Effects of Brushing and Shot-Peening Residual Stresses on the Fatigue Resistance of Machined Metal Surfaces: Experimental and Predicting Approaches
Mechanical brushing of machined AA5083H11 surface, performed in optimized conditions of brush wire hammering, generates distributions of compressive residual stresses. These distributions are controlled by the process parameters such as the pressure of the brush wires on the surface, the speed of rotation or the number of passes. X-ray diffraction (XRD) measurements relative to different surface preparations show that the stresses due to brushing are less deep and that the maximal values in compression are the same as the ones from shallow shot-peening treatment (without defects). Moreover, the bushing provides high quality surface at a microscopic scale (low roughness) and integrity state of the treated surfaces, better for cyclic stability of compressive stresses. The stabilized state of residual stresses resulting from brushing and shot-peening is determined by finite element analysis. These analyses are experimentally validated by XRD using the psi-tilt method on tested fatigue specimens. Fatigue results show that the good surface topography generated by the wire brushing process compensates the reduction of the amplitude and the depth of the compressive residual stress profiles compared to shot-peening so that it could provide an equivalent fatigue improvement rate (20 to 30% of σD 2.106 cycles) of the AA5083H11.
Paolo Scardi and Cristy L. Azanza Ricardo
N. Sidhom et al., "Effects of Brushing and Shot-Peening Residual Stresses on the Fatigue Resistance of Machined Metal Surfaces: Experimental and Predicting Approaches", Materials Science Forum, Vol. 681, pp. 290-295, 2011