AC cleaning gone?

[Infidel]

haven't welded for a couple of days and got a new tank of argon and hooked it up today, tried to weld a tab on an aluminum tank i built and there was black crap and it was welding like i didn't clean the aluminum at all. I tried it on some new clean 6061 stock and there is no white ring around the weld and still black crap in it? I tried new tungsten, gas lens, acetone on everything including the filler after stainless wire brush. I tried everything from 10%-50% ac balance and nothing? could this be bad gas? I also tried changing flow from about 5cfh-20cfh I wouldn't think bad gas would make the ac cleaning disappear?

Machine is 250ex, about a month old, haven't had a single problem yet and machine is welding perfectly, here is the last weld i did before switching out the bottle.

[zoama]

Sounds like bad gas to me. Take the tank back and swap it.

[Infidel]

I hope it is bad gas, unfortunately i have no time to exchange it this week now since this was my only day off and they are already closed. I tried it on some cold rolled steel in DC and it seemed to work fine? I didn't really get any pinholes or anything. I flipped it back to AC and can hear the frequency so i know AC is coming on, but there is absolutely no ac cleaning at all. every once in a while it will kind of start to come back then go away again. I got the bottle from Praxair, and I'm not going back to the place after i swap the bottle anyway. last three times I've gone in the fill rate went from $35 to $45 an today $56.....less then a month on all three, wtf.

[zoama]

Can you post a pic of the bad weld ?

[Brian Ski]

Can you post a pic of the bad weld ?

Good idea... BTW what would the weld look like with Argon co2 mix??? Just curious if their is co2 in it.

[Infidel]

So here is a random weld on the same plate about a week ago, near same specs. nice even AC cleaning, and pretty clean looking weld. The next one is with the new bottle. lol. notice the lack of cleaning and black stuff in the weld. I also found this thread on another site that seems to be pretty close to my problem. http://weldingweb.com/showthread.php?t=62633

[Rambozo]

I got the bottle from Praxair, and I'm not going back to the place after i swap the bottle anyway. last three times I've gone in the fill rate went from $35 to $45 an today $56.....less then a month on all three, wtf.

Sounds like you need a bigger bottle, too.

Since you can hear the AC and there is some cathodic etching even around the bad welds, I would bet on bad gas, too. I've never seen the results of trying to use 75/25 on aluminum, but that would be my guess. It would be nice if there was some easy way to test gas. I know for other applications there are little glass tubes that have a color changing chemical inside to test gases. It would be nice for something to distinguish pure argon from 75/25 gas blend.

[zoama]

If you were using 5356 filler and your new bottle contained some CO2, the magnesium in the filler will react with CO2 forming magnesium oxide and carbon.

[Infidel]

i only got 4043, and i tried rods from 3 different batches earlier, no luck, i'll be sure to give you guys an update when i get the new bottle and try it out.

[Winky]

I’m glad it turned out to be just bad gas … strange the way it looked. I’ve had moisture contamination before but never anything like you’ve encountered. Just upgraded from an 80 cf tank to a 150 tank … haven’t used it yet … I’ve always done business with Airgas I find them to be pretty good; only once have I found their info to be faulty … when they tried to convince me to use pure tungsten … my bad … probably should have specified I was using an inverter LOL.

[Infidel]

Since i said i would update once i got a new bottle here's what i've done this week, all the aluminum is on the new tank, except the catch can on the left, and the coolant surge tank. welder is doing great.