Internal defects of die-cast parts: Brittle characteristics and causes of occurrence

(1) Feature：
If the grains of the base metal of the casting are too large or too small, the casting is prone to breakage or fracture.
(2) Causes of occurrence:
① Excessive impurities such as zinc, iron, lead, and tin in the aluminum alloy;
② The alloy liquid overheats or is kept at high temperature for too long, resulting in coarse grains;
③ Intense cooling causes the grains to become too fine.