TIG Porosity

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Hello,I am having a problem when tig welding a long but beveled joint 1/8 to 1/8 square tube.  Edge to edge not end to end.  I can weld perfectly for a few inches then as the torch gets hot the welds get porous.  Bubbles and pop.  The torch is leak free, I checked it with soapy water everywhere, at the reg and at the torch itself.  I replaced all internal components of the torch.  Tungsten is 1/16 grey tip, 130 amps, A18 filler. The only thing I can think of is the dust that seems to be in the joint despite me grinding and cleaning all of the metal.  Should I wire brush it and can steel grinding dust deep down between the steel cause this problem, even a little.  BTW the dust has stuck in places should I will get a wire brush anyways.  But once again could the dust be causing the porous welds.I have welded with stick for years but never had this problem.Thanks
Reply:Is this a new torch or new power cable? What type of machine?Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Had the torch for a while, only tiged ss sheet and ms sheet.  This is the first time this grinder dust has been here, its a very dusty shop
Reply:Brush the dust off, I don't think that is the problem but it could be. What CFH are you using and what size cup? Check for leaks on the torch when its hot since its only after welding that you are getting porosity. I have never had it happen but maybe the tungsten isn't holding up well to 130 amps. If you are welding near the tungstens amp limit you need to have a small flat spot on the end instead of having it needle sharp.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:11-12 CFM, I welded loads of 1/8 square tube end to end, same settings with no problem, I move hot and fast hence the high amps.  That what I was thought and it worked until now.  The dust is sitting in the v groove but stuck to the joint because I was using the grinder.
Reply:11-12CFH is a little on the low side, try around 15CFH to see if it helps any. If that and cleaning the dust off doesn't help start looking at your arc length/torch angle and things like that to see if you are pulling air into the weld from bad angles.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:I did try higher flow rate but it had no effect, I am just going to get a brand new wire brush and clean it down.  I will report back.
Reply:Obvious question but, did you grind the mill scale off the material (past the weld area) before putting them together?Or is mill scale trapped between the joint right where you are welding?Dave J.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:I ground the millscale back 1.5 inches from the weld area.
Reply:have you tried cleaning it with some sort of solvent then drying it with compressed air?  I had the same issue with a fab table I was building for somebody.  it still had traces of trans fluid on the sq tubing from the guy's garage floor
Reply:Originally Posted by bullfrogg0have you tried cleaning it with some sort of solvent then drying it with compressed air?  I had the same issue with a fab table I was building for somebody.  it still had traces of trans fluid on the sq tubing from the guy's garage floor
Reply:Could be moving to fast and uncovering the weld to early. Speed coupled with the slightly low CFM could be the issue. Pictures are worth so much with stuff like this.(Home)Miller Maxstar 152 (sold)MM211/spool gunLincoln AC 225C(Work)Dynasty 350Powcon 300STLincoln SP-175TWeldlodgic AWS150sWeldlodgic AWS300Custom Resistance seam weldersCambridge Vacuum EB weldersI smell something burning.
Reply:Originally Posted by atariCould be moving to fast and uncovering the weld to early. Speed coupled with the slightly low CFM could be the issue. Pictures are worth so much with stuff like this.
Reply:Clean your metal.I'd use 3/32 or even 1/8 tungsten for the amps your running. Your over working that small 1/16 tungsten at 130 amps15-20 cfm argon flow is where you want to be.How much tungsten stick out are you using?JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:Sorry I have no pics, I went at it again today and fine for a while then the torch got hot a porosity again.  Opened up the torch and found the gas hose kept melting whenever the torch got hot.  I am going to get a 3/32 tungsten and and collets along with some new ceramics.  It seams the WP17 torches cant stand 130 amps for more than 6 inches of welding.  What torch would you recommend?
Reply:I have used #17 torches over 160 amps walking the cup for much longer than 6".  They get really hot and I've burned up a few but never had that problem. What brand torch is it?Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:*cough* no brand *cough*, I have just bought a new CK WP17 though and I will get my tungstens later.  These are red tip ones though.  May perform a bit better.  I have burned #9 torches to bits in the past but never a #17 until now.  Will the bigger tungsten perform much better in your opinion.  The old ones were 1/16 grey tip.
Reply:I think at that amperage 3/32 sharpened to a point will do better for you, a good torch should help too Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Sounds like the problem is worked out but I will second cleaning is key. I know we were getting new headers welded in our boiler. They are some kind of thin walled semi exotic alloy. The company that was doing the work was just cleaning them like any other weld and they were getting an 80% failure rate. They then cleaned the tubes with acetone and dried with a torch and went to a 20% failure rate. Not great but was a big improvement. They still ended up getting fired. The new company that came in had one seeping weld out of a few hundred welds.
Reply:Had that same issue with 1" Square tubing before and the only way I stopped it was with some 70S6 mig wire........welded perfect.....try it and see what happensWas using 70S2.......and it bubbled up....weird I know but the steel tube is the only time that happened  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Compressed air blowout from both ends, then wet swabbing steel tube insides, followed by second air blowouts--from both ends, and visually checking the tube innergoes a long ways towards cleaning the tube inner; and eliminating porosity problems. [I think I'm the only one that would rather 'waste my time' swabbing the tubes--ratherthan waste more time, dealing with intermittent porosity, etc. ]Blackbird