No abstract

Many engineers want to prevent crack defects because the defect is fatal to casting products and the desire has induced many studies of the crack generation. However, this study is intricate because the casting involves a complicated process; Casting products experience large thermal variations from pouring temperature to room temperature, phase transformation and mechanical contact with mold during the process. Especially, a crack phenomenon like hot tearing involves an interaction between stress and metallurgical properties. In this paper, we studied the relationship between hot tearing and thermal stress considering metallurgical properties. We performed thermal stress analysis as computational method and proposed a hot tearing predictor including thermal and mechanical stress phenomena and metallurgical characteristics. The proposed hot tearing predictor is verified by the results of applying this predictor to different casting conditions.

No abstract

In the present study, effect of cooling rate on the formation of the porosity in the thick aluminum sand casting was investigated. Nowadays large scale thick aluminum casting replaces steel frame for vacuum chamber for semiconductor production, with the consideration of weight and cost reduction. Several thick aluminum castings were manufactured using chill with temperature measurements. The castings were inspected by using 3D computed tomography in order to quantify the porosity defect density in the castings. Effect of the thickness of the chill on the porosity defect density were discussed.

No abstract