rashid111 wrote:
For a reed plate for accordion - I have a piece of Russian made
"latun'" - L87 type. When trying to match it to American brass
I tried different types from McMaster, including "engravers brass" -
which is the hardest they offer. Still Russian material is harder ...
so I was wondering may be what I have is a bronze alloy (it is
somewhat
darker in hue compared to brass). It is important to have right
hardness as I punch out reed slots on a fly wheel press

How does say 220 bronze alloy compare to brass in terms of hardness ?
I need to have a copper alloy with hardness of say 7075 Al (150
brinell
or thereabout), something w/o any health related issues.


TY
Rashid

I'm sure you know that brasses and bronzes will vary in hardness
depending on how much they've been worked. Used to be you could get
1/2 hard, 3/4 hard or full-hard brass sheets, for clock making in
particular. You can add a lot of hardness to brass by rolling it or
hammering it, up to the point where it gets brittle and cracks.

A spark spectrometer would make fast work of figuring out the chemical
composition but you'd never know what state your original parts were
in.
You'd have to polish and etch a piece and look at it under a
metallurgical microscope to see the grain structure.

Might be what you've got is phosphor bronze, that's used quite a bit
for non-ferrous springy parts. I've got some that was used for R.F.
sealing strips in military radio equipment, it's a little darker to
look at than yellow brass. There was a chemical test that someone
posted awhile back in RCM, turned brass one color and bronze another,
might be you could go over to groups.google.com and see what turns up
in the archives.

Stan