Analysis of the causes of cracking of grey iron castings.

After the grey iron casting is completed, the grey iron casting produces the phenomenon of fracture casting defects, and the analysis of the causes of cold cracking of grey iron castings has the following points:

1. The structural design of grey iron castings is unreasonable, and cracks are caused by changes in internal stress, such as disc castings; or the wall thickness is uneven, the wall thickness and the wall thickness of the wall are in conflict with the internal stress changes at the junction of the wall, or the fillet radius is too small or too large are the reasons for the design of the casting.

2. The unreasonable ratio of molten iron leads to high phosphorus and sulphur content and is not proposed in time, the liquid iron is seriously oxidised, and the strength of the alloy is low, resulting in the change of the internal stress of the casting exceeding the design value and causing fracture.

3. In the process of moulding, grey iron castings produce flash on the parting surface and lead to sand inclusion, and illegal operation in the process of sand removal and cleaning of castings will also lead to fracture.The characteristics of cold cracking of grey iron castings are: the cracks are distributed in a continuous linear manner, and there are no bifurcations, and the fractures sometimes show a slight oxidation colour; however, most of them have a bright white metallic lustre.