Abstract
A load of the cantilever type was applied to a test piece cut from a single crystal of ice. When the test piece bent, the load applied to the test piece was reversed. This cycle was repeated. Work hardening did not occur though this cycle was repeated many times. This is explained as follows. Dislocation with the Burger's vector of the a-axis was responsible for the deformation of the test piece. Dislocation with the Burger's vector of the c-axis did not occur. Therefore, the dislocations are not tangled, and work hardening does not occur.
