TIG and aluminum - porosity?

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Hey all, first post though I have been lurking for some time. Sorry for the lengthy read.I have decided to start playing with AL lately. I am a hobbyist fabricator, for years my trusty MIG has helped me to modify/create many vehicle components. I am sharing a small garage space with a friend, who owns a Syncrowave 180sd..so of course I am going to use it! I have Tig'd mild steel many times over the years, I am no pro but no major issues there.My question is regarding the 'bumps' on this AL test piece I welded. What is the cause? is this porosity? or a different issue. I have not seen this before with 'professional' weldsSyncrowave 180SDWelds on the left had the knob towards 'penetration', the right I moved it towards 'cleaning' (trialing settings as I went along)Machine was at 100 amps, foot pedal 100%  in the beginning, less as material heats up during a pass.3/32 Red tungsten, ground to a point with small flat#7 cup, no gas lens~12 CFH [I think this is my problem?] Did not realize it was so low until i shut the machine down. I was in an open garage, very little wind. 4043 rod (I think, why dont they stamp these things like steel! rhetorical question..)material thickness 1/8"Dedicated stainless brush and acetone used for prep. I do not know the material, came from the scrap bin at work. Also note I wire brushed the entire piece after welding to see if it would clean up at all.comments/critique welcome. I know these are poor welds...no need to tel me again. Thanks! Attached ImagesLast edited by Chicken; 04-12-2015 at 11:49 AM.
Reply:What you are seeing isn't porosity. It's coming from the fact you overheated the material.I didn't see the material thickness, but 100 amps is low on average unless you are welding something like 16 ga.Alum is very heat sensitive and a great heat sink. Low amps simply heats up the whole piece and won't for a puddle fast. It seems backwards, but more amps faster put less heat into the piece overall.if you are welding 1/8", you want your amps up to at least 150 amps. I go 180-200 amps, but I can back off the pedal faster than the students can. Pound the pedal to the floor and as soon as the puddle forms, start backing down and fly to out run the heat build up in the piece. When doing multiple beads on a small piece like that for practice. Cool the piece between beads. If you can pick up the piece bare handed, it's cool enough to run the next bead.I'd also question your filler choice. Seems a strange one. Most use 4043 or 5056 on average. 4043 has a tendency to form those pimples regularly if you get things too hot..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Thanks for the response, I made a couple edits to original post.Material is 1/8" 1"x3" boxyou are right on the filler rod...I believe it is 4043. I dont know why I was thinking 3036.I did not think it was porosity, as I am familiar with that regarding steel. Glad you clarified what was happening to the material. I'll tell ya, AL seems *** backwards. lower melting point, requires more current blah blah. I plan to get in the garage and repeat on the other side of the piece today, hoping for some improvement of course.  Originally Posted by DSWWhat you are seeing isn't porosity. It's coming from the fact you overheated the material.I didn't see the material thickness, but 100 amps is low on average unless you are welding something like 16 ga.Alum is very heat sensitive and a great heat sink. Low amps simply heats up the whole piece and won't for a puddle fast. It seems backwards, but more amps faster put less heat into the piece overall.if you are welding 1/8", you want your amps up to at least 150 amps. I go 180-200 amps, but I can back off the pedal faster than the students can. Pound the pedal to the floor and as soon as the puddle forms, start backing down and fly to out run the heat build up in the piece. When doing multiple beads on a small piece like that for practice. Cool the piece between beads. If you can pick up the piece bare handed, it's cool enough to run the next bead.I'd also question your filler choice. Seems a strange one. Most use 4043 or 5056 on average. 4043 has a tendency to form those pimples regularly if you get things too hot.
Reply:Common problems when starting out (I know 'em, I do 'em all the time!) are too much arc length (torch too far from workpiece), and too much torch angle (basically out runs your gas, and too much arc length, and invites oxygen to get pulled into the shielding gas). The other issue on aluminum is that you really do have to let the puddle form up, let the cleaning action burn a nice spot away, then you've absolutely got to motor out. Probably faster than you're really comfortable with your first few dozen times. If you hang out too long, you'll just get the whole piece too hot like was mentioned, and it'll start flowing like water, and looking very "fuzzy" on the weld for lack of a better term, not shiny and smooth.A small piece like that will probably only take an inch or two of welding when you're starting out before you have to give it a solid 5+ minute cool down, and even then it'll probably be borderline too hot towards the end of it. Keep practicing! It's tough compared to MIG for sure!Thermal Arc 186 AC/DCHobart Handler 125
Reply:These points make sense, thanks for the input.As for arc length, I am doing my best - BUT compared to steel I swear this stuff just jumps up on my electrode all the time. Causing me to sharpen the tungsten quite often. Even when I dont dip the electrode, it always seems to melt into an odd (non symmetric) shape. Any tips of stopping this? Adjust AC balance? The small piece sure does get hot. I will have to get more scrap to practice with. For the speed/rate comment, I am going as fast as I can! Good practice for feeding rod, as I am pretty poor at it still. Though I watch Jody's videos and it looks as though he is leisurely dabbing along (not sure on material thickness)Regarding starting the weld. Do I ease into the pedal, letting it clean a nice spot and then put it down (the pedal) to form the puddle? Or Just hammer it from the start, still waiting for the puddle to form?Thanks again guys.  Originally Posted by DefCommon problems when starting out (I know 'em, I do 'em all the time!) are too much arc length (torch too far from workpiece), and too much torch angle (basically out runs your gas, and too much arc length, and invites oxygen to get pulled into the shielding gas). The other issue on aluminum is that you really do have to let the puddle form up, let the cleaning action burn a nice spot away, then you've absolutely got to motor out. Probably faster than you're really comfortable with your first few dozen times. If you hang out too long, you'll just get the whole piece too hot like was mentioned, and it'll start flowing like water, and looking very "fuzzy" on the weld for lack of a better term, not shiny and smooth.A small piece like that will probably only take an inch or two of welding when you're starting out before you have to give it a solid 5+ minute cool down, and even then it'll probably be borderline too hot towards the end of it. Keep practicing! It's tough compared to MIG for sure!
Reply:You can't keep quite as tight an arc as you can with steel /stainless when tig welding alum. Alum tends to hump up more when you add filler and will engulf your tungsten if it's not back a bit farther.As far as starting, simply hammer the pedal to the floor. The EP will clean the material. If it's so dirty you need to make a pass to break up the oxides in advance, you should probably be brushing it more with a stainless brush in advance..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I was not referring to making an entire pass cleaning, but rather sort of moving the torch in a small area before forming the puddle. (as I have seen Jody do when tacking pieces)As I can watch the cleaning action work in the area, was not sure if the idea was to let it do some work before creating the puddle. I will make sure to put the pedal to the metal.