Some embarrassing Al welding pics inside. Help please

admin

Hello,I guess this is my introduction and first post asking for some advice and criticism on some welds. I mostly work on cars in my garage and build exhausts, intakes, and various brackets from a variety of metals as I need them. I have an HTP 200 inverter TIG machine and usually weld steel and stainless steel, but occasionally I weld some aluminum too. But I always feel like its a fight with Aluminum. I had one of these battles over the weekend.  I needed to weld up some brackets for mounting an  intercooler and radiator in my car. I haven't really touched the welder in months, so I'm always a bit rusty and unpracticed. That is part of my problem. So I made a couple practice welds on some aluminum scrap to get my skills back and adjust the machine. And that went OK. I was making decent welds on some .125" flat alumiunum plate. So I was ready to try and weld some tabs onto the intercooler. I wire brushed the intercooler the new bracket. I also wiped both with acetone on a clean paper towel. I cleaned my aluminum welding rod with a scotch brite pad, nice and shiny now. I started out with my gas flow rate set to about 10cfh, I have a 2 dial gauge setup, not a floating ball type meter. But the gas sounds like its flowing steady and makes a pretty strong hiss at the cup. I'm using a 3/32" Zirconium tungsten sharpened to a point, now slightly dulled from practice welds. The wave balance is at about 70% forward, and frequency 120Hz.  I strike an arc and pretty get a slightly dirty puddle, and when I go to dip the filler rod to tack the parts together, the puddle just explodes into a black messy crusty ball. Voila!:What is going on here? It happened at the tack on the left also, and I ground it down so I could go back and weld over it. But I was fighting this all the across the bead and had to weld it 2 or 3 times to even get a very crappy modestly strong weld.  I'm set up and willing to run some beads this week. If someone can coach me a little bit, I'd love to learn past this annoying little problem. I am able to make some pretty decent welds in steel and stainless. I just don't know what I'm missing with aluminum.
Reply:I don't think 10 cfh is enough, try around 25. Also, if you touch your filler to the tungsten it will do that.
Reply:From both your settings and the picture I'd say you gas flow is to low, try 25cfh instead.Have we all gone mad?
Reply:25cfh seems really fast. I'll give it a try. But just to compare my gauges calibration, Thats enough to get a pretty good breeze on your hand if you hold in front of the torch. Is that right? It would blow out a candle at several inches distance, even if it wasn't argon...
Reply:The joint that you're working on looks like it will put your torch at an odd angle. While the 10 may have worked for you out in the open, you'll need the extra to make up for the less-than-ideal torch positioning.
Reply:From the picture, you've got poor inert gas shielding of your weld area / weld deposit.Since you mentioned 10 cfh sounded like it was hissing like crazy, pull off that #4 cup I'm guessing you must have on there, and put on a #6 or so size cup, and adjust flowrate to 15 cfh.  Heck, if that doesn't work, maybe your flowmeter isn't working right, or you've got a leak somewhere, try turning the flow up some more, or down some more.  Repeat tests (on freshly cleaned aluminum surfaces similar configuration and material thickness as what you need to weld) until you get nice shiny weld beads with no scum floating in the middle of the puddle either.  Don't forget to let both pre-flow and post-flow do their things.  You need to keep the hot metal shielded at all times until it has cooled off sufficiently (including the metallic tungsten electrode itself.)Try reducing your tungsten stick-out and reduce your arc length if at all possible.  If you are stuck way out there because of a tricky weld joint, you may need a gas lens.Too much flow can cause problems as well, so if changing the cup size, stick out, arc legth don't help, try reducing your flow as well.  Too much flow can cause atmosphere to be sucked into the gas stream, thereby contaminating it with some oxidizing elements (such as, oxygen and nitrogen.)
Reply:"I strike an arc and pretty get a slightly dirty puddle, and when I go to dip the filler rod to tack the parts together, the puddle just explodes into a black messy crusty ball. "When you get the puddle started right before you add the filler metal, the weld puddle should have a mirror look to it.  If there is a lot of contamination floating in the puddle, then you will have problems getting a good weld puddle to flow.  Since you are doing a fillet you can crank up the frequency as high as you want"The wave balance is at about 70% forward, and frequency 120Hz."  Are you balancing more toward cleaning (+) or to penetration (-)  I would go with a more balanced wave until you get a better puddle to flow.  Your frequency can be as high as you like.  This will only tighen you the AC arc.
Reply:Try loosening your backcap and pull your tungsten out. Then remove your cup and collet assy. Look inside and see if your backcap cut off the gas flow port. Happened to me several times.
Reply:You don't say what amp setting, might as well switch to 1/8 tungsten, clean and sharp and bump the amps up.-the higher the frequency, the lower the heat input--but the tighter the arc-the more unbalanced--'greater penetration' setting you go--the higher the heat-higher heat input does what increased cleaning can't do. The pundits cannot fathom this.-on large, yet relatively thin items, they can have lots of heat soak and spread--on initial tacking/welding--before the parent area starts to ramp up in temp. and begin to act like it doesn't mind being welded. Focused heat via max. penetration setting, low AC freq. helps to counter this,with minimum heat input to the assembly. Inverters are really good at focused heat on AC, so use this feature. Playing the arc over, up and down the area to be tacked, to help ramp up the heat soak for a few seconds can help.Your picture shows a real lack of decent cleaning/prep---and the welds promptly show that-dirty,smutty puddle even before adding filler--that's a clue that problems are unfolding.Polished items Blue Circled---have rouge and wax embedded in the skin--youneed to clean/sand a bunch more. Aggressive brushing or padding, with solvent, before any sanding or you can embed the stuff right back in.Red circled--there's lots of AL oxide on the skin of that .125 plate-evidenced by themill marking still seen--you need to remove all the heavy AL oxideRed circled--on cut edges shows lube/trash/wax still on them. If any of that goop is onthe hidden edge butted--that's more contamination.Cut off the tacks and have at it-again for cleaning and prep. Think about doing a decent sandingjob on those sawn edges & radius the corners, if appearance means anything. If you don't redo all that wasn't done, the end result will look worse than it does now. Cowboy uP.http://weldingweb.com/attachment.php...1&d=1308029249 Attached ImagesBlackbird
Reply:What are your amps set at? I see the freq. is 120. Try as Jakerau suggested, a larger cup, and then the gas at 15. 25 is more than you should need on this small kind of weld. I'd set the freq. at 80- it gives you a wider wet area, and believe it or not, many times on smaller parts it helps start the puddle much better.  The wider puddle will also allow you to wet both sides of the joint, meaning the filler can do it's job easier.  Try about 160 amps. Make a quick puddle, and go.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Also it.    Has happened to me not because of settings or gas flow but sometimes you get badly recycled aluminum that has actually had steel and other contaminants in it
Reply:Thanks for all the tips. I'm a bit busy lately but I did make it out to the garage last night and welded on another related project. I am assembling a custom fan shroud to work with the bigger intercooler to get everything to fit into the nose of the car. So, the intercooler job above was welded with the the amperage dial wide open at 200. I was throttling with the pedal somewhat, but did have to punch it wide open to get the puddle started.- Looking again at the regulator gauges I realize i was reading the LPH scale instead of the CFH scale, I was actually running 25-30 CFH. Maybe a bit too fast. So, I am dropping to about 20CFH going forward.-The one thing that I gathered from above that seems to make sense is the polished aluminum containing rouge and oils. I was afraid of using sandpaper or a flap disk on the aluminum because I didn't want to embed sand or other contaminants from the paper into the surface. But really I probably needed to be more aggressive than just the wire brush. So for this next round of aluminum welding I sanded a bit with my belt sander, wire brushed, and wiped with acetone. This was thinner, brand new metal. So everything was clean I believe.  With this thinner stuff, 1/8" bar joined to .095" sheet, I set the max amperage at 100, and didn't use more than 1/2 pedal and only for brief bursts. Frequency 80Hz, balance 68% forward (EP?). Towards more penetration. 3/32" tungsten with zirconium, sharpened to a point. It stayed pretty sharp. A #7 cup and gas lens handling gas duty, and Gas flow at 24CFH, Better results, still at the mercy of my sloppy skills, but at least I was getting a decent puddle to flow with less bizarre contamination...Pictures:Torch and the material to weld.Gas regulator with metric and english readings understood this time.A decent pass, minus the end where the heat got a little out of control. Originally Posted by RojodiabloWhat are your amps set at? I see the freq. is 120. Try as Jakerau suggested, a larger cup, and then the gas at 15. 25 is more than you should need on this small kind of weld. I'd set the freq. at 80- it gives you a wider wet area, and believe it or not, many times on smaller parts it helps start the puddle much better.  The wider puddle will also allow you to wet both sides of the joint, meaning the filler can do it's job easier.  Try about 160 amps. Make a quick puddle, and go.
Reply:Good to hear it improved for you. When you run along and it gets hot, you see the puddle falling in, it is okay to stop& restart to allow the area to cool as necessary.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:The part was not very clean.Dave Powelson nailed it.I can still see the numbers stamped on it from the manufacturing process,as DAVE mentioned.Also the amps required for this piece could be high because of the total area of the weldment.It is like a car body. That aluminum weldment has a huge area to give off its heat.Aluminum is trying to get rid of its heat.The weld on that bracket looked cold and dirty.Last edited by Donald Branscom; 06-16-2011 at 12:49 PM.AWS certified welding inspectorAWS certified welder
Reply:I'm currently working with 3/16 aluminum plate in a 12 T bar set up using a miller synchro 351, the tungsten is 5/32 and the filler is 3/32 with the amps at 174 and shielding gas is %100 argon at 60cfh.  The heat definitely has to be that high in order to get a puddle going and the gas flow that high for shielding purposes.  Aluminum is definitely the hardest thing I have had to work with so far and tigging it is a pain due to my lack of experience and slight body shake causing tungsten sticking at times.  Best thing I can suggest is to jab the filler into the puddle as soon as it starts to form and have patience because aluminum does not behave like any other metal you will work with.
Reply:Once you have a couple hundred hours of welding clean aluminum of all differant configurations you will be in love with it. Its so forgiving and always so clean and the easiest metal of all to work with. I love building boats. Mac
Reply:Originally Posted by Tool MakerOnce you have a couple hundred hours of welding clean aluminum of all differant configurations you will be in love with it. Its so forgiving and always so clean and the easiest metal of all to work with. I love building boats. Mac
Reply:Try and get the parent material to "puddle" first. You may not get it to fuse the two together but make sure you have a nice shiny pudddle started then you no your close on the heat and go in and add some filler. Sounds like its just cold and not taking the filler and it hits the tungsten and now your contaminated and filled with soot!HTP Invertig 201Lincoln Idealarc SP250Miller 180 AC StickBy farmall:They should have held the seagull closer to the work, squeezing evenly for best deposition.
Reply:Originally Posted by Big65moparI'm currently working with 3/16 aluminum plate in a 12 T bar set up using a miller synchro 351, the tungsten is 5/32 and the filler is 3/32 with the amps at 174 and shielding gas is %100 argon at 60cfh.  The heat definitely has to be that high in order to get a puddle going and the gas flow that high for shielding purposes.  Aluminum is definitely the hardest thing I have had to work with so far and tigging it is a pain due to my lack of experience and slight body shake causing tungsten sticking at times.  Best thing I can suggest is to jab the filler into the puddle as soon as it starts to form and have patience because aluminum does not behave like any other metal you will work with.