한국주조공학회

In order to determine the plane strain fracture toughness of Al-Si-Cu-Mg alloy castings, solution heat treatments have been conducted at 530℃ for 8hr and aged for 10hr at 145℃, 160℃ and 175℃. Effects of aging treatment and of Si contents on the fracture toughness have been investigated by a three point loaded bend test, using the artificial notch. The results obtained are as follows; 1) The fracture toughness is appreciably affected by the aging treatment temperature and Si contents. The specimen aged for 10hr at 145℃ has the highest fracture toughness. 2) Increasing Si contents from 5% to 9% results in decrease of fracture toughness. 3) Increasing the aging temperature and Si contents, C.O.D. value was decreased. The specimen aged for 10hr at 145℃ has the highest C.O.D. value. 4) Dimple patterns were observed in the specimens of containing under 7% Si, while mixed cleavage-dimple patterns in those of over 8% Si.