Rear strut tower brace material

[Bill the arcstarter]

Gerald.Kloth@ipst.edu wrote:

>Many people are under the impression that stronger steel is also
>stiffer.  This is not so.  The modulus of elasticity (stiffness,

Correct.  The 'better' steels can, if properly heat treated- have a higher
yield strength.  That is - you can deflect it farther w/o it taking a
permanent set etc.

I was making a part out of steel.  Couldn't find any low carbon 1018, so I
used some 4145.  First operation involved welding it onto a mandrel to
permit subsequent operations.  All was well until I tried to turn throught
the welded portion!  That steel hardened right up adjacent to the weld.  I
had to take it out of the lathe and heat it all red hot, and re-anneal
before I could continue!

Turns out 1018 steel might have a peak tensile strength of 60Kpsi.  Quickly
quenched (welded heat affected zone) 4145 produces 275kpsi - nearly 5 times
that of the 1018!

So sometimes using a better steel isn't really what you want. :)

Now - if you want stiff - tungsten carbide has a modulus of about 90Mpsi
(compression), or about 3x as stiff as steel.  So who'll be the first to
make a tungsten carbide sway or rollbar? :) Problem is expense and lack of
tensional strength...

-Bill