How to Prevent Steel Casting Defect Problems?

What problems will large foundry manufacturers encounter in the process of steel castings? We all know that every manufacturer will encounter some problems in the process of making castings, such as porosity, shrinkage porosity and convection, etc., so what should large foundries do when these problems occur?

First of all, we need to analyze the cause of the defect, and then customize a set of preventive measures according to this reason.

1. Avoid porosity in the sand core:

If you want to prevent the air bubbles generated in the sand core or sand mold from entering the metal liquid in the cavity, then it is necessary to ensure that the air content of the sand core is very low, or you can also use appropriate exhaust to prevent the formation of sand core porosity. In addition, we must also ensure that the sand core is completely dry, otherwise we cannot use clay-based sand core or mold repair glue.

2. Avoid the appearance of shrinkage holes:

Because of the influence of convection and unstable pressure gradient, there is no way to achieve upward shrinkage of castings with thick and large sections, so large foundry manufacturers should follow all the laws of shrinkage to ensure good shrinkage design, and use computer simulation technology to verify the actual pouring samples. Control the flash level of the sand mold and the core sand connection; The thickness of the paint on the mold should be controlled, and the temperature of the alloy and mold should also be controlled.

3. Avoid convection:

The hazards of convection are related to the time of solidification. Generally, thin-walled and thick-walled steel castings will not be affected by the hazards of convection, but castings with medium wall thickness will be affected by convection hazards.

4. Reduce segregation:

Segregation is prevented and controlled within the standard range or in the user-permissible area of the composition limit. If possible, try to avoid channel segregation.

5. Reduce residual stress:

Do not quench the aqueous medium after the solution treatment of light alloys, whether it is cold or hot water. If the stress of the casting does not seem to be large, a polymer quenching medium or forced air quenching can be used.

6. Given datum point:

Large foundry manufacturers must specify reference points for dimensional inspection and machining positioning.