OK, so I converted some of the 8% retained austenite to martensite from the regular HT of O1. No big deal. Do not want to argue about it. It is what I was taught in 2006 and the best O1 filet knife I ever made resulted from it with absolutely no change in the HT except 3 days under dry ice. You make a O1 filet knife (1/8") that cuts through 80 fish and is somewhat flexible with no sharpening. Not scientific, but without making the knife just plain harder than it should be it worked pretty good.
I never said dry ice was as good as LN. Just that it did improve my filet knives. 80 fish is a lot of bones. Cryo is expensive for hyper eutectic alloys, but it does improve them to a certain degree.
https://www5.kau.se/sites/default/fi..._pdf_16802.pdf