Hardening and tempering
Hardening is a treatment to increase hardness and strength of steel. Steel is heated until austenitized, then cooled rapidly (or quenched) in water, oil, or gas. Hardening makes steel drastically harder, but lowers toughness. Tempering equilibrates the steel for hardness and toughness that are ideal for intended use.
This treatment maintains high luminance with little surface deterioration of the treated material, and can be used for metallic molds and various metal