[TheForge] rigid vs. springy steel

[Bruce .]

Here's a question you metal munchers might be able to field:

I have had a few applications in which I need thin but rigid steel.
What steel is best?

Consider for example a corkscrew -- it's a helix that holds its shape,
it's rigid.  But a spring with a comparable shape is flexible.  What's
the difference?  I suspect that it's simply the relative dimensions --
a spring is relatively thinner wire wrapped on a relatively larger
mandrel, and vise-verse the corkscrew.

But is that all there is too it, or is there a metallurgical difference as well?

Although I've contemplated making corkscrews, the immediate
application is a prybar for roofing and siding nails and similar
stuff.  It would be flat, like these:
http://www.homedepot.com/p/Dasco-Pro-Pry-Bar-Set-3-Piece-91/202585548#.UfDoym1cWgw
but of thinner steel.  (If I can't make it thinner, I'll just use a
commercial one.)

I'd like it as thin as possible for a number of reasons, but I don't
want more than minimal flex to the thing.  So I'm wondering what steel
to use.

I have, BTW, considered using thin steel and putting longitudinal
bends ("ribs" or "nerves" or "corrugations" -- whatever you want to
call them -- as are used in larger HVAC ducts to prevent oilcanning of
the large flats) in it, but this partially defeats the purpose, as the
result would effectively be thicker -- so why not use thicker metal
and be done with it?

This is not any sort of critical problem, but I've had similar
problems before and left them unaddressed.  This time I thought I'd
ask....

-- 
Bruce
NJ