The quenching of steel is to heat the steel to a temperature above the critical temperature Ac3 (hypoeutectoid steel) or Ac1 (hypereutectoid steel), keep it warm for a period of time to make it fully or partially austenitized, and then rapidly cool it at a rate greater than the critical cooling rate. A heat treatment process that transforms martensite (or bainite) to below Ms (or isothermally near Ms).

Process: heating, insulation, cooling.

The essence of quenching is that supercooled austenite undergoes martensite or bainite transformation to obtain a martensite or bainite structure.

The purpose of quenching: (1) to significantly 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; (2) to meet the iron content of some special steels through quenching Special physical and chemical properties such as magnetism and corrosion resistance.

Scope of application: The quenching process is the most widely used, such as tools, measuring tools, molds, bearings, springs and automobiles, tractors, diesel engines, cutting machine tools, pneumatic tools, drilling machinery, agricultural machinery, petroleum machinery, chemical machinery, textile machinery, aircraft, etc. The parts are all using a quenching process.