Definition and purpose of quenching steel workpiece
Heating the steel to a temperature above the critical point Ac3 (hypoeutectoid steel) or Ac1 (hyper-eutectoid steel), holding it for a period of time, making it all or part austenitized, and then cooling at a rate greater than the critical quenching speed, The heat treatment process for transforming supercooled austenite into martensite or lower bainite structure is called quenching.
The purpose of quenching is to transform the supercooled austenite into martensite or bainite to obtain martensite or lower bainite structure, and then mix with tempering at different temperatures to greatly improve the strength, hardness and resistance of the steel. Grindability, fatigue strength and toughness to meet the different requirements of various mechanical parts and tools. Special physical and chemical properties such as ferromagnetism and corrosion resistance of certain special steels can also be met by quenching.