white dusting on aluminum tig welds

[Clavacle]

I seem to get a slight cover of white dust on my fillet welds when tig welding at high amperatures, does any one know the reasons/effects of this. I have tried all the obvious fixes(gas lens, changing work angles, more, less gas, ect.) to no avail. It's the same dusting that occurs normally on the outskirts of a normal weld, it just covers the weld it self. Any help is appreciated.

[Aerometalworker]

I seem to get a slight cover of white dust on my fillet welds when tig welding at high amperatures, does any one know the reasons/effects of this. I have tried all the obvious fixes(gas lens, changing work angles, more, less gas, ect.) to no avail. It's the same dusting that occurs normally on the outskirts of a normal weld, it just covers the weld it self. Any help is appreciated.

Base Material?

Filler?

Machine?

Joint type?

[Clavacle]

Base Material-6061 aluminum tube 2 x 2 x 3/16
Filler-5356 1/16th or 1/8th aluminum rod
Machine-Syncrowave 250
Joint type-fillet weld

[ZTFab]

What do you have the balance control set at?

Any particular reason you are using 5356 and not 4043...like anodizing the part(s)?

What are you using for shielding gas?

- Paul

[Clavacle]

I was using the 5356 wire because that is what the company was using befor I got there. After reading your post I was talking with my boss and we deceided to get a bunch of 4043 for me to mess around with. I am using 100% argon for shielding gas.

[ZTFab]

It sounds to me like you might be overheating the aluminum or the balance control is biased to the penetration side. What # is your balance control set to?

Can you get any pics of the weld(s) for us to look at?

- Paul

[BWS29128]

Pre-Anodized or Heat-Treated 6061?

Is the 6061 already anodized? Does in come with any type of protective coating that you might not be getting completely stripped prior to welding it? Is your base material 6061-T6? If it's already been heat treated that may have something to do with it. Let's see what SundownIII has to say about it...he deals with more of the 6061 than I do.

[SundownIII]

Clavacle,

As mentioned a photo would help us help you.

How easily is the "dust" removed? Does it wipe clean with acetone/rag or does it have to be brushed with SS brush?

Amp setting, balance setting, tungsten size/type, cup size would all help. Also, how much stickout are you using with your electrode. I generally use one or two cup sizes smaller for doing a lot of filet welds

Without the above info, I would guess that the "dust" is coming from the oxides being burned off. Since it is a filet weld, it doesn't dissipate the same as it would with a butt or lap joint.

I'm assuming the base material is not anodized.

[Clavacle]

Here are some pics for you guys. My AC balance is set at 8. I am welding with a 1/8 tungsten, with 3/16 stick out. i am using a gas lens with a #6 cup. The base material is 6061-T6 and is not annodized. The whiteness does not come off with a rag of acetone, but a scrub or two from a SS wire brush make it look like it was never there.

[HMW]

I've had that but its usually beside the bead not on it. Did you try a different bottle of gas. Sounds dumb but some just works better than others. Curious to see what you find

[SundownIII]

Clavacle,

Looks to me like there's still contamination in the bead. Hard to tell if it's coming from the base material or from the tungsten. What type tungsten are you using (old school taught pure for the Sync 250--not anymore)? I would recommend trying 1/8" zirconiated. The second photo, towards the right side, shows something (contamination) on the bead which may have come from the tungsten.

Another factor/question which comes to mind is how was the base metal cut? Was it sheared, saw cut, or cut with plasma. There have been documented cases where the base material, when cut with plasma, introduced a degree of contamination to the weld. Poster (can't remember name) had problems building an aluminum skiff with metal which had been plasma cut. Found he had to grind the edge to remove the contamination.

Balance set to 8 (more penetration) seems a little high, but the etched zone (where cleaning occured) seems more than adequate. I don't think that's your problem.

Don't know what your amp setting was, but I'd try running a little hotter and faster when using 5356 filler.

Also, I'm assuming you did a good job of cleaning the filler material (scotchbrite and acetone wipe). If not, that can also introduce oxides into the weld.

One other thing, I'm assuming you're keeping your filler in the covering gas envelope. Removing it completely and then moving back to the puddle will also introduce oxides.

Keep us posted.

[FusionKing]

I get that look on a "wash" over
I see where it had the tungsten touched before the present welding.