SS color

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I'm welding up some thicker than normal tubing (16ga) and having problems getting that "look." If I get it, it doesn't penetrate enough. What I did notice is when I'm done at the end of the bead is if I completely let it purge on the weld til it's done, the weld looks the same. A very dark purple, not burnt or black , just DARK purple. Now if I do the exact same weld, stop the arc and pull away, the blue and gold comes back which makes me believe the contaminated air is what causes the nicer look when it's cooling. This makes me believe that I'm moving slow enough the puddle is cooled enough that it doesn't turn into straw, or I'm on the verge of burning the rod.I'm dabbing at about once every sec or so, maybe a bit faster. This is 16 ga 304 and I've tried .035 and .045 rod. Usually I see the straw when welding thick to thin no problem. I'm experimenting right now with cups and cfm right now, any help along the way would be awesome. I'm at 13cfm right now and 45 amps pedaled back
Reply:It's tubing. Are you backpurging?? Without it, you will get some discoloration as the coverage is lacking on the other side of the weld.....And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Yep, I'm back purging at about 15 cfm. The backside of the weld is a light gold.
Reply:Here is even with the heat low, .035 wire, and about as small as I can make the bead with the filler still laying down. No real penetration. You can see in a few spots were it wanted to come through. But these are butted with no air gap. If I get it hot enough to go all the way through, the weld is twice the width, and just doesn't seems to look right.http://img163.imageshack.us/gal.php?g=sstube.jpg
Reply:Oh, I thought maybe AR contamination or something, but don't think so. When I tack the tubes together, I just hit it hard and fuse it. When I do that, the color is always light,shiny standard SS colors.
Reply:Here's penetration to the back. But you can see the shrinking I guess you would call it in the rod. I notice mild steel does it too when the rod gets cooked, it wrinkles to the center.http://img197.imageshack.us/gal.php?g=sstube.jpgAny help would be great.I've tried gas lens w a 6 cup, and down to a 4 w/o a gas lens
Reply:Some more experimenting,.....035 rod 34 amps and welding it very slow, letting the heat set into the material, rather than giving it 45 amps and running seems to work much better. I had to feed more rod than dab, so it's a bit inconsistent. But the rod isn't burnt I don't think.http://img64.imageshack.us/gal.php?g=sstube.jpg
Reply:It looks like you are either overheating it, and/or pulling contaminates into your weld pool. How clean is the area around the weld? I hit mine with a file or pearl disc about 1/2 inch back from weld area.
Reply:I'm running a bur on the inside to clean the cut, then wiping everything with acetone, but that's it. Is there an oxidize layer on SS that has to be cleaned or something ?
Reply:Originally Posted by 10secgoalHere's penetration to the back. But you can see the shrinking I guess you would call it in the rod. I notice mild steel does it too when the rod gets cooked, it wrinkles to the center.http://img197.imageshack.us/gal.php?g=sstube.jpgAny help would be great.I've tried gas lens w a 6 cup, and down to a 4 w/o a gas lens
Reply:Metarinka is right about the speed and heat. With higher heat, you establish a weld pool faster and can move before the area gets too hot. Low heat, you sit there waiting while things get hot enough to start moving and overheat it.
Reply:I've tried faster and it didn't seem to work. I'll try it again and take a pic. It's weird because when I do a v band (much thicker) to the 16ga, it comes out perfect. Floor it and run.On some of the stuff it's beveled. It headers I'm working on. So after I cut and end up cleaning the edges because I use a chop saw. It leaves a slight bevel. But sometime if I don't have to cut it, then they are butted. But generally even with a bevel on this stainless, it fuses right away and I don't really get a key hole. This is a single pass.On some of the edges I have seen contamination coming up when it gets hot. Not sure if I or anyone would see it normally because I've got magnifying glasses in the helmet.I has seen something online about copper backing, and some pics of a bunch of wiring bundles up in a box. Think I could stuff a bunch of that behind the weld in the tube.Would a smaller tungsten change it at all ? At 1/16 right now. Can't see it would, but a thought. I think I got it all. I'll get some more up with me welding faster, see what we can come up with. Thanx for the help thus far.
Reply:I work welding 16 gauge tubing for a multi national company, and the purple/copper colour (not the grey) that you have in parts of your weld is about as light as you will ever get a weld (with full penetration) if you are adding filler (unless you happen to be operating an orbital welder, but that's cheating). Some very good points already made, and from what I can see by your fotos I would advise that you try to keep your arc length shorter, If your arc length is more than about 2mm you will get a grey/blue weld every time.Your root, although not too bad, is reject able because you burnt through the tube with one of your tacks, also it is a bit flat in places (you want it to look like a wedding band).Try changing your technique, using a back and forward (stack of dimes) technique is good for some things, but not really ideal for thin SS tube (also you'll struggle to get the wedding band root by doing it that way). Try to create a puddle, add a little filler push it slightly to one side of the join, add a bit more filler, move slightly ahead (about 1/16 of an inch)and to the other side, add a little filler...ect (your 1 sec gap between dips is about right) When you get it right, it is like pushing a glob of molten filler (with dancing black dots) around the tube, and will come out looking like a wedding band on both sides, with very tight ripples.  Sorry I cant give you a starting point on the amps, because every diameter tube is different, but keep on at it, it takes a lot of practice to make good welds on thin SS tube with filler, and IMHO is one of the more difficult aspects to tig welding, although most people these days (including me sometimes, when the fit up allows) just weld them without filler.PS. Keep your tungsten sharp like a needle, if you dip it even slightly, don't even bother continuing (another quick way to burn SS), stop and resharpen every time.Hope this helps!
Reply:No, it helps a lot.I didn't know/ have never gone back and forth while welding. I used to just run with it. Now I like to fill with the rod, rather than dab. So I stop, add until it's filled, then move forward. but never back. With AL I will sometimes lift the torch a bit to get it out of the way of the puddle building, then come down and forward. I'd say I'm closer than .045 or really close to that from the puddle. I point the torch towards me, and add the rod at the leading edge of the pool. I would be surprised if I can get the rod between the part and the tungsten. Oh, the piece is perpendicular to me, and I weld towards me if that's any help.Now I tried hotter and in some I moved so fast the looks of the weld didn't look so great. Others were better looking, but not great penetration. Certainly no band. But every stop and start is a nicer color. I even tried pulsing at 1.8 pps and 60/40 balance, and also 100pps , same balancehttp://img683.imageshack.us/gal.php?g=81503870.jpgThis is the guy I buy my SS from. I know he back purges, but have no idea what kind of penetration he gets. But he says he's never had a SS failure.http://www.mandrel-bends.com/private/private2.jpgStarting to hope I've got a leak some where. Never had this much trouble welding anything
Reply:This is all .035. I payed more attention to the arc length this time and even with the mag lens in there I'm dam close. I'd say about .030 away.I've the purge tube wrapped in tin foil and I grounded to that and the arc was acting a bit funny. So the welds walk a bit.http://img197.imageshack.us/gal.php?g=ss3zp.jpg
Reply:While the pics where loading I ran a bead on top of the 16 2in tube. Just enough to gett he bead to think about flattening out. About .070 wide, and it's still grey, and bright at the tail of the bead. Contamination ? The top one is the .070 wide bead.http://img44.imageshack.us/i/burnt.jpg/
Reply:ahh, so you move, stop, add filler, move ect.. that explains the root and beads looking the way they do.... The beads (the one at the top in particular) that you have done on the side of the tube in your last fotos are how you want your butt welds to look (although obviously wider), and when you can get them to look like that welding the whole tube in 2 beads max, you'll have some pretty looking welds. For some reason the weld in the same foto looks a bit under filled, maybe its the angle you took the foto, I don't know.  Try moving and dipping the filler as you move, maybe just pausing (very) slightly at the edges (or when you add the filler) so that it wets out a bit. Also, try moving forward a little less between dips, this is where a slight side to side movement helps to stop the bead piling up too much. As for the colour, don't stress about it, violet (anything up to dark blue) is a perfectly aceptable colour for an SS weld.Last edited by Baila La Pinza; 01-21-2010 at 02:47 PM.
Reply:Originally Posted by Baila La PinzaAs for the colour, don't stress about it, violet (anything up to dark blue) is a perfectly aceptable colour for an SS weld.
Reply:Originally Posted by SupeOn what basis is this acceptable?  From the standpoint of corrosion resistance, almost no codes permit that degree of heat tint.  AWS D18.1 is the standard reference.  ASME allows heat tint levels of 1-3, which is light straw to light blue.  Latest AWS revisions permit the same.
Reply:In the US, the AWS code governs food grade/hygienic services, which would cover 316 tube.  Most I've ever seen allowable in food grade service is level 4, which is a maximum O2 content of 100ppm.
Reply:I went back and took pics of the same material I did a few months ago, but this is 2.5 in dia. I don't think it's heat soaking because the first bead I lay on the 2in is the same as the last. If it was I would imagine the color would diminish as I weld.The first pic is SS to a mild V-band, so that may help because the MS will dissipate faster. But everything else has a good color to it. But I don't think is was fully penetrating.http://img7.imageshack.us/gal.php?g=dsc01496vg.jpgBut I've welded the 2in here just like the stuff in the link and it looks like ****. Is there a test to see if I'm contaminated ? I saw I think you heat the tube without run and run it to test the color ? Feasible ?
Reply:Pretty much all been said, one other thing (unless i missed it)  to watch for is torch angle... easily lost when working around small diameter tube/pipe and can mess up shield quality if laid back too far for example (draw some air in from behind etc) Originally Posted by 10secgoalIt headers I'm working on.
Reply:Your right. But I'm not looking for the color as far as looks go. But my understanding was the color will tell you the heat of it, too hot or too cold. I just don't want it to be too hot, and crack is all. It could be green for all I care lol.Sorry. I meant with the test to run a a stringer without filler. Wet it and run to see the color it leaves. sounds feasible ?
Reply:Yes and no, depends on the quality of the gas shield. Low heat input weld with good gas shielding from a regular sized ceramic may be 'straws' and light blues. Put a giant ceramic on the torch and the same heat input may result in a virtually colour free weld i.e the hot weld is covered by shielding gas for longer and so has more time to cool before it's exposed to the atmosphere.Put a trailing cup on the torch or put the weldment in an inert chamber and you could cook the crap out of it and still end up with a colour free weld.It's easier to get 'good colour' with thicker parts because there's more mass acting as a heat sink. Small diameter thinwall tube takes practice... heat, speed and gas shield all have to be right, not much margin for errorAn autogenous weld (without filler) won't really be a true comparison... filler cools the puddle some but because of this heat input isn't the same, welding manually you typically end up travelling faster or with less juice to compensateCracked welds... you're talking about >carbide precipitationherehere<Another good one, http://www.gowelding.com/met/austenitic.htmlFar from definitive but every cracked/broken header i've ever seen, been able to trace the crack back to an obvious initiation point- incomplete penetration (centreline cracks), craters, undercut etc. Only in a couple of cases i've seen corrosion accompanying the cracks, these ones had been welded and welded and welded and then a final pulsed autogenous pass had been made to get 'the look'  There's a thread around somewhere with plenty of  pics, some corrosion in the HAZ and many cracks from the various craters and the like
Reply:Informative post, seriously. Thank you. I'll read that link. I've been reading and searching with no progress. One of those things were if you just don't know the right term, you'll never find it.I'll try longer post flow, see if that solves it. But makes perfect sense, sure your right.These headers will always turn a brownish color from oxidation, so oh well. The weld may get there first lol. I'll just try to improve technique to get the band on the back without burning it.
Reply:I might just be getting it. I think now I may be getting a little wide on the root from the pics I can find online. Looks like dead center in the back of the tube is about all the width in need ?http://img168.imageshack.us/gal.php?g=87674189.jpg
Reply:short arc length helpswith getting it hotter faster actually putting in less heat
Reply:You might want to check your gas supply.  I have my argon bottle have to much oxygen in it before.  Rare but it could happen.  You might have a loose gas connection somewhere letting O2 in or a cut in the line somewhere.  Do you have another bottle to try for giggles?
Reply:Originally Posted by 10secgoalNo, it helps a lot.I didn't know/ have never gone back and forth while welding. I used to just run with it. Now I like to fill with the rod, rather than dab. So I stop, add until it's filled, then move forward. but never back. With AL I will sometimes lift the torch a bit to get it out of the way of the puddle building, then come down and forward. I'd say I'm closer than .045 or really close to that from the puddle. I point the torch towards me, and add the rod at the leading edge of the pool. I would be surprised if I can get the rod between the part and the tungsten. Oh, the piece is perpendicular to me, and I weld towards me if that's any help.Now I tried hotter and in some I moved so fast the looks of the weld didn't look so great. Others were better looking, but not great penetration. Certainly no band. But every stop and start is a nicer color. I even tried pulsing at 1.8 pps and 60/40 balance, and also 100pps , same balancehttp://img683.imageshack.us/gal.php?g=81503870.jpgThis is the guy I buy my SS from. I know he back purges, but have no idea what kind of penetration he gets. But he says he's never had a SS failure.http://www.mandrel-bends.com/private/private2.jpgStarting to hope I've got a leak some where. Never had this much trouble welding anything