[TheForge] RE: Harening Steel

Mon Sep 9 20:18:01 2002

Jim,

Nice summary.  After going around the block on this I come back to whare I
started. The basket wouldn't support the load until it was hardened. So I
guess I was hitting the yield strength on the basket and not just a rigidity
issue.

I don't mind if the chandelier has a little wobble in it I just don't want
it to lay over.

I still haven't done any testing on this. Was at a craft show all weekend
and today I was helping my daughter move.

Thanks to everyone that contributed to this thread.

Bob Ehrenberger
Shelbyville, Mo

To: [email protected]
From: jim wallbridge <[email protected]>
Subject: [TheForge] Re:  Hardening steel
Reply-To: [email protected]

Mike Schermerhorn said:  Hardening the steel baskets (or any of the
quench & temper steels, including
tool steels), does not make it any stronger as far as resisting bend.  The
amount that a piece of steel will deflect or bend under weight is called the
Modulus or Modulus of Elasticity, or Modulus of Rigidity, and as strange as
it sounds, is the same for a piece of annealed or fully hardened steel.

Bob Erenberger replied:  This does sound strange.  I will have to
test this myself. From my
experience in making tools a hardened tool is much more rigid than an
annealed one.
--
It is true that up to the yield strength that both a soft and a
hardened piece of steel will behave the same in tension as well as
bending.  What is different is the yield strength which may differ by
a factor of 5or more  (for instance  40 KSI vs 280 KSI) , above this
the behavior is very different The soft steel will bend generally in
a ductile manner which can be thought of as  similar to a material
with a very low modulus while the hardened steel will continue to
bend (stretch) in an elastic manner with the original modulus.
Simplistically for a load somewhat higher (say 1.5 times) than the
yield strength of the soft steel, the hard steel will almost retain
its shape while the soft steel may bend like a wet noddle.
Hope this clears up what I think is confusion.
jim
(James ME Wallbridge P. Eng.) Libertarian, Metallurgist, Wood & Metal
Worker, Fly Fisher,  Resident of Calgary,  Canada's new head office
location of choice.  Permission is hereby given to use any
information herein, as an attributed quote, unless the body of the
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