Quenching is an integral part of any metal alloy heat treating application. It helps define the metal's microstructure and is a critical step in determining whether a part will meet specifications and properties after tempering. Having a full understanding of the types of quenchants available and in what applications they are best used will improve a heat treater's overall operation.
Since the beginning of the Bronze Age nearly five thousand years ago, metallurgists have used heat treating and quenching to influence the final properties of metals. Heat treating offers manufacturers control over hardnessa, toughness, and corrosion resistance. Quenching helps to further influence hardness, and reduces the level of distortion and residual stress created during the manufacturing process. The primary and critical role that quenching plays is to control the rate of cooling in a metal. If it is cooled too slowly, the metal will become more brittle, reducing its overall hardness. If it is cooled too rapidly, there will likely be distortion and cracking. The key to controlling the rate of quenching and, in turn, the rate of cooling, is choosing the right quenchant for the application.