Experimental and theoretical investigations of structural mechanisms and plastic strain localization effects in AlMg6 alloy under dynamic loading

This paper is concerned with substantiating one of the mechanisms of plastic strain localization under high rate loading associated with structural transitions in the defect structure of materials. For this purpose, a series of experiments were carried out to study the localization of plastic strain in skewed specimens of the AMg6 alloy subjected to loading in a split Hopkinson pressure bar. The temperature fields generated during the plastic deformation tests designed to identify the characteristic stages of strain localization were investigated " in-situ " using a high-speed infrared camera CEDIP Silver 450M. The values of temperatures in the strain localization zone indicate that in the AMg6 alloy under the implemented loading conditions the mechanism of strain localization caused by thermoplastic instability is not realized. Structure analysis of dynamically loaded specimens was carried out using the Olympus GX-51 optical microscope and FEI PHENOM G2 ProX scanning electron microscope. It supports the structure-dependent regularities of the strain localization mechanism under dynamic loading. The experimental results of dynamic loading with a subsequent investigation of the temperature fields, the structural studies with an optical and electron microscope, as well as the data of the numerical modeling considering the kinetics of the mesodefect accumulation in the material suggest that one of the mechanisms of plastic strain localization in the AMg6 alloy under realized loading conditions is caused by structural transitions in the defect structure of the material.