Abstract
The generation of residual stress in bronze castings was investigated in the same methods as reported previously. The results obtained are as follow;
1. Approximate for cooling curves of cast bars is obtained and the temperature differences in the cast frameworks composed of a center bar and two outer ones, which have different cross sectional areas, are estimated. The observed temperature differences are smaller than the estimated values by 10∼20%.
2. The stress in the center bar, teh cross sectional area of which is larger than those of the outer ones, changes from compression to tension casting is cooled.
3. The temperature at which teh stress in the center bar changes from compression to tension and the residual stress begins to grow shift from 650°∼600°C to 500°C as the ratio of the crosssectional areas decresses from 3.82 to1. This shift of temperature is attributed to the shift of temperature difference curves to the same direction.
4. As the stress relaxation by plastic deformation occures at higher temperature, the compressive stress in the center bar during the cooling is less than 0.15∼0.25kg/mm2, but below about 600°C the plastic deformation hardly occurs and thus the stress grows as the temperature difference decreases.
