What causes "Green" in the Arc?

[Blaster]

I'm having intermittent issues with contamination and I'm trying to follow some clues. Over the past few weeks I've been welding the same material for these Fireworks Racks I'm making. I've made thousands of the same welds, in the same material, using the same supplies and settings.

6061 with 4043 - 1/4" Angle and 1/8" square tubing Butt Joints. After I "cook" the start of the weld a bit, see the Shiny on both sides, add the rod and max the pedal (30/70 175Hz 185-250A) and the filler immediately forms a black speckled oxide layer on top of a ball. Nasty

I'm also seeing for the first time, along the ragged saw-cut edge sometimes, a Bright Green spot (in the plasma) that forms on one side or the other and trails away. Often it happens on one of the bad starts (I don't continue the weld when it does it). Is this Copper from somewhere?

I also have seen, on just one side of the 1/8" Thorated Electrode, Bluing. I have a good 12sec Post Purge so I'm thinking it's a shielding issue (I have also just changed tanks but this only happens 5-10% of the time so, I would think "bad gas" would be more consistent). I'm inside, out of any breeze, in the exact same location on the table as all the other welds. I have changed Tungstens several times, cups, and O-Rings. Raised & Lowered the flow some but, as I said, I've been using the same settings for so long now without this happening that I don't think I have something set wrong.

Trying to find some commonality to when it happens, using a different brush, Electrodes, different batch of filler (happens on both the 3/32 and 1/8 though). I have a CK Superflex WC Torch with the ArcZone Gas Lens "kit" (Really like those ArcTime Electrodes that came with That ) But what else can I look for and what's with the Green?

[performance]

Green is contamination of the tungsten, from either the filler or the base metal. You've mentioned nothing of your cleaning techniques before welding. A saw can contaminate the aluminum. It should be dressed back, and any oil on the blade can mess with things, and hence the carbon formation on the top. You may be overheating the tungsten too.

[Blaster]

OK, so the green dot I see on the edge of the cut isn't actually originating At that spot? It's streaming off the Tungsten and just showing-up at one tiny spot on the edge of a cut?

It's not something I've noticed before, maybe it's happened and I was just not looking for a problem then

This green thing happens on a cold electrode as I'm preheating right away. I've had it happen, changed electrodes, gone back and it will still show some green.

The bluing is something else I haven't noticed before and, as I said, I'm just noticing it on One side only. It seems to be on the Same side of the torch each time and got me to change the O-Ring on the push-on collet body and change to a new cup (didn't help).

I cut everything with a Dry carbide blade, I use a SS brush, I'll try Acetone and see if that stops it from happening...

[jakeru]

Do you have an extra tank to try?

You said it just started (although intermittently) after switching the tank, and that you've done thousands of these welds.

Another idea is if it just happens when adding filler, are you pulling the molten tip of the filler away from the shielding gas too quickly? Try to make a conscious effort to let the tip of the filler rod linger in the gas coverage (with torch angle pointing a bit towards it) and don't forget to post-flow.

Bluing on the tungsten is poor gas quality, gas delivery problem, inadequate post-flow...

[TheGary]

You have probably checked this but I will ask anyway. Are all your hose fittings and your flow meter all tight. It does not take much contamination to do what you are describing. If a fitting is even hand tight it will create a vacuum and suck in air from the room and contaminate the gas. Also check along the hose for a nick or a burn spot that might be letting it draw in air. If the cup on the torch is not tight it can pull in air also. If you have too much tungsten sticking out it can do it also. If you like a lot of tungsten stick out put a gas lens on your torch, it straightens the gas flow and allows more stick out before it starts to swirl and draw in air. I am just covering some posibilities of the cause, if I have repeated something allready stated. sorry

[everlastsupport]

You have probably checked this but I will ask anyway. Are all your hose fittings and your flow meter all tight. It does not take much contamination to do what you are describing. If a fitting is even hand tight it will create a vacuum and suck in air from the room and contaminate the gas. Also check along the hose for a nick or a burn spot that might be letting it draw in air. If the cup on the torch is not tight it can pull in air also. If you have too much tungsten sticking out it can do it also. If you like a lot of tungsten stick out put a gas lens on your torch, it straightens the gas flow and allows more stick out before it starts to swirl and draw in air. I am just covering some posibilities of the cause, if I have repeated something allready stated. sorry

I have seen a bad o-ring on the back cap cause this as well.

[sportbike]

Seems like you are good to go now.

Post up a picture of the racks you are welding.