Extreme porosity in Tig welds, please help

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I have been welding with this Tig welder for a while, it has worked well, but has occasionaly given this problem, where it just generated poros bubbles at one place in a job regardless of how much I cleaned it up. I was able to address in the past by re doing the well till it worked as it was not common and I figured it was just that I had not cleaned properly or there was some crap in the metal...For some reason in this job this problem is now so common that I cannot continue on this project. I have three different pieces from different origins and each shows the problem... I cannot complete a weld.Here is the problem.The steel is mild steel, 2.5-3mm thick.  I have cleaned with a wire brush, stainless brush. I am using welding grade argon, Thoriated tungsten 2.4mm and size 6 cup. I have tried other variants and different argon flow rates (5-20), different  The problem seems to occur at all settings.  I also tightened all argon line fittings. If I leave the argon bottle open it will leak very slowly, its done this since I got it.I have noticed that when the issue happens I see the weld flaring a bit and there are sparks which I assume is the metal being ejected from the weld... I notice that after the weld cools aside from the extreme porosity there is often a light brown aura near the weld which brushes off.If you look at the pictures you can see what the welds look like, terrible... If you can help me work through this I really appreciate it.My next step is to try cutting out all the weld expecting there to be some subtle contamination that is embedded in the welds... Bearing in mind that I have tried grinding back the welds, in that case I still got the porosity occuring at similar spots.Thanks Attached ImagesLast edited by oohogwash; 07-19-2008 at 12:37 AM.
Reply:That looks to me like an A) no gas issue, B) wrong gas issue, 3) plasma cutter crud.You said you're running Argon, so that should take care of B).Trigger your machine, and see if it opens the gas valve... make sure your gas valves are open, stool isn't sitting on the gas hose.I bring up the issue of plasma cutter crud, because I've found that unless you hit the cut with a grinder, it leaves an oxide that is a nightmare to try and weld to.... makes little volcanos.Leaking argon valve, some cylinders want the valve all the way open.  They have a seal on the backside that seals the threaded stem.
Reply:Internal contaminants in the tube. Clean the INSIDE with a bottle brush dunked in acetone, or a ream rag dunked in acetone. I have seen this before. The other possibility- wind blowing hard enough to push away your shielding gas. I weld right by the ocean a lot, this can be a serious problem, even when you think there is not much wind.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:What type of filler are you using?I was just wondering, does this have to be tigged? Maybe you could use stick.
Reply:You state you have a slow leak, I would try and eliminate that if posible. I would soap all the fittings and see where the leak is. tank valve, regconnections, hose, solinoid in the machine, everywhere. Examine the hose well and look for burn or holes as well. Loss of shielding gas would cause these issues.As said internal contaminents could be an issue. I have had that problem in the past where I pulled contaminents into a weld thru the steel from the back.
Reply:Your shielding gas is being blown away. The photo looks like it is outdoors,are you working outdoors?  Rusty table, straw or dirt on the ground.TIG is very suseptable to having the shielding gas being blown away.Last edited by Donald Branscom; 07-19-2008 at 02:12 AM.AWS certified welding inspectorAWS certified welder
Reply:The welding is indoors, I will try more to eliminate any leaks...While you guys were replying which I REALLY appreciate, I did a test weld on two pieces of box steel... it was perfect...I double checked the gas and it seems ok,Then I ground out the weld, with grinding wheel then dye grinder with tungsten carbide tip. I am tempted to use stick on this, I did a small test and might just do that...I just hate being beaten... and tend not to give up without exploring alternatives.I noticed that when I ran the weld over again it festered up again, I do suspect that there are contaminants being dragged in... This is a suspension arm that has been extended... which was one reason that I wanted to tig, however I could stock weld these problem welds as I still intend to weld plates over the top of this... I can tig those. I will need to grind it flat. If it is sucking contaminants from between the steel plates I dont have many options to get it out other than dismantling.....do I ? So maybe I just stick it and tig the plates over the top... is that reasonable.. (I have this tig everthing mentality at the momement I confess)
Reply:For general info do not just crack the argon open but open the valve completely. Have no idea of your porosity problem.
Reply:You say this is a suspension arm that has been extended, was it originally covered in grease and oil? Contaminents soaked into the material may be a problem if so. Usually heat will help to bring out the impurities. Can you heat it lightly with a torch and see if crap bubbles out of the material?I have had a few issues with grease on equipment parts and we usually heat them to try and drive out the grease. A caution, do not to heat the part up too much. How much is too much on this I can't say.
Reply:Thanks for the tip on Argon..It was pretty clean actually. I think the contaminants are coming from the inside... I bet there is some treatment that has been applied to prevent rust...I am thinking I will take special care on the other side one (which I have not started yet) to clean and see how it goes...If that works I will think about what to do with this one, I guess the stock weld will be ok on bits that have this problem...
Reply:Once the porosity is there, its hard to get rid of.  Grinding off the old welds sometimes isn't enough.  It just keeps coming back because its in deeper than you grind.  Is the fan from your welder blowing on your work?DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:You may not have enough argon flow, allowing it to be blown away easily.  I run 20cfm as a minimum.  I know it's not always needed, but when I compare the cost of a small loss in coverage to the cost of the gas, I'd rather not have to grind out a weld.  You may be letting your arc get too long, and be losing coverage due to that.
Reply:If you're getting porosity it's GOT to be either not enough gas (or wrong gas - use Ar of course) of containiments either in the metal, or in the filler rod (unlikely but possible).Wrong [too much] angle of holding the tig torch can also suck in surrounding atmosphere contanimating the weld.Does it happen on different chunks of metal (that came from a different source) as well or just this particular piece?  At least knowing that can narrow it down to it being just the metal or not."A winner isn't someone who doesn't lose, a winner is someone who doesn't quit."
Reply:Originally Posted by David ROnce the porosity is there, its hard to get rid of.  Grinding off the old welds sometimes isn't enough.  It just keeps coming back because its in deeper than you grind.David
Reply:I remember now, a case like yours.I was welding on a steel intake manifold and the metal kept bubbling and it even looked like oil was coming out of the metal.I found out it was sintered metal which is made by compressing powdered metalinto a shape, and there is a special filler wire for wire feed made just for this type of metal.AWS certified welding inspectorAWS certified welder
Reply:I really doubt this is a gas issue, looks nothing like any gas problems ive ever delt with.  Usually the surrounding metal will be burnt and look very rough.  This has a smooth and consistent color.  It looks like your welding way to hot and im betting thats pulling lots of junk in from the backside.  Try welding something with a clean back, or welding cold enough as to not burn though.  I bet the problems will go away.What does your tungsten look like after this happens?  Does it have a large glob of metal on it or does it lose its point and burn away.  Glob of metal and its contamination from the base metal or filler.  Burnt tungsten is gas issues.Have we all gone mad?
Reply:I moved ahead with other bits of the job, I found that my welds were better ...Then came back to this and noticed that this discoloration still occurredHaving read the responses , I think that whilst it may be partly the metal and my other work is ok, I have been lazy and should be more careful... I think I am running too hot, and am dragging in impurities... I am backing of my heat in my work as this will be reducing the quality of my over work as well.Having said that this steel has something in it as even when i welded over without problem (not along cut edges) I got the brown aura...I would post more pics but darn camera played up...As I said, I believe that I have been getting lazy, my welds have worked nicely even when I dont do detailed preperation ... I have returned to a detailed cleaning strategy which is improving all my work... my fault on that...Thanks for your help guys, this forum is awesome.. wish I had found it ages ago..
Reply:A good rule when welding with any process is if you think you are in trouble you probably are and need to stop.
Reply:Are you sure you have 100% Argon?Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:looks to me like you need a new torch or gas lines although gas is flowing it looks very restricted. are your lines plastic and have you gotten your torch really hot ever just my two cents ive had that problem or one real similar
Reply:Quote: "I also tightened all argon line fittings. If I leave the argon bottle open it will leak very slowly, its done this since I got it."If the argon is leaking when you leave the bottle open, you have a problem with the shield gas.  When you have a pressurized system that is leaking out argon, and then you "step on the pedal", wherever the gas was leaking out now becomes a vacuum drawing atmospheric contaminants in.  It's known as a "Venturi effect".  While the system is under pressure (leave the argon bottle open), it will "leak very slowly".  When you start to weld, the gas flowing through the lines draws air into the system via a suction (venturi), and the atmospheric contamination could very well be the problem with the porosity.Check all your gas connections with warm, soapy water until you no longer "leak very slowly".  You'll spend less money on gas, and your welds will imporove.Regards, KbnitI r 2 a perfessional
Reply:You are using the correct rod for tig? I read all the replies and didn't see this asked yet , unless I missed it....Mike
Reply:I can tell you right now two MAJOR things I found eliminate this from happening.  I had the same problems when I first started.(1).  You have to get some small sanding discs that you can run on a small 90* air hand grinder and get all the mill scall off the steel.  I can see you may have wiped it all off, but can also see that it was not ground/buffed with these disks.  This is a must and solved 80* of the issues I was having.(2)  as other mentioned you need to really clean the inside of the tube with acetone.  Both these things made my porosity problem nearly disappear.  Before that I stuggled and struggled to get a clean bead.  Now I can't screw it up even if I try!  The little sanding discs on a rubber mandle for your 90* air grinder works SUPER quick and really is the ticket.  I will bet if you do not have them and you take your grinder and grond two pieces of the same material and do a butt weld the problem does not show.  Its an easy check and should give you a good feeling this is the problem.Good luck.Best Times with 434 Naturally Aspirated Vette60 - 1.261/8 -  6.37@ 107.25 MPH 1/4 - 10.08 & 134.9MPH1/4 - 9.60@144MPH
Reply:I missed this clue the first time I read your post. Sorry.Can't believe it.It looks like from the photo that you are welding a square tube.What is happening is that as you weld, heat builds up inside the tube and the expanding gases want to escape. Make porosity in the weld.Try this drill a small hole (1/16) in each tube and then grind out the old weld and re weld.It should work fine.Then AFTER the weldment has cooled, Fill in that small hole quickly or just put in a rivet into the small hole.AWS certified welding inspectorAWS certified welder
Reply:This idea is a dirty trick and only a last resort: if you cannot get the porosity out, re-weld it using stainless filler. The stainless is less sensitive to contamination and will "fix" the porosity.Ian TannerKawasaki KX450 and many other fine tools