"The other Thomas Gardner"
wrote in message ...
Egads. How embarrassing: I'm so ignorant, I thought you were just making
the word Kasenit up (i.e. ``casing it doesn't require quench...''). Never
dawned on me that was an actual product name. Obviously, that's something
I hadn't run across yet.

Tommy ``big doofus'' Gardner.

Artemia Salina wrote:
On Fri, 14 Oct 2005 15:50:41 +0000, The other Thomas Gardner wrote:


Artemia Salina wrote:

If the heat treating is just for wear resistance have you thought
about
case hardening? I don't know much about the commercial process, but
Kasenit doesn't require quenching.

What grade(s) did you have in mind with that statement? The less
exotic
I can get on the processing the better, in my book. The less
deformation,
the less post treat processing, all that, the better.

It seems that I may have been wrong about this after all. I could
have sworn that I'd read something online about using Kasenit and
not having to quench. I even remember being impressed by that because
it seemed like that would lessen the chance of the parts warping.
Now, as I attempt to look that reference up, I can't seem to find it,
and most discussions of using Kasenit talk about quenching as part
of the process. Disappointing.

Kasenit turns the surface of plain steel or certain low-alloy steels
designed for case-hardening into very high-carbon steel -- plain
high-carbon, if you start with plain carbon steel. It works by diffusing
carbon into the steel, from the outside in. Thin cases may be only a couple
of thousanths of an inch thick. It's possible to produce thicker cases using
special methods, and some industrial process can produce a 1/4-inch-thick
case or even more.

Hardening any steel by martensite conversion (which is the hardening process
we're talking about here) requires a rapid quench through a certain critical
range of temperatures. Different alloys require different quench rates.
Plain high-carbon steel requires the fastest rate of all, on the order of a
few seconds, which is why it typically is quenched in plain water or brine.
Air-hardening steel, as the name implies, is at the other end of the scale:
the quench rate can approach an hour. But that's not case-hardening with
Kasenit. That's through-hardening of a special alloy made for slow quench
rates.

If you want maximum hardness from a thin case in steel, such as one you get
with Kasenit, you have to use carbon-steel quenching rates and methods. That
usually means a water quench. There are some rare exceptions, such as
extremely thin blades or very large, thick masses of steel or iron that you
surface-heat with a flame or other means (thus, flame-hardened lathe beds),
which self-quench when you heat them quickly and then take the flame away.
But think in terms of water quench if you want a really hard case, on the
order of Rc 62 or higher, for any normal application.

What you probably read is that you don't have to *temper* a case the way you
do with through-hardened steel. That's generally true, if the case is thin
and if you aren't going to beat it with a hammer. But you then have a
brittle, if extremely hard case -- perhaps Rc 70. It makes a great wear
surface for bearings of many kinds but you wouldn't want to try it on a very
thin section that had to flex, or it would crack.

Ed Huntress