"Ed Huntress" wrote in message
...
"Mark Rand" wrote in message
...
On Thu, 10 Feb 2005 17:43:14 -0500, "Ed Huntress"

wrote:

"Will" wrote in message
...
Not that I really know what I'm talking about, but wouldn't the coil
or
leaf
spring most likely be 5160 or something similar? Shouldn't you be
able
to
harden one of them to 56-60 Rc? And how about valve springs?

I don't know the alloys that are used for either one. I happen to
remember
the axle alloys because I looked it up last year.

In any case, valve springs are very small and would be of limited use.
I
doubt if there's any advantage to using either one for cutting tools,
and
Rc
56-60 is pretty marginal for cutting steel. It's generally accepted
that
you
need Rc 60 or more. 60 points of carbon isn't enough to do it, unless
it's
combined with enough chromium to boost the hardening potential of the
carbon. I don't think that's the case with suspension-spring steel,
although, again, I'd have to look up the alloys used for valve springs.


David Forsyth in South Africa has used ball bearing races as a source of
metal
for cutting tools :-

http://iwr.ru.ac.za/~iwdf/lathe/boring.html

Bearing races are made from either a carburizing grade (usually SAE 8620)
or
a through-hardening high-carbon steel (SAE 52100, which is 1.00% chromium
and 1% [100 points] carbon). 52100 will harden up nicely for cutting
tools.
It's a good clean steel and it's quite strong.

However, for the record, I doubt if it will cut one bit better or last
more
than slightly longer than carburized low-carbon steel. Like plain-carbon
steels, its tempering temperatures are quite low, so it won't take any
heat
in cutting without going soft. The chromium content may increase the wear
resistance somewhat.

--
Ed Huntress

I fully agree.
Harold