[Cold Lap]

Got my first TIG welder about 3 weeks ago. Have been MIG welding on and off for several years...shadetree mechanic. Anyway I am struggling with the concept that I had seemingly conquered in MIG welding, i.e. creating a single pass fillet weld using, standard parameters, that will pass the hammer test...

So far it's "no go" with my TIG welds as they appear to be breaking at the weld joint. Specifically, I am trying to create a fillet weld with 1/8" to 1/8" mild steel.
Gas: 100% argon
Gas Flow Rate: 20CFH
Amperage: 115
Polarity: DCEN
Electrode:3/32" tungsten 2% Ceriated Ground & Annealed
Filler Rod ER 70S-02 1/16"

I am attaching a view of the weld joint area after it was subject to hammer test...It appears, to me anyway, to show fusion, but maybe not enough penetration?



One question that pops up is why do welding calculators suggest a MIG machine require more amps, 160 or so, to weld the same thickness with, say .035" MIG wire? Should I even expect a TIG fillet weld on 1/8" steel to pass the hammer test with a single pass weld?

[tungstendipper]

How much amperage? Looks like your torch distance wasn't constant. Try using more amps and shorten your arc length.

[Louie1961]

We need to see pics of the weld before you hammered it. The pic you posted is not helpful to me at least.

[Louie1961]

some thoughts:

115 amps is arguably not enough. I would be at 130-ish or more
20 CFH may or may not be enough gas depending on your situation (what size cup, gas lens or not)
Ceriated tungstens are not great, and I have heard horror stories that the annealed ones cause problems with contamination-I recommend 2% lanthanated (blue band) or thoriated (red band).


https://www.youtube.com/watch?v=CqL8k8GVDtM

[cj737]

some thoughts:
115 amps is arguably not enough. I would be at 130-ish or more This is my suggestion too.
20 CFH may or may not be enough gas depending on your situation (what size cup, gas lens or not) That should be PLENTY of gas unless he's using a #12 or larger cup

But you also need to increase your filler rod size from 1/16" to at least 3/32 for 1/8" material to do a proper single pass weld. Your metal needs to be really clean on both sides and edges, then drive the weld in with some higher amps to get complete penetration of the filler rod. ER70S2 wire. Shoot a picture of the weld after you've laid it, then both sides of the weld after your bend/break test.

A #7 or #8 cup with a gas lens will serve you very well. About 15CFH is all you'd need.

[Cold Lap]

I will run another bead and post before and after pics in next couple of days. Does anyone know why the amps listed on the MIG machine suggest so many more amps required to weld same metal thickness?

[cj737]

I will run another bead and post before and after pics in next couple of days. Does anyone know why the amps listed on the MIG machine suggest so many more amps required to weld same metal thickness?

Completely different process, completely different polarity.

[Louie1961]

But you also need to increase your filler rod size from 1/16" to at least 3/32 for 1/8" material to do a proper single pass weld.

That is not true. 1/16th filler is plenty big to do a single pass weld on 1/8th material. In fact I prefer it. I find that 3/32 filler tens to chill the puddle too much.

[Louie1961]

Does anyone know why the amps listed on the MIG machine suggest so many more amps required to weld same metal thickness?

There is no one right answer, check out this video from Jody on tig welding from 80-160 amps on 1/8th inch cold rolled steel. Oh, and he does it with 1/16th filler.

https://www.youtube.com/watch?v=DmVCLi6cxok

[Lightning]

What is that, a tapeworm?

[Cold Lap]

What is that, a tapeworm?

No...tapeworm would have held up better...

[Poland308]

https://library.ctr.utexas.edu/digitize ... 1501-1.pdf
Just posted this link under another topic as well. It’s about bend testing fillet welds in a structural setting. The direction you apply the bending force can also make a good weld fail sooner than it normally would.

[Bill Beauregard]

I believe people tend to lay the torch down too far. Hold a very close arc length, and focus the arc on the edge of the puddle. You likely could weld with less argon. I don't think filler size is a significant factor, you just have to consume more of it. Don't move ahead until the puddle penetrates. TIG won't fill a narrow crack as well as stick would.

[Cold Lap]

https://library.ctr.utexas.edu/digitize ... 1501-1.pdf
Just posted this link under another topic as well. It’s about bend testing fillet welds in a structural setting. The direction you apply the bending force can also make a good weld fail sooner than it normally would.

I was hammering on it as I saw in AWS publications...but I will give this document a sniff...thank you very much! I have seen Jody etch the pieces he welds, from time to time...I wonder if he has done any videos where he put the weld to the hammer test? If so, do you have links?

[Bill Beauregard]

I feel I've seen everything Jody has done. He's into measurable, or at least repeatable destructive tests. How big is the hammer? Who, or whom? swings the hammer?

What your hammer test does show is that penetration is not what it could be. Single pass welds have attributes we desire. Less distortion is the big one, less time, less cost are attractive, but would three passes be out of the question?

Other joints are ground away to provide penetration. Filets are used very often in training because they require less joint prep. A joint such as is prepped for butt pipe welds 37.5 degrees, with 1/16" land, and 3/16" gap is easy to get full penetration. Full penetration in a filet isn't going to happen. Try to avoid judging yourself on hammer testing a filet. In real application a filet might be three passes on each side. Go ahead and break that with a hammer.

[Cold Lap]

I feel I've seen everything Jody has done. He's into measurable, or at least repeatable destructive tests. How big is the hammer? Who, or whom? swings the hammer?

What your hammer test does show is that penetration is not what it could be. Single pass welds have attributes we desire. Less distortion is the big one, less time, less cost are attractive, but would three passes be out of the question?

Other joints are ground away to provide penetration. Filets are used very often in training because they require less joint prep. A joint such as is prepped for butt pipe welds 37.5 degrees, with 1/16" land, and 3/16" gap is easy to get full penetration. Full penetration in a filet isn't going to happen. Try to avoid judging yourself on hammer testing a filet. In real application a filet might be three passes on each side. Go ahead and break that with a hammer.

Ok this makes sense and was the response I was hoping for.

I have no problem doing multiple passes but I just assumed that the parameters you see on TIG welder door charts and calculators, for a given material and thickness, were meant for a single pass weld that should not break. And since I was applying those parameters and, "failing" the hammer test, I assumed my whole approach was wrong.

But, I am inferring from your reply, that my understanding about those charts and their meaning may be wrong...maybe those charts are best used to determine guides for fusion in a single pass and not so much full penetration in a single pass?

Thanks for your help.

[weldin mike 27]

What do you refer to as pass? A single sided fillet weld will almost certainly break if hammered so the weld opens. Its just joint physics. You just need to observe what happens in the weld zone when it breaks. Yours looks fine for a beginner, as tig is very easy to get lack of fusion on. This is because people get wrapped up in the dip,dip,dip,dip,dip,dip motion that they forget to allow a second for the pool to fuse in.

[Bill Beauregard]

A hurried, or not enough amps TIG weld will fail to wet to the bottom of a filet. Where you aim the arc is very important. If you focus on the edge of the puddle, you will introduce enough heat to wet all the way down. Think WET, you want it to flow a little. That parent metal must be very hot, either from the arc, or through conduction from the puddle.

Willie

[Cold Lap]

What do you refer to as pass? A single sided fillet weld will almost certainly break if hammered so the weld opens. Its just joint physics. You just need to observe what happens in the weld zone when it breaks. Yours looks fine for a beginner, as tig is very easy to get lack of fusion on. This is because people get wrapped up in the dip,dip,dip,dip,dip,dip motion that they forget to allow a second for the pool to fuse in.

I do get a bit "dippy" for sure....I need to take few breathes in between

[Cold Lap]

As suggested...better results with multiple passes...

[weldin mike 27]

Looking good mate

[Poland308]

Even at that your bending the direction that the weld is the weakest. Bend one identical in the other direction and you will see clearly the importance of locating your welds depending on the stress that they will see.