"Ed Huntress" wrote in message
...
"Proctologically Violated©®" wrote in message
...
Dizzying, but clear--I think!
Where'd you learn alladis?? Sounds like you were a heat treater in a
former life! Dat is a tough job!! Esp. in the summer...

I was the Materials Editor at _American Machinist_, back when the top
trade
magazines were taken seriously. I also covered heat treating. Learning
that,
and EDM, and gearmaking took me about three years of reading textbooks on
the train twice a day.

Which meant I had to visit a lot of heat-treating shops, and, in the
summer,
I was damned glad to get out of them at the end of a day. The gearmaking
shops ruined my leather-soled shoes from all of the sulfated cutting oil.
And I had to wear suits, even in steelmaking plants.

Sounds like the train rides mighta been pretty long! Lotsa reading??!!
Was this in your Mount Vernon days?
The only thing I have encountered in the summer that is worse than a heat
treater's shop is a foundry. We got one in Queens, about the only one left.
Talk about hell on earth... goodeffinggawd... And the noise!!!
Oh, and add, to this ambiance, the fact that drug dealers&friends use the
sidewalks during the summer the way you and I would use a beach--replete w/
towels, coolers, and rinse-offs under the nearest fire hydrant..

Metallurgy is just too goddamm complicated!
----------------------------
Mr. P.V.'d
formerly Droll Troll


d8-)


But, the diff. between the SS tubing I have and CR is like night and day:
SS is clearly stiffer. Sometimes, depending on finishes, you can't tell
by
looking at it, but you can tell by banging it/tugging on it. Also much
harder! which mebbe is the flip side of stiffness?

Stainless, even in the annealed state, is quite a bit harder than annealed
mild steel. Once the mild steel is cold-rolled its hardness goes up
considerably. But stainless's hardness goes up even more from
cold-working.
It work hardens like crazy, as we all know from machining it.

However, you can prove to yourself that stainless is not quite as stiff.
Take equal-dimensioned sticks of stainless and any carbon steel, wire,
strips, or rods, hard or soft, and put the stainless in a vise, hanging
out
enough so you can measure deflection (a few inches to a couple of feet,
depending on thickness). Then hang a weight on the end and measure the
deflection. Don't put on so much weight that it bends permanently; you're
measuring springiness, not strength.

Then do the same with the stick of carbon steel. As you'll see, it will
deflect slightly less than the stainless.

Hardness has nothing to do with stiffness, although it's closely related
to
strength. You can put more load on a hard/strong piece of steel before it
will break or take a permanent bend. But, within the "springy" range, it
doesn't matter if the steel is plain-carbon or high-alloy, heat-treated as
hard as it can be or annealed. Within that springy range, the stiffness
will
be the same. Except for stainless. It will be slightly less stiff. (Going
from memory, the carbon steel has an elastic modulus on the order of 31
Mlb.; stainless is around 28 or so).

I think I know what you're basing your assessment on. The stainless is
enough harder and stronger than plain-carbon steel that you find it's a
b*tch to bend it permanently. And, because it work hardens so quickly,
it's
even more of a b*tch to bend it back. So it seems extremely "stiff." But
it's not stiff. It's just miserable to cold-work.


The sears blades: Yeah, I couldn't vouch for the edge (did seem crappy,
in
retrospect), but tryna bend a bent blade back into shape (roots,
donchaknow), was pert near impossible. Needed O/A.
Mebbe not hard, but incredibly tough--which, IIUC, has its own measure of
sorts.

What they probably did was to go to a low-cost alloy that's tough and that
has just enough carbon to harden a little bit. A manganese alloy will be
very tough, and around 30 or 40 points of carbon will let them get it a
little bit hard without being brittle.

It's easy on toes, but it dulls awfully fast. I had a Power Products mower
made around 1957 that I held on to for over two decades, just because the
blade was hard as hell. When the blade wore out I trashed the mower. g

--
Ed Huntress