverage, just make sure you dial in 1.5A per 0.001" of thickness (about 180A for 1/8" thick aluminum), because that is what you need at the beginning of the weld to get the puddle started; then you need to back off the amperage via the footpedal as the aluminum starts to quickly wick heat away into the rest of the part.  Also filler wire size plays an important role, it should not be overly large especially if you are scared to pour on the power at the beginning.  1/16" filler rod diameter, but most importantly, keep your arc tight and straight (no more than about 3mm or so, and keep the tungsten within 10-15° of the vertical/normal/perpendicular to the joint/surface), and avoid gaps!  Gaps make everything 10x more difficult.  With parts butted up together properly, you can easily pour on the power and fuse the joint almost instantly so long as you're not wearing your skirt and are wearing your big boy pants when you mash the footpedal down.  That first pic in post #17 could have been easily done if you would have just poured down the gigawatts.  Don't be scared, but in order to not be scared, keep practicing on scrap.  You need to push and "mentally power through" that initial scared-ness of using a lot of amperage by learning the timing.  Learn to pour the power quickly, but you also have to react fast because you need to learn _when _to add filler (at 90° to the tungsten I might add, to the leading edge of the puddle, and quickly! ), and when to move right along and simultaneously determine when and how fast to ease up off the footpedal. It's a large balancing act with 5-6 different variables that you have to learn how to control with precision.

As much as you described the situation, you never actually told us anything about the machine, it's settings, your technique, torch setup, tungsten stickout, arc length, or anything else that really matters.   Hopefully all those things are 100% in order, that way you can simply focus on technique which will come with practice.  I know I get out of practice quickly if I don't have any projects on the horizon, and I _have to_ get scrap the dial my brain in all over again.


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## GunsOfNavarone (Apr 16, 2020)

I'm with Brino, AC balance and consider the area your heating up. The bottom piece has more mass...whereas the top piece you just have the wall of itself to heat up. Keep you cone focused more on the area that is going to take more heat to get flowing. Sometimes dropping down you wire size on you rod could help you. Using your pedal, you may have to watch and react. If you AC balance isn't correct (normally 70/30 at least to start) its difficult to bust through that oxidized layer (which is pretty much always on aluminum)
Looking at you welds, it looks like you have enough heat to get the piece puddling, but adding that wire sucks it out. I see a lot of technique issues. Just because you rock at steel doesn't mean it will translate to steel. Make yourself a bunch of coupons, learn cause and effect. With what your doing, you may want to practice welding a ticker piece to a thinner piece. Being you puddle want to flow towards gravity, it's complicating what your trying to do, if that is how it's positioned while your welding... I know that all makes for a aggravating situation...that add all kind of issues to welding


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## Franko (Apr 17, 2020)

Thanks for the tips, General Zod.
My general method is to use the settings on the inside of the lid and tweak on practice pieces of the same thickness until it feels right.

I honestly couldn't tell you what the power settings were, It was almost a year ago on that project.
It's a good bet they were about what the chart on the door recommended.
I usually keep my foot in the peddle until I see the sluminum shine and puddle. Then back off start feeding rod and try to move fast.
I was probably using 1/16" rod and the tungsten was just slightly proud of the gas nozzle. At little further out when doing inside corners.

TIG welding is hard. Probably one of the hardest things I've tried to learn. I probably have no chance of getting real good because I just don't do it every day, and I think that's what it would take. I practice a long time before I start every project to remind myself of technique and acquaintance muscle memory. I've don't may jobs that were good enough (not too ugly) and some that turned out very pretty.


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## rock_breaker (Apr 28, 2020)

Many important things have been brought up in this discussion but not put as I would say it so here is my $ worth. When welding different thicknesses together I try to use the thicker metal to control the puddle and the amount of heat going into the thinner metal. This is based on welding steel with a DC welder and stick rod. A novice could look at my work and tell you correctly that I am not a "welder", however I have a home-made fork lift attachment for my tractor that will lift the front of the tractor with the fork tips.  

Experience  is the key factor in all of this and changing one thing at a time is probably the next important.
Have a good day
Ray


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## GunsOfNavarone (Apr 28, 2020)

Yeah...what @rock_breaker says! Good to hear you around the forums Ray...
TIG is hands down the most technical of all the welding styles. SO MUCH technique, torch height, angle, foot/amperage control, rod feed, diameter of rod, feed rate....some I didn’t even bother to post. 
Lots of good training videos on YouTube using practice coupons. I was entirely MIG many years ago, once I became proficient in TIG, I never looked back.


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