And indeed, the term "brazing" covers a multitude of processes.
Using, for example, pure copper to join stainless steel parts, where the items are brought above the melting point of copper in a hydrogen furnace.
Or using something like nicrobraze, a nichrome alloy.
All of those maerials do flow like water at the braze temperature, yet the process is called "furnace brazing."
Jim
Actually, I was just commenting, and am not in need, but I appreciate your concern.
This thread has been a good refresher course for me. It likely shows that I do not do a lot of silver soldering (brazing).
Harold
My understanding is that, yes, the heat will anneal the copper of a boiler. However when the boiler is pressure tested ( hydraulically) and the annealled copper deforms to accomadate the pressure, it then work-hardens and will not deform again UNLESS the pressure is allowed to rise above the test pressure (typically 2x the working pressure). There have been many articles and letters on this subject in Model Engineer mag over the years (decades?). Mike in BC
I'd be very suprised if a single pressure cycle would produce much in the way of work hardening - there's some thought that it may be possible to create work hardening with vibration type repeated stress, but for a single cycle substantial (permanent) mechanical deformation would probably be required.
What is likely to happen is that an annealed bioler deforms during pressure test up to the degree to which it should deform under that pressure, and then does not spring back the way a harder one would. If you return to the test pressure, it shouldn't deform further, even though it is probably still fairly soft.
If you had something like a perfect uninterrepted sphere of annealed copper and increased the pressure (say there is trapped water and you turn up the temperature) to a point that exceeds the yield strength, and the source of pressure keeps up with the resuling increase in volume, then yes it should expand (permanently) until it has work hardened to a yield strength beyond the stretch applied by that pressure - probably a factor of at least 2 in volume, perhaps much more. But your boiler is not a sphere - it most likely expands a little in the geometrically weakest direction until the strengths are more balanced, and then stops expanding (unless you turn up the pressure unreasonably at which point it will probably fail before the volume has increased all that much)
Not unless you run it through many cycles. Unless you've built an unstayed haystack boiler, that will be a huge number of cycles.
Don't believe _anything_ you read in Model Engineer. It's like usenet with senile dementia.
I have tried several and I like harris silvo (or close to that). It is cadnium free and melts at approx 1500. A propane torch will work for small to tiny things.
I looked on line to find what I wanted and called a local distributor and they shipped it right to me. Get a jar of white flux too.
chuck
There are _laws_ regarding the structural strength of jewelry? Not picking on you, just never even imagined such a thing.
Abrasive wrote that, not I.
Bob Sw>
They address precious metal content, not strength. Don't want lead in your earring.
Or nickel, these days.
Are you allowed nickel in the US ? Over here, since recent years, it's strictly verboten in anything with skin contact. Makes some nice mokume gane ideas sadly unworkable 8-(
If you sell a ring saying it is xx% silver from the grade of base metal - and then solder on a bezel and re-size it to a new finger .... what else... Your percentage is way off unless the solder is close to the grade.
This is much like TIG - where the filler = base metal and when done nicely, the weld is ground down and polished - and the lines are not there...
Martin
Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
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