water and oil and other commonly used quenching medium is not ideal, has been increasingly unable to meet the requirements of heat treatment production, for this reason, to improve the original quenching medium. For example, the addition of inorganic salts or organic polymers in water can reduce the cooling rate of the low-temperature zone of the workpiece during quenching to varying degrees, thus preventing or reducing the tendency of the workpiece to quench and distortion or obtaining higher quenching hardness and deeper hardening layer depth, thereby improving the quality of the quenched workpiece. For quenching oil, it is still a promising quenching medium after increasing its cooling rate and improving some of its characteristics on the basis of retaining its original advantages. For example, the development of high-efficiency multi-purpose quenching oils such as coolants, antioxidants, brighteners, etc. can obtain stronger cooling capacity, more reasonable cooling rate distribution, longer service life, and better maintain the brightness of the surface of the workpiece. Or it can reduce the distortion and cracking tendency of the workpiece, so as to realize the multi-use of 1 oil. In addition, the improvement of quenching tank , the use of stirring, spraying, ultrasonic and other enhanced cooling, can improve the cooling rate of the oil, to meet the requirements of quenching process.