[Gavin Melville]

Hi,

For some time I have noticed I'm not getting full penetration on aluminum tube.

The settings;
200+Amps AC, 25% Cleaning (or 75, Kempii is backward here), 120Hz rounded squarewave.
12 LPM Argon, electrode 2% lanthanated 2.4mm. Filler Rod 4043, cleaned of course.
Aluminum is 6261 - slightly stronger version of 6061. Cleaned. One inch square, 3/16 wall thickness. Actually 25 x 5mm.

The side faces were bevelled, the fillet joint not. I've tried gapped, bevelled, plain, plain gapped. All the same.

Yes - I did have a little oopsie and dipped the electrode. The electrode is running OK, tip kinda rounded, purple when cooled. The puddle looks OK, no cracks post weld. Some small bubbles in the weld after "disassembly".

The problem is that when I had to take some frames apart I noticed the penetration wasn't very deep. To get them apart you have to beat the daylights out of it ie. it's not really lacking strength. By day lights I mean big vise, 4lb hammer, many strikes.

Any thoughts ?

[noddybrian]

Up front I don't do much aluminum compared with other material but my thoughts are - if using 200 amps the 2.4mm tungsten is too small - surprised it tolerates it - I'd move up to 1/8" ( 3.2mm ) - 4043 filler has little inherent strength & relies on parent metal dilution - other alloys are likely more suitable but the biggest thing I think is you maybe not getting the base metal hot enough initially by lack of power or too long an arc length then adding filler till it spreads across the joint not into the root - then as it's a short run per side you are unable to chase it into the root & the weld pool is mostly over heated filler - not a true puddle of base metal with filler added this contributes to the break point being the weld - usually while my welds are not that pretty I would expect the box to break in the HAZ on the edge of the weld where the heat input affects the parent alloy not the weld - sorry if that sounds harsh - not meant to - I'm sure wiser aluminum guys will chime in soon.

[nelson]

Hi,
I'm just a noob but I would try 2 passes at high amps, 1/16 filler just to add a bit for 1st pass then cool and run a 2nd. That last pic looks scary...almost zero penetration...that plus 4043 not being the strongest alloy...

You sure that tube is similar to 6061?

[Gavin Melville]

Thanks. I see it that way too, while the AL is shiny and liquid when I start adding filler, it's not deep. I'll try a 3.2 electrode shortly.

[Coldman]

Hi Gavin,
Couple things that I see -
I think the welds are a bit cold for that joint and thickness, don't forget heat is being disbursed in three directions. Preheat may help, so would more amps and/or the addition of helium. Bevelling the joint would assist penetration.
Changing to 5356 filler would be a better strength match to your parent metal.
Finally I think those welds are under sized, put another run over the top and that should solve the shrink cracks you have there.
Rounded square wave can also limit penetration, try straight square wave if you have it.
Cheers.


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[Olivero]

Try 4943, its known to be stronger than 4043, especially in fillet welds.

I think you need to bevel more and bring your amps down, 200 A is too much for 3/32" Bring the bevel in so its a 3/16" thickness instead of 1/4" or whatever it is.

If you need to get 4943, call Hobart and ask for a sample of their maxal TIG, stuff is fantastic.

Its odd that your cracking in the center of the weld, I only ever really see that when I fusion weld aluminum which I don't really do because it almost always breaks once the joint cools and looks similar to that.

I think you might be bridging the weld so instead of welding into the joint, you are creating a blob that hits the top piece and then bottom piece but not penetrating the root. You need to wait for the puddle to generate and since your metal is so fat, you don't have to worry about burning through, so put the heat to it after beveling it, wait until you see that puddle before adding filler, you should be able to SEE the 2 pieces joining at the root.

[exnailpounder]

You don't get full penetration on AL. If you did it would all drop out on you. I think you're dipping in the keyhole and bridging the weld instead of fusing the two pieces ad then adding filler(re-enforcement). Wait for the two puddles to fuse into a point and then dip. Like Coldie said, looks like your welding cold. You should have an instant puddle ...no waiting...turn up the heat.

[Gavin Melville]

6261 and 6061 are quite close.

http://www.makeitfrom.com/compare/6261- ... 1-Aluminum

[Gavin Melville]

Try 4943, its known to be stronger than 4043, especially in fillet welds.

I think you might be bridging the weld so instead of welding into the joint, you are creating a blob that hits the top piece and then bottom piece but not penetrating the root. You need to wait for the puddle to generate and since your metal is so fat, you don't have to worry about burning through, so put the heat to it after beveling it, wait until you see that puddle before adding filler, you should be able to SEE the 2 pieces joining at the root.

I can't get 4943 in New Zealand - just get blank looks.

Agreed about bridging. I probably have two puddles which I bridge. I've always had trouble with fillet welds, perhaps this is why.

[LtBadd]

Try 4943, its known to be stronger than 4043, especially in fillet welds.

If you need to get 4943, call Hobart and ask for a sample of their maxal TIG, stuff is fantastic.

Remember he is in New Zealand, phone call might not be enough.

Its odd that your cracking in the center of the weld, I only ever really see that when I fusion weld aluminum which I don't really do because it almost always breaks once the joint cools and looks similar to that.

If I read his post correctly, the cracks are from multiple 4lb hammer strikes...

To the OP, I'll repeat what others have wrote, 5mm AL is pretty thick at 200 amps, bevel if possible, use 5356 filler if available, try preheat.

Checking a Hobart AL filler metal selection chart, they don't even list a 6261 base metal....

[exnailpounder]

Try 4943, its known to be stronger than 4043, especially in fillet welds.

I think you might be bridging the weld so instead of welding into the joint, you are creating a blob that hits the top piece and then bottom piece but not penetrating the root. You need to wait for the puddle to generate and since your metal is so fat, you don't have to worry about burning through, so put the heat to it after beveling it, wait until you see that puddle before adding filler, you should be able to SEE the 2 pieces joining at the root.

I can't get 4943 in New Zealand - just get blank looks.

Agreed about bridging. I probably have two puddles which I bridge. I've always had trouble with fillet welds, perhaps this is why.

I get the same look here. Salespeople are willfully ignorant and lazy. If they were so knowledgeable they would be high-priced welders but they choose to be parasites and sell you things and get a cut and look down their noses at the people who actually get dirty for a livin. I forgot to mention I hate salesmen and truck drivers

[LtBadd]

I forgot to mention I hate salesmen and truck drivers

Beer truck drivers?

[exnailpounder]

I forgot to mention I hate salesmen and truck drivers

Beer truck drivers?

No...not them!

[Poland308]

Ironic how you have to have enough knowledge to know what info to leav out to get what you want.

[Olivero]

Lol, its possible. Welding aluminum takes a bit of practice in general.

I understood the part of you hitting it with a hammer, it's still odd it cracks in the center is all I am saying. I have destruction tested my welds before and then normally break at the edge of the welds, more so the HAZ than the weld itself.

You don't NEED 4943, 4043 is still fine, so if its hard to get, don't bother, its just made to be a bit stronger than 4043 and especially in fillet welds but not like a night and day difference.

I used to weld fillet's like what I think is happening here, just pull the electrode out a smidge more so you can really get into the corner.

[exnailpounder]

Try 4943, its known to be stronger than 4043, especially in fillet welds.

I think you might be bridging the weld so instead of welding into the joint, you are creating a blob that hits the top piece and then bottom piece but not penetrating the root. You need to wait for the puddle to generate and since your metal is so fat, you don't have to worry about burning through, so put the heat to it after beveling it, wait until you see that puddle before adding filler, you should be able to SEE the 2 pieces joining at the root.

I can't get 4943 in New Zealand - just get blank looks.

Agreed about bridging. I probably have two puddles which I bridge. I've always had trouble with fillet welds, perhaps this is why.

I get the same look here. Salespeople are willfully ignorant and lazy. If they were so knowledgeable they would be high-priced welders but they choose to be parasites and sell you things and get a cut and look down their noses at the people who actually get dirty for a livin. I forgot to mention I hate salesmen and truck drivers

Can anyone actually dispute me on this?

[Coldman]

Those cracks are not hammered cracks they are hot short cracks (shrinkage) caused by undersized weld with insufficient heat.
5356 filler is the best choice for this joint for strength.

@Exie , I will dispute you on this.


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[Gavin Melville]

They aren't hot short cracks, it looked fine before I beat it to death. If you look at the vice marks you can see how hard it was to break.

[Olivero]

Nail,

I don't think a whole lot is demanded of store clerks or the guys at the desk in the stores anymore, they just sell the stuff they have, says MIG tip on it, well does it fit all MIG guns? Nope, but why would they bother learning it all if they are just selling supplies. I think the idea is that you know what you need and they just look for whatever you say so they don't need to know what you are talking about, just be able to spell the word you are saying which google can fix if you can't.

But I have seen some good sales people out there too, some guys that really know what they are talking about and used to work in the field but for whichever reason no longer does.

[Coldman]

Ok, I didn't zoom in for a close look. I Stand corrected. So the weld has reasonable strength for the probable duty intended already. If you want the best strength you can get out the joint then what I said previously still applies.


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[Otto Nobedder]

I see in the original pictures a complete lack of root penetration. I also saw a comment that you can't get root penetration without the weld dropping out.

That's nonsense. I see in the broken weld picture you didn't even nick the edge of the tube. You're building a weld bridge, not making a weld joint. The root must break the edge of that tube if you want strength in the joint.

Steve S

[Gavin Melville]

I realise I'm not getting root penetration, but the comment about the weld dropping out wasn't mine. A work in progress.

[cj737]

You've gotten all the right information, but its scattered all over the place within these posts...

- 200 Amps is low for the wall thickness, especially on an ally joint. Bump it up.
- Probably, your tungsten is too far away from the joint when you hold the cup into the notch. Lay your filler wire along the joint, place your cup, then look how far away it is. Ideally, it will be just farther than the filler thickness.
- Preheat both pieces to establish a puddle faster.

You can experiment with these settings by tacking. If you can get the weld to be more concave than convex, you're getting it deeper. 1"x3/16" square tubing is a fright to weld because the heat accumulates so quickly that you can not loiter once you get your puddle, but you have to get the puddle right first. Start away from the corner, then back up to it, or weld from the middle of the face around the corner to the next. Starting and stopping in the middle and tie-ins in the middle. Easier to avoid blowing out your tubing if you are welding fully around the tube.

[Gavin Melville]

Thanks,


All that makes sense. If I join the faces first and extend the weld a little around the corner I get better results on the fillets. I'll try starting in the middle on this. I've only got 230 Amps, so that will have to do.

In the past I've ended up with concave welds once I got things hot enough, needing a second pass.

I was hoping for small neat welds

[cj737]

In the past I've ended up with concave welds once I got things hot enough, needing a second pass.

You might try your smash test on those "concave" welds too. Don't discount them due to their appearance. As long as you are getting sufficient fill, the height of the weld doesn't matter as much