Welcome to Our Website; E-mail: info@shangangsteel.com

We can provide samples for free

Send your inquiry: info@shangangsteel.com

Bearing steel production technology
Bearing steels production technology
Steelmaking process and refining technology outside furnace

Common quenching medium

When the workpiece is quenching and cooling, the proper quenching medium must be selected in order to obtain a reasonable quenching cooling rate. At present, the cooling quenching medium used in production is water and oil. When the cooling quenching medium is 20℃ tap water, the workpiece temperature is 200 ~ 300℃, the average cooling rate is 450℃/s; When the workpiece temperature is 340℃, the average cooling rate is 775℃/s. When the workpiece temperature ranges from 500 ℃ to 650℃, the average cooling rate is 135℃/s. Therefore, the cooling characteristics of water is not ideal, in the temperature range of 500 ~ 650℃, its cooling speed is very small, and in 200 ~ 300℃, the cooling speed is very large.

Common quenching medium


Water is the earliest, most widely used and most economical quenching medium. It is cheap and easy to obtain, non-toxic, non-combustion, stable physical and chemical properties, and strong cooling capacity. By controlling water temperature, increasing pressure, increasing flow rate, circulating water and using magnetic field, the cooling characteristics of water can be improved, deformation and cracking can be reduced, and ideal quenching effect can be obtained. But because these methods need to increase special equipment, and the performance of the workpiece after quenching is not very stable, so it can not be widely used. So said. Pure water is only suitable for quenching a few steel parts with low carbon content, low hardenability and simple shape.

Common quenching medium

quenching oil

  • The mineral oil used for quenching is usually based on the neutral paraffin base oil which is highly refined. It has the advantages of high flash point, low viscosity, less oil smoke, good oxidation resistance and thermal stability, long service life and so on. It is suitable for quenching oil. Quenching oil is only used for workpiece with good hardenability, small wall thickness, complex shape and small quenching deformation. Quenching oil pollution to the surrounding environment, quenching is easy to cause fire.
  • The main factor affecting the cooling capacity of quenching oil is its viscosity value. At room temperature, the cooling capacity of oil with low viscosity is larger than that of oil with high viscosity. With the increase of temperature, the fluidity of oil increases and the cooling capacity increases. The cooling capacity of quenching oil can also be improved by properly increasing the service temperature of quenching oil.
Common quenching medium

Molten salt, molten base

  • The characteristics of this type of quenching medium is not change of state in the cooling process, the workpiece quenching mainly by convection cooling, cooling speed, usually in the high temperature area in the region of the low temperature cooling speed slow, quenching, the excellent performance of hardening power, quenching edge to form small, basic no crack, but the pollution to the environment, poor working conditions, energy consumption, high cost, often used for complex shape, Quenching of workpiece and die with greatly varying section size. Molten salt sodium chloride, nitrate, nitrite and so on, the workpiece in the salt bath quenching can obtain higher hardness, and the deformation is very small, not easy to crack, usually used for isothermal quenching or fractional quenching. Its disadvantage is that molten salt is easy to aging, oxidation and corrosion of the workpiece. Molten alkali sodium hydroxide, potassium hydroxide and so on, it has a large cooling capacity, the workpiece heating if not oxidized, quenching can obtain silver gray clean surface, but also has a certain application. However, molten alkali vapor is corrosive and irritating to the skin, so pay attention to ventilation and take protective measures when using it.