Introduction of metal quenching process such as stainless steel plate

The so-called metal quenching is the method of quickly bringing the metal back to room temperature after heat treatment (such as annealing), in order to prevent the microstructure of the metal from being significantly changed during the cooling process. Quenching results in an increased hardening of the steel at the same temperature as fully annealed.

Specialty polymers, forced air convection, fresh water, brine and oils are all available for quench processing. Water is an effective medium when the goal is to achieve maximum hardness in stainless steel. However, using water can cause the metal to crack or deform. If extreme hardness is not required, other media such as mineral oil, whale oil or cottonseed oil can be used in the quenching process.

Effect of Quenching Rate
The quenching speed is slower, and the thermodynamic changes of the stainless steel plate are more opportunities to change the microstructure. Sometimes this result is preferred, which is why different media are used for quenching. For example, oil quenches much less rapidly than water. Quenching in a liquid medium requires agitation of the liquid surrounding the metal to reduce surface vapors. The steam pockets are quenched by air cooling until evaporated.
Why quench?
Typically used to harden stainless steel plates, quenching from water above the austenitic temperature will result in carbon being trapped inside the austenitic lath. This leads to a martensitic hardening and brittle phase. Austenite refers to an iron alloy with a γ-iron base, and martensite is a hard steel crystal structure. Quenched steel martensite is very brittle and stress resistant. Quenched steel usually undergoes a tempering treatment.
Typically metals such as stainless steel plates will be tempered in an oil, salt, lead bath or in a furnace with air circulated by a fan to restore some of the ductility (ability to withstand tensile stress) and toughness lost through transformation to martensite . After the metal has been tempered, it is cooled quickly, slowly or not at all, depending on the circumstances, in particular whether the metal is susceptible to post-temper brittleness.
Heat treatment of metals involves ferrite, pearlite, cementite and bainite temperatures in addition to martensite and austenite temperatures. The delta ferrite phase transformation occurs when iron is heated to high temperature iron form. According to the UK's Welding Institute, it is formed "from a low carbon concentration in iron-carbon alloys cooled from the liquid state before transformation to austenite".
Pearlite is easily formed during the slow cooling of ferroalloys. There are two forms of bainite: upper and lower bainite. It is produced at a slower cooling rate than the martensite formation, but at a faster cooling rate than the ferritic and pearlitic forms. Quenching prevents the steel from decomposing from austenite to ferrite and cementite, with the goal of obtaining the martensitic phase in the steel.