The most recent #Sachgeschichte (about chains) claims that the cooling bath for hardening is water (it's surely oil: water would visibly boil and Leidenfrost effect would make cooling insufficient).
I've used WDR's contact form to tell them that and we'll see what happens.
Follow
Or maybe I'm wrong, Leidenfrost causes it not to violently boil, and the colling is fast enough for their purposes?
@robryk Clearly you'd need to conduct an experiment. ;)