The article presents the results of the study of the effect of combined preload on the change of mechanical properties of the aluminum alloy 2024-T3 at room temperature. The disclosure changes in the mechanical properties of the alloy were explained during the analysis of the deformation process in the material at the micro level (material grain). Experimental studies of the deformation process and its implementation mechanism at the micro level were carried out using the thin foil method using a Hitachi STEM HD2700 transmission electron microscope. Electron microscopic examination of the foil revealed an inclusion of minor phase particles in the aluminum matrix, which create a noticeable contrast in the image - dark inclusions against the background of the light matrix. The change of the dislocation density after combined loading was also found, because the scalar density of the dislocation in the material is in this case lower than after the tensile test, despite the same residual plastic deformation of the samples.