On the Theory of Kinking

Abstract

The concept of a kink-band is introduced It is a thin plate of sheared material in a crystal, transverse to a slip direction, bounded by opposite ` tilt walls ' of dislocations. It is shown that if the angle of kinking shear γ exceeds a critical value (estimated to be 3½°) the stress concentration at the edges of the band is sufficient for the creation of new dislocation pairs or loops, and that if the applied stress exceeds a certain value, inversely proportional to the square root of the diameter of the kink-band, the kink-band will grow by this process. The stress field of a kink-band is similar to that of a slipband, a plate of deformation twin, or a crack under tangential stress. In suitable circumstances these may act as sources for each other. The successive generation of kink-bands, inside each other, from the same source, will produce a kink of the kind experimentally observed.