On 19 June, 17:47, "Arfa Daily" wrote:
Many years ago, my brother in law, who was a mechanical engineer /
toolmaker, gave me a bag of 'case hardening powder', which I still have.
Does anyone know what exactly this stuff is (it's white,

No idea. Never heard of the stuff - in white at least.

Kasenit is the usual case hardening powder. Greyish, maybe describable
as light brown , and stored in tins because it doesn't enjoy
moisture. It's very easy to use.

Cyanide hardening compounds are (IMHE) supplied in pellets, not as
powders (or made up in solution) - again because of moisture. They're
safe enough to handle (keep away from moisture and especially acids),
but they are a hazard to work with. Like cyanide electroplating
solutions, they're beyond most home workshops.

The only common white workshop powder I can think of would be silver-
soldering or brazing fluxes - fluorides.


Case hardening is best used to make mild steel components more wear-
resistant. It's a poor way to make cutting tools. It's also a poor
steel metallurgically, and as good steels are cheap these days, you're
better making tool edges from the good stuff directly.

The powder itself is a secret recipe that has changed in the last few
years anyway. It's broadly a mix of a carbon donor (hoof and horn, but
_not_ bone) and also a carbon dioxide donor (barium carbonate),
possibly also a nitrogen donor, i.e. a cyanide.

If you have case-hardening powder, there are two ways to use it. The
best way is to pack piece and powder into a sealed iron box, then
roast the lot in an oven for some time. No-one does this. People who
used to do it commercially, now use liquid baths instead. The workshop
way is to heat up the workpiece to a dull red, then immerse it in the
tin of powder and leave it to cool. Repeat for deeper diffusion. Avoid
the fumes. Then harden and temper the workpiece as for a higher carbon
steel.