Stainless woes (tig)

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Hey all, hope someone can help!When welding 316 stainless, my welds arn't comming out nice and shiney/orange looking, instead the look dark grey in color and appear to be oxidized, also as its cooling it looks like mill scale is forming, hence the gray color.I'm pretty sure i'm cleaning it thouroughly, ie brushing down with a stainless brush then wiping over with acetone before welding.Straight argon is spot on to the flow meter, ive tried from 5-20ltrs per min flow but nothing helps.Electrode is red tip(ceriated) and ground on a dedicated grinder.Any ideas as to what could be wrong or what i'm doing wrong?I'm starting to think there is a problem with the torch, if air was getting in somewhere, would it cause the above?The torch is prolly 30yrs old but appears in good condition.Cheers Rob
Reply:Rob,It sounds like you either have a shielding gas issue or way too much heat.If the torch was leaking somewhere between the flowmeter and the cup, it could cause an issue.What thickness is the material and how many amps are you using? - Paulhttp://all-a-cart.comWelding Cart Kits and accessories
Reply:To tell the difference between a system problem and a human welder problem, make a test spot weld on clean stainless steel.  Melt a small puddle with the torch held 90 degrees to the plate, with a 1/16" arc gap, hold the toch in place after the weld to allow the weld to cool under the gas post purge.If the spot weld has good color, then you are probably doing something wrong when you weld, like too much heat, wrong torch angle, excess arc length (over 1/8"), etc.If the spot weld color is bad, then you have a leak in the gas system, or wrong/bad gas.  On a couple of occasions, people have reported being sold the wrong gas, a CO2 mix instead of pure Argon.A leak somewhere in the shield gas system.Pressurize the system by running the gas and plugging the nozzle, then bubble check every connection.  Bad O-ring on the back cap?
Reply:Hi guys and thanks for the replies.ZTFab, i welding shed 10 pipe its wall thickness is roughly 2.8mm and i'm using about 60 amps on it?I rechecked the torch today and there may be an issue with it, as i wriggle the hose i can hear the gas flow change for whatever reason, this cant be right can it?Pulsar, ive done as you suggested in regard to the test weld, its color is still dark even on 45 amps.Post purging is difficult on HF as i have to lift the torch 2" to break the arc, then i can do it but i feel its too late then and it usually leaves a butthole in the job.Heres a pic of my trials.Thanks for your time.Rob
Reply:Also heres a pic of my very first tig job, its just a basic MS ButtWeld log manifold that i made last week, it turned out ok i guess after a bit of practice.What do you guys think?After making this i thought i'd have a crack at a stainless one, but seeing its for a mate i need to get things sorted first before i proceed.Cheers Rob
Reply:Need to cap those butt welds!  Not too bad though.
Reply:Hi and thanks,What do you mean by cap?Rob
Reply:those look like you are going to slow, because 60 amps for sch 10 def isnt too much.  I usually run 90-100 amps on .065 wall 304 stainless.  If I stay to long in one area it will look alot like you are showing.  Or if I wash over it soon after laying the first bead it will also look like that.Try turning your gas up?  I usually run at 20 CFMHave we all gone mad?
Reply:Rob,   Thanks for posting the pics. It helps to see what you're doing.The change in gas flow as you move the torch is probably from the hose getting slightly crimped and could be causing you problems. Check the length of the hose and make sure it doesn't have any hard creases in it. ...and you can always do as Pulser suggested and plug the cup to pressurize the system and check for leaks.What type of filler are you using? (What grade and diameter)In this pic, I circled an area that looks decent...but it also looks like it was fused. That leads me to believe that your problem might be from pulling the filler outside of the shileding gas between dips into the puddle which can contaminate a SS weld in a hurry.- Paul Attached ImagesLast edited by ZTFab; 08-10-2007 at 12:21 AM.http://all-a-cart.comWelding Cart Kits and accessories
Reply:Well on that pipe you run your root pass, hot passes to fill it up and then you cap it with a final pass.  Your weld should be convex not concave.  You need another pass or two to cap it off.  Are you fusing it?  If so you need to put some filler material in there and fill up that beveled edge.  I imagine you are using those el bends you buy online for building turbo manifolds and such that are prebeveled.
Reply:Hi All, Snowboarder, thats interesting, i'm picking up somemore stainless tomorrow and will do some more expirementing with heat and speed, ive tried more gas less gas and its still the same.Is stainless that much harder to weld than mild steel?ZTFab, filler is 316 wire in 1.6mm thickness, i tried plegging the cup and all seems ok, i can't find any leaks.Your correct about the circled area its fused, you may be onto something with the distance i'm pulling the wire out, i have noticed its black on the end to some extent.How far can i roughly pull the wire from the arc and still keep it shielded?Assuming my gas flow is ok, how big is the shielded area around the arc using the 1/2" cup?WelderBoy, thanks for clearing that up and yes the bends are beveled and were fused, no filler at all.I only used filler on the flange as there were gaps that had to be filled.Cheers Rob
Reply:Rob,  In my Opinion, I would set the filler down for now. Don't use any.Try just fusing for a bit until you get the heat control down and then you can start adding filler. SS is much easier to overheat than Mild Steel and learning to fuse the material first will teach you better control.It's just going to take some practice but you'll get it.- Paulhttp://all-a-cart.comWelding Cart Kits and accessories
Reply:I am assuming you don't have a foot control, which, if true , makes it very difficult for a beginner .If possible , get an experienced friend to show you how he does it - using YOUR tig set up .[SIZE="5"Yardbird"
Reply:Well to me it looks like way too much heat..That's resulting in burn thru...And your sucking the crap thru the puddle from the backside..And depositing it on the frontside..Remember crap crap and more crap will wick itself to the heat any way it can.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Clean the metal prior to welding, with a flapper wheel or something.  Any contaminants will burn when welding.  What this does is get particulates in your weld, or in your shielding gas...making it much less than pure..and it will leave the surface dirty like this.Also...take note to the above comments made about pulling your wire from the argon sheild.  From there, it's all about heat control and speed.
Reply:Hey engloid!Long time no post..Still racin' the bike?Sorry about the slight hijack.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Hey Guys, did some expirementing on the weekend and found out where i was going wrong.........Its just like Zapster said, too much heat and pulling crap into the weld from inside the pipe, the darkest areas in the weld have a coresponding bubble on the inside of the pipe.More gas seemed to help too and kept the filler rod tip cleaner.I found out today that i can get a pedal for my machine, and at $500 it aint cheap but could be a worthwhile investment, what do you guys suggest??Thanks again everyone for the tips and advise, makes a big difference when you know your heading in the right direction.Cheers Rob
Reply:TransTigger,Am I reading this wrong, $500 for a pedal, no way!If you look up the size of potentiometer needed for your power supply, you may be able to find a used foot pedal with the same ohm rating, even an for entirely different brand of welder, and if the connector is different from you machine you can change the connector.
Reply:Originally Posted by ZTFabRob,It sounds like you either have a shielding gas issue or way too much heat.- Paul
Reply:What does that manifold do there seems to be no intake or exhaust,or is there something on the other side Victor SuperRanger O/A                                         Solar migLincoln Powermig 140Southbend 9in lathe350# kohlswa anvilMiller Maxstar 150 stl etc....
Reply:It looks as if you are aspirating air from a leak in the hose to the torch it will pull air and cause the burned look is your tungsten clean or dirty after you weld? if its contanimated look for an leaky hose
Reply:Originally Posted by TransTiggerI found out today that i can get a pedal for my machine, and at $500 it aint cheap but could be a worthwhile investment, what do you guys suggest??
Reply:Originally Posted by TransTiggerHey Guys, did some expirementing on the weekend and found out where i was going wrong.........too much heat and pulling crap into the weld from inside the pipe, the darkest areas in the weld have a coresponding bubble on the inside of the pipe.
Reply:Originally Posted by EngloidThe only way it will pull stuff from the back side is if you actually blow a hole into the metal.  I've done hundreds of xray welds that had sugaring on one side from the first pass.
Reply:What he's suggesting is that if you run multi-pass welds with stainless, after the root pass is in, the contamination will not come from sugaring on the backside of the root pass during subsequent passes.  You should not be putting enough heat in fill and cap passes to draw impurities up from the backside of the previous pass.Sugaring refers to the chrome carbides which form on the backside of a stainless steel joint when exposed to oxygen.  You will not get these with a back purge.If you want to check your penetration you just fit up and weld some drops. The only way to KNOW is to SEE unless you have a UT handy.I'll let Engloid cover the "sugaring" although it is covered in most competent books/manuals.Anything worth doing is worth doing RIGHT
Reply:Originally Posted by sn0border88Ok, im curious.  Ive always been taught that one way to make sure I was getting full penetration on my tube welds was to look for the little white swirls to the side or in the back of the pool.  That these were impurities getting pulled from behind the weld and boiling out the front.
Reply:Originally Posted by SupeWhat he's suggesting is that if you run multi-pass welds with stainless, after the root pass is in, the contamination will not come from sugaring on the backside of the root pass during subsequent passes.
Reply:Ok I follow you now, I dont have any problems sugaring when I purge, it always comes out nice and clean.Have we all gone mad?