Aluminum to Stainless???

[Riddle]

Can aluminum be welded to stainless? (or steel for that matter)
I've seen it on this site, but I can't find it now.
I'm making some hood decorations (fins) for an '88 Camaro. The fins will be 1/8 alum. They will be tack welded to an 1/8 alum plate that will sit on the hood. The plate will have 8 - 5/16 bolts bolted through the hood. The problem is the bolts have to be welded to the plate because the fins will cover the bolt heads (won't be able to get to it to tighten). I can get aluminum bolts (which would be easier) but I don't trust their sheer strength. Plus, I have the stainless bolts in stock and would have to order the alum bolts.
Any suggestions?

[Hemirambler]

Hi Riddle,

I've heard of guys "welding" aluminum to steel, but suspect it is more of a brazing process than a true welding process - possibly a mechanical bonding process like sintering rather than true welding - I dunno. I do suspect it falls into a very "tricky" skill set that may not be something you want to try on a critical part - like one that could blow off into your windshield. So I suppose it's possible - somehow - but.......erhhh not for me!

I would consider something like a "Pem" nut or Pem stud - you could press these into your 1/8" thick plate prior to welding it to your Fin and work the design into such a way to hide the fastener head - then simply bolt it in place from underneath - they make all sorts of styles,sizes and materials - " 5/16 " bolts sound awfully big - I might consider something less - but without seeing your design I sure don't want to sound critical.

Do a search on Google for Pem - they're not cheap, but may save tyou a lot of headache.


Just thinking out loud!

Jacin in Ohio

[Riddle]

Hey, thanks for the quick response!
I have some threaded rivets, but...after they are clinched, they would leave a gap underneath. And the plate needs to be flush to the hood.
The only reason I said 5/16 is, I have plenty. Plus, if I use alum bolts, I would rather have a bigger bolt for strength.
BTW, do you know if alum bolts are strong? They would be a lot easier to weld to the plate.
Thanks,
Jason

[Gene_Olson]

Harris puts out a product called Al solder which will solder just about anything to anything.

The rep demonstrated by taking a piece of 16ga stainless and soldering to an Aluminum pie plate. STRONG bond.

The solder has a ZERO fluidus range though, it must be cut in tiny pieces and set in the flux at the edge of the CLEAN and fully fluxed joint. When temp is reached it will wick into the joint.

If I were doing that, and (sight lines permitting) I would drill and tap the al, screw in the stainless studs into clean fluxed threads, set a chip of solder at the top heat to temp and you're NOT gonna pull that apart.

Gene

[roadietom]

I worked at Linde many yrs ago and we had disimiliar joints consisting of SS , Aluminium and pure silver, the silver was the material that both SS and Aluminum were welded to, these joints were used for cryogenic service(liquid gases) at high pressure and extreme cold. I once as can experiment welded some Aluminium to SS for a friend using silver braze rod of the highest purity, worked ok and did stick too.Ohh and what was used was 4043 to weld the silver to the aluminium and Silver to weld the SS to the Silver, using the TIG process. Hope this helps you out. Tom

[Riddle]

Cool, thanx for the info guys! With answers like these, it's too bad this site isn't about financial security...we'd all be rich!

[kneilson]

Tom, My only exposer to Alum/steel welding was an example plate that was 1" carbon steel clad with aluminium 1/4". It was done using explosion welding as the process of bonding. To my memory the material was used for tankage in the cryogenic industry. I will be trying what you suggested with the combination of alum/silver/steel. My questions are....... 1. What joint design would be easy to start with.......2. Is it an actual fused weld of intermixed metals or is it a cohesive bond made with dissimilar alloys.............Kerry

[roadietom]

Yes Kerry, the bigger joints were explosion welded using silver as a filler for the "sandwich" And I imagine it works for carbon steel as well like what you've seen. Yes it is mixed as welding implies in the smaller joints where a band of pure silver is used. The strength of the welding is highest using the band method over joining them together without a band of silver, but i'm talking about very high gas pressures of around 800 or more lbs of internal gas pressure in extreme cold conditions. The procedures used by Linde were ASME code certified for cryogenic services and were fillet or socket welds. I hope this is of help for you knowing it is a possiblity. Tom

[Hemirambler]

Hi Jason,

One reason I suggested checking out PEM type fasteners is that they are installed FLUSH - either the nuts or the studs.
I think I know the rivets youare talking about - are they like some of teh auto manufactures used to hold door mirror on and such??


Back to aluminum bolts - a very ROUGH rule of thumb is that aluminum is 1/2 as strong as steel - but keep in mind we aren't even talking specific alloys so that is a "loaded" statement.

Some aluminum alloys (7075) for instance can approach the strength of steel so yes SOME aluminum is quite strong - as would be the case for aluminum fasteners - HOWEVER the act of welding will likely compromise it's strength due to the welding process itself.

Again it's awfully tough to make good suggestions without knowing exactly what youare doing, but I think I would look into using smaller fasteners (but more of them) - I say this for several reasons - first it would allow me (I think) to possibly use a Pem stud. I don't mean to sound anti welding or brazing or soldering, but the problem with those processes (especially if you don't have a lot of experience with them) is that they are PROCESS dependant. Meaning that if you don't do things exactly correct you may not get anywhere near the strength as you think you have.

Keep it simple silly (KISS)


You might consider posting a sketch and see what neat idea these guys come up with. I personally always like feedback as early in the process as possible - makes it that much easier to incorporate when something really slick is mentioned!!!!


Good Luck!!!


Jacin in Ohio


Just thinking out loud again

[Riddle]

I believe you're right Jacin. I got the Alum bolts and tried welding one to some scrap. Wow. They are definately NOT very strong. They melt too fast, even keeping the heat away from the head.
So...I talked to a guy at DB Roberts (http://www.dbroberts.com/) who told me ... PEM is the best way to go. Fortunately, there is a distributor 2 hrs from here, so I 'll get some tomorrow. I have some pics of what I'm doing, but I have to wait until tonight to post them.
Thanks again for the great advice!
Like I said before, If only there was a forum that gave financial advice as well as you guys give metal working advice...we'd all be rich!
Jason

[scotty]

http://www.tinmantech.com/html/aluminum_joining_to_steel.html

[maggifinn]

http://www.fronius.com/welding.technology/products/migmag/tps3200_cmt.htm

[Gene_Olson]

interesting.

I tracked down this article on their site.

CMT super fine control of wire feed
Cold metal transfer (relatively cold anyway)
brazing to steel and welding to Aluminum in the same pass.

http://www.fronius.com/weld.vision/02_2004/english/02cmt.htm

G.

[Boogiemanz1]

Hello Maggifinn, Welcome to MetalMeet. I see you just made your first post. By the age of the thread you posted to I see you are reading the Forums.....great way to start, lots and lots of info there. Thanks for posting the link.

Also check out the Gallery, lots os cool stuff there.

You may notice that we prefer to use names, keeps it friendlier. If there is any questions, let us know, and we like to read introductions and see photos of your projects, etc.........later........john