Stainless and Aluminum pipe question...

admin

Hi everyone, new the the forum, and had a quick question...When I try and tig a butt joint on a thin piece of stainless or aluminum my arc seems to focus on one pipe and not the other. I have to force it to hop over...as soon as i get some filler in the middle I am then able to start welding without issues. but it is getting really annoying trying to get a puddle without opening the hole...For aluminum I am using pure (green) with a balled end and stainless i am using 2% thor (red) pointed...I have my amps set at 90 but probably using 70-80...its a Lincoln square-wave 175...Thanks for any help...Alec
Reply:Heat it up back away from the joint until the temperature is near puddle on both sides of the joint. Then move to the edge, puddle on the very edge, and with or without filler wash together. Heat there till you get penetration you want, add filler, and move along adding filler for a slight crown on the joint. Pure tungsten doesn't work well with square wave. Use anything other you like.
Reply:I will give that a shot...can I use 2% thor for both stainless and aluminum
Reply:Originally Posted by blowermaxI will give that a shot...can I use 2% thor for both stainless and aluminum
Reply:what size tungsten are you using?  3/32" or 1/8" sharpened to a point (2%La) would have you way ahead of a balled pure tungsten.  Also you haven't been anywhere near as specific as you need to be.  Why leave out details?  Are you doing 1/4" aluminum with only 70-80A????  You need a chitload of amps with aluminum in order to outrun the heat-sinking.  Otherwise you'll go nowhere fast. 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC
Reply:Originally Posted by blowermaxHi everyone, new the the forum, and had a quick question...When I try and tig a butt joint on a thin piece of stainless or aluminum my arc seems to focus on one pipe
Reply:Originally Posted by Oscarwhat size tungsten are you using?  3/32" or 1/8" sharpened to a point (2%La) would have you way ahead of a balled pure tungsten.  Also you haven't been anywhere near as specific as you need to be.  Why leave out details?  Are you doing 1/4" aluminum with only 70-80A????  You need a chitload of amps with aluminum in order to outrun the heat-sinking.  Otherwise you'll go nowhere fast.
Reply:Originally Posted by GambleThat's normal. Do a dip of filler one pipe then the other and join them. Then focus the arc on the bead and it will be on both pieces.
Reply:Use pure (green band), zirconium (brown band), tri-mix "rare earth" (grey band), or the E3 (purple band) tungstens for aluminum. They all will "work" but not all will yield the same quality arc characteristics. Thoriated type tungsten well handle the amperage better with less degradation but the point will "kings crown" as I call it meaning the taper will still be there but the very point will "shatter" and divide into a bunch of little points almost like metal shavings on the corner of a magnet which causes the arc to be inconsistent and not very crisp. This is why it's not recommended to use thoriated tungsten on aluminum especially X-Ray quality since you can get tungsten spitting and some very fine granules will embed into your weld. Pure works, but doesn't hold up well. It's good for thicker, non-critical welds on aluminum. It's too soft, therefore the top degrades fast and starts to ball up which causes a more unstable arc thus a wider bead. Plus, I find pure tungsten isn't made as consistent of quality as the others, meaning, when the top does ball up sometimes you're left with a pin point at the very end which makes the arc do some crazy stuff and I've seen it spit off into my weld.Personally, I prefer the zirconiated and the E3 type tungsten for aluminum. Both give equally clean, crisp, and smooth arc characteristics. The rare earth type has excellent arc qualities is a softer tungsten so the taper on the top degrades too fast and doesn't leave as focused of an arc when welding thin material. Text books say to ball the tungsten when welding aluminum but I strongly disagree. Put standard taper on the end and then just knock the very very tip off on the grinding wheel because that tiny point is capable of spitting off into the weldment. The tip of your tungsten will naturally ball up to the size it needs to be for the amount of amperage and percentage of cleaning action you're using. Why have more of a ball than what is needed?? It just causes instability of your arc.Keep aluminum super clean brand new or old repair. Clean is key. On old stuff, I degrease with a strong solvent (gasoline, acetone, etc) then I'll chemical clean clean with a mild caustic or acid ("the works" drain cleaner, vinegar, etc) then I'll steam clean, lightly power brush with a dedicated stainless steel wire wheel (I say lightly because you can actually force the oxide layer and other contaminants further into the base material), and finally wipe with 90% denatured (rubbing) alcohol. Taking all the necessary preliminary steps to ensure a quality weld seems like a pointless, drawn out process but saves a lot of time and headache down the road and (nearly)eliminates the need to go back, grind everything out, and do this process over again. Here's a saying I've always used; "you don't have the time to do it correctly right now but you'll have the time to go back and fix it later..??"-Hillbilly
Reply:On stainless, purging always helps. There are ways around it but none work as well as a purge. They use aluminum, copper, and brass backer blocks and they also have on the market a flux coated tig rod for large weldments with a thin wall thickness so you don't need to spend all the time/money letting something large purge with an inert gas. They are nasty to weld with and you can't make any secondary passes because it will just burn the inside anyway. Above all, practice practice practice is the key.-Hillbilly
Reply:My son has a friend who just graduated from welding school, his second job in 3 months is for a duct builder. They weld stainless ducts from 4-200". He talks of a purge product of "rubber" hose with half cut away. They place it across the joint and tape it in place. As he tells it, stainless doesn't conduct heat very quickly, so he has moved on soon enough to avoid melting the "rubber". I pressed him for more information, he knew little more about it. It seems someone else makes those decisions.
Reply:Originally Posted by Hillbilly2008Use pure (green band), zirconium (brown band), tri-mix "rare earth" (grey band), or the E3 (purple band) tungstens for aluminum. They all will "work" but not all will yield the same quality arc characteristics. Thoriated type tungsten well handle the amperage better with less degradation but the point will "kings crown" as I call it meaning the taper will still be there but the very point will "shatter" and divide into a bunch of little points almost like metal shavings on the corner of a magnet which causes the arc to be inconsistent and not very crisp. This is why it's not recommended to use thoriated tungsten on aluminum especially X-Ray quality since you can get tungsten spitting and some very fine granules will embed into your weld. Pure works, but doesn't hold up well. It's good for thicker, non-critical welds on aluminum. It's too soft, therefore the top degrades fast and starts to ball up which causes a more unstable arc thus a wider bead. Plus, I find pure tungsten isn't made as consistent of quality as the others, meaning, when the top does ball up sometimes you're left with a pin point at the very end which makes the arc do some crazy stuff and I've seen it spit off into my weld.Personally, I prefer the zirconiated and the E3 type tungsten for aluminum. Both give equally clean, crisp, and smooth arc characteristics. The rare earth type has excellent arc qualities is a softer tungsten so the taper on the top degrades too fast and doesn't leave as focused of an arc when welding thin material. Text books say to ball the tungsten when welding aluminum but I strongly disagree. Put standard taper on the end and then just knock the very very tip off on the grinding wheel because that tiny point is capable of spitting off into the weldment. The tip of your tungsten will naturally ball up to the size it needs to be for the amount of amperage and percentage of cleaning action you're using. Why have more of a ball than what is needed?? It just causes instability of your arc.Keep aluminum super clean brand new or old repair. Clean is key. On old stuff, I degrease with a strong solvent (gasoline, acetone, etc) then I'll chemical clean clean with a mild caustic or acid ("the works" drain cleaner, vinegar, etc) then I'll steam clean, lightly power brush with a dedicated stainless steel wire wheel (I say lightly because you can actually force the oxide layer and other contaminants further into the base material), and finally wipe with 90% denatured (rubbing) alcohol. Taking all the necessary preliminary steps to ensure a quality weld seems like a pointless, drawn out process but saves a lot of time and headache down the road and (nearly)eliminates the need to go back, grind everything out, and do this process over again. Here's a saying I've always used; "you don't have the time to do it correctly right now but you'll have the time to go back and fix it later..??"-Hillbilly
Reply:Originally Posted by Hillbilly2008Use pure (green band), zirconium (brown band), tri-mix "rare earth" (grey band), or the E3 (purple band) tungstens for aluminum. They all will "work" but not all will yield the same quality arc characteristics. Thoriated type tungsten well handle the amperage better with less degradation but the point will "kings crown" as I call it meaning the taper will still be there but the very point will "shatter" and divide into a bunch of little points almost like metal shavings on the corner of a magnet which causes the arc to be inconsistent and not very crisp. This is why it's not recommended to use thoriated tungsten on aluminum especially X-Ray quality since you can get tungsten spitting and some very fine granules will embed into your weld. Pure works, but doesn't hold up well. It's good for thicker, non-critical welds on aluminum. It's too soft, therefore the top degrades fast and starts to ball up which causes a more unstable arc thus a wider bead. Plus, I find pure tungsten isn't made as consistent of quality as the others, meaning, when the top does ball up sometimes you're left with a pin point at the very end which makes the arc do some crazy stuff and I've seen it spit off into my weld.Personally, I prefer the zirconiated and the E3 type tungsten for aluminum. Both give equally clean, crisp, and smooth arc characteristics. The rare earth type has excellent arc qualities is a softer tungsten so the taper on the top degrades too fast and doesn't leave as focused of an arc when welding thin material. Text books say to ball the tungsten when welding aluminum but I strongly disagree. Put standard taper on the end and then just knock the very very tip off on the grinding wheel because that tiny point is capable of spitting off into the weldment. The tip of your tungsten will naturally ball up to the size it needs to be for the amount of amperage and percentage of cleaning action you're using. Why have more of a ball than what is needed?? It just causes instability of your arc.Keep aluminum super clean brand new or old repair. Clean is key. On old stuff, I degrease with a strong solvent (gasoline, acetone, etc) then I'll chemical clean clean with a mild caustic or acid ("the works" drain cleaner, vinegar, etc) then I'll steam clean, lightly power brush with a dedicated stainless steel wire wheel (I say lightly because you can actually force the oxide layer and other contaminants further into the base material), and finally wipe with 90% denatured (rubbing) alcohol. Taking all the necessary preliminary steps to ensure a quality weld seems like a pointless, drawn out process but saves a lot of time and headache down the road and (nearly)eliminates the need to go back, grind everything out, and do this process over again. Here's a saying I've always used; "you don't have the time to do it correctly right now but you'll have the time to go back and fix it later..??"-Hillbilly
Reply:No matter what machine you use, as long as it has alternating current capability, well give you cleaning action with aluminum because of the DCEP half of the cycle and this is called Catholic bombardment which breaks up the oxide layer on aluminum and magnesium alloys. -Hillbilly
Reply:But once you start getting into welding aluminum with DCEN current with helium, it's a whole new all game. Lol -Hillbilly
Reply:But once you start getting into welding aluminum on DCEN with helium, it's a whole new ball game. Lol -Hillbilly