Help! trying to solder 303 stainless to copper

I find

a real wealth of information on solders of all types.

This data sheet for Indalloy flux #2 is recommended for stainless steel:

Also this application note:

recommends these solders for stainless steels #1E (52In 48Sn) #106 (63Sn 37Pb) #121 (96.5Sn 3.5Ag)

However, the solder task will still be difficult Jeff Lindemuth

You need flux, not just flux-core solder. I personally prefer a long Oxy Acetylene feather (very carburizing flame), but a propane torch should do it if that is what you have. Polish/clean the coiled ends of the stainless, and flux immediately after polishing. Beware of overheating the stainless (it conducts heat poorly, as you should know). I've had good success with Eutetic Castolin 157 for soft-soldering stainless, but any other highly active acid flux that needs to be washed off afterwards should do. NoKorOde or other typical copper plumbing flux won't cut the stainless oxide layer.

You need a special flux to solder SS. Any welding shop should be able to supply it. Lane

Photo or sketch in dropbox please? This should not be a problem. I've had very good results with Harris Staybrite on stainless-to-stainless and stainless-to-brass or copper, and Harris indicates that Staybrite is suitable for use on stainless. Are you using Stay-Clean flux? Only problems I can think of would be work not clean or overheating. I would heat the copper with the torch, let the copper carry the heat to the joint. Directing the flame directly on the joint can overheat the flux and render it inactive.

There are stainless steel that can be silver soldered with Staybrite ( bAg1 ) and then there are other stainless steels that require different silver solders. Hardy and Harman have a nice booklet on silver brazing and selection of filler alloys and fluxes. I don't have the booklet closeby but a silver alloy with a bit of nickle in it will work better for the stainless steels that are hard to solder.

I will look up 303 and see what the recommendations are for filler alloys.

Dan

Ted

H & H lists 303 with 304 in the table of recommended filler alloys. All the alloys they recommend have some nickle in them or maybe lithium. BAg3 is one of the ones recommended. But BAg1 ought to work. At least it has for me on 304. Could not get it to work on some 7-17ph stainless.

Dan