On Sunday, October 14, 2012 7:14:47 AM UTC-7, Doug White wrote:
[ soft-solder to stainless steel]

It works fine if you have the right flux. I used to solder to stainless
RF connectors all the time, using a small bottle of clear liquid flux.
Unfortunately, I don't remember the brand or name of the stuff. The
catch is that it is an acid...

It takes an acid flux to solder nickel or nickel alloys, like stainless.
I use Nokorode liquid flux and it's acid and somewhat sticky, and one does NOT
want to keep it near the fine tools or next to delicate metal items.
There's fumes, I suspect; nearby objects corrode.

The acid flux also works well on brass, and it's how to make a good
solder connection to a battery (NiCd or the nickel-plated ends on a AA cell).