Comprehensive Introduction To Quenching

DALIAN, China - Aug. 14, 2022 - PRLog -- Quenching is a heat treatment process that heats the steel above the critical temperature, holds it for a certain period of time, and then cools it at a rate greater than the critical cooling rate, so as to obtain an unbalanced structure dominated by martensite (or bainite or single-phase austenite as required). Quenching is the most widely used process in steel heat treatment.
There are four basic processes for heat treatment of steel: annealing, normalizing, quenching and tempering.
Purpose Of Quenching
It is to make the undercooled austenite undergo martensite or bainite transformation to obtain martensite or bainite structure, and then cooperate with tempering at different temperatures to greatly improve the rigidity, hardness, wear resistance, fatigue strength and toughness of steel, so as to meet the different use requirements of various mechanical parts and tools. It can also meet the special physical and chemical properties such as ferromagnetism and corrosion resistance of some special steels by quenching.
The metal heat treatment process is to heat the metal workpiece to a certain temperature and maintain it for a period of time, and then immerse it in the quenching medium for rapid cooling. Common quenching media include brine, water, mineral oil, air, etc. Quenching can improve the hardness and wear resistance of metal workpieces, so it is widely used in various tools, dies, measuring tools and parts requiring surface wear resistance (such as gears, rollers, carburized parts, etc.). Through quenching and tempering at different temperatures, the strength, toughness reduction and fatigue strength of metals can be greatly improved, and the coordination between these properties (comprehensive mechanical properties) can be obtained to meet different use requirements.
In addition, quenching can also make some special properties of steel obtain certain physical and chemical properties, such as quenching to enhance the ferromagnetism of permanent magnet steel, stainless steel to improve its corrosion resistance and so on. Quenching process is mainly used for steel parts. When the commonly used steel is heated above the critical temperature, the original structure at room temperature will be completely or mostly transformed into austenite. Then the steel is immersed in water or oil for rapid cooling, and austenite is transformed into martensite. Compared with other structures in steel, martensite has the highest hardness. Rapid cooling during quenching will cause internal stress in the workpiece, and when it is large to a certain extent, the workpiece will be distorted or even cracked. Therefore, it is necessary to choose a suitable cooling method.
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