alum weld help

[ja baudin]

Ive heard it was the silicon boiling out because of too much heat/ not moving fast enough. Doesn't happen with 5xxx series because no silicon is present.

Don't know if that's correct though.

[H80N]

Ive heard it was the silicon boiling out because of too much heat/ not moving fast enough. Doesn't happen with 5xxx series because no silicon is present.

Don't know if that's correct though.

In my case anyway... do not think it was moving too slow and cooking the puddle... but the few times that I have encountered it... I had no idea which alloy I was welding on...unmarked and unknown...may have been 7000 or 2000 series "unweldable" ... so we may have ended up with a metalurgical frankenstein....

in the cases where the pics are posted here the beads do not look overheated or flat either... I am just as curious as everybody else...
Am hoping that Galen and his crew of weld engineers and technicians can find a good answer for us...

[ryanjones2150]

alum weld help

On one of the parts I was working on here at the house where I had that problem, I took it to the drag shop and used the transformer machine (I have an inverter at home). Using filler metal from the same tube (4043) on the transformer machine, I didn't have that problem. I wonder if the difference in power sources has anything to do with it. Aside from that, pretty much everything about the machines is different, hose, torch, etc. Add to that, I originally thought I was using 2% lanthanted tungsten, but today I pulled my tungsten out to freshen it up and it was thoriated (for sure though the tungsten at the shop is 2% lanthanted). So there is a chance it's the same one, but that was a while back AND I welded some aluminum today with that thoriated and had no problems...nice and shiny and smooth.

Thanks for posting that tid bit from Hobart. It's good to know people.

[H80N]

Ryan

you might want to download the "hobart guide for aluminum welding"

it is a free PDF that will help sort out which fillers are best for each alloy, setup parameters...selection etc...

http://www.hobartbrothers.com/downloads/HobartAluminumGuide.pdf

you might also consider picking up some Hobart/Maxal 4943 filler the next time you are at the LWS... it replaces 4043 in most applications.. with improved wetting, flow and strength..

http://www.hobartbrothers.com/product-details.html?name=Hobart%26reg%3B+MaxalMig+4943

http://www.maxal.com/MAXAL_4943_Draft_Final.pdf

[ryanjones2150]

alum weld help

Excellent, I'll do that. Plus, when I go into my LWS, this gives me something else off the wall to ask for! They pretty much expect that from me, but here lately, my jobs have been pretty run of the mill. So I'll bet a hamburger dinner that the guy at the counter will have never heard of Hobart 4943 filler metal. Thanks again!

[ryanjones2150]

alum weld help

As I expected, never heard of 4943 filler metal. But, surprisingly enough, they actually stock it...just not in TIG wire, mig only. I can't expect them to know every single thing in their stock room of course. But this place is leaps and bounds better than the big national companies I've experienced. Went into one the other day, the name of the place starts with air and ends in gas, asked for a #17 TIG torch...guy told me there is no such creature or he's never heard of such a thing. At first, I thought he was messing with me. Nope, even after I showed one to him that was laying on his shelf, he still said he's never heard it called that. It only says it on the side.

[pat h]

Agree with everything in the above post, however where strength is really lost in a real world test, is vibration/flex, as the hazed area will fail with much less input then 27ksi, when vibration is introduced. All metals exhibit this, how many welds i have i seen fail, very few, but next to the weld, where the metal was overheated, undercut, or poorly fitted is the failure break.

100 percent agree

[pat h]

Can't figure out what's going on here any ideas what would cause the tiny bumps?

what material
what welder what filler

welding a crack or over surface what thickness didn't look like a nesasary weld I call bs on the whole thing, but I agree with previous post.

[H80N]

As I expected, never heard of 4943 filler metal. But, surprisingly enough, they actually stock it...just not in TIG wire, mig only. I can't expect them to know every single thing in their stock room of course. But this place is leaps and bounds better than the big national companies I've experienced. Went into one the other day, the name of the place starts with air and ends in gas, asked for a #17 TIG torch...guy told me there is no such creature or he's never heard of such a thing. At first, I thought he was messing with me. Nope, even after I showed one to him that was laying on his shelf, he still said he's never heard it called that. It only says it on the side.

Ryan

who i your LWS..?? where??

[ryanjones2150]

alum weld help

Coastal Welding Supply is my preferred one here in Beaumont, TX, but there is also the national companies, tri-gas, Praxair, and airgas. The national companies really don't like dealing with the one-man-shows like me. They prefer to deal with the big industrial contracts here since we're in the heart of the petrochemical industry. Coastal really is pretty good, you just either have to know what you're looking for or have a good relationship with the guys there, like I do. They've even offered me a job. Plus, they're open until noon on Saturday.

[Hobart Aluminum]

sorry for the late reply

Hey guys,
Sorry for the late reply. I've been on the road pretty much non-stop and I've been struggling to get caught up on emails when I came across Heiti's' email.

I spoke with Bruce Anderson who was the former owner of Maxal (and Alcotec) and who was one of Alcoa's metallurgists back in the day and he has seen this situation with both 4XXX and 5XXX filler metals and he is certain that the rough surface is aluminum oxide islands. If you look in the original picture you can see that the % EP (the portion of the AC waveform that cleans the oxide off) was probably turned down to much. There is almost no etch zone along the edges of the weld and since all aluminum has oxide on it (unless you mechanically remove it by sanding, wire brushing, etc) it floats to the surface of the weld and solidifies there.

I think inverters are more likely to exhibit this phenomenon because they are more adjustable in regards to AC balance and adjusting the amperage levels independently on EP and EN whereas transformer based TIG welders are not able to adjust nearly as far to the EN side of the waveform if they are adjustable at all.

This aluminum oxide (and even more detrimental is hydrated aluminum oxide) can come from the base metal, improperly stored filler metal, removing the filler metal from the shielding gas envelope while welding, drafts or fans slightly blowing your shielding gas away which allows small amounts of humid air to contact the molten puddle and produce more oxide, absorption of moisture into the gas hoses which introduces moisture into the arc, etc.

Bruce mentioned that many years ago a customer complained about this very problem and what it turned out to be was that he was storing his filler metal in an open metal tube sitting on the floor. There was enough temperature differential between the surface of the floor and the air temperature at the top of the cut length that over time moisture would condensate on the bottom portion of the filler and form hydrated aluminum oxide. If you held up the filler up to the light under the right conditions you could see the bottom half of the filler metal was frosty white (indicating that the oxide had absorbed moisture).

Also, a few posts back someone mentioned that in a transverse butt weld that the weld will always fail in the CL (centerline of the weld). This is not necessarily true unless the filler strength is not as strong as the HAZ or there is some discontinuity in the weld. If the correct filler metal is selected for the base metal and the weld is performed correctly the weld should fail in the HAZ. Here is a graphic from NASA showing 6061-T4 welded with 4043, 4643 and 4943 and you'll see that in all cases the weak link is the HAZ (you can see the filler metal strength in the center of the weld is strongest with the 4943).

The moral of the story in full penetration transverse butt welds is that as long as the filler metal strength is at least as strong as the HAZ there isn't much benefit in choosing the strongest filler metal.

Do not be disheartened!!! Most welds made in production are fillet welds where the weld strength is DIRECTLY PROPORTIONAL TO THE FILLER METAL STRENGTH so choosing a stronger filler metal has huge benefits.

Hope this helps

[H80N]

Thanks Galen...

we know how busy you are..

the response and info were well worth the wait...

[WillieB]

I'm reluctant to admit I don't understand the graph. Is it showing distance fron the center of the joint? Or is the weld bead in the center with two HAZ, one side different from the other?

[aametalmaster]

Or is the weld bead in the center with two HAZ, one side different from the other?

That's how I see it...Bob

[H80N]

Think this presentation should clarify it a bit....

http://awo.aws.org/wp-content/uploads/2014/energyconference/TonyAnderson-TheUseofAluminuminCryogenicApplicationsandNewFillerMetalDevelopments.pdf

Do not let the cryo part confuse the issue... just look at the specs and results...