In materials science, quenching is the rapid cooling of a workpiece to obtain certain material properties. It prevents low-temperature processes, such as phase transformations, from occurring by only providing a narrow window of time in which the reaction is both thermodynamically favorable and kinetically accessible. For instance, it can reduce crystallinity and thereby increase toughness of both alloys and plastics (produced through polymerization).
In metallurgy, it is most commonly used to harden steel by introducing martensite, in which case the steel must be rapidly cooled through its eutectoid point, the temperature at which austenite becomes unstable. In steel alloyed with metals such as nickel and manganese, the eutectoid temperature becomes much lower, but the kinetic barriers to phase transformation remain the same. This allows quenching to start at a lower temperature, making the process much easier. High speed steel also has added tungsten, which serves to raise kinetic barriers and give the illusion that the material has been cooled more rapidly than it really has. Even cooling such alloys slowly in air has most of the desired effects of quenching.
Extremely rapid cooling can prevent the formation of all crystal structure, resulting in amorphous metal or "metallic glass".
Read more about Quenching: Quench Hardening, Quenching Distance
Other articles related to "quenching":
... Non-photochemical quenching is measured by the quenching of chlorophyll fluorescence and is distinguished from photochemical quenching by applying a bright light pulse to transiently saturate photochemical quenching ... Non-photochemical quenching is not affected if the pulse of light is short ... in the absence of any photochemical quenching, known as maximum fluorescence ...
... collisions, are expected to lead to jet quenching. 2010 CERN announced the first direct observation of jet quenching ...
... The two important aspects of quenching are the cooling rate and the holding time ... Some processes feature quenching and then removal from the quench media, then holding in a furnace ...
... Quenching distance is an important property in the study of combustion ... For example hydrogen has a quenching distance of 0.64 mm ...
... Glass rollers hold the ribbon throughout various parts of the process, supporting its weight and continuing the drawing process ... The process continues as the ribbon is drawn upwards into a chimney like structure, where it is quenched or rapidly cooled ...