Gas pressure in finally filled region in die cavities and defects in aluminum die castings.

Casting defects which occur at the finally filled portion in practical board-shaped ADC12 die castings were studied by examining the change of gas pressure in the die cavity. When the gas pressure in the die cavity at the finally filling stage of molten metal reduces from 1.8 to 0.2kgf/cm2 by altering the casting condition and by placing vents, the molten metal flow accelerates from 2.0 to 5.0m/s, resulting in the occurence of a few casting defects at this portion. These die castings have few blisters on their surfaces even after heat treating at 495°C for 4h.