[Vince]

It's driving me nuts, cause I love welding and am getting pretty good at it especially on aluminium and stainless. It's the mild steel that's driving me insane. I'd be quite happy if it were a problem all the time, cause I'd be able to eliminate the variables to pinpoint the problem one by one; but it's an inconsistent every now and that that's driving me up the wall and I can't figure out why. Here's the deal:

- 1" round pipe, 90 deg joint to 1/4 inch flat stock both hot-rolled as far as I can tell,
- 1.6mm copper coated filler wire, sandpapered clean and wiped with pure "pro analisi" acetone (I've got a tiny chem lab too),
- #5 cup,
- Machine is a Gys 200amp AC/DC with HF, set to 160amps, but doesn't really matter since I'm working with a footpedal.
- Both pieces are clean. All mill scale ground off upto an inch from the weld, wiped with acetone
- Inside of the pipe also cleaned about 1/2 inch from the weld,
- Pipe id short, with other end open (no trapped expanding gas)
- Tungsten is clean freshly sharpened,
- Gas is pure Argon
- I weld in a dedicated room, no breeze of any kind, and I always use a 3M half-face mask when working.
- As far as I can tell, it's not a gas related issue (the machine is quite smart and will not strike a single spark if there's insufficient gas-flow, the amount of gas does not seem to matter I've tried several settings all with same result.

White-ish sparks (I guess, coz they seem green under the hood) start flying almost immediately I light up and that's way before the puddle even starts to form. Once I get to the point where I can see a puddle I already know what I'll see when I power off. The edges of the puddle pretty much boil and give off sparks every now and then. The strange thing is I can completely mitigate the problem if I use the lay-wire technique, light up on the filler wire and haste over the weld pieces, so I know it's not a filler problem.

Just to prove my point I've taken two rustiest piece of crap scrap pipes I could find and TIGed them with no filler with absolutely no sparks or porosity anywhere.


Could it be there's some crap inside one of the metals? I'd love to hear if anyone else has had similar frustrations and what you did to remedy the problem.

Kind regards,

Vince

[weldin mike 27]

Hey,

Welcome to the forum. What you are discribing is my pet hate. I gave up tig work for a while because of it. What is your tungsten stick out length? This is more critical with steel because the pool reacts so violently to atmospheric contamination . I have only about 3mm poking out as I only have a normal cup. I have heard that the filler wire movment can interupt the gas flow. Try a slightly bigger cup with minimum stick out (not to be confused with arc length) and see what happens.

Mick

[Vince]

Thanks Mick.

Great idea on the length of the tungsten sticking out. That's one of the things I have not tried yet. I normally have it out about 8 - 12mm.
One more observation I've made is that if a put the torch at a rather steep angle, lets say above 30 degrees to the weld plane (i.e. decreasing the penetration) there are fewer sparks, and sometimes if a lay the filler fast enough I can get away with almost no porosity. That's kind of why I more and more suspect metal composition as the prime reason.

I'm gonna get me a gas lens today and try a shorter electrode setup as soon as I get home.

The filler wire movement I don't think is my culprit. Sparking and crackling starts without using any filler.

Cheers.

[foamballer]

I've also come across this when there has been slag from a stick weld at the back of a joint, so when you get full penetration with the tig, it draws in some of the slag and sparks start flying.

[Vince]

I've also come across this when there has been slag from a stick weld at the back of a joint, so when you get full penetration with the tig, it draws in some of the slag and sparks start flying.

You bring up an interesting point. Aren't pipes initially curved and than machine line-welded together? Now that I think about it, it mostly occurs when I weld pipes.

[weldin mike 27]

Hey,

Glad we could be of assistance , my greatest pain, was when the welds would have porosity that you couldnt see, only bubbling up in the crater. When a second pass waa washed over, the whole thing bursts up in to junk. Try the short stick out, also try to keep the torch on a steeper angle, so that sufficient gas flows behind the torch for trailing shielding. Also if have to shallow torch angle, you will end up with undercut at the back of your puddle. Very annoying.

Mick

[Vince]

I am now armed with a whole range of different gas lens options. Fingers crossed.
The welding gurus at the local welding machine repair shop stake their reputations on there being some sort of impurities in the base metal of one of the parts; in which case the gas lens should help exactly nothing.

Edit to add: they also said that lately many manufacturers were cutting costs by adding bottom of the line ceramics even to their top of the line machines and that they eventually decided to unpack the new machines and literally throw away the prepackaged crap and replace it with decent cups. They wouldn't however say which companies resorted to such practices.

[Alexa]

Vince.

A few quick questions:

Was the mill scale brushed off or ground off next to the joint?
Does the problem occur equally if you attempt to weld only on the pipe and only on the flat bar?

What is your filler classification (ex: ER70S-)?
Will your weld be a fillet or full pen?

Tanks.
Alexa

Edit: I am curious to know if using a larger cup resolved the problem?

[Vince]

I've actually read a whole lot about weld porosity, so my last attempt (yesterday) was a bit psychotically cleaned.

Firstly ground of with an angle grinder, than filed with a fine file as to remove any sharp gouges left by the grinder, than 99.9% acetone. The inside of the pipe was firstly filed to shiny using a round file and then smoothed out using a round plug grinding stone in a hand drill, finally acetone. Hm... now I've got me thinking that maybe, I'm using the wrong sort of cloth to rub acetone; it's just an old T-shirt. Could that be the culprit? Adding that to my list of potential suspects. Cheers.

I think it's ER70S2, but don't hold me on that till I doublecheck.

If I light up on the flat bar it starts out ok, but as soon as I get to the corner of the pipe sparks start to fly. I should add that I haven't cleaned the flat-bar as thoroughly as the round pipe. Only ground it shiny. Running a clean, freshly sharpened tungsten on the flat bar works smoothly. Also I've noticed that cleaning the flat bar took much more work i.e. pressure. The mill scale removed from the pipe very very easily. Maybe thats a clue?

Cheers and thank you for all your replies.

[Alexa]

Vince.

If I understood correctly, you are able to weld the flat bar, but not the pipe.
Carbon steel pipe is weldable even without acetone, as long as the scale is removed.

Try grinding deep and flat an area on the side of the pipe , and depositing a short bead just to see if it works. I want to see if you still have the problem when you are well below the surface of the pipe. What is the alloy designation of the pipe?

Tanks.
Alexa

[Otto Nobedder]

Vince, I suspect that since you can do it fine with lay-wire, perhaps when free-handing you are pulling the filler out of the gas stream? This will immediately produce oxide on the filler that you introduce with your next dip, and the puddle will behave like welding uncleaned rusty metal, sparks, porosity, and all.

Just a thought. Next go, pay attention to your filler feed and see if this may contribute. This problem is more pronounced on small pipe because the gas tends to flow tightly around the pipe.

BTW, 12mm stickout shouldn't be an issue with a #5 or bigger cup in your draft-free weld shop, even without a gas lens.

To test whether the base metal is a factor, do the same carbon-carbon weld with 309 and see what happens. If 309 gives you a noticeable improvement, you should probably scrap your practice metal and buy a known alloy, even if drop-ends from a fab shop.

Steve S

[Vince]

Success!

After spending hours eliminating all the possible variables, I've finally found the problem. Ok, actually three separate problems which all lead to the same conclusion: sparks and porosity.

It wasn't the base metal or the cleaning or a gas problem. It's a grounding issue. Erm,... well ok it's me. I'm a numskull.

Allow me to elaborate. Since I'm too lazy to have ground (the electro positive side) permanently attached to the vise, I forget to reground the work-piece pretty much every bloody time. After a while I've notice I get so annoyed several things start to happen. Firstly I will start literally dropping the torch on my lap. I figure it's ok since I'm wearing a thick leather apron. Big mistake! Don't know why exactly but tungsten tip contaminated with partly burned leather = lots of sparks.

Second thing I do is I start dropping my filler wire on the workbench, which is naturally covered with mill scale powder since, I was too lazy to clean the work top after initial cleaning.

Thirdly and perhaps the strangest one is the fact that I'm using a magnetic square to keep the pieces at 90 degrees. It's got a little port you can weld through and I do. Having done so the filler wire is apparently magnetized a little bit while it's molten. So in effect I am constantly dropping a slightly magnetized filler wire on the workbench covered in mill scale and fine metal particles. All in all it's a recipe for disaster. Can't believe it took me so long to notice there's fine powder on the filler tip. This I think is why aluminium and stainless are always ok for me.

Having remedied all of the above I can in all honesty say that I've never been happier with a weld. Even on a few scraps I've had laying about it looks great.
That said, having tried the gas lens for the first time today, I am head over heels in love. What a beautiful, elegant thing it is. I'm never looking back.

Thank you all for contributing your thoughts and ideas on the subject. Your help is much appreciated.

Kind regards,

Vince


Edit to add: I've gone a bit to Myth buster-y about the whole research and have ended up with a few photos. Time permitting, I will post them somewhere from work tomorrow.

[Otto Nobedder]

Not a set of problems I would have expected, but I will file them away for future reference!

Glad you have it worked out!

[ritzblitz]

Congrats, having just remedied an issue I was having, I know the feeling. It's great!

[Weber Sarge]

Biggest problem I've ever had was grounding that lead to odd porosity and sparks . Make up one of Jody's hold-down fingers , just built mine and love it as it gives a nice grounding point directly close to the work .
Sarge