Single toroidal roller burnishing of 2024-T3 Al alloy implemented as mixed burnishing process

Based on a comprehensive experimental study, single toroidal roller burnishing (STRB) of the 2024-T3 Al alloy can be successfully implemented as a mixed burnishing process. Optimum values of various governing factors provided minimum roughness and significant enhancement of the fatigue life of the treated specimens. With a planned experiment, regression analysis, and optimization procedure based on a genetic algorithm, the optimum factor values were established under a minimum roughness criterion. The derived model predicted a minimum roughness Ra = 0.074 μm. The experiment with optimal process parameters provided an average roughness (Ra) of 0.01 μm. STRB under these optimal conditions yields a relatively homogeneous surface in terms of microhardness with a surface microhardness increase coefficient of 37.6%. The parametric study of the residual surface hoop and axial stresses conducted via X-ray stress analysis shows that the STRB with near-optimal process parameters introduces significant residual stresses. STRB of the 2024-T3 Al alloy, implemented as a mixed burnishing process, produces a mirror-finish surface, improves the fatigue life by more than 2000 times, and increases the conventional fatigue limit by 35.1% compared to the reference condition.