[sausageroll]

Hi Everyone,

As a spinoff from my other thread (about keeping the electrode clean, which I have now mastered, thanks for your input) I am now wondering about something else.

I have noticed that now I am using 8 seconds of postflow to keep the electrode shiny, the very ends of the weld are coming up with that loverly purple yellowy colour. The rest of the bead however, is not. Im just running ugly lines on a bit of stainless here, mainly to test that the electrode stayed shiny after a few mins of welding, rather than actual practice.

So my thoughts are, clearly the argon shield is what makes that colour appear in the end of the bead. Am I welding too fast? (removing the shield before the bead has cooled) or should I use higher gas flow? (tried that, didn't seem to help much) or a bigger cup? (tried no.6 and 10 and marginal difference)

Is it just a skill thing of hitting the sweet spot with the power so it cools quickly whilst still in the shield? Im welding 2mm stainless plate and I tried varying currents from 20 amps (unstable arc) up to about 90 amps and I tried going slower and faster but all kinda look the same.

Any input would be great.

pete.

[Wes917]

Looks like you need to clean your material better. Scotch brite it and wipe it with acetone. 2mm is close to .080 I'd set my machine around 70 amps and use the pedal. What angle are you holding your torch at? This could cause this also. What size cup are you using? I'd use a 7 cup and gas lens and a 3/32 tungsten. You could use 1/16 but 3/32 is usually what's in my torch.

[Otto Nobedder]

The biggest culprit, and I'm guilty of this ALL the time, is putting in more heat than the weld needs. That, with a "push" angle, lets very hot metal see atmosphere before it's "set", or immune to the effects of atmosphere.

If it wire-wheels clean, let it go. I do x-rayed, ASME coded welds often. They are dark grey when I'm done. They shine up nicely with a wire-wheel. The welds always pass. (I hope I didn't jinx myself by saying that... )

Don't sweat the color too much yet. You'll find that sweet spot with time and practice.

Steve S

[Superiorwelding]

I also agree on to much heat input. Lower your amps or increase your travel speed and you will be fine. What thickness is the material?
-Jonathan

[steeldr.]

When practicing as per your picture, increase your speed and always start a new weld bead on a cool part of your test plate.Also,if the test plate is too thin, there isn't enough material to reduce the temperature of the weldment (bead) after the bead is exposed to the air. The dark color on the beads are oxides, they are formed when the weld is exposed to the atmosphere (out of the argon envelope from the cup), this occurs at aprox. 800 deg.F.
hope this is of some help.


ron.

[Oscar]

I'd venture to say you are using way too long of an arc and too much torch angle, which again contributes to too long of an arc length. For 2mm stainless, you need to hold an arc length around 1mm or less, and also reduce your stick out as much as possible. Welding in "stitches" also helps with minimizing the localized heat input---try 3/4" long beads, then back-step another 3/4". Practicing on the same heat-soaked piece over and over again is an exercise in futility. Get multiple pieces to practice on, otherwise you're just chasing your own tail.

[Mongol]

There is some good advice here but I would suggest that if you start changing thing just change one thing at a time. If you change five things at once you're not going to know what it was that helped the most should you come across the situation again.

And Steve makes a good point, if it cleans good it usually is good. BUT, I will say that when I took my stainless pipe test for my current job I was specifically told not to brush the weld when i was done. But they still make us brush all our welds, even if it's a gold ring all the way around.

And if you're really concerned about heat input and color, take a look at this article: http://www.bssa.org.uk/topics.php?article=140

[sigfreed14]

that sounds nice purple and yellow . that yellow color is called straw ask any good blacksmith. befor tig and stick mig and all that good stuff they had an anvil, Forge .coal coke car coal a bellows. forge welding it still works today. DA a Big ass hammer to pound the dog u know what out of . the colors look cool . keep up the good work good luck.