Aluminum 6G

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We used to only require a 3G aluminum cert at my shop, and it did me well for the past 15 years. All of a sudden, we are now required to have a 6G. I've been practicing for the past week, and my beads have been looking good. (I would like to post photos, but there's the whole homeland security / cameras on a federal installation issue.) The problem I've been running into is on the radiographic (X-ray) inspection. There are many small (VERY small) bright spots that the tech says are tungsten inclusion. I don't see how that's possible, as the tungsten shows no indication of damage after welding. Here's the prep and parameters I'm welding to:3 inch 6061-T6 pipe J-beveled, 0" gap between coupons, wire brushed clean with austentic stainless bristle brush, wiped first with 100% IPA, followed with an acetone wipe.3/32" 5183 filler rod, scotchbrite cleaned, IPA and acetone wiped.3/32" 2% Thoriated Tungsten (I know, I know, it's radioactive, but the WPA specifies it.) balled just to the diameter of the tungsten.30 CFH 100% ArgonMiller Syncrowave 350, max amps set to 215, AC balance at 7, 12 second postflow. Actual welding current averages about 160-180 amps, according to a coworker watching the amp meter.Interpass temp is not to exceed 250 degrees, checked with temp stick.As I said, I'm not having trouble with the bead profile, the visual inspection passed, just the crap showing up on the x-ray. Anyone have any tips I might try? We are allowed 4043 filler as an alternative, but I saw no difference in the performance.TIAMiller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:2% thoriated without inverter power will eat that tungsten a little bit. Seems silly, but it's what you have to work with. Try turning the balance up(can't remember if you can on sync's)Less chance of issues if you can get the heat out of it.Besides that, I'm at a loss. I had to do aluminum with pure, but it was on an old machine with sine wave, so it worked fine. Will they shoot a practice one for you with a different tungsten to find out for sure? I'd be interested to see that.
Reply:1/8" Tungsten will hold together better.  Can you pre-heat? That also might help.
Reply:tiny inclusions in x-ray1-3/32 is small as others have noted. I've become a fan of ceriated---very recently,prior was hooked on 2% thoriated. IMHO the ceriated outperforms the 2%--on aluminumand ss.Balling the tungsten purposely, is some old schoolholdover---written by someone that has never seen the difference in performanceon AC, on aluminum, especially thicker aluminum....of focusing that arc withsharp point on the tungsten (which has a very small, 45 degree 'blunt' to it.)2-Going much more unbalanced is going to help not hurt you. Increasing the AC frequencymakes this unbalanced arc stiffer (if that's do-able on your machine).3-Gas Lens???? apparently you're not using one--those help in a bunch of ways--includingallowing you to cut back on the argon flow. The high flow rate that you're using, just maybe entraining some oxygen---producing the inclusions the tech has interpreted as tungsten. Gas lens really help control that, etc.4-???Stupid question from me---have others in your shop--passed the 6G?? --if so, the tech should compare those x-rays to yours--and be able to SHOW you what he'scomplaining about.--if so, then try using the same machine, torch, etc. that the successful candidates used5-If all of the above, produces no better results, try a new, fresh argon bottle....if still no joy.....then consider changing the argon gas hoseto one that is teflon lined. The rubber liner inside those hoses, can gas off, deteriorate and age--just a tad with the result showing up in x-ray.I saw that occur on heavy aluminum welding.Blackbird
Reply:All good suggestions, thanks! I'm stuck using the 2% thoriated, so I can't change that parameter. The syncrowave is strictly a 60hz machine, so no frequency adjustment. I hadn't considered not balling the tungsten, or trying a 1/8", so I think I might try that first. If I understand correctly, I should grind to about a 45 degree angle with a blunt point? I can adjust the balance, it ranges from 0 to 10 and I'm at 7 right now. Should I go higher (numerically)? I don't know why they are spec'ing 30 CFH argon flow, I've always had good luck with 20. I will keep the gas lens in mind next trip to the LWS.One thing I did check was the max current 3/32" 2% thoriated was rated for, and as I recall it's about 230 amps, unbalanced. I don't think I've ever exceeded 190 amps.Let me ask this. What if the interpass temperature was too hot? Some of the samples I sent for x-ray I wasn't real careful on checking that parameter. (I got in a hurry ) I've notice over the years of welding aluminum that if it starts to get too hot, the bead looks as though there is sand embedded in it if you keep welding it. Anyone know what happens if the base material gets too hot?I have another sample ready for testing, so we'll see if I'm still having the same problem. I'm just about out of argon on the machine, so that will get changed out on Monday.Thanks again to all for the help! Miller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:Forgot to answer Blackbirds question. I was picked as the "trailblazer" for the 6G, so no one else has tried it yet. I was 29 when I certified 3G and my eyes and steady hand were much better then. I wish I would have went for the 6G at that time! Now I'm 1 month away from 46, wearing bifocals and not quite as steady as I used to be. I WILL pass, but it may take a bit more time. Fortunately, welding is a sideline job for me at my company, and not required for my continued employment. (I feel for the poor guy who's job is on the line based on passing a cert test!)Miller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:Originally Posted by bratkid63All good suggestions, thanks! I'm stuck using the 2% thoriated, so I can't change that parameter. The syncrowave is strictly a 60hz machine, so no frequency adjustment. I hadn't considered not balling the tungsten, or trying a 1/8", so I think I might try that first. If I understand correctly, I should grind to about a 45 degree angle with a blunt point? I can adjust the balance, it ranges from 0 to 10 and I'm at 7 right now. Should I go higher (numerically)? I don't know why they are spec'ing 30 CFH argon flow, I've always had good luck with 20. I will keep the gas lens in mind next trip to the LWS.One thing I did check was the max current 3/32" 2% thoriated was rated for, and as I recall it's about 230 amps, unbalanced. I don't think I've ever exceeded 190 amps.Let me ask this. What if the interpass temperature was too hot? Some of the samples I sent for x-ray I wasn't real careful on checking that parameter. (I got in a hurry ) I've notice over the years of welding aluminum that if it starts to get too hot, the bead looks as though there is sand embedded in it if you keep welding it. Anyone know what happens if the base material gets too hot?I have another sample ready for testing, so we'll see if I'm still having the same problem. I'm just about out of argon on the machine, so that will get changed out on Monday.Thanks again to all for the help!
Reply:Okay, here's an update. I switched to the ceriated tungsten, 1/8" in size, sharpened and blunted as described and turned the AC balance all the way to 10 (max penetration). I noticed the arc is much more focused and controllable. It seems to push the heat into the groove a lot better.One thing I noticed that may cause a problem. After running a pass, I looked at the end of the tungsten and it had eroded partially away, leaving a jagged looking face where I had ground it. I switched to the thoriated (prepped the same way) and the same thing happened to it. FWIW, I noticed no real difference in performance between the ceriated and thoriated. I tried regrinding the face of the tungsten slightly, and melted the end just to the point it was rounded to the diameter of the tapered end of the tungsten. That seemed to help a bit, but there is still some erosion. (Forgot to mention, I switched argon to a fresh bottle.)On a slightly seperate but related subject, what is the best tungsten and prep for use on an older Miller Dialarc 250 sinewave machine for AC aluminum? I've heard pure tungsten works best for sinewave. I've been using thoriated, but the arc wanders a lot. I haven't tried the tapered tungsten prep on it yet, don't know if I can expect the same results as the squarewave machine with the AC balance.Thanks for all the help!Miller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:Are you using continuous HF? If so, you might want to turn the HF intensity down to the minimum that will start and sustain the arc. It may be contributing to the erosion.
Reply:sneak some other tungsten in and paint it red on the end!
Reply:BTW, I sent you a PM on this. Check your WW mailbox.Here's a link to a post I did a year ago showing b/4 and after on electrode:http://weldingweb.com/vbb/showthread.php?t=23430In the example above, the end of the 2% thoriated, formed a small, smooth ball of meltthat flowed tangent to the ground, radiused taper, without lots of little erosion ballson the end.On this erosion biz....If erosion is noticed, then the 'missing tungsten' is going somewhere-----presumably right into the weld.The more current flowing thru the electrode, the greater the chance for erosion to occur.With your current machine that you have to use, possibly doing one heck of a preheat,with the idea of trying to limit the total current flow thru the electrode, to control or eliminateerosion would help.       In combination with the above--try the pure tungsten, for erosion control.Somebody out there, has had radiographic success with aluminum pipe. ???Are you able to query the genius that wrote up this WPS???Blackbird
Reply:I know this is a silly question, but are you purging the pipe?
Reply:No purge on the pipe, spec doesn't call for it. The bead on the inside looks good, minimal oxidation on the surface. Is purge something standard on aluminum pipe?  I know it is on stainless, or you end up with the burnt sugar on the inside bead.Anyone care to weigh in on the proper tungsten / prep for my Dialarc 250HF (sinewave, no AC balance control) for AC aluminum?Miller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:I always been told to use green/pure or red/2%...  but for what its worth, I always use red.. I find the green goes away to fast with higher heats... the tip just keeps getting shorter and shorter...
Reply:Bratkid,My opinion is that the back of the root pass has the least coverage of inert gas. Therefor i always purge; even on steel pipe.I dam both ends of the test pipe with foil taped around it. I put the argon in on the bottom of the pipe, and put a pencil size hole in the top foil dam; if the hole is too small there will be blow out pressure on the last bit of weld.A final measure I use is to put masking tape over the v groove, and pull it back in about 3 inch increments as I fill in the root.I am curious to know where the inclusions are showing on the x-rays.
Reply:Hello bratkid, everyone has very thoroughly covered a number of avenues to consider. I might only add a couple of additional ones. Try using a oil-free chemically cleaned file for the final prep on your joint prep. and drop the scotchbrite for cleaning the filler rods. When you use the file be sure to only stroke it in the direction of cut and file the inner edge from the root face back around 1/4" or so, file the land, file the bevel face, and file the outer surface of the pipe from the bevel back onto the pipe a 1/4" or so. Do this just before welding and clean the file often. Wipe your rods with a clean lint-free cloth that has been dipped in acetone just before using. Scotchbrite can possibly be the culprit for contributing some of the indications that you are seeing. Good luck and best regards, Allanaevald
Reply:The best suggestions yet have come from this forum. Anyone out there able to read x-rays? These are a couple images of my last coupon I turned in. (These are still practice pieces, not ready for the test yet!) There is obvious porosity, and I think I know where that came from. What's got me bugged is they said there was an area with lack of fusion in the root. I think I see what they mean (second photo, top left of the bead, thin black line), but I'm a bit stumped on how it happened. All the passes looked like they went in good.Anyway, here they are: Attached ImagesMiller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:Hello again bratkid63, the nature of aluminum certainly doesn't lend itself to open-root weld joints. Is there any possibility that your torch angle could have been favoring one side of the joint over the other, or that you could have been slightly off-center with where you were directing the arc? I am sure that you are well aware of the lack of cleaning action of the arc on the backside of an open-root groove so that means that it needs to be absolutely clean and the heat has to be very evenly distributed between the two pieces. Another possibility occured to me here, are you dabbing the filler wire or are you using a lay-wire type of application for the root? I ask that because if you are using a lay-wire style you may be blocking the cleaning action of the arc at the front of the weld pool and this could possibly contribute to the issues you see in the X-rays. A bit more to think about. Best regards, Allanaevald
Reply:1--bratkid63---you don't mention if the latest coupons showed any tungsten inclusions. Did They?2-Since you're attempting to fine tune the process and your technique, if you haven't alreadydone this----suggest you mark notch say--the 'up' --outer end of the coupon when fixtured for 6G,with notches representing 12, 3, 6, and 9 o'clock positions; to help give you an idea ofwhere things are going good and where they are not.Blackbird
Reply:Hello Dave, great suggestion. At least that way he might have something in his memory of that particular area that he could relate to a problem or issue. Best regards, Allanaevald
Reply:Bratkid,I liked aevald and Dave powelson's suggestions, and I have to add these ideas also: should you file, use a new,nicolson super shear file ( it's designed for soft metal and doesn't clog as readily as a mill file or flat bastard) and use it on aluminum only. Clean it by scraping across fresh aluminum only.Is there a possibility that your torch angle is too oblique and entraining air into the gas plume?When you are dipping the filler rod are you keeping it within the gas plume, or are you allowing it to come out of the plume, and contaminating it in the air?Also, as Dave suggested, indicate what part of the "oclock" position is shown in the x-rays. It will help us figure this out.
Reply:Originally Posted by dave powelson1--bratkid63---you don't mention if the latest coupons showed any tungsten inclusions. Did They?2-Since you're attempting to fine tune the process and your technique, if you haven't alreadydone this----suggest you mark notch say--the 'up' --outer end of the coupon when fixtured for 6G,with notches representing 12, 3, 6, and 9 o'clock positions; to help give you an idea ofwhere things are going good and where they are not.
Reply:No tungsten inclusions this time. They show up as bright white spots. The darker spots that look like bubbles are the porosity. I may have had the cup a bit too far of an angle. Either that or it's the 30 CFH argon flow spec'ed, or I got in too much of a hurry on the last pass and didn't allow sufficient time for it to cool. Next coupon is only getting 20 CFH. Definately dabbing the rod. I don't think it would be possible to lay it in the groove without it melting away to nothing. I only pull it out of the puddle as far as required to keep it from melting too soon.I like the idea of notching the pipe. Have to do that next time. One thing I'm lucky is the access I have to a full NDE department. My department provides a lot of service to them and their equipment, so they are more than willing to help us out anytime we need something. Besides, they just got a new $20M x-ray robot system and it's easy for them to just toss a coupon on the table and let the machine do it's thing. The machine fills a whole high bay in a hangar. It can fit entire segments of a shuttle booster rocket in it. Pretty awesome stuff. Sure going to miss it if the layoff comes Miller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:Originally Posted by bratkid63No tungsten inclusions this time. They show up as bright white spots. The darker spots that look like bubbles are the porosity. I may have had the cup a bit too far of an angle. Either that or it's the 30 CFH argon flow spec'ed, or I got in too much of a hurry on the last pass and didn't allow sufficient time for it to cool. Next coupon is only getting 20 CFH. Definately dabbing the rod. I don't think it would be possible to lay it in the groove without it melting away to nothing. I only pull it out of the puddle as far as required to keep it from melting too soon.I like the idea of notching the pipe. Have to do that next time. One thing I'm lucky is the access I have to a full NDE department. My department provides a lot of service to them and their equipment, so they are more than willing to help us out anytime we need something. Besides, they just got a new $20M x-ray robot system and it's easy for them to just toss a coupon on the table and let the machine do it's thing. The machine fills a whole high bay in a hangar. It can fit entire segments of a shuttle booster rocket in it. Pretty awesome stuff. Sure going to miss it if the layoff comes :cry::cry::cry:
Reply:I have always read that Brown-1% zirconium-AWS EWZr-1 tungstens were for x-ray quality welds on aluminum. I know that your WPS says one thing but it might be wrong. -DanOwnerDW Metalworks LLCMiller Trailblazer 302Miller 8RC FeederMiller Passport PlusMiller Dynasty 200 DX W/Coolmate 1Hobart Handler 135Hypertherm PowerMAX 30Smith O/A Torch SetPlus much much moreOK, so I got some gas lens collets with #7 cups. As far as tungsten, I don't think anyone will be checking to see if I'm using a particular type or not, so if I know which one will work the best, that's what I'll use.Something else I discovered is there are different grades (purity) of argon gas. I went to exchange a bottle at our logistics, and I noticed some gray bottles with white stripes on them. They were labelled as "Argon, Grade A, 99.997% purity". I called the gas supplier directly and asked what the big deal was with these as opposed to the standard brown bottles. They said the brown bottles were industrial grade, and the purity wasn't guaranteed to any specific level. Now I know I'm really stretching, suggesting the argon is to blame for my lack of skill, but it's not costing me anything to use the higher grade, so it can't hurt. Maybe there was some impurities (air) in the industrial gas bottles that added to my porosity problem. One can only hope the answer would be that simple! Miller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:Hello bratkid63, eliminating variables is never a bad thing. As you stated, it certainly won't hurt to go with the verified "pure" shielding gas. Give it all a go and let us know if you have any additional changes in the results. Best regards, Allanaevald
Reply:Originally Posted by bratkid63OK, so I got some gas lens collets with #7 cups. As far as tungsten, I don't think anyone will be checking to see if I'm using a particular type or not, so if I know which one will work the best, that's what I'll use.Something else I discovered is there are different grades (purity) of argon gas. I went to exchange a bottle at our logistics, and I noticed some gray bottles with white stripes on them. They were labelled as "Argon, Grade A, 99.997% purity". I called the gas supplier directly and asked what the big deal was with these as opposed to the standard brown bottles. They said the brown bottles were industrial grade, and the purity wasn't guaranteed to any specific level. Now I know I'm really stretching, suggesting the argon is to blame for my lack of skill, but it's not costing me anything to use the higher grade, so it can't hurt. Maybe there was some impurities (air) in the industrial gas bottles that added to my porosity problem. One can only hope the answer would be that simple!
Reply:Quick update:Just got back to being able to take some time to practice again for the test.  I'm 99% sure I know where the contamination was coming from. Aevald called it in an earlier post. It appears the scotchbrite cleaning of the filler rods is doing more harm than good. The "cleaned" rods left the beads with the appearance of sand in them. (I did wipe them with acetone after the scrubbing.) I tried a rod right from the box, and the bead came out looking much cleaner. The best I can figure is some abrasive material from the scotchbrite must be embedding itself into the filler rod, and is left behind in the weld bead.What is a good method of cleaning the filler rod, or should I even worry about it? I hope to be ready for the test in a couple more weeks.Miller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:Originally Posted by bratkid63Quick update:Just got back to being able to take some time to practice again for the test.  I'm 99% sure I know where the contamination was coming from. Aevald called it in an earlier post. It appears the scotchbrite cleaning of the filler rods is doing more harm than good. The "cleaned" rods left the beads with the appearance of sand in them. (I did wipe them with acetone after the scrubbing.) I tried a rod right from the box, and the bead came out looking much cleaner. The best I can figure is some abrasive material from the scotchbrite must be embedding itself into the filler rod, and is left behind in the weld bead.What is a good method of cleaning the filler rod, or should I even worry about it? I hope to be ready for the test in a couple more weeks.:cool2:
Reply:We're using Alcotec rods. I think that's a pretty decent brand, am I wrong?Miller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:Alcotec makes excellent mig wire.  Never used their tig rods.  I wipe my alum tig rods with acetone if they've been sitting outta the sealed tube for awhile.  When the dull is gone from the surface, they're clean.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Originally Posted by bratkid63We're using Alcotec rods. I think that's a pretty decent brand, am I wrong?
Reply:I know this thread is old, but I think I finally figured out what my problem was. We spent a good portion of the last month experimenting with different variables trying to figure out where the porosity is coming from. We switched to welding flat plate that I machined to the same joint configuration as the pipe, just to eliminate (or at least reduce) variables in weldor technique. We got the same level of porosity on the plate as we were getting in the pipe, no matter what variable (AC balance, interpass temp, high freq intensity etc.) we changed.What it finally turned out to be is a bit embarrassing, but easily overlooked. I determined that somehow air must be getting into the argon supply. Early on I replaced the torch and leak checked every fitting, so I thought I was leak-free. If I had been more observant, I would have caught the fact that the pressure gauge on the flowmeter was moving down rather quickly after turning off the valve on the argon bottle. When I finally did notice this, I realized I still had a leak, but another leak check of the fittings produced no results. I turned my attention to the hose between the flowmeter and the gas solenoid. It was about 18 years old, as I put the machine together when we bought it back in '91, and looked a bit sorry. I went ahead and changed it out with a new one and that alone stopped the gas leak. Ran a couple more plates this week, and they came out free from porosity! Hopefully I'll be running my 6G before Thanksgiving.Miller Thunderbolt AC/DC (Sold)Miller Dialarc 250HFMiller MM251Miller MM200 (Sold)Miller MM130Miller Spot WelderVictor O/A rigMiller Spoolmatic 1 (Sold)
Reply:thanks for the update, this was a very interesting postMechanical Engineer
Reply:X 2Glad to see it was all sorted.I hate when i overlook the simple things first and waste a lot of time chasing the wrong thing.
Reply:Originally Posted by bratkid63I know this thread is old, but I think I finally figured out what my problem was. We spent a good portion of the last month experimenting with different variables trying to figure out where the porosity is coming from. We switched to welding flat plate that I machined to the same joint configuration as the pipe, just to eliminate (or at least reduce) variables in weldor technique. We got the same level of porosity on the plate as we were getting in the pipe, no matter what variable (AC balance, interpass temp, high freq intensity etc.) we changed.What it finally turned out to be is a bit embarrassing, but easily overlooked. I determined that somehow air must be getting into the argon supply. Early on I replaced the torch and leak checked every fitting, so I thought I was leak-free. If I had been more observant, I would have caught the fact that the pressure gauge on the flowmeter was moving down rather quickly after turning off the valve on the argon bottle. When I finally did notice this, I realized I still had a leak, but another leak check of the fittings produced no results. I turned my attention to the hose between the flowmeter and the gas solenoid. It was about 18 years old, as I put the machine together when we bought it back in '91, and looked a bit sorry. I went ahead and changed it out with a new one and that alone stopped the gas leak. Ran a couple more plates this week, and they came out free from porosity! Hopefully I'll be running my 6G before Thanksgiving.