Heat treatment of automobile parts

Application of quenching cooling medium for heat treatment of automobile parts

Quenching oil

Quenching oil is generally applicable to the following parts and materials:

(1) mold

The production of crankshaft, connecting rod, knuckle and other transmission components all need mold, the mold size is large, not hardenable, the workpiece is easy to crack if the cooling speed is too fast. Therefore, fast and over speed quenching oil should be used.

(2) gear

This kind of products usually need carburizing heat treatment to increase the wear resistance and fatigue resistance of gears. The deformation and high precision of small and medium gears should be considered, so quenching oil is generally used as cooling medium.

(3) leaf spring

The thickness of such parts changes greatly, which is easy to produce cracks and may not harden, so it is necessary to use fast quenching oil.

(4) standard parts

This kind of small parts with various materials are generally produced in multi-purpose continuous furnace and cooled by quenching oil. In addition, small products made of bearing steel, high-speed steel, stainless steel and other materials are also produced in multi-purpose furnaces with quenching oil as cooling medium.

The temperature of quenching oil is generally 60 ~ 80 ℃, and it is equipped with cooling and mixing device to ensure that the oil is not easy to age. During the use of quenching oil, it is necessary to strictly implement the requirements of heat treatment process, prevent external pollution, monitor the state of oil products, and take timely adjustment measures to ensure the good use of oil products.

Automobile parts adopting water-soluble quenching cooling medium generally include the following categories:

(1) crankshaft

As the core part of the engine, the continuous production process is high, and PAG type water-soluble quenching and cooling medium is the most common.

(2) Small shaft products

There are many kinds of small shaft products, such as axle shaft, connecting rod, axle sleeve, steering knuckle, steering ball head, steering arm, steering interface, etc. no matter the structure is simple or complex, PAG water-soluble quenching cooling medium can be applied. It is suggested to apply it after passing the specific test.

(3) Carburizing and quenching workpiece

Many auto parts need to be carburized or carbonitrided to increase wear resistance and fatigue strength. The common materials 20Cr, 20CrMnTi and 20CrMnMo used quenching oil as cooling medium.

(4) Induction heat treatment workpiece

Induction heat treatment is required for crankshaft, half shaft, spline shaft, transmission shaft and other workpieces. Generally, PAG water-soluble quenching and cooling medium can meet the heat treatment requirements.

Before using PAG water-soluble quenching and cooling medium, the concentration of the medium shall be checked. Generally, the range of concentration change is ± 1% of the set value. The quenching and cooling medium shall be fully stirred. The oxygen in the air can effectively kill bacteria, prevent or minimize various pollutants.

Inorganic polymer water soluble quenching cooling medium

In the actual production process, for some 45 steel, 40Cr and other thick and large pieces, the hardness and metallographic structure of the core are strictly required, and many manufacturers can not meet the process requirements by using water and salt water for quenching. After using polymer inorganic water-soluble quenching cooling medium, good hardness gradient and metallographic structure are obtained.