Concerning the simpler carbon steels, why is it that so many persist in this practice, and continue to recommend it to be the critical temperature at which a blade should be quenched in the hardening process? Non-magnetic happens at 1414° in all steels, and is only the second phase of fully Austenitizing steel. Phase three, or actual critical temp, varies with the type of steel, but 1450° is about as low as any can achieve full austenitization, with 1475° to 1500° being most often more ideal, depending on carbon content and other alloys, which may require even higher heat. Between these two temps, grain growth is insignificant if at all. Those not having an oven, or other way of controlling heat can simply heat to one or two shades of red above non-magnetic and be close enough to produce a good solution of the iron and carbon with a reasonably good carbon dispersion. Of course even a short soak at temp will benefit even more, but without heat control is not easily done.