Plastic flow instability at the necking stage in zirconium alloys

Regular features in plastic-strain macrolocalization are examined at the parabolic stage of strain hardening in the É635 and Zircaloy-2 zirconium alloys. Instability of the plastic flow is observed, which is manifested as a periodic variation of space-time distributions of local strain as revealed by means of speckle interferometry. The data obtained are discussed within the framework of a synergetic model for the plastic flow evolution at the final stage.