Thanks bushveld. It is actually pretty easy to observe that when relatively high carbon steel is heated, the non magnetic point as the heat increases is a very sharp point. As the piece cools, it will remain non magnetic till it is noticably cooler. I don't believe it is good metallurgy, but high carbon steel can still skate a file when quenched while its non magnetic and below the curie point. It sort of sounds technical, but there are simple videos of observing the recalescence point of steel, basically black heat color seeming to heat glow again, as it cools. I'd like to see how your 20 turned out. Take care.
