Help with TIG welding

[CarbedNotch]

Brake cleaner can be dangerous to use as a cleaning solvent around welding. It can generate Phosgene gas, which is poisonous, when exposed to the welding arc. Check out the following thread and link.

http://www.millerwelds.com/resources...light=phosgene

http://www.brewracingframes.com/id75.htm

Thank you for the heads up I never knew this

[Blondie_486]

I had something quite similar happen last week and again today. Seems to be in the steel as everything before the porosity laden spot welded fine and after it welded fine. Just had 2 spots in the sheet I guess where it had been contaminated at the mill. I don't know the origin of the steel as we bought it off a third party. I was also working with an aluminum extrusion (which came from an extruding mill in New Jersey (I should have stuck to the extrusions made in Jackson Ohio))over the weekend and lo and behold what did I find in it? A steel sheet metal screw. I guess quality is out the window nowdays!!!

So maybe it's nothing you've done wrong but just a bad spot in the material. The shop next door just rejected an entire load of sheet steel today because of laminations.

[popspipes]

When tigging steel it can be overheated easily causing porosity, I notice it on the thin gage pipes I make. Adding filler will fix the problem temporarily, but if overheated again it will do the same thing again.
I believe you were using a gas lens, keep the tungsten sharp, a touch of flat on the end, a contaminated tungsten will make the problem worse as will contaminated argon.
I have tigged stainless for years and the mild steel is tougher getting used to.
A foot or finger control is a great help, takes a bit of practice to get the hang of it.
Purging the tube would be good too, lack of it really shows up on thin gage materials.
I am using about 10 cfh argon .040 tungsten, 5/16" cup on the work I am doing. I wouldnt go too high on the gas flow as it can cause turbulence.

Maybe some of this will help you, I am kind of new to the steel tigging as well.

[4sfed]

I am having trouble welding some DOM A 513 tubing with my Miller Maxstar 150 STL model. the tubing is 1 1/4" OD by .095 wall, Notched at a 45 degree angle. The only area of the tubing that gives me trouble is the back side of the 45 angle, as soon as i start to drop in filler, the filler starts to bubble, if i add more filler, the weld looks okay for a second, then bubbles again, the weld there looks like a glob of swiss cheese. Thanks Alan

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Any chance you are making a closed cavity with this weld? The air trapped in a tube expands when heated and can contaminate the puddle.

Jim

[aspeyrer]

Any chance you are making a closed cavity with this weld? The air trapped in a tube expands when heated and can contaminate the puddle.

Jim

Nope, tubing was open at both ends.

[aspeyrer]

popspipes, I think i will try to weld the entire piece of tubing, except the back side of the 45 degree angle. I will weld the backside of the 45 degree angle after the tubing has cooled, like maybe the next day after, and see if it makes a difference

[popspipes]

clean and brush the area helps too, once its overheated addding filler will correct it, but dont overheat it again or the problem will reoccur.
I have found that the more quickly you do the weld the better it is for the steel as far as the gassing goes.
Different alloys of steel react differently too I have found.
You will get it, steel just takes some getting used to.

[aspeyrer]

I have been Tig welding since last Feb, and its only tight angles that give me these types of problems. The steel doesn't look "overheated". I always sand the steel then wipe with acetone.

[popspipes]

If youre welding deep in a corner, tungsten sticking out more than normal etc, then its gas coverage thats the problem.
In that situation an uncontaminated tungsten and a good cup is even more important.

[tigguy]

No contaminants on the inside of the pipe? Shipping oil, grease? Cleaned all of the mill scale off, inside too?

[aspeyrer]

No contaminants on the inside of the pipe? Shipping oil, grease? Cleaned all of the mill scale off, inside too?

actually the inside of the tubing was cleaned, it was a short piece, so cleaning wasn't diffucult. I will try extending the tungsten and upping the gas, thanks to all

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Yeah, i know, shameless plug for me