| 摘要 |
The occurrence of porosity defects in solidifying metal can be predicted by a computer simulation numerically analyzing the solidification process of molten metal comprising (1) dividing a mold and a mold cavity into a plurality of elements; (2) providing each of the elements with material properties of casting metal and mold, and process variables as initial data; (3) calculating a liquid fraction of each of the elements in successive predetermined time increments to examine whether nor not each of the elements is in solid-liquid coexisting zone; (4) calculating pressure gradients between each of elements in the solid-liquid coexisting zone and neighboring elements thereof by numerically analyzing an interdendritic flow of the molten metal; (5) calculating gas pressure in the molten metal in each of elements in the solid-liquid coexisting zone; (6) comparing the gas pressure with an equilibrium pressure, and calculating a porosity amount for each of elements where the gas pressure is higher than the equilibrium pressure; and (7) repeating the calculations of the steps (3) to (6) until the solidification of the molten metal is completed. Since the above method takes the effects of interdendritic flow of molten metal into consideration, the occurrence of porosity defects can be predicted accurately and directly.
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