The characteristics of thin-walled samples made of the 8011 aluminum alloy and Kh18N9T stainless steel after double-sided ultrasonic hardening of the surface layer are presented. The dependences of the change in the yield strength and the relative elongation of the sample layers made of the aluminum alloy 8011 and stainless steel Kh18N9T after their rupture on the depth of the strengthened layer are presented. The results of cut tests with ultrasonic sample hardening are presented. The coefficient of increase in the axial strength of the samples after ultrasonic hardening is determined. The microstructure of a sample section made of aluminum alloy 8011 with and without double-sided ultrasonic hardening are presented. It is shown that the microstructure changes after double-sided ultrasonic hardening, nanostructures appear at a depth of 20–30 µm, and the particle sizes are 40–80 nm.