passing aluminum x-ray?

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Ok, so I am currently at a tig welding school and everyone is having issues passing the aluminum test. Out of 10 students who turned in a 2g and 3g plate only 3 plates out of the 20 passed. All due to excess porosity. I know this is a common problem with aluminum and cleaning is critical. The instructor and I have been trying different methods of welding the test plates to see if we can find one style that will work better etc., but it seems to be hit or miss no matter what we do.So the test plates are .063" 6061 T6. The rod is 5356, 3/32. Gas is 100% argon. We have fixtures with back up gas set between 10-12cfh. 1/16 gold lanthanated tungsten, #4 or 5 cup and standard collet body and gas flow set at 15cfh. We are using a synchro wave 351. We are filing the edges to be welded, wire brushing the area to be welded with a stainless steel brush dedicated for aluminum only. Then cleaning with acetone (we've tried alcohol as well doesn't seem to matter). The filler rod is also wiped with acetone prior to welding. Using about 90amps.We've tried welding fast, slow, more rod, less rod, more gas, less gas, gas lens collet body and nothing seems to matter. We are having about a 15-20% passing rate on all the plates we've turned in.Any ideas from you guys? Does anything stand out? Thanks in advance.
Reply:Are you hitting the pedal and just dabbing your filler, and moving along?I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:Originally Posted by weldermikeAre you hitting the pedal and just dabbing your filler, and moving along?
Reply:Try bumpin the amps a bit and manually pulse each dab. Watch your key hole and fill and move, fill and move etc. while working that pedal with every fill.I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:No dabbin, push that sucker in there.I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:What seems off to me is small cup and large filler rod.Small cup - not much for shielding - and may cause the tungsten stick-out to be too long.Large rod - chills the puddle too much each time.If neither of those end up being the problem, then I'm all out - pics of the welds could help - lots of these guys can pick out problems that way.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:Originally Posted by weldermikeTry bumpin the amps a bit and manually pulse each dab. Watch your key hole and fill and move, fill and move etc. while working that pedal with every fill.
Reply:Come to think of it I think I can set the machine up to pulse on its own. Then I can just concentrate on feeding the rod and keeping a short arc correct?
Reply:Sound like your instructor needs instruction.#1. Why on earth is he having you use backing gas on alum when it naturally skins over underneath? Your arc is on the topside. Touch the 2 coupons together at the start, and gap 1/16th" at the end, and push the puddle through, do not keyhole. The plate will close up on it's own. DO NOT TACK THE ENDS!!!  CLAMP THEM!!!#2. What good are 1/16th thick 2g or 3g test coupons good for when they only qualify for groove anyway? They are 5" long school plates, right? You know that groove is only 20% of all welding right? You would still need to do fillets. Ask your destructor why, why, why, he is not x-ray testing 14 gauge coupons which qualify both groove and fillet in one test?????? Is your destructor Mr.Tig?#3. Why is he making you weld with a 1/16th tungsten, then 3/32 filler, then a #4 cup? You can't keep a decent gas flow with that. Move up to #6 minimum. I bet you are getting air in from the topside.#4. Are your gloves clean enough to eat a sandwich with? My tests are done with brand spanking new or washed gloves. Good Lord, Good Luck. Last edited by shovelon; 11-08-2014 at 07:41 PM.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:Originally Posted by Wolverine76Come to think of it I think I can set the machine up to pulse on its own. Then I can just concentrate on feeding the rod and keeping a short arc correct?
Reply:Originally Posted by weldermikeNo dabbin, push that sucker in there.
Reply:Originally Posted by Wolverine76I will give that a shot, but what about the masses? This is a military welding school. I am the only civil service guy in the class. I have been welding for a few years, but most of the students who go through this course will have never touched a tig torch before starting this class.The school is 40 working days long and students are required to pass 2g and 3g in aluminum, mild steel, stainless and inconel. I had to do all of that plus magnesium and titanium. Point being that in the amount of time alloted for this and then trYing to teach newbs to pulse the pedal could be a long shot, but I will give it a shot. What would you say would be a good starting amperage when using the pulse method? 100-110?Sorry I guess you probably assumed so already, but these are all butt welds.
Reply:Hey I posted from a treestannd while freezing my nuts off today hunting lol go easy on me. Sounds like the typical military. Take a chef and make him a welder. You got two weeks to do it. Oh....and it's gotta pass xray when everything we gave you is completely f'd up. Get on it. Yawn, good luck.I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:Originally Posted by shovelonSound like your instructor needs instruction.#1. Why on earth is he having you use backing gas on alum when it naturally skins over underneath? Your arc is on the topside. Touch the 2 coupons together at the start, and gap 1/16th" at the end, and push the puddle through, do not keyhole. The plate will close up on it's own. DO NOT TACK THE ENDS!!!  CLAMP THEM!!!#2. What good are 1/16th thick 2g or 3g test coupons good for when they only qualify for groove anyway? They are 5" long school plates, right? You know that groove is only 20% of all welding right? You would still need to do fillets. Ask your destructor why, why, why, he is not x-ray testing 14 gauge coupons which qualify both groove and fillet in one test?????? Is your destructor Mr.Tig?#3. Why is he making you weld with a 1/16th tungsten, then 3/32 filler, then a #4 cup? You can't keep a decent gas flow with that. Move up to #6 minimum. I bet you are getting air in from the topside.#4. Are your gloves clean enough to eat a sandwich with? My tests are done with brand spanking new or washed gloves. Good Lord, Good Luck.
Reply:Originally Posted by Wolverine76My bad on the cup size I think k it's actually a 6 or 7. The back up gas is not the instructors fault. The engineer who does the x-ray reading insists on the backup gas. I will run some plates with no back up gas when I get back there next week. Haven't tried not clamping it. That is another thing I'll give a go. As far as the coupons go who knows, I'll ask. As far as I know that's what the navy requures, but I'll find out. I will also try a 3/32 tungsten.  Thanks for all of the advice, but no reason to be a dick.I guess it makes people feel good sitting behind a computer. Just remember you didn't always know what you know. Again thanks for the advice it's the best I've got and exactly what I was looking for. Just didn't need the narcissism.
Reply:Thanks again, I'm going to try all of what you suggested when I get back to work Wednesday. If I had to guess I think they are going by AWS D1.2, that seems to ring a bell. This site needs a thanks button. I will let you know how it goes.
Reply:Originally Posted by Wolverine76Thanks again, I'm going to try all of what you suggested when I get back to work Wednesday. If I had to guess I think they are going by AWS D1.2, that seems to ring a bell. This site needs a thanks button. I will let you know how it goes.
Reply:We never had our welds RT'd in tech school; however , we did once we were qualifying at our duty station. What branch of service are you working for?For 0.63" wall Al tube test I found what worked the best for me was 3/32 2% thoriated, using only a stainless wire brush, and a fine Jewelers file for the bevel. In my experience 1/16 tungsten is crap for Al high freq welds because it seems to lead to a lot of tungsten inclusion. I find that it is much more frequent for Chinese made tungsten as well. Note that unless it is new old stock one cannot procure American made tungsten anymore as the plant closed in ~2009.I also found the use of liquid cleaners was large in part useless and increased the chance of contamination from the particles left behind from the application and removal medium.
Reply:Shovelon pretty much covered most of it only thing I have to add is take a scotch brite to your filler and use weldo on both sides of the joint  how all the stuff I dealt with Milspec wise was done that got xrayedSent from my iPhone using TapatalkMiller Xmt 350Lincoln Ln-25Ahp 200xSmith Gas Mixer AR/HTig is my Kung FuThrowing down dimes and weaving aboutInstagram http://instagram.com/[email protected]
Reply:I'll toss in small suggestion in here.  Make a slight change to your cleaning procedure.First wipe down with acetone.Then wire brush the joint and immediately begin welding.Brushing first and then wiping with acetone seems more likely to me to flush contamination into the area being welded.  It also allows more time for the oxide layer on the aluminum surface to renew itself.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector