In the production process of alloy steel castings, the most worrying problem is the generation of cracks. In fact, the causes of cracks can be generally divided into hot cracks and cold cracks. In the process of solving it, we should analyze the causes and solve them step by step.

1. thermal cracking

Reason: solidification mode of casting and thermal stress and shrinkage stress of casting during solidification.

Solution: Aging heat treatment should be carried out in time for castings with high casting stress to avoid cold cracks caused by excessive residual stress. When necessary, the casting shall undergo an aging heat treatment after cutting the riser or welding.

2. cold cracking

Reason:

1. The uneven wall thickness of the casting structure casting causes casting stress and sometimes cold crack defects.

2. Irrational design of gating and riser system For castings with uneven wall thickness, if the inner gate is set at the wall thickness part of the casting, the cooling speed of the thick wall part of the casting will be slower, resulting in or aggravating the difference in cooling speed of each part of the casting, increasing the thermal stress of the casting and causing the casting to generate cold cracks.

3. The chemical composition of alloy materials is not up to standard. The high content of carbon and other alloy elements in steel makes castings prone to cold cracking.

4. Control the unpacking time. Casting will crack if it is unpacked too early and the sand falling temperature is too high, and if it is impacted or squeezed during sand cleaning.

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