Weld aluminum to stainless?

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There will be pics of the final product but this post is the reason I am posting this project. I am in the process of making an oil drain can for my overhead hoist. I had laying around an old 1/2-3/4? keg that was just perfect, looked neat, and was fairly light. Just looking at it and feeling the weight I took for granted it was aluminum. I pulled the valve out and found a nice 2.25" aluminum pipe that fit in the valve slot just perfect. Found another aluminum pipe that slid inside of that pipe with about 1/4" gap when pushed to one side for an air vent. Tapped the outside pipe and made a T-handle bolt and eveything was looking great! Then I welded the bigger pipe to the keg snout so it wouldn't leak when emptying. I just quick wire brushed the joint and started to run a real quick bead not trying for looks just trying to seal it up. Nothing much out of the ordinary, just dirty which I expected from residue beer coming up the joint and the unclean inside of the joint. Got to the end and stopped welding and the weld was popping like the noise a stick weld would make when the slag is popping off. Once again I thought well maybe is is the residue beer steaming up and cooling the aluminum to fast, not a big deal for this situation. Then I was looking at the weld and was thinking its weird how the keg side of the weld had a brown burnt look and the pipe side had the normal white line. After closer inspection and a file test I came to the conclusion that the whole keg is stainless. So here is my stainless to aluminum weld. The rest to come later.
Reply:What is the "file trick"... im guessing its because stainless is harder than the aluminum?  I have an old keg sitting around that im trying to find job for also. ( any other ideas? ) So far all i can think of is a garbage can.  Me and my cousin pondered over what material it was , figured aluminum would be too expensive and probably stainless. I'm sure they make both.
Reply:Are you saying you welded aluminum to stainless using aluminum filler and it actually welded?  I would really have to see that to believe it.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:I'm thinking it's more along the line of arc brazed..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:Brazed, like maybe the aluminum sort of ran down into the threads and created a seal?Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:Originally Posted by DougAustinTXAre you saying you welded aluminum to stainless using aluminum filler and it actually welded?  I would really have to see that to believe it.
Reply:Originally Posted by DougAustinTXAre you saying you welded aluminum to stainless using aluminum filler and it actually welded?  I would really have to see that to believe it.
Reply:ive   welded around  steel bushings in  aluminum  molds   with aluminum filler and it sure looked like the 2 fused , even after grinding it down .     it was done more to fill the gap between the bushing and mold  .   not to try fuseing them together .    i dunno>Innovations are what i leave behind for History
Reply:I am highly suprised myself. i was thinking around the lines of arc brazed also2-Lincoln idealarc 250/250, lincoln 225 ac/dc welder, lincweld ac 180c, hobart handler 210, hobart stickmate lx 235/160, Hypertherm Powermax30local 26 I.B.E.W Electrician
Reply:Originally Posted by lj408What is the "file trick"... im guessing its because stainless is harder than the aluminum?  I have an old keg sitting around that im trying to find job for also. ( any other ideas? ) So far all i can think of is a garbage can.  Me and my cousin pondered over what material it was , figured aluminum would be too expensive and probably stainless. I'm sure they make both.
Reply:Just "would this work" question"--Can JB Weld be used to bond two dissimilar metals like this?
Reply:I do not think JB Weld cares about the metals being bonded.  So long as the metal is clean and free of oil and particulate matter, it should perform similarly regardless of the metal.  The mechanical configuration and surface preparation of the joint is most important for a strong bond."Great spirits have always encountered violent oppostion from mediocre minds."  --  Albert Einstein
Reply:It's possible to braze aluminum to stainless steel with a two-step process . . . tin the stainless with a copper-based brazing alloy, then use an aluminum brazing alloy to join the copper to the aluminum.
Reply:Originally Posted by 4sfedIt's possible to braze aluminum to stainless steel with a two-step process . . . tin the stainless with a copper-based brazing alloy, then use an aluminum brazing alloy to join the copper to the aluminum.
Reply:One time I was welding a stainless bung to a aluminized pipe. I grabbed aluminum rod by accident thinking it was stainless rod. I started welding and it seemed different but ended up welding the whole thing. I noticed after I was done what I did and cut it off and re-welded it. I was suprised that it welded but i guess between the stainless and aluminized it worked. weird.
Reply:Use a copper-based alloy to tin the steel,  It can be silicon bronze, phosphor bronze, nickel bronze or even silver solder, then I use Aero Braze, flux-cored aluminum brazing rod from TM Technologies to join the aluminum to the copper.  The common element is the zinc in the aluminum rod.Jim.
Reply:Harris sells a low melting temperature solder (4xx deg F melting temperature) that can supposedly join aluminum to ferrous/steel/stainless steel.  IIRC, its primary ingredient is Cadmium or Tin.There are other brands of solders that might fit the bill for this application as well: http://www.kappalloy.com/tecz-solder.phpOf course, a solder joint wouldn't be appropriate for any application subject to even moderately high temperatures, as the solder would have low strength at an elevated temperature.  (Something like a Beer keg probably isn't going to get very hot, however.)That is interesting idea 4sfed, about "tinning" the stainless with Bronze and then joining it to aluminum using Zinc-aluminum braze.  Sounds like that solution would withstand much higher temperatures than the Tin or Cadmium-based solders.  I may have to play around with trying that some time.
Reply:The for now finished product. Will have to see what hooks or trays I want to add for tools and parts. I wanted a semi flat drain pan so you can set the oil filter down on the side of where your draining so it doesn't get covered in oil. The same for any parts your pulling off a vehicle that have fluids in them, if you drop a bolt it doesn't run down to the middle like a funnel and it was cheaper.  I put the pan over a pail and pushed on a 3" plastic disc in the middle of the pan to try and get some funneling effect and that is when the dent happened. I thought the ridges would straiten out first but it creased instead, won't bother me. There is a 1/4" screen in the hole and a stainless pipe welded to the bottom that snugly fits in the aluminum pipe. I put the wheels to the inside so cord and air hoses don't get caught on them as much. The setup is still very sturdy and would take quite a bit to knock it over.