[Jheatac]

Hello.

Hoping someone can help a beginner out.

I'm having extreme porosity on my second pass. The first pass goes down well for a beginner. When I try to go over it a second time it looks like a recreation of the moon.

I'm using a Lincoln SW200 @ 200a, straight argon 15cfh, 3/32 2% Lanthenated tungsten, 3/32 ER70S6, welding on 3/16 and 1/4 hot rolled mild steel. I cleaned the mill scale back from the weld about 1/2 inch. I run a wire brush over it between passes

I'm making some support poles and this is the second one from the same materials. The first one didn't have this problem.

I have tried a different set of filler. Different manufacturer and all
If I grind out the junk I can get a decent weld the first time but still can't go over it a second.

[weldin mike 27]

I feel that you have porosity in your first pass as well. This is evident in the stops that bubble up. The second pass just let's the horror out. Tig porosity is a horrible thing that we all fear and is almost impossible to get rid of once you have it. My suspicion is that you have too long a stick out. If you are using a normal cup and Collet body, you can only stick out about 3-4 mm. Gas flow also depends on the size of the orifice. So you might need to go up or down depending on the hole size. Can you get a decent weld on flat plate?

[MinnesotaDave]

Did you clean the oil out of the interior of the pipe?

Sort of looks like galvanized pipe, but you said it wasn't so that's not it.

Btw, when cleaning out the oil, do not use chlorinated brake clean spray. The fumes from any remaining liquid can be transformed into phosgene gas when welded.

[Poland308]

I feel that you have porosity in your first pass as well. This is evident in the stops that bubble up. The second pass just let's the horror out. Tig porosity is a horrible thing that we all fear and is almost impossible to get rid of once you have it. My suspicion is that you have too long a stick out. If you are using a normal cup and Collet body, you can only stick out about 3-4 mm. Gas flow also depends on the size of the orifice. So you might need to go up or down depending on the hole size. Can you get a decent weld on flat plate?

I’m seeing the same issues in the first pass.

[Oscar]

Yup, you can see a little bit of the orange dust of death. Too long of a stickout coupled with possibly too long of an arc length and you have trouble.

[snoeproe]

Second pass pulls out the porosity of the first pass. I like 70s-2 filler rod.

[EngineerIsWelding]

If your gas coverage is marginal, the different contour of the weldment(s) in the 2nd pass might make the difference by changing how the argon shield drains away.

Just for fun one time, after I messed up and had porosity on a small weld, I tried to heal it. Going over it with the same filler rod and adequate gas only reduced the porosity a very small amount. I tried 308L (or maybe it was 308L-Si) and it worked much better. Not sure why. Maybe the solubility of nitrogen in steel with a bunch of nickel and chrome is less, or maybe it had something to do with the added silicon. In any case, I generally wouldn't feel comfortable trying to heal a weld that way. Especially not something structural or otherwise important!

[JayWal]

I've had the same experience with 309. If it's something dirty or oily like maybe a welded fitting on hydraulics, I find I have less porosity with 309 than er70

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[SCsoldier04]

Yes dabbing a little as filler rod always helped me with porosity.


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[krl]

Its an old thread, but did You figured out what the issue was and found a solution?

Im also a beginner and have the same issue now. The second pass I made on one of the welds on the last project, looked exactly like this. The gas flow should be OK. The tungsten stikout might be exessive, but not sure. On thing thats for sure, is that even though I cleaned the outside on of the sqare tubing, unfortunatelly I didnt do anything with the inside.

Is it likely, that the dirt and oil from the inside is being drawn into the weld, and explodes during the second pass, looking like whats on the original picture?

Next time I fire up the welder, I will do some tests for sure, cause I need to figure this out. I will try to make double passes on the same tubing and tubing, thats perfectly clean.