On Tue, 21 May 1996 Ryan75@aol.com wrote:
>   I've also heard of a cryogenic procedure performed on all sorts of items
> that increases toughness and wear resistance; I wonder if this would work on
> aluminium cylinder heads...

The cyrogenic treatment of tool steels is well documented to increase 
toughness and wearability. It's been used since the '30's, at least. The 
effects of the process depends on the material being cold quenched. For 
aluminum, the main effect is stress relief. Toughness and wear resistance 
isn't affected. The best results are obtained from high carbon tool 
steels, where you can get toughness without brittleness and the increase 
of 2-5 times in wear resistance. You can probably do it yourself, if you 
like to play. You take a styrofoam cooler outside, put your drill bits, 
and Craftsman tools in the bottom, go to your local oxygen supply house 
and get some liquid nitrogen (you have to rent the flask), pour it into 
the cooler, put the cover on, and walk away. After the nitrogen boils 
off, you should have some better, longer lasting tools.

*******************************************************************************
Dirk Wright 						       wright@uspto.gov
"I speak for myself and not my employer"                   1974 Porsche 914 2.0
"A real hifi glows in the dark and has horns"
*******************************************************************************