Effect of self-organised behaviour of defective material structure on localization of plastic deformation and fracture under static and dynamic loads

Dynamic loading tests of specimens made of AMg6 alloy were carried out on a split Hopkinson pressure bar apparatus, whereas static loading tests were performed on the Testometran electromechanical testing machine. The temperature value in the localization zones contradicts the traditional concepts of the mechanism of plastic shear localization caused by thermoplastic instability. A microstructural analysis of the tested specimens was made using an optical interferometer-profile meter and an electron microscope. The structural analysis revealed a correlated behavior of the ensemble of defects, which can be classified as a structural transition providing the localization of plastic strains. The data of experimental studies and structural analysis suggest that one of the mechanisms of plastic strain localization in the specimens of AMg6 aluminum alloy at the examined loading rates is due to the jump-wise processes in the defect structure of the material. However, the character of specimen fracture under static and dynamic loads is quite different and is governed by different responses of the defect subsystems.