I am currently experimenting with the various metalurgical advantages of cryogenic treatment of engine componenets, namely crankshafts, and was curious as to whether any other members had any knowledge or information on this subject.
I am in the process of cryogenically treating an EJ207 crankshaft using liquid Oxygen however I was contemplating substituting the cryogenic medium for liquid helium allowing me to drop to 4K or -268 Celsius. My concern is that lowering the temperature this close to absolute zero may result in a breakdown of the molecular structure of the crankshaft. The only material that I know that has benefited from this level of cryogenic treatment is A06 Nitride Steel which saw and incredible 280% increase in sheer and torsional strength.

Any ideas? Unfortunately the only means I have of testing a cryogenically treated crankshaft is in an engine which I would rather not do if it will fail prematurely.