Influence of Semi-Random and Regular Shot Peening on Selected Surface Layer Properties of Aluminum Alloy

This paper attempts to compare regular shot peening (RSP) and semi-random shot peening (SRSP). A characteristic of the first method is that the peening elements hit the treated surface in sequence, with a regular distance maintained between the dimples. The other method (SRSP) is a controlled modification of the shot-peening process, which is random by nature. The shot-peening method used in this study differs from conventional shot peening (shot blasting and vibratory shot peening) in that it allows controlled and repeatable determination of the configuration and distribution of impacts exerted by the peening element on the workpiece surface, which makes the process more repeatable and easier to model. Specimens of EN-AW 7075 aluminum alloy were used for testing. The following variables were used in the experiments: ball diameter, impact energy, and distance between the dimples. Microhardness distribution in the surface layer, 2D surface roughness, and surface topography were analyzed. FEM simulations of the residual stress distribution in the surface layer were performed. It has been found that regular shot peening results in reduced surface roughness, while semi-random shot peening leads to higher surface layer hardening.

Study of Surface Layer Hardening after Treatment Complex Tool

The results of experimental studies of the thin surface layer of samples made of steel 45 after treatment with surface plastic deformation (SPD) multiradius roller (MR-roller) are presented. On the basis of the apparatus of the mechanics of technological inheritance, taking into account the effect of the solidified body, a model of the process according to the scheme of multiple loading-unloading of metal, taking into account the phenomenology of the SPD process and the properties of the material, is created. Distributions of parameters of the stress-strain state in the deformation centre are obtained, the parameters of roughness and microhardness of the surface layer are investigated.

Tool for Strengthening of the Component Surface Layers

The operational characteristics of metal components are often determined by the status of surface. In mechanical loading of solid bodies, the impact of the surface properties on formation and spreading of surface cracks is obvious, mainly as regards cyclic loading. Therefore, it is important to pay attention to knowledge of surface properties and their improvement.Cold plastic deformation is the easiest way to change the mechanical properties of the materials. The possibility of surface strengthening by ball or roller burnishing was found 80 years ago and since then has spread mainly into engineering and the automotive industry.In the authors’ workplace, experiments for surface layer hardening without ultrasound were realized with a newly developed device where the compressive force was applied statically, not dynamically. In the experimental part, we focused on the status of surface layers, especially the microstructure, hardness and roughness.

Development of Parameters Describing Heterogeneous Hardened Structure

The technique was developed with the purpose of definition of parameters for surface layer uniformity after mechanical hardening. It was found that one of the most effective methods of surface plastic deformation that provide precise adjustment of uniformity level of surface layer hardening is presented by static-pulse treatment technique. This method helps to develop hardened surface layer 8 mm deep with virtually uniform or heterogeneous structure.