Need help with process of soldering copper to stainless steel

mos68x - Monday, March 30, 2009 - 1:28am

I need some help getting some silver solder to adhere to sandblasted stainless steel (aluminum oxide blasting media I think). I have 304/316 stainless plates of either thickness', 0.030 or 0.060 and I'm trying to get some solid copper wire to solder to the plates for electrical connections. I started with my digital soldering iron at 750F, but didn't get the electrical 60/40 solder to stick very well. Then I bought a 230W soldering gun and it worked better, but still not good enough. I bought some Harris High Temp Black Flux and it just dries out before anything will stick. I grabbed some miuratic acid as well and tried a drop on the stainless but all it did was make the metal black and the solder roll off worse. I bought some Solder-It Silver solder paste and it doesn't work either, everything just rolls off the stainless or if it does stick I can't get it to wet in the groove for the copper wire so that I know it joins good.
I'm about to buy and try some silver solder wire that claims an acid core, but before I do I wanted to get some advice and help in the process of making these two metals stick together. All I'm trying to do is get a solid core 12AWG to solder into a .075 groove in some 16GA 304/316 stainless steel sheet metal that has been blasted to make it rougher. If my electrical load is light enough on the setup I will then change it to 22GA sheet metal with an appropriatly sized solid copper wire to it as well.
Once I get the stainless wetted once with the solder I'll be able to work with it easily after that...right? I might have to change the wires later so I'm hoping that it will be like electrical soldering and that once wetted it is much easier to deal with.

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Try this place

warren - Monday, March 30, 2009 - 9:20am

Here is a link to a place that I think will have your answer. I have used some of their fluxes and excellent products.

http://www.ccis.com/home/hn/

www Metalrecipes -- heat and beat to the desired shape, repeat as necessary.
warren

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solder

lin - Monday, March 30, 2009 - 9:21am

I am not an expert, but I have been making stained glass and copper or steel hummingbirds and butterflys. I use a lead free solder and gel flux from the glass shop. Doing thin metals, the solder joints were strong, but on the thick stuff, it wouldn't hold. I resorted to pre-heating the thick metal with a propane touch and then applying a thin layer of solder. When I attached the wings, I added more flux and solder and it joined strongly with what I had pre-applied. I don't know if the lead free solder will work for electrical connections, but you could try the pre-heat trick. Good luck, Lin

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To successfully solder to

Rich Waugh - Monday, March 30, 2009 - 9:31pm

To successfully solder to stainless steel you need theproper flux. I prefer Johnson's Stainless steel soldering flux that I get form the HVAC supply house. I use 60/40 lead/tin solder and have the solder pre-melted in an electric melting pot. I use a 350 or 500 watt Lenk soldering iron and keep the tip scrupously clean at all times.

The stainless should be sanded with 400 grit SiC paper immediately prior to soldering and wiped clean with acetone. The same for the copper wire. It also helps to have the end of the wire hammered flat to get increased contact patch.

The stainless takesmuch longer than the copper to heat, and is a poor conductor of heat, so I suggest you tin the contact spot before you introduce the copper wire. Once tinned, simply place the wire on the tinned spot, flux and re-heat the joint area and add a bit of additional solder.

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Stai less steel flux

visitor - Tuesday, June 30, 2009 - 5:53am

Dear sir we manufacture fluxes for steel contact 09449008361.

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Need to flux

visitor - Saturday, November 7, 2009 - 10:16pm

Stainless steel 304 will need to be fluxed before you can wet the soldier onto it. I would also suggest tinning your wire before you start soldiering. This will help in setting the wire onto a clean surface before oxidation occurs.

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