Soorty aluminum weld

[cpbeattie]

I am new to aluminum welding but not to MIG. I am using a MM180 with the Spoolmatic 100 with .035 inch 4043 wire. When I have tried welding coupons I get a nice looking weld but a black/brown soot (referred to as "smut" in some manuals) along both sides of the weld. I am use pure Argon, clean the metal first with acetone and use a dedicated SS brush to clean off the Al oxide per instructions. The wire is over 2 years old as is the Argon gas. Could that be an issue?

[Daniel]

If the wire was still in a sealed wrap, it should be alright.
Argon flow at about 20 to 25 cfm. The angle of the spoolgun should be 90 degree to the work to 5 degree pushing the puddle.
That's the way I find the best for the cleanest weld. Once you're done with the pass you should be able to wipe the little bit of soot created with a wipe of your glove. You'll never really be able to get a soot free weldment with a spoolgun, but very close though.

[cpbeattie]

Sooty Aluminum

Daniel: Thanks. No, the Al was unwrapped and on the spool gun for 2 1/2 yrs. What is worrying me is that my welding supplier said that he thought the Argon could have gone bad. I have never heard or read of that. I did buy a new spool of 4043 and will try it out tomorrow. Now learning how sensitive Al is to oxidation. Learning goes on forever.

[aametalmaster]

http://www.thefabricator.com/article/aluminumwelding/how-to-recognize-minimize-weld-smut

[cobymoby]

In the past I have received bad bottles of gas and even empty bottles with the plastic shrink wrap still on the valve.

I would swap out that tank since it has been sitting for so long.

[big mike]

Unless the gas fill plant is a real $#!* hole or they use shoddy processes each cylinder is vented,vacuumed and filled.I would buy getting an empty cylinder but "bad gas"? I would say is highly suspect.
The argon "went" bad?.......inside a cylinder?That counter guy needs to go back to gas school.
Depending on cleanliness you could have.....insufficient flow,oxidized wire or gun angle issues.

[Country Metals]

It is possible that a new guy was filling bottles and he grabbed an argon bottle and filled it with 90/10 or something like that.

[cobymoby]

The empty bottle thing has happened twice. The bad gas thing has happened once. You know what happens when you run a bottle empty and it starts sputtering on TIG? The whole bottle was like that. I could feel the gas flow but it was as if it was not argon.

[cpbeattie]

Sooty Al Welds

Thanks to all for replies. The article from thefabricator.com was very good and anyone wanting to know a little more about GMAW welding of aluminum should read it. I tried new wire and it didn't help. I don't have a picture of my welds but just imagine 2 very dark stripes on both sides of a clean weld. So, either the gas shield is insufficient because of my cup to work distance/technique or the gas is something other than pure argon. I'll work more on my technique and if that doesn't help I'll exchange the tank and see what gives then. Life without a challenge would be no life at all.

[Country Metals]

I did some aluminum welding about a year ago and I could not get the soot on one side of the plate. I tried everything even pointing the gun angle at a severe angle just to place the soot. I ended up fabricating new plates and it solved the answer. I still have no idea why it happened. They were both 1/4" plate, small bevel, cleaned w/ new sanding pad and ss wheel, and both pieces were from the same plate.

It could have been a job that was messing with me. It happens about once every 3 months or so.

[cpbeattie]

Sooty Al Weld Pictures



Here are a couple of pictures of my sooty (smuty) Al welding using a Spoolmate 100 on my Millermatic 180. I use 100% argon (or at least that is what is labeled on my tank) and welding techniques specified by Miller--fwd drag, etc. Any ideas. I changed to a new roll of Al .035 wire too. The welds to the left on the first pic have been cleaned by a bursh. I can also clean off the smut by wiping down with a cloth. The various lines are at different wire speeds and voltage. Any ideas? Or ,is this all normal? I can't say as it is the first time with Al. Chuck

[bob_e95482]

The black smoke is typical of spoolgun Al welding. Make sure to push, not pull, the weld. If you pull, the smoke will be in the bead. I use a weave and can get a stack of dimes looking bead.

[cpbeattie]

Sooty Al Welds

Thanks Bob. I didn't know if this was normal or I had bad technique, wire or gas. I know the welds are shiny so think the gas shield is working pretty much. I was just wondering about the black soot along the sides. I assume after making a tack you have to clean the tacks of the smut before completing the weld. I know TIG is better for Al as all of the boatyards around here have a TIG welder for repairing boats with SS or Al. I'm just a hobbyist playing around with the fabricating small things for personal use. Chuck