Abstract
In the study of residual stress in castings, measurements of stress during of the castings are of immediate interest to foundrymen and investigators of this subject. The author reports the results of experiments of silumin castings made by an apparatus designed on the strain-hindering principle. Stresses in the castings were measured at the strain-hindering frame work by electric resistance strain meter. The results obtained are summarized as follows:
1. When being the ratio of cross sectional areas of the cast bars A/Ao>1, the stress in the center member at the first stage, i.e., during the solidification, is compression of less than 0.005kg/mm2, and changes to tension as soon as the solidification completes. The rate of stress increase is large at first, and gradually slows off. The maximum stress at room temperature under the conditions in this experiments was less than 0.6kg/mm2.
2. When the stress-hindering is released, the strain-time curves of castings agree well with the stress-time curves.
3. It is suggested from the results of measurements of elastic strains that plastic flow occurs throughout cooling from solidification to room temperature.
