A study of the plastic deformation of copper single crystals

Abstract

Single crystals of copper having uniform rectangular cross-sections, and of known orientations, were tested in axial tension using a “soft” tensile machine in which the applied load was independent of the resulting strain. During the course of stepwise loading of each specimen, a delay was found to occur between the beginning of the addition of each small stress increment and the resumption of plastic strain. The length of the delay time, in the order of a few seconds, was found to depend to some extent on the length of the waiting period, prior to the addition of a stress increment, during which time the load on the specimen is constant. The effect may be considered as a type of yield point phenomenon. Other results of this work indicated an effect of dissolved hydrogen on the mechanical properties of the specimens, and a transition point in the stress-strain curves of the specimens during the early stages of plastic strain.