The crack defect of magnesium die casting

    The crack is irregular and filamentary crack on the smooth surface of the castings. It is deep in the casting, sometimes even penetrate the entire casting. There are two kinds of crack defect of magnesium die casting is more common, one is the crack is produced under the external force, the other is the shrinkage cracks when casting shrinkage. The shrinkage crack is usually along the grain boundary, and its color is a bit dark under the microscope. The crack is produced under the external force is likely to penetrate the grain, and its color is bright under the microscope.
    The causes of the defects:
Melt containing impurities;
The protective gas is not sufficient;
Mold temperature is too low;
Improper use of release agent type;
The geometry of the die element is impaired;
The ejection position and configuration is inappropriate;
The casting geometry shape design is not good.
    Magnesium die casting have crack is often because of poor filling. Rhyolite is a potential source of crack. When casting is shrinkage or ejection, the casting will be fracture along the site of poor bonding. Some cracks appear to look like crack defects, but in fact, because of the melt flow is poor and lead to the non filling situation.

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