[TheForge] Re: Hardening steel

[jim wallbridge]

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 
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