Ned Simmons wrote:

In article SGu1f.8119$oc.7024
@newsread2.news.pas.earthlink.net,
says...

Actually, it's the plain carbon steel that is brittle at low temps,
adding some molybdenum does wonders for low temp strength.

You might want to read up on the 'Charpy' test for impact resisitance.
You put a large notch in the sample piece, use a pendulum to swing a
heavy weight into the sample. At -40 (F or C) carbon steel just snaps.



Also search on "brittle to ductile transition temperature"

Ned Simmons
Thanks for the lead. I've been to several of those articles. It's a
land in which I need a native guide. As random luck would have it, I
had already seen some of them while I was flailing around the internet
trying to do this research on my own. What a tyro like me needs is a
simple article with a chart that shows test results. Something that
would, say, show Charpy test results for test pieces with a percentage
of a single alloying material changed.

Or, alternatively, answer this: if Molybdenum is the right metal to
lower the temperature point of material failure, should I just assume
that adding, say 1% more to the next batch will lower it's brittle
temperature without adversely affecting the overall strength. Where
overall strength is measured by shackles that can hold up a beer tent's
lines in hurricane force winds.

I know I don't know the terminology well enough to ask this clearly. My
language probably causes pain in anybody knowledgeable enough to answer
the question.

Bill

--
Bill Swears

They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety.

Ben Franklin, 1755 "Historical Review of Pennsylvania"

To think that was once a right wing comment. In the land of Homeland
Security it seems.. Suspiciously left-wing.