Cryogenic toughening of metal parts

[Martin S.]

Has anyone experience with cryogenic hardening or toughening of parts? It was featured in a video series about rebuilding and modifying VW type 1 trans axles and it worked well on the gears. We have a renter at our house who works in a hospital lab and he recently brought home a couple pails of liquid N2 to wow the kids by making home made ice cream with it. After I thought of dropping some lifters in, or get a deeper container and do a cam.  

[Torben Alstrup]

Cryogenic enchancement has been around for quite some time now. BUT! You can´t just drop X piece of steel into the liquid, leave it and then take it up again. If you do that you will make the material brittle and you will be worse off than you were before.
Cryo enchancement of materials require a contolled decent to - 180 C, then dependant on material "X" amount of time in the deep zone. Then a controlled rise to zero, then a contolled heating typically to about 250 degrees C and cool off.  Then youre ready to take advantage of the reinforced material.

Does it work(?)  - YES! Cast iron and steel being the materials that benefits the most.

T

[richie]

Yes I have done it, valve springs worked well, ring & pinion didnt

[Dougy Dee]

Works good on gun barrels and saw blades too.

[Martin S.]

Thanks! that process sounds like it could be a DIY project. As long as the cold part is not too long. If it was 20 minutes or so, that wouldn't be a problem to do at home. Interesting.

[Brian Rogers]

I seem to recall a story of guy packing axels and ring and pinions in dry ice and just let it evaporate over night. This was from the late 60s.