Shiney stainless TIG welds

[kjlindgr]

Hey all. I've done a lot of TIG welding in the past but I've always wondered how some of these guys get the shiney rainbow colored welds on stainless. My welds are usually grey and dull looking.

I hear from talking to others that I'm welding too hot and basically cooking the welds too much. I've tried welding cooler and moving faster but I still can't get these kinds of results. Will back purging make welds like this? Anything else I can try?

[Jolly Roger]

I always brushed mine to get rid of the discoloration, can't really tell you how I did it. It's been years since I've worked with stainless.

[Samurai Dave]

That's art, a thing of beauty

That is a NICE weld!

My instructor welded a sample that looks just like that. I kept it and put it on my workbench as an inspiration. I'm not there yet, but I'm working on it.

Stainless HATES heat, which is why it turns dark grey. But then how do you weld it? With harsh language? The trick with the heat is to get in and get out. Do this with the foot control. Try rocking it back and forth to keep the puddle fluid, yet not so much heat all the time. On many TIG rigs, you can set frequency and pulse adjustments to dial-in enough foreground heat to melt it, but back it off to a lower background heat to reduce the heat input, while keeping the puddle fluid. It is a balancing act. If you are running a TIG rig that lacks controls (or you lack familiarity with them) then the foot control will work.

If I slam the foot control down and keep it there, I can weld stainless all day long. The welds will hold, but they look dark grey because I have baked the metal. In order to get to the nice golden color then it takes the finesse of "threading the needle" as my TIG instructor likes to say.

Initially I tried giving very little heat, hoping to get to the golden color by just being super sloooowwwww. What happens is that the heat spreads over the entire area. By the time it is hot enough to melt and form a puddle, whole area of the stainless is fried. Remember that stainless HATES heat. The solution, intense heat on a localized area, form the puddle, dip the rod, back off the heat, move, repeat. Once you get a rhythm down, you will see the difference.

The thickness of the metal will matter too. Try 1/8" coupons. I tried to start with material thinner than 1/8" (because it was cheaper), but with frustrating results. The 1/8" is thick enought to be more forgiving because there is more metal to absorb the heat. If I'm welding 20 gauge sheet and put too much heat, I'm done. At a minimum I have a black bead, and worst case have punched a hole right through. Don't try the thinner stuff until you have a rhythm down. The 1/8" will build your confidence.

Initially try no rod, just run beads on a sheet of 1/8". Get the beads the color you like, then try adding some rod. Post some pictures of your progress. Make notes on the metal as to what the setting were when you were running the bead. Eventually you will find a combination that works.

Stick the tip of the electrode right near the puddle. No "long arcing" (tip is greater than 1/4" from the puddle) allowed. It takes too much heat to get a puddle started. (I know, again with the heat...) I crash (dip) the tip in the puddle more often than I like during this part of the learning curve, but the alternative is to be long arcing and never crash the tip, with black beads to show for it. Use as small a diameter tungsten as you can get away with. Smaller arc = less heat. 1/16th tungsten will weld 1/8" stainless just fine.

I'm no expert by any means, but this is what has worked for me so far. TIG is like performing surgery, very precise and pays well. When it comes to cosmetics in stainless, it is hard to beat a TIG weld. (Unless of course you are talking about one of MY TIG welds, but I'm getting there.)

[dabeldesign]

What's up with the edge of that weld? It looks like that tube will snap right off the flange and take the weld bead with it!

[BWS29128]

What's up with the edge of that weld? It looks like that tube will snap right off the flange and take the weld bead with it!

I agree with you, but since it looks like it's a header-tube, it's probably not going to be under much stress, right? Probably just has to put up with a lot of vibration and a ton of heat, unless I miss my guess....?

Also, I'm wondering if some of the discoloration isn't coming from two different base-metals...? That bracket appears to be forged or stamped and the pipe is very obviously SS.....could the bracket have a higher Nickel (Ni) percentage than the pipe? I've seen "rainbow" colors when welding Iconel and 316 flanges, but never with 308 or 309 pipe.

I wish Aeroweld would chime in....his welds look like this all of the time...(at least, whenever he wants them to, that is...)

[kjlindgr]

Thanks for the tips guys. I've tried rocking the pedal before to get in and out without heating it up too much but maybe I need to get out of it even more. I've welded enough stainless and tried enough techniques but they all seem to turn out grey and cruddy looking to me. They hold great, but they look like poo until I take a wire wheel to them...but that isn't what I'm going for. I'm looking for this nice golden weld without any grinding or polishing.

The main thing I weld is exhaust piping and turbo manifolds like in the picture above. The turbo manifolds are thicker walled tubing so that's what I'm really trying for.

Eventually I want to be this good...but I hear that Full Race has a robotic welder so I think most of these are done with that:

[TS-Off-Road]

A perfect weld on stainless will have no discoloration. The colors are a result of oxygen contamination from a lack of shielding gas coverage.

[BWS29128]

A perfect weld on stainless will have no discoloration. The colors are a result of oxygen contamination from a lack of shielding gas coverage.

I've heard this too....I wonder if different blends of shielding gas could result in discoloration? (ie: 98Ar/02He)?

[ZTFab]

Here are some pics of some SS work that I've done.

It's not "perfect" but it's always done the job. Getting the combination of heat and shielding gas just right helps in the quality of any weld.

- Paul

[BWS29128]

Paul,
When you get a second, can you describe your equipment, shielding gas, filler rod, base material, etc etc etc.....? Those are GORGEOUS welds!!!
~Clint

[kjlindgr]

Those are GORGEOUS welds!!!

Yes they are!! If you could share more information on your setup, that would be awesome!

[ZTFab]

Thanks for the compliments guys.

These were done on my Syncrowave 250DX (of course).

Both are 304 SS. The square is 1"x.120" and the round tube is 2"x.065" (16ga).

Base setting on the machine was around 100 but I always use the foot pedal to get it where it feels good for what I'm welding.

Shielding gas is 100% Ar at about 20cfm with a #5 cup, no gas lens. 3/32", 2% Thoriated Tungsten. 1/16" 308 filler on the square tube and fuse welded the round tube.

A huge problem when welding SS can come from pulling the filler rod out of the shielding gas between dips. If you are using filler, make sure you keep the filler close enough to the weld pool to remain inside the gas cloud, if not it will contaminate the weld in a hurry.

I hope that helps.

- Paul

[fun4now]

wile i'm not a pro by any means i have herd to increase the flow and the post flow as well. i do know SS is verry unhappy with air..
so far my atemps with SS have been good, i increase the flow rate and the post flow times a little when i do SS. although i have done verry little of it, what i have done came out verry nice.
looks like ZTFab has it down pat.

[cwillis]

Stainless hints

I work for a company that makes airplane engine parts for GE, and Rolls Royce and all the material we use is ethier SS or Inconel 625, and 718. you mentioned back purgeing this will help to keep the HEAT DOWN!!!!! all we use is straight Argon with 5680 welding wire on the stainless. The biggest thing when it comes down too it is the correct heat right size wire and speed too hot and you get what has been happing to you deep grey and nasty lookin weld all of our ss welds turn out a nice golden color, the rainbow color is the pefect heat angle wire and speed. And how we do it for example on a but joint no gap when the two plates fuse then you have the right heat I then ease up a bit but still keep it to a good puddle and just dab the rod into the front of the puddle. If you want to back purge then be carefull because if it is to high then it will blow back at you and then it looks realy bad.
I hope this helps out and makes some since. I will try and get some pics of some ss welds we got on the floor now. Good luck

[Craig in Denver]

Wow

I found this posted 8-14-07 and couldn't let it die. LOOKIT these welds!!