ZYB type gear slag pump gear carburizing layer depth

Carburizing depth

For the carburized ZYB gear slag pump parts, the depth of the carburized layer will directly affect the performance of the oil pump, especially for the parts affected by torsional or bending load such as the shaft, the surface stress is the most, and the stress gradually decreases along the radius centripetal.

In order to make the parts continue to work, it is required that the depth of the parts seepage layer can make the stress transferred to the core lower than the core strength. If the stress is greater than the yield limit of the material, plastic deformation will occur.

After unloading, the elastic deformation of the permeability layer is restored, but the core cannot be restored. Under the cyclic action of alternating load, cracks will occur at the junction of the permeability layer and the core, and gradually expand. Therefore, for the steel with a low core strength, the fatigue strength can be significantly improved by increasing the thickness of the permeability layer.

However, the depth of the permeability layer should not be too deep, because the increase of the depth of the permeability layer is often accompanied by the increase of the surface carbon concentration, resulting in the increase of large carbide and residual austenite volume, resulting in the decrease of fatigue strength and impact toughness.

Visible according to the use of parts, choose the appropriate depth of carburizing layer is necessary.

In daily design of carburizing layer depth of parts, most of the experience or formula calculation method.

The American Institute of Metals (ASM) recommends that the depth of carburizing layer can be selected according to the load of the slag pump. The reference value is shown in Table 3-2.

The selection of the depth of carburizing layer for gear shaft is based on the load factor and many years of practical experience in production.

Because the gear shaft is subjected to alternating load, the force is alternating bending and torsion compound stress, so the gear shaft is required to have high fatigue strength and impact toughness.

The material of the gear shaft is 20Cr steel, and nitrate is used as the cooling medium during heat treatment and quenching. The strength of the core is not high after quenching. In order to obtain high fatigue strength and impact toughness, it is required to have enough depth of carburizing layer.

After carburizing on the camshaft surface, the depth of carburizing layer is required to be 1. 2-2. After OMMO grinding, the carburizing layer is required to be greater than 0