Investigation of the Mechanism of Influence of Stress Corrosion on the Development of Macroplastic Instabilities of Aluminum–Magnesium Alloy

Macroscopic jumps of plastic deformation (few percent in amplitude) on creep curves of aluminum–magnesium alloy, caused by a local effect of concentrated solution of hydrochloric acid on the alloy surface, have been revealed and investigated using a complex of high-speed methods for studying the dynamics of deformation bands and discontinuous deformation. Results of computer simulation of the formation of fractal morphology of the corrosion front and elastic stress fields under stress-corrosion conditions are presented. It is shown that, in the complex structure of corrosion boundary, containing “peninsulas” and “fjords,” the level of local stress at fjord vertices exceeds the level of applied stress by ~1–1.5 orders of magnitude, which may lead to collective responce of many dislocation sources and development of macroscopic dislocation avalanche, causing a strain jump in the creep curve.