ABSTRACT
Hot steel has been quenched into water or oil , to harden it , for a millenium at least , and the technique has acquired many subtle variants. Numerous solutes , some of the ancient ones with magical overtones, have been added to quenching water to improve swords and armor ; in recent years , polymer additions have enhanced control over quenching rates in heat treatme nt shops . In this process, 1000 K/s would be reckoned an exceptionally high rate of cooli ng, dangerous because apt to cause cracking.
