"Buerste" wrote in message
...

snip

But the poster thinks that cyro treating is going to make his piece
harder, sharper and tougher, ain't gonna' happen like he thinks. I'll
refer to my bud George Fisher of "Ion-vacuum Technologies"
http://www.ivactech.com/ George knows cutting tools and materials and is
probably one of the top 10 physicists on the planet. We've discussed cyro
treating many times and I relayed his opinion. It seems you'll get a
different opinion from people that do cyro for a living...kind of like
global warming.

The effects of cryogenic treatment aren't a matter of opinion, Tom. There's
been extensive testing over the years in independent labs. This was fully
settled by the time I was covering materials for _American Machinist_, back
in the late '70s.

In cases where conversion from austenite to martensite is not complete, cryo
treatment can complete the conversion. This eliminates the room-temperature
austenite phase that paradoxically keeps the piece from achieving its full
potential hardness, and also contributes to brittleness or other weakness
through a mechanism I don't remember. (Hey, it's been 30 years.)

But the effects are slight. They can pay off in some kinds of press tooling,
which is where the method was being applied in those days. Adding small
margins of performance can add tens of thousands of hits to the life of a
blanking tool, for example.

--
Ed Huntress