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Silver Solderinng Stainless and Copper

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Silver Solderinng Stainless and Copper

Postby ZeroGee » Mon Aug 12, 2013 9:41 am

I was searching the internet looking for materials/techniques to solder copper to stainless and came across http://www.muggyweld.com on YouTube, particularly SSF6 silver solder. I’ve not yet tried it, but I’m very impressed with the videos they’ve shown.

If anyone has tried it, let me know what you think. The stuff isn’t cheap, but if it works as shown, it would be a godsend to those of us who need occasional SS welding or are trying to make show-quality still heads.

ZG
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Re: Silver Solderinng Stainless and Copper

Postby FullySilenced » Mon Aug 12, 2013 10:33 am

ZeroGee,

they are great demo video's i would like to try them as well but the cost is .... up there... but if i was going to try 56% silver i would start here i think...

http://www.homedepot.com/p/Lincoln-Elec ... gkAHJI4v-s
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Re: Silver Solderinng Stainless and Copper

Postby hard times » Mon Aug 12, 2013 1:29 pm

Wonder if you could use a sterling silver ring
or a coin.
Suppose it would be to soft?
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Re: Silver Solderinng Stainless and Copper

Postby ZeroGee » Mon Aug 12, 2013 8:32 pm

Actually, I was hoping someone here tried some of the MuggyWeld products. It looks almost too good to be true.

Here is the catalog: https://muggyweld.com/pdfs/catalog.pdf. Description and prices of the products are there.

I use an oxy/propane brazing torch (now) to do most soldering and brazing. It's more than adequate for the job. I was impressed by the neat, clean silver solder joints using SSF6 silver solder rods.

ZG
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Re: Silver Solderinng Stainless and Copper

Postby Kapea » Mon Aug 12, 2013 11:17 pm

Thank you for the link. I've been looking for the Cool Blue heat dissipation paste. I used to get it from the welders I worked with. I no longer work with them, and my supply ran out.

Woo hoo! Good stuff amigo!
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Re: Silver Solderinng Stainless and Copper

Postby myles » Fri Aug 16, 2013 12:19 pm

There are some 10% silver SOFT SOLDER alloys available that are recommended for joining copper to stainless steel, but I haven't tried them myself.

I think if you physically stabilize the joint with rivets or some other method, and pre-tin the copper, then by all accounts it is possible to soft solder it and get a good seal with the right flux.

I am a little bit cautious about the idea of structural joints between stainless and copper with just soft solder on its own. I have always brazed with high % silver instead of soldering.

BUT and it is a big BUT, I haven't done it on a keg yet. Might try it on a bit of stainless ,skirt off-cut just to see if it is as difficult as I have been thinking.
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Re: Silver Solderinng Stainless and Copper

Postby Chrismass » Fri Aug 16, 2013 7:27 pm

I've recently purchased around a pound of 56% silver solder w/o flux as well as a pound of staybrite 8. The best possible prices I have found are from http://airgas.com/. I got 1oz coils 56% silver 3/32'' for around 26$ each which includes shipping! That's an excellent price based on even the wholesale places in Brooklyn charge near 40$ per oz. All their stuff tells you if it is ROHS/NSF certified as well which makes me feel a hell of a lot more comfortable.

@Myles, Have you tried using rivets yet in a still build? I'm considering purchasing a whole bunch of copper rivets which are relatively cheap (Around 12$ per pound) and using them to reinforce the seam for the copper cone of my boilers eventual whiskey head.

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Re: Silver Solderinng Stainless and Copper

Postby myles » Sat Aug 17, 2013 3:07 am

Chris it is my preferred construction method. Soldered riveted seams.

http://www.artisan-distiller.net/phpBB3/viewtopic.php?f=1&t=3084&hilit=6kw+pot+still

The copper onion will get a work over because I fancy a bigger keg opening. 4" possibly 6". If you are using thinner copper sheet you need to use washers, or the river will just punch through the sheet.
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Re: Silver Solderinng Stainless and Copper

Postby ElectricEd » Sun Dec 08, 2013 9:39 pm

I posted this on Home Distiller a while back and reckon it would be of value to post here. It has saved me from heaps of frustration since finding what the problem was.

I wrecked several SS tri-clamp flanges while trying to figure out how to braze SS to copper. Here's what I found, it is collated from several product guides that I found:

Brazing for Tri-clamps
Tri-clamps are made from Austenitic stainless steel. Austenitic stainless steels are non-magnetic. The Austenitic steels are based on the 18% chromium 8% nickel composition although the chromium addition can vary from 15-22% and the nickel from 6-11%. These steels cannot be hardened by heat treatment and must rely for their mechanical properties on mechanical working. This means that any thermal joining treatment will reduce the mechanical properties in the 'heat affected zone'. Austenitic steels if heated between 55O °C and 750 °C will precipitate complex Chromium Carbide. This will render the material susceptible to a rapid corrosion process known as weld decay. The degree of this precipitation will be a function of the carbon content but it is obvious that most thermal joining processes will be a potential hazard. The steels can be stabilised by the addition of either niobium or titanium and all Austenitic steels that are to be brazed or welded should either be in this condition or have a low carbon content. (302, 303, 304, 310, 316, 321, 325 and 347).

Fluxes
The use of a flux is essential when brazing stainless steel in air. With components where the joint area can be easily heated up to brazing temperature, Easyflo flux can be used. However, should prolonged heating be necessary, a flux metal reaction will take place when this flux is used. This reaction will form a film on the surface of the stainless steel so that it cannot be 'wetted' by the brazing alloy, and the addition of fresh flux will not remove this film. In these instances it is necessary to use Tenacity Flux No 5 flux. This has improved high temperature properties and does not react with stainless steel. The only problem is that the residues are not water-soluble and have to be removed with caustic soda, or mechanical methods, such as grit blasting.

Only use 56% silver. eg SilBRAZE 56IN from BOC, but can only be bought in 1/2 Kilo packs. $700+
SilBraze Tenacity Flux No 6 flux. Clean up with 10% caustic soda. About $77. (Tenacity Flux No 5 no longer available)


I could not justify spending $700 plus on the rods, so just used Comcoat 356T and knocked off the flux coating.
Using ordinary Cigweld No2 flux, you can see it filling up with the Chromium Carbide as you try to do the brazing. When it goes dark grey to black it's all over, if you haven't finished the brazing it is another stuffed joint that cannot be fixed. The Chromium carbide completely covers the tri-clamp and there is no way to clean it off in the places that you need to get the silver braze into.

The Tenacity 6 flux is fantastic, it just keeps hanging on. Even if you think you've finished and cool it off, only to find that you've missed a bit, you can apply a little more flux to the missed area and reheat and carry on.

So there you are, a flux that really works on stainless steel!
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Re: Silver Solderinng Stainless and Copper

Postby Cedar Grove » Wed Jan 28, 2015 9:03 pm

You say Silver Soldering, but it sounds more like Brazing. What;s the melting Temp?
For a soft Solder Joint, that is Lead Free try Eutectic 157. The melting Point is 430F, and is available from different Suppliers. If You cant' find the 157 locally, Others make the same Formulation under another name. It is also much cheaper than Silver bearing Brazing Alloys. I have some 96% Tin, 4% Silver Solder, but have not tried it with Stainless.
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