On the Detection Range of Strain Figures and Their Characteristics

抄録

We have studied on the following items : 1. The detection range of strain figures. 2. The relations between Luders' line and strain figures. 3. The equivalency of strain figures between a strain caused by mechanical stress and that caused by thermal stress. As a result of our researches, we have reached the following conclusions : 1. The yielding of steel or Fe-C alloy is due to the failure by slip of one phase of the two phases, such as ferrite and pearlite or pearlite and cementite. In an appropriate structure, we can detect the strain figures of steels from 0.05% to 3% in its carbon-content and some special steels. The strain energy of yielding disappears at the temperature of A₁ point. 2. Luders' line corresponds in position to a strain figure at a low temperature ; in other words, a strain figure appears at the same place that Luders' line runs ; but not at a high temperature, when it becomes a false figure. 3. The strain energy of mechanical stress is equivalent to that of thermal stress. Note : The details of their characteristics shall be illustrated by photographs.