Silver solder aluminum to carbon?

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Allen Gun Works

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Does anyone know if it is possible to silver solder aluminum to carbon steel? I am not concerned about the cosmetics of it, as it will be durakoted afterwards. I just need to know if it will be possible. Also, this is a very light aluminum piece. I would epoxy it, but I would like to be able to polish it afterwards and make it look like it belongs there.

If this is not possible, could someone suggest a better way short of tig welding it. (I don't have a tig welder, yet)
 
Can be done with Liquid Flux

The welder here at the shop uses something called “Liquid Flux No. 3, from the Indium Corporation”. I have no idea who and where this company is, but I am sure that a short trip on the net will help you with that.

If you are unable to find it, send me a PM and I can ask the welder on Monday where he got it and how much he paid. The tubes of liquid flux are part of his personal stuff that is in his own tool rack and I do not wish to make any deal until I speak to him on Monday. Maybe he can sell you one of the tubes rather than you go out and buy a whole box full.

I hope this helps
Robert
 
The brownell's cataloge has the stuff you need in their gunsmith tools section, (about 2 pages just for solders of different sorts) Takes a while to get though.....:(
 
You may also want to look into getting some turbine solder. It's much the same as silver solder, but with a lower melting point. Used extensively in the power industry to minimize the effects of heat on turbine blades.
 
You may also want to look into getting some turbine solder. It's much the same as silver solder, but with a lower melting point. Used extensively in the power industry to minimize the effects of heat on turbine blades.
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The melting point of the higher content silver solders range between 700-1500 degees farenheit.

Aluminum melts between 850-1200 degrees. See the problem.

So you are going to have to be very careful with a thin peice of aluminum.

Your aluminum will disappear before your eyes as you try to get your solder flowing especially when using an oxy/acetylene torch, and it won't take long. I know I've done it.:redface:

Not to discourage you but soldering aluminum can be tricky.

I would recommend a solder with a much lower flow temp than any of the higher content silvers and using a propane or map gas type of torch as you can raise the temperature more slowly.

I would go to a welding shop and tell them what you are trying to do, they will be happy to sell you what you need.

Practicing on a couple scrap peices first would be a good idea if you are not experienced.

Just my 2 cents.
 
The local common silver solder is braze 450 or 45% silver and I believe it has the lowest melting temperature of the sivler/copper silver solders. It melts at 1140 F and doesn't really flow for another 200 degrees or so. Much like Liberty has commented, I don't think you could silver solder aluminum. I think small pieces would melt first and large pieces would suck away the heat to quickly until they melted.

cheers Doug
 
You can regular solder aluminum, my cousin did it to his car's AC piping: using that magic flux and regular iron, he applied regular tin solder, then wrapped a piece of foil around the pipe, heated up and voila, no more leak. I'll find out the flux brand as soon as he is online.

Okay, he happened to be online this odd time of the night over there, and told me that the flux is simply AlFl, aluminum fluoride.
 
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I could be wrong but after 25 years in the gunsmithing trade and a B pressure ticket there is no real way to bond aluminum to steel. There are some high tech solders out there but they work little better than some of the good epoxies. My best advice is screws. Sorry! You never said what you were trying to stick together. Knowing that might help a bit for other options. There is always a way to make something work! Rod Henrickson
 
I have to agree with the above post... I don't believe there is any solder that will be compatable with aluminum and ferrous. If the shapes fit well the best epoxy and screws may do the job.
 
I'm a tig welder and your right you can't weld alum to steel with any common welding processes, explosion welding is one way of bonding them together but not practical, but they can be soldered the tricky part is the difference between the expansion rates of parent metals steel is a lot less than aluminum this can cause cracks, depending on the size of your parts. also aluminum melts at a similer temp as most silver solders 1100 -1200F
read the bottom of this page starting at Cladding or Coatings
http://www.aws.org/wj/2004/02/046/
 
Thanks for all the suggestions. Lots of good info. I think I have ruled out welding or soldering. Since it is a light piece I am going to try some expoxy of some sort and then file it out to match. I am going to use dura kote as a finish so it should look alright.

I won't be doing this project for another month or so when I get home. Will post some pics with the final result.
 
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