Originally Posted by Armaegis
Materials do not necessarily change when cooled to cryo temperatures. Everything hinges on composition and the existing microstructure, as well as any residual stresses and/or deformations.
Material phase changes are usually reversible, especially if the temperature changes are made gradually.
Changes that are not reversible:
- precipitation (ie: of solute alloying elements, carbides, etc)
- change in grain...