And us ECS guys think liquid Helium at 4K....
RS
"That which you manifest
is before you" - Enzo the dog
________________________________
From: Mark
Haynes <haynes386 at netzero.net>
To: spridgets at autox.team.net
Sent: Tuesday,
August 16, 2011 1:42 PM
Subject: Re: [Spridgets] Hardening Steel
Only Case
Hardening is surface hardening. True hardening of the steel involves
raising
of the temperature of the steel to a point where the grain size is
modified to
be smaller and is more orderly thus increasing the
intercrystalline bonds
reducing the potential for dislocations. The trick with
hardening is to get
the crytalline structure consistent inside to outside and
then 'freeze' it by
quenching at that state.
Subsequent to quenching, most steels are then
annealed to increase the
toughness (resistance to deformation).
Harder does
not equal tougher. Toughness is an independent variable based on
the amount of
abuse (non-engineering term here) that it will take before it
starts to show
signs of yielding.
In gross generalities, a stronger steel is more brittle,
however this is a
relative term. My point being that as a steel becomes
stronger, the percentage
difference between the yield point (where it starts
to deform plastically) and
the failure point (where it catastrophically fails)
is reduced. Thus as
stronger steel in the same application will yield later
(at a higher load),
but it won't put up with the same percentage increase in
load beyond that as
long as a weaker steel will before it fails.
Hardening of
steel is more of an art than a science unless you have a
limitless database of
minor variations in each specific steel you are working
with.
So to answer the
question, at a given load assuming no annealing has taken
place, a harder
steel will fracture more suddenly than a weaker steel, not
necessarily at a
different load though. Some tougher steels are harder, some
harder steels are
more brittle, some softer steels are tougher, it all depends
on what the alloy
and the heat treatment is.
Sorry for the dissertation, I'm just off of my load
frame testing Aluminum at
4 K (-269*C or-453*F).
Mark Haynes
It only goes one
way-Pay it Forward
HAN6L12977
HAN5L8016
Date: Tue, 16 Aug 2011 12:14:00
-0400
From: Allen Hefner <lbc77mg at gmail.com>
Here's a question for you
metallurgists out there. If one axle is harder
than the others, wouldn't it
be more brittle and prone to breakage? Is a
softer metal better able to
handle being banged by the engine power and
brake force?
Just askin'.
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