Porosity curiosity

[gold03]

I have a funny thing happen once in a while when I'm TIG welding. The steel starts to act like it is boiling. bubbles and spits a bunch. After it is like a Arrow chocolate bar and needs to be ground out and done over. Some times it just does it again.

Ideas?[S

gold03

 

[Dr Crankenstein]

Are you using straight Argon?

Leaking gas line? If you have a cracked hose, it can draw air and contaminate the weld.

Junk material? I've had steel with "veins" of impurities straight from the mill.

 

[headwork]

Sounds like some sort of contamination either in the steel or on the steel. The cleaner everything is the better.

 

[gold03]

I am using straight argon. My miller is new and I can't find anything wrong with the line. I think it is contamination in the steel. Now that I think about it, I've only seen this when welding on my 49. It did it on the bones from 47 too though. If I move away from that spot it welds fine.

Like I said the metal starts to boil. Spits tiny balls of steel onto my TIG torch.

Gold03

 

[pcdimis]

Make sure both sides of the weld joint have been sanded and clear of rust, I had this happen to me and it turned out that I was pulling rust into the weld puddle from the back side of the material. In some cases I have cleaned the material with Nitol (2% nitric acid diluted in water) this will generally pull any surface impurities from the material.

 

[gold03]

yeah I can see the rust thing happening. That would explain it on the bones I tried to weld. I don't think it would take much to make a mess of things.

Thanks for the input guys.

gold03

 

[ProFabActon]

Mill scale, rust, oil are not your friends. A little breeze easily will blow away your argon... almost the same result.

 

[Dirtyrat]

welding a casting will bring the impurities out of it as well...

 

[mine_us_3]

Also, having your tungsten pulled out too far will do the same thing. I agree with prior posts, it is most likely coming from rust on the back side of where you are welding. Depending on what you have for a torch head, I have only seen this happen one time, but if you un-screw your cup from the collet body there is a white plastic-ish ring that is snapped on there and I have seen it leak causing porosity.

A little tip, if you get porosity and want to just make it stop quick and cover it up, dab a little bit of 312 stainless steel filler rod in your puddle and it will go away. Don't ask me why, but it does.

 

[gold03]

Thats funny about the stainless steel trick. I might try that next time.

gold03

 

[ProFabActon]

Mild steel is one of the harder materials to weld nicely with a TIG because mill scale on the metal tends to kind of foam up... you need nice shiny clean stuff. Make sure you have nothing blowing your shielding gas away. You make try a gas lens collet body setup if you need to pull your tungsten out to reach a tight spot.
Not a fan of the stainless trick BTW. Been a professional TIG welder for 30+ years.