Impact of slide diamond burnishing additional parameters on fatigue behaviour of 2024-T3 Al alloy

One of the methods for increasing fatigue life of symmetric rotary metal components is slide diamond burnishing (SDB). This method is implemented on conventional and computer numerical control machine tools by means of simple equipment, which is its main advantage. The SDB basic parameters are diamond insert radius, burnishing force, feed rate, and burnishing velocity. The additional ones are number of passes, working scheme, and lubrication conditions. The effect of SDB additional parameters on the fatigue behaviour of 2024-T3 Al alloy was experimentally studied. Groups of smooth and notched hourglass-shaped specimens were slide burnished using different combinations of additional SDB parameters and then were subjected to bending fatigue tests. The residual stresses, introduced by SDB, were measured by X-ray diffraction technique. The near-surface microstructure of the slide-burnished specimens was investigated. Based on the results obtained, it was established that SDB produces two main effects, which depend on SDB additional parameters. The essence of the macroeffect is creation of residual compressive stresses in the superficial and subsurface layers. This stresses retard the formation and growth of fatigue macrocracks and thus increase the lifetime of slide-burnished components. The microeffect is expressed in modifying the microstructure of the surface and subsurface layers, correspondingly, refining the grain and homogenizing and reducing the pores in the material. Such microstructure is characterized by increased plasticity and fatigue crack resistance. The fatigue life depends on the combination of these two effects. Thus, the desired fatigue behaviour of the slide-burnished component can be ensured through an appropriate selection of the governing additional SDB parameters.