Contamininated Stainless TIG welds

[Winnfield]

I am welding 304 Stainless tubing, and my welds seem to be getting contaminated somehow. As I am welding, I can see a crust forming around the puddle. I can weld through it, but when I am finished, it almost looks like there is some slag on the weld, but its as hard as the metal, it seems. I am using Argon shielding gas at about 20 cfh, and my filler is 308L(?) Could the filler rods being handled by hand cause this kind of contamination? Sometimes the weld are beautiful, other times, they look like crap. When I am welding, I can sometimes see the crust forming after I dip the end of the filler rod in the puddle. Could I possibly be taking the rod too far away from the puddle occasionally? Does it have to stay under the shielding gas? Thanks for any help...

[boykjo]

Sounds like to me you have some stainless with some trash in it. Find some 316 and see how it welds. Not knowing your abuilities, if you are a beginner watch your heat (amps) 40-50.. your weld should have a rainbow color when done..........

[Rocky D]

Are you back-purging your part?

[Winnfield]

Thanks for the responses guys....I have been welding it at about 42-45 amps and I am back-purging. I had a couple weld today turn out perfectly, but most of them exhibited the same problems. I am really beginning to suspect the filler rods. Is storage/handling/cleaning of the rods critical like it is with Titanium? I know the last time I welded Ti, if I touched the rod with my bare hands without cleaning it off it caused problems...

[Rocky D]

No, it is not as critical as Ti welding, you could have contamination on the inside of the tube. Wipe everything all down with acetone, and see if that helps.

[Winnfield]

I bet thats the problem!!! Thanks! I think I wasn't cleaning the cutting oil from my tubing notcher out of the tube.... Thanks, man.

[atlantafab]

maybe your filler is not as clean as you thought? or possibly the base metal needs to be cleaner.
- uh, yeah - guess you got it