Wiki-Quenching

One of the manufacturing processes for kitchen knives, which involves heating the metal and rapidly cooling it from that state. The structure of the metal changes during the heating and rapid cooling processes, resulting in a transformation to a harder metal. When cooling the metal, water, oil, air, etc. are used, resulting in differences in the characteristic features of the finished metal.

Related websites
Decoding Japanese Knives: Understanding Parts and Names | KIREAJI