Rapid cooling. When applicable, the following more specific terms should be used: direct quenching, jog quenching, hot quenching, interrupted quenching, selective quenching, spray quenching and time quenching.
The quenching media may be water, brine, oil, special solutions, salts or metals; and the intensity of the quench is determined by the temperature, volume and velocity of the media. In the case of air hardening tool steels the quenching medium is air at room temperatures.
The procedure consists of heating the material to the proper austenitizing temperature, holding at that temperature for a sufficient time to effect the desired change in crystalline structure and then quenching in a the appropriate medium. After quenching, the material is reheated to a predetermined temperature below the critical range and then cooled at a suitable rate (tempering).
Subjects: Mechanical Engineering