Advice sought re unusual TIG aluminum problem

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A friend of mine and myself are having a bit of a "head scratching" problem with an aluminum project.  Background:  My friend is a professional, certified welder in the nuclear power industry and is highly experienced with TIG.  I am a non-professional welder that has a good experience with TIG.We have been working on a long term project made from aluminum channel, plate and rectangular tubing.  The project involves both new as well as older (10 years) material.Recently we started having problems with weld contamination and tungsten erosion.  The problems are inconsistent.  We will be running a 10" bead and all of a sudden in one location we start experiencing contamination and significant electrode erosion.  We can then move over to some test pieces and they weld just fine.  If we go back to the bad spot, use a carbide burr to remove the old weld and clean up the base metal, the problem persists when rewelding.Tungsten being used is pure tungsten, and the problem occurs with multiple electrodes.  We've tried both 3/32 and 1/8" electrodes - same problem.  We've tried two different gas mixes - a helium/argon mix as well as pure argon - same problem either way.  We've tried different filler rod, from different manufacturers.  We've wiped down the filler rods with MEK, and switched to new gloves. Remember, in one spot on the project everything welds fine yet in a different spot things go to hell.  Same welders - same equipment - same gas - same machine settings, and even the same metal.  None of the problem areas involved the older aluminum - only the new stock.Cleaning is very thorough, and the stainless steel wire brushes have been replaced. Typical cleaning starts with soap and hot water, then MEK, then wire brush, then acetone, then wire brush again (have also tried it with acetone cleaning as final prep).  We've also tried ProClean for cleaning the aluminum - same result.  We tried the tip shared on a different post on this forum of using the TIG torch w/o filler rod to heat the base metal to bring the contaminants to the surface.  We we do this, the tungsten erosion is the worst.Equipment is a Miller Syncrowave 350.  Gas flowmeter is set to 35 - 50 cfm.  We are at a loss to figure out the root cause of the problem.  The metal is prepared much more thoroughly than normal, yet this has not helped.  The same project has had a few hours of welding in different parts but w/o a problem until recently.  We're not touching the tungsten to the base or filler metal either.Here are some examples of the problem.  The fist photo shows one of our typical welds that does not have problems.  (Note that this weld was made a few minutes after some of the problem welds shown below):Here is a bead that started good (outside of the photo area to the left) that went bad:The next photo shows an example of a problem area.  Note that the spatter balls visible on the surface are actual pieces of eroded tungsten.Here are a couple of more problem beads:We are really at a loss to understand the root cause of the problem, as all of the basic stuff can be ruled out (gas, tungsten size, machine settings, filler rod, glove contamination, etc). The problems seem localized; ie we can get a good bead in one location but a bad bead in another location.  Two different people welding experience the same problem, and the worst areas are where the tungstens are eroding the most.Any ideas as to root cause of the problem?Thanks much.Scott
Reply:Hello Scott, I hope this doesn't sound too simplistic, but, are you welding on closed hollow sections by any chance? If you are welding tube/pipe to other pieces and you have gotten to the "last" area of "open" seam where a tube/pipe gets welded you could be experiencing venting issues from the heated gases inside of the hollow portion of your weldment. If it is occurring in other areas the same basic principle could still apply as tightness of fit-up in areas other than where you are seeing this phenomenon could still allow this sort of thing to  occur. If in fact this is a possibility, try drilling a weep hole in the parts prior to fit-up to allow for internal expansion in areas other than in your weld joint/seam. Just a thought for your consideration. When you have the chance, try to include a bit more information, although, I realize you have already done a pretty good job of that. Good luck and best regards, Allanaevald
Reply:Had another thought here too Scott, I know that you said that you had thoroughly cleaned the weld zone. But, have you used any sort of machining or cutting fluids compounds that might be sticky enough to remain lurking inside of some of your parts? Maybe the processing of this material may have introduced something that could cause this? There have been instances of contamination where various machining compounds, material preservatives, etc. have "melted/liquefied" when welding has taken place and then run down internally and been drawn into the welding area from the backside while welding has taken place. This could be a tough one unless you have a real certainty of your part integrity prior to starting. Just another thought. Best regards, Allanaevald
Reply:I saw that you said your gas flow was around 35-50 cfm. try cranking it way down ( 12-15 cfm)L-Tec PCM-VPi II Hobart Handler140Millermatic 35Lincoln Power arc 4000Lincoln Ranger 10,000 ( 3 ) Longevity Tigweld 160SX Purox O/A setup100lb anvilXLO/servosource cnc mill
Reply:I bet it's your torch.When it welds great, I'm sure you have the flow you need, but when it welds like crap take a quick look at the regulator and see if it's restricting your flow.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:+1 on the flow settings.  About 20cfm would be about the highest I'd go.At high cfm on an outside corner you may not notice a problem, but on inside corners it will show up.My machine has a very high surge when I first hit the pedal so I have to release that for a second before I weld.  When I forget on an inside corner I get contamination and have to fix it.Otherwise it looks like contamination like said above.  Were the aluminum pieces wiped down prior to welding as well?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:Hi Allan, thanks much for the feedback. Of the two problem areas, one is an open hollow, and the other is a closed hollow with multiple weep points.  In some instances though, the problem occurs immediately after the arc is created, in other places it's after a minute or two of welding.As far as cutting methods, we've used two different methods for cutting the metal where it's being welded.  One was a bandsaw (with and w/o lubrication), and the other is a brand new cutoff wheel in an angle grinder.  One thing that may be an influencing factor is that some of the channel that we're welding may have been splashed with some waste engine oil / transmission fluid / hydraulic oil mix a few months back.   I've been wondering if this could have somehow contaminated the metal, but we've been extremely thorough in our cleaning regimen.
Reply:Originally Posted by MinnesotaDave Were the aluminum pieces wiped down prior to welding as well?Dave J.
Reply:Originally Posted by GambleI bet it's your torch.When it welds great, I'm sure you have the flow you need, but when it welds like crap take a quick look at the regulator and see if it's restricting your flow.
Reply:Dave / Blackhawk:  Thanks for the advice re the CFM.  I've tried it on a 20 - 25 cfm setting, but will try it again.  Will also try a new bottle of gas mix.
Reply:Scott, as aluminum is typically porous you "may" be experiencing issues from that exposure. With oil-soaked aluminum, soaking in acetone(immersed and for a couple of hours or more) will essentially aid in "wicking out" the oils. Then cleaning with alcohol prior to welding should do the trick. With the overall description of your problems though this may not be what is happening. Too, if oil is soaked into the material, the heat will boil it out, thus exposing it to the arc and causing it to burn and convert to carbon immediately. Also possibly causing issues similar to some of what is seen in some of your photos. Good luck on this, I will be interested to see and hear what your final determinations are. Best regards, Allanaevald
Reply:The black specks are oxides. You have a gas or gas delivery problem. Air is getting in there from somewhere. Check your collet to see if it is crushed, or twisted. Check to see if your collet body is seated. Check your backcap for a hole or missing o ring. Check to see if you have a hole in your gas hose, ect.What size cup are you using?Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Another vote for gas here.  Seems to be the problem almost always on Aluminum.Your "good" bead doesn't look perfectly clean either to me.  Bad gas on Aluminum will cause the arc to sputter and can cause intermittent contamination issues, even though the gas is bad all the time.  It makes little sense that it will do this, but you can be welding fine for an inch, then the arc sputters and you get contamination.  My largest tank has contaminated gas in it, I use it just for steel and plan on changing suppliers when the tank runs out.  I thought my machine was bad initially.  Here's my thread, you'll see the same type of problem.http://weldingweb.com/vbb/showthread.php...light=AluminumAlot of good advice that applies to your problem is given.Last edited by Drf255; 06-21-2013 at 05:27 AM.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Originally Posted by shovelonThe black specks are oxides. You have a gas or gas delivery problem. Air is getting in there from somewhere. Check your collet to see if it is crushed, or twisted. Check to see if your collet body is seated. Check your backcap for a hole or missing o ring. Check to see if you have a hole in your gas hose, ect.What size cup are you using?
Reply:Dirty filler? Good torch angle?When is the weld going south, as soon as you start melting the aluminum or when you start adding filler or when you start moving?
Reply:Originally Posted by Drf255Another vote for gas here.  Seems to be the problem almost always on Aluminum.Your "good" bead doesn't look perfectly clean either to me.  Bad gas on Aluminum will cause the arc to sputter and can cause intermittent contamination issues, even though the gas is bad all the time.  It makes little sense that it will do this, but you can be welding fine for an inch, then the arc sputters and you get contamination.  My largest tank has contaminated gas in it, I use it just for steel and plan on changing suppliers when the tank runs out.  I thought my machine was bad initially.  Here's my thread, you'll see the same type of problem.http://weldingweb.com/vbb/showthread.php...light=AluminumAlot of good advice that applies to your problem is given.
Reply:Originally Posted by shovelonThe black specks are oxides. You have a gas or gas delivery problem. Air is getting in there from somewhere. Check your collet to see if it is crushed, or twisted. Check to see if your collet body is seated. Check your backcap for a hole or missing o ring. Check to see if you have a hole in your gas hose, ect.What size cup are you using?
Reply:Originally Posted by Donoharm+1you probably have a crack in the gas hose, when you move to torch it closes sometimes and then good results, I had the same problem once drove me nuts.an unrelated advice.. drop the pure tungsten, a proper sized lanthanated is milion times better
Reply:Originally Posted by VPTDirty filler? Good torch angle?When is the weld going south, as soon as you start melting the aluminum or when you start adding filler or when you start moving?
Reply:Ironically I had this same exact problem yesterday while welding up a lawn mower transmission case. Would be welding along just fine then all of a sudden run into a problem area. I found a couple problems, I had the doors open and every now and then a breeze would blow threw the shop. The other was just simply gas coverage, either the torch angle was off down in corners or weird out of position areas or air was getting in from the gap between the parts being welded. If you have a gap in your parts back it with something to stop air from getting in on the back side.
Reply:Originally Posted by scsmith42Will do.  Using a 3/8" cup.
Reply:+1 on shovelon response. at least a 1/2" cup w/gas lens and reduce flow of argon 15 cfh or so. too much turbulence with that high gas flow you are using. creating a vortex that is randomly bringing in o2 from surrounding air.
Reply:+1 on shielding gas too. When I've gotten a bad cylinder the tungsten don't much like it, and establishing a clean puddle just isn't gonna happen from my experience. While this problem would be constant, and yours is sporadic. I'd lean towards the delivery problem as others have already noted.Last edited by Softwireman78; 06-21-2013 at 01:33 PM.Late to bed, and early to rise. Fish like hell so I don't have to make up lies. Syncrowave 200MM211 & Spoolmate 100
Reply:Originally Posted by MinnesotaDave+1 on the flow settings.  About 20cfm would be about the highest I'd go.At high cfm on an outside corner you may not notice a problem, but on inside corners it will show up.
Reply:scsmith42, I'm not sure if I read the entire thread correctly but did you say soap and water ?    the contamination you're seeing/showing would come from soap and none of the other (listed) solvents would touch it.I'd say that soap and water are not good cleaning agents, if they are used then I'd want to flood the metal for five minutes with a warm/hot water before going past this stage. Soap will create a film that the porous oxide will retain, but NOT the metal which isn't porous. This few mil film will retain both water vapor and soap water solution mixtures so I've never used soap to clean aluminum in 40 some years of working with the metal.  This is why poorly stored sheet with mill scale left on will discolor and 'get chalky'.Brushing will smear, not lift soap. Acetone won't solvent soaps, alcohol won't dissolve and remove soaps, so I think you may be adding this contamination by soaping the surface?If you take a piece that is not cleaned with soap and rinse it for a while, then air dry then use the hydrocarbon solvents for greases, then brush with a clean SS brush just before the weld, it will tell you if the "carbon pepper" spots are from the soap.It may be something else; but from what I've read that's what I'd check - if I were having this problem shown in the images posted.And, if you're using a small tooth brush just before you weld to abrade grooves in the oxide, then wash them in hot water to get the soap off, dry and then rinse in acetone to get the grease off, then sharpen on their side on the bench grinder to make the wire tips sharp, then use that tooth brush not one that is left from the other methods before.Cheers,Kevin MorinI didn't see it mentioned yet but what is your balance setting?http://all-a-cart.comWelding Cart Kits and accessories
Reply:I didnt read the replies, bit I have had this problem with ac welding aluminum. It was the tungsten. Presumably not enough post flow and the deterioration of the tung. I changes to an e3 hybrid tungsten and have no more issues.
Reply:I might guess that there might be condensed water inside the argon tank before it was filled.  You might be getting little droplets of water spitting out into the puddle while welding.  Dedinately something pretty reactive by the looks of the puddle.  i also agree that the "good" bead in the first picture is not 100% clean.  If you are using over 35 cfh-  you could well be getting a vortex sucking air in from the back side of the cup-  kind of entraining air from behind.   I have that problem on inside corner sometimes- especially if I am lazy and leave on the big gas lense cup and jump to inside fillet.  A small regular cup seems to work better where i can get the cups mouth closer to the puddle( on inside corner fillet)
Reply:Humor me and use a hybrid tungsten and report back.  I use the purple e3's.Green and red tungsten would always do this for me. weld fine all day and then out of the blue would just not weld and spatter all over. tried new lens/cup/argon, etc. ended up being the "oldschool traditional" tungstens.
Reply:I'm going to agree with the people who have mentioned gas flow and torch angle. I have had both of those mess with me and cause similar problems. I only skimmed the thread so I might have missed it but I didn't see much mention of filler prep. You say you clean them with MEK but have you sanded them down a little to remove any heavy oxidation? If the rod is old this may be necessary. Nylon mesh pads work great but whatever you use, avoid aluminum oxide abrasives. Give it a few good scrubs then a quick wipe. I just use isopropyl alcohol. In fact that's the only solvent that's in my shop and I have never had problems with just that and a stainless wire brush. If something is very greasy I pre clean it with Castrol superclean. I haven't found anything that cleans as quick or as well and it also lightly etches aluminum. After that, a thorough wash with water, wire brush and wipe with alcohol. At one point you said you didn't have problems till you added filler though so I would really look at the filler. Otherwise is the angle of your torch changing when you add the filler or is the filler changing the flow and allowing air to get sucked into the stream or something like that?Lincoln precision TIG 275Millermatic 140 MIG
Reply:Many thanks to everybody who contributed; I've learned a lot from your sage advice.As many had advised, the problem was indeed the gas.  I obtained a new bottle and swapped it for the old one, and voila - the welds look better than ever!  We ground out the bad welds and the new beads came out great!Now that the problem has been identified and isolated, I will introduce the advice received in this string re gas lens, cup size, lower CFM, etc into my welds going forward.Kevin, I live on a farm and a lot of my metal stock gets dirty, dusty and occasionally oily. I've used dishwashing soap and hot water for cleaning dirty surfaces for years, followed by a good hot water rinse, drying and wire brushing, and then MEK (but now acetone).  Usually it's Dawn dishwashing soap, as it does a good job of cleaning up dirt and oil, and I will use a plastic scrub brush similar to what you would use when srubbing car tires.  I continue to scrub while rinsing, so as to help get rid of all residue.I'm not a professional though, so I'll keep your advice in mind in the future.  Thanks for the feedback.