"Bob Powell" wrote in message
s.com...
I keep a metallurgical souvenier, a short length of high-grade chain
with a couple of links that are stretched to about 2X their nominal
length.
snip
Just a wild guess, it broke at around 20,000 lbs force on a 3/8" chain.

Hmm, 4130-ish? But even then the max. elongation is what, 30%? I don't
know of anything that's up around 100%, gold maybe?

If the load is born equally in both sides of the link (unlikely given the
stress concentration between links), that means it failed at 90KSI... If
the load is concentrated on one side of the link, that doubles to 180KSI.
Most likely it's the first case plus stress concentration bringing the guess
to between 100 and 300KSI (the highest I've heard of for steel alloys). In
any case some impressive steel!

Tim

--
"I have misplaced my pants." - Homer Simpson | Electronics,
- - - - - - - - - - - - - - - - - - - - - - --+ Metalcasting
and Games: http://webpages.charter.net/dawill/tmoranwms