This article considers the influence of the size of processed workpieces during their strain hardening based on the impact of deformation waves on the processed surface. For the first time, the specificity of the hardened layer formation by wave strain hardening (WSH) makes it possible to draw attention to the fact that, with equal volumes of hardened samples and processing modes, different diagrams of microhardness distribution in the surface layer are observed. The aim of this work is to establish the relationship between processing parameters, workpiece dimensions, and the WSH nature for the first time. The experiments are carried out on a specially designed bench. It is established that WSH occurs not only from the front side (along which the processing was performed), but also from the backside, while leaving the original material hardness in the middle of the sample. The results obtained form a basis for the further development of WSH technology.