How to choose the right quenching medium for forging forging?

Suitable quenching medium and reasonable quenching operation method should be selected according to the material, mechanical property requirements and shape and size of the forgings, which should have suitable cooling characteristics. On the premise of ensuring the quenching effect, select the quenching medium with slow cooling capacity to prevent quenching deformation and cracking caused by fast cooling capacity of the quenching medium. When quenching and cooling, the appropriate cooling rate and cooling time should be controlled.

Because the forging waste heat quenching temperature is higher than the ordinary quenching temperature, quenching immediately after high temperature deformation, so the forging waste heat quenching parts have good hardenability, so carbon steel and alloy steel forging waste heat quenching generally choose N22~N32 oil as quenching medium. The oil output temperature of quenched parts is generally 100℃~110℃.

As mentioned above, the oil is easy to age, there is smoke, affect the environmental protection, can use polymer quenching medium, among which the polyethylene glycol (PAG) quenching medium is used more, its cooling performance is good, the forging cooling uniformity is good, in the long-term use of the performance is relatively stable.

The quench tank shall have sufficient volume and be equipped with a continuous conveyor belt, whose operation speed can be adjusted to ensure the necessary cooling time. In addition, the agitation system, cooling system and heating device of quenching medium are equipped, and the temperature of quenching medium is automatically controlled to strictly control the temperature fluctuation range of quenching medium. If it is oil, it should also be configured with quenched oil fume exhaust device.

The quenching medium should be monitored, maintained and maintained regularly to ensure that the quenching medium has the required cooling performance. For fast quenching oil, the cooling capacity of the oil should be measured regularly, and the ratio of the oil should be adjusted accordingly. It is forbidden to bring water into the quick quenching oil in any way, and regularly precipitate, filter, clean up impurities such as oxide skin in the oil tank and circulation system to keep the quenching oil clean.

For water-based quench liquid (polymer quench medium), in long-term batch production, the cooling characteristics of quench liquid should be controlled according to the following methods.

The viscosity method must be used to measure and control the concentration of the quench solution used for a long time. The kinetic viscosity should be measured once a week with a viscosity meter to convert the concentration coefficient. In the production process, the refraction index of the quench liquid is measured on time, and the concentration of the quench liquid is obtained by multiplying the index by the concentration coefficient measured in this week.

It is important to measure the cooling capacity of the quench regularly. Because with the growth of the use of time, the impurities in the quenching medium increase, medium aging and even deterioration. It is inevitable that the ground high cooling rate and 300℃ cooling rate of quench liquid are increased, and the temperature corresponding to higher cooling rate is decreased, which increases the quenching tendency of forging. The technical personnel should adjust the concentration of the quench liquid appropriately according to the measurement results and the actual situation on site.

The impurities such as powder, rust and gasified skin in the tank liquid and circulating system should be settled, filtered and cleaned regularly, and the quenching medium should be kept clean. It is forbidden to mix oil into the quenching liquid tank in any way. If oil is mixed into the quenching liquid, the quenching agent will fail. When not in use for a long time, the quenching agent circulation system should be run regularly to prevent anaerobic bacteria from forming in the quenching system. Bacteria generated in the quenching agent will cause the quenching liquid to stink and turn black.