>>>*I first heard of cryogenics back in the early 70's. That was interesting. I have done a lot of metals heat treating, things like connecting rods in an oven at 450? for 8 hours. Then we left them in there until they cooled slowly to room temperature which usually took another 3-4 hours or so.

The process hardened steel connecting rods or I should say we thought so. We did that to reharden the beams after grinding off all flashings and polishing them. Connecting rods are shot peened to about .125 ARC which work hardens them, grinding removes that.

The only messing around with cold temps I ever personally did was with the racing tires. During the Winter season we stored the used ones in a big old deep freezer. About as cold as we could get was around 30?F below zero, one long ways from Cryo temps.

Tires react because the rubber has lighter volitiles that dry out when stored and that did work. When the track officials tested the tires for chemical softeners, our used tires always tested as brand new which got us dirty looks from the competition and accusations of using "something" on them. But they also had sniffers, ours always passed too.

MHO is that extreme low temps have quite a serious effect on many materials...*EB