Abstract
On metallic mold casting of aluminum alloys, the air gaps formed between the mold surface and solidified layer have remarkable effects on the solidification rates of the alloys. The solidification rate and temperature distribution of aluminum alloy, AC8A in the metallic mold were determined to find the correlation between the air gap and casting conditions. The test results were compared with those calculated by electric analogue method.
The results obtained by the above tests were as follows.
(1) The heat transfer rate in the air gap was nearly 800-2000kcal/m2hr. °C within the scope of the above tests.
(2) The volume of air gap gradually increased with the progress of solidification until the thickness of solidified layer reached 10-15mm., where no further increase of the volume was observed.
(3) The volume of air gap was smaller when the solidification rate was lower in casting; that is, the volume was smaller when the mold had thicker wash coat, higher temperature, or thinner wall.
(4) Accordingly, the required total heat transfer rate (α2) between the mold surface and the solidified layer could be determined by measuring the heat transfer rate in gap aid the thermal coductivity of the wash coat on the mold.
