quench oil classification 

1. Ordinary quench oil (quenching of oil temperature at 60 C)
The ordinary quenching oil is mainly applicable to hardened iron alloy, such as small size bearing steel and die steel parts quenching. In the past, only different grades of machine oil were used as quenching oil. In the early 1980s, in order to improve the cooling performance of oil, thermal oxidation stability and antirust property, the mechanical oil was added with the refrigerant, antioxidant and antirust agent, and the common quenching oil with different brands was developed. Its performance is better than the mechanical oil.
The common quenching oil can be used for quenching in salt bath, box type furnace and well type furnace, and is not suitable for mixing with other oil products. When the oil is changed, the oil tank should be cleaned thoroughly. The best use temperature of the product is 50~80 degrees centigrade, and the maximum usage temperature is not more than 80 C, so as not to affect the service life. The mixing or oil circulation device should be installed in the tank to further improve the cooling capacity of the oil, so that the surface of the workpiece can be cooled evenly, and the new oil should be replenish regularly to the oil tank.

2. Light quenching oil (quenching of oil temperature at 70 C)
Light quenching oil is a kind of cooling medium which is heated and quenched under controlled atmosphere. Its main feature is the bright surface of the parts after quenching. It mainly deals with small parts which are no longer processed after quenching, such as precision instrument and instrument parts, watch and small amount of cutting tool parts. In addition to satisfying the cooling performance requirements, the light quenching oil can prevent the oxidation products from forming large micelles to adhere to the surface of the parts and replace the insoluble products that have been attached to the surface of the parts to ensure the light of the surface of the quenched parts.
The light quenching oil is mainly used as the cooling medium for the quenching furnace, which can be used for the quenching of small and medium bearing steel, die steel, the instrument and instrument of the measuring and cutting tool and so on. It can also be used in the non protective atmosphere quenching furnace to treat the steel with good hardenability. The use of the oil is good at 60 - 80 C. In use, the water content must be controlled. When the moisture content is more than 200 g/g, the light intensity drops sharply. The quenching oil must be treated. Otherwise, the quenching quality of the parts is seriously affected.

3. Fast light quenching oil (quenching of oil temperature at 80 c)
Fast bright quenching oil is also used for quenching in protective atmosphere as cooling medium. The difference between this oil and bright quenching oil is that it has a fast cooling speed and is mainly used for hardening materials with poor hardenability and large size parts in protective atmosphere.
Quick bright quenching oil is mainly used in automobile, tractor, bearing and textile machinery industry to protect atmosphere quenching. It can be used for automotive gear carburizing and carbonitriding quenching. It can also be used as cooling medium for other steels quenched in protective atmosphere or in non-protective atmosphere furnace.
The highest oil temperature in use is not more than 100 C, which ensures that the oil has long-term and stable cooling capacity and good quenching and brightness. It is strictly prohibited to mix water and other oil products. A small amount of water may seriously affect the surface state of quenching parts. Carbon black and sulphur content should be strictly controlled in the protection atmosphere, and it will also affect the quality of parts after quenching.

4. Vacuum quenching oil (quenching of oil temperature at 80 c)
In some special industrial departments, the general heat treatment technology can not meet the use requirements, so the development of vacuum heat treatment technology. The vacuum quenching oil is suitable for quenching large and medium sized aviation structural steel, Zhou Chenggang, die steel and other alloy steels.
For the first time, 10 ~ 20min should be pre pumped under 66 x 103Pa to remove the mixed air from the oil to prevent the air mixed in the oil from the vacuum to bring the oil into the pipe and the vacuum unit.
The vacuum heat treatment process can make the workpiece not oxidize, do not decarbonized, do not increase carbon, reduce the deformation, not only improve the life of the parts, but also do not pollute the air, so there are some special requirements for the quenching oil.

1) low saturated vapor pressure
The saturated vapor of the oil is low and the evaporation amount is small. In addition, the evaporation of oil varies with the change of temperature and pressure. The pressure decreases, the temperature rises, and the evaporation will increase. The evaporation is large, which is easy to cause pollution in the furnace and affect the vacuum effect.

2) good cooling performance
Because of the decrease of pressure and the decrease of boiling point under vacuum heat treatment, the workpiece is liable to boil. The workpiece surface is clean, the film boiling stage is lengthened and the cooling intensity is reduced. Therefore, quenching oil is required to have a high cooling capacity in a wide range of pressure.

3) good brightness and thermal stability
The workpiece is liable to react with residual carbon, sulfur, oxygen, water and acid in quenching oil, so vacuum quenching oil should have high brightness and thermal stability.

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