Aluminum TIG skin

[WillieB]

Thicker stock, running beads, lap joints, and fillet welds are no problem. 16 gauge 6061 butt welds or outside corner joints run well for inches, then keyhole, and start to form a grey "skin", It becomes hard to get a shiny puddle to form. I struggle with it eventually getting the hole filled. I don't notice the inches of perfect, I notice the ugly mess I had to fix. I can't help thinking it is a gas issue, I've usually used 12-15 CFH with gas lens with #8 cup, and 3/32 thoriated or 2% lanthanated ground long point and blunted like a slightly used pencil. I find it difficult to use 4043 1/16" 3/32" is less prone to melt before it reaches the puddle. Bringing it in from the side seems to help a little, but doesn't cure the problem. I'm holding the torch 15 degrees off perpendicular to the bead, and square to sheet or splitting the difference for the corner joints. A copper backer doesn't seem to help.

How do I fix this?

[H80N]

Argon flow might be a little bit low for the gas lens...

are you cleaning the areas to be welded..??

stainless brush.. acetone etc...

there may be a heavy oxide layer that you are fighting...

what are your settings..?? amps... freq... balance... etc..??

weld pics..??


anything here look familiar..??

http://www.millerwelds.com/resources/articles/common-TIG-GTAW-welding-problems-visual-guide-graphic

[WillieB]

New sheet, washed with acetone, then abrasive cleaned, various brands of the discs described as stripper. Norton calls them Blaze. As I once had a similar problem while using mostly worn discs, Ive tried a Radnor stainless 4" disc brush, a small drill chuck style stainless brush, Scotchbright pads, and an all carbide burr. I am convinced I've cleaned thoroughly. This doesn't behave like dirty metal. Dirty metal will wet out, and clean, but leave black specks in the weld. This is forming the grey "skin" I see when I've experimented with DC aluminum. I've tried varying argon flow. When I see experts do it on you tube, it all happens without problems.

[H80N]

New sheet, washed with acetone, then abrasive cleaned, various brands of the discs described as stripper. Norton calls them Blaze. As I once had a similar problem while using mostly worn discs, Ive tried a Radnor stainless 4" disc brush, a small drill chuck style stainless brush, Scotchbright pads, and an all carbide burr. I am convinced I've cleaned thoroughly. This doesn't behave like dirty metal. Dirty metal will wet out, and clean, but leave black specks in the weld. This is forming the grey "skin" I see when I've experimented with DC aluminum. I've tried varying argon flow. When I see experts do it on you tube, it all happens without problems.

Did you look at the link I posted??

where you could start settings.. (courtesy of Sundown III..)

AC
Set frequency to about 120
Postflow set to about 8 seconds.
Amps to about 80. (You won't need it all but control with pedal)
1/16" or 3/32" Tungsten sharpened to a crayon point (I prefer lanthanated or ceriated)
Balance set to 75%
No pulse

[WillieB]

Did you look at the link I posted??

where you could start settings.. (courtesy of Sundown III..)

AC
Set frequency to about 120
Postflow set to about 8 seconds.
Amps to about 80. (You won't need it all but control with pedal)
1/16" or 3/32" Tungsten sharpened to a crayon point (I prefer lanthanated or ceriated)
Balance set to 75%
No pulse

After reading your link, I tried your settings with better success, It's still a problem back stepping a long bead. As I start a short section, I find it necessary to heat away from the joint keeping the arc from blowing through the gap that is sure to form until everything is hot. Then I can move in, bridge the gap with filler, then, focusing the arc on the wet puddle of filler, Im able to move along at a reasonably quick pace. The resulting weld bead looks flawless with not crisp stack of dimes but discernible, even ripples. It seems the secret is not allowing arc or gas,(I don't know which) to pass through the gap. I'm usually using a backer bar of 1-1/2" copper square stock. I have two pieces 6 & twenty inches, one corner is radius-ed to leave room for the back of a bead. I've ruled out the cause of the problem being the copper by not using it sometimes. Might my problem lie in the gas lens? Is it diffusing gas to the extent it looses concentration as it passes into the gap? I've had enough tonight. Tomorrow night I'll try a plain cup to see if Different gas flow helps start this joint. It's a lot of trouble and expense, might back purge help?
These scummy, difficult, ugly starts are frustrating.
Once again, thanks for your help!

[WillieB]

PS Someone needs to do a tutorial for dummies on posting a digital photo I find TIG welding kitchen foil easy compared to using technology, I need physics to explain how something works. Physics say this stuff won't work!

[H80N]

Andy Aluminum TIG Videos...

Willie

here are some videos that Andy did on Aluminum..

lot of good technique in them..

http://www.youtube.com/watch?v=FadO0hqTaN0

http://www.youtube.com/watch?v=6ay_oYg0LUo

http://www.youtube.com/watch?v=oTZfDndPkl0

http://www.youtube.com/watch?v=FpxzVq6YsoM

.

On posting pics....

http://www.millerwelds.com/resources/communities/mboard/showthread.php?14055-Posting-Pictures-on-the-Forums

[WillieB]

Willie

here are some videos that Andy did on Aluminum..

lot of good technique in them..

http://www.youtube.com/watch?v=FadO0hqTaN0

http://www.youtube.com/watch?v=6ay_oYg0LUo

http://www.youtube.com/watch?v=oTZfDndPkl0

http://www.youtube.com/watch?v=FpxzVq6YsoM

.

On posting pics....

http://www.millerwelds.com/resources...-on-the-Forums

I tried with coaching to upload photos! I'm going to next try to take photos and upload.

Andy's series of videos is great, but doesn't address my issue. On flat, fillet even inside corners, and especially on flat beads in the middle of a sheet, all goes fine. my issue is when there is a joint. Cleanly cut sheet in a butt joint or outside corner joint tacks OK if I can make it happen in one second or less. If it takes more a grey skin forms, I must add heat, the thin (1/16" and thinner) either melts a hole or expands to create a gap. Even clamped together a gap forms as it melts away. I'm convinced it's bad gas coverage in the joint causing oxidation to form. My brain tells me for penetration I want to focus the arc at the leading edge of the puddle where some of the arc is directed down the gap. In practice, this causes a keyhole and the skin making it impossible to wet the advancing bead. I find it essential to keep the arc back fully on the wet puddle. Backstepping a long joint, it is necessary to restart a bead at frequent intervals. it's these starts that trip me. also, if I get too far ahead of myself allowing arc exposure into the open joint, once again I'm screwed! A hole opens up, skin forms, I pause, move into hole fill mode. It wastes time, money, and worst, it looks bad.

[Ltbadd]

If I understand your problem, here's what I suggest. Heat flows thru aluminum very fast, when you start the metal is cold and as you progress the thin sheet is heating up so after several inches what was originally enough heat is now too much and your seeing the result. So as you progress you need to keep the puddle full, move fast and even back off the amps.

[FusionKing]

What you are doing wrong is probably nothing. You more than likely have everything prepped and set correctly as well. In fact you are more than likely doing way more to get good results than you ever will at some point in the future.

If I could be there I would be able to help you more in 30 seconds than all the videos in the world. All because on videos they don't mess up on purpose!
The only thing I see you doing wrong here is overthinking. You want it to keyhole IMO in many cases esp. When repairing something.
This "skin" only happens when you "fry" the aluminum.
You need to get braver about dabbing the rod in....faster may be a better way to put it. Wet-dab-wet-dab etc.
when you get "good" you'll know when to stop a sec and let it cool. When you get really good you'll speed way the heck up when you know it's getting too hot.
There have been several guys here in the past who have basically described exactly what you are saying. It ain't gas......you just are putting in too much heat for your speed. It's called technique.
You'll get there, just keep trying.
For what it's worth tho.....I would never practice butt welding 16 ga sheet. There is virtually no purpose on earth for that. Proper fabrication would always eliminate a weld like that. At least almost always.
I hope this helped some

[H80N]

Well put...

I agree that you are probably cooking it....

aluminum wants you to move at a pretty good clip.. (especially the thin stuff)

was hoping to see some pics of your "problem" beads...

[WillieB]

What you are doing wrong is probably nothing. You more than likely have everything prepped and set correctly as well. In fact you are more than likely doing way more to get good results than you ever will at some point in the future.

If I could be there I would be able to help you more in 30 seconds than all the videos in the world. All because on videos they don't mess up on purpose!
The only thing I see you doing wrong here is overthinking. You want it to keyhole IMO in many cases esp. When repairing something.
This "skin" only happens when you "fry" the aluminum.
You need to get braver about dabbing the rod in....faster may be a better way to put it. Wet-dab-wet-dab etc.
when you get "good" you'll know when to stop a sec and let it cool. When you get really good you'll speed way the heck up when you know it's getting too hot.
There have been several guys here in the past who have basically described exactly what you are saying. It ain't gas......you just are putting in too much heat for your speed. It's called technique.
You'll get there, just keep trying.
For what it's worth tho.....I would never practice butt welding 16 ga sheet. There is virtually no purpose on earth for that. Proper fabrication would always eliminate a weld like that. At least almost always.
I hope this helped some

The butt weld I've only done as practice. I can do fit up perfectly by using a big flat belt sander. Most of my sheet welds are outside corner. On thicker material I.E. oil tank, I can make a perfect keyhole just wide enough to provide full penetration, and a smooth radiused profile inside. Thin stuff, the keyhole expands instantaneously after skinning over. I'm then a hole filler, not a welder.
I appreciate your help on this, it's very frustrating!

[WillieB]

Well put...

I agree that you are probably cooking it....

aluminum wants you to move at a pretty good clip.. (especially the thin stuff)

was hoping to see some pics of your "problem" beads...

I'm on my way to posting pictures. I caught up with my son long enough to take a random picture of the dog from the computer and post it. If I can remember the process I can do it!!! The last photograph I took was with 35 MM type film, 1982 Cannon as I recall. I have a mild case of a techno phobia. Technology isn't good for my blood pressure!

[H80N]

I recall. I have a mild case of a techno phobia. Technology isn't good for my blood pressure!

Techno Phobia..???????????????????????

E-GADS Man..!!!!

you have purchased a Miller Dynasty 280DX....

Probably the most advanced techno welding device available without holding a TOP security clearance...!!..

Once you master that... YOU WILL BE THE KING OF THE UNIVERSE..!!!

http://www.youtube.com/watch?v=MYjzOl3lACU

Keep on pluggin... you will get there...

[WillieB]