How do crane wheels prevent cracks

In the process of forging the crane wheel, there may sometimes be cracks, so if you encounter this situation, how to deal with it?

1. Increase the hydrostatic pressure

The generation of cracks is related to the stress situation and the plasticity of the material, which is a state of the material, which not only depends on the organizational structure of the deformed object, but also depends on the external conditions of the deformation (including the stress state, deformation temperature and deformation speed).

The three-way equal pressure will not cause the crack propagation of the crane wheel. Even if there is a small unoxidized crack in the deformation, it can be forged under the action of high three-way compressive stress. For low plastic materials, reverse thrust extrusion and sleeve upsetting are used to increase the value of hydrostatic pressure to prevent cracking. Reduction of compressive stress during extrusion and drawing is a very effective measure to prevent cracking (e.g. hydrostatic extrusion).

2. Strictly control the deformation temperature

Deformation temperature has an important effect on the plasticity of the material, low temperature, serious cold deformation hardening, plasticity decline; The temperature is too high, easy to overheat, overburn. Magnesium alloy and other close-packed hexagonal lattice metal materials at room temperature only one set of slip surface (that is, the base surface), when the temperature exceeds 200℃ to add a new slip surface, therefore, it should be ensured that in the deformation process, can be fully recrystallized, and as far as possible in the single-phase state deformation.

3. Adopt appropriate strain speed

The strain speed has a great influence on the low plastic material, and the appropriate forging equipment should be selected according to the specific material. For example, a factory MB5 magnesium alloy is easy to crack when hot forging on a hammer, but no forging crack occurs when forging at the same temperature on a hydraulic press. The reason is that the recrystallization process of magnesium alloy is slow and the deformation is easy to crack at high speed. The recrystallization temperature of the alloy is 350℃ when it is deformed on a press, and it needs to be deformed at 600℃ under impact load to obtain a complete re-structure.

4. Intermediate annealing is required if necessary

When the degree of cold deformation is too large, it is often easy to cause the crane wheel to crack, and middle annealing is needed to eliminate some defects caused by hardening and deformation.

5. Adopt hot pressing deformation

During hot deformation, due to the smooth recrystallization process and other reasons, the defects caused by deformation are partially eliminated, and the plasticity is improved.

6. Improve the organization of the blank

In order to improve the plasticity of the material, it is necessary to avoid the occurrence of low melting point substances and brittle compounds on the grain boundary.

7. Use high temperature homogenization

High temperature homogenization can improve the non-uniformity of the structure and improve the plasticity of the material.

Through the above measures, you can prevent the crane wheel to avoid cracks, to ensure the quality of the crane wheel.