Effect of Laser Shock Peening and Shot Peening Composite Strengthening on Fretting Fatigue Performance of Riveted Piece

The effect of shot peening as well as laser shock peening and shot peening composite strengthening on the fretting fatigue behavior of aluminum alloy riveted pieces was studied. The effect of surface strengthening technology on the surface integrity, fretting wear resistance, fatigue properties and fretting damage characteristics of aluminum alloy was studied with fretting wear test machine, fatigue test machine, X-ray diffractometer, laser confocal microscope, and field emission scanning electron microscope. The results show that shot peening as well as laser shock peening and shot peening composite strengthening can improve the fretting fatigue performance of riveted pieces, with the fretting fatigue life increasing 12 times after shot peening and 5.4 times after composite shot peening strengthening. The surface strengthening treatment changed the location of the fatigue crack source. The crack initiation location of the original riveted piece was about 30° in the round hole of the riveted piece, and changed to nearly 90° after shot peening. The depth of residual compressive stress layer of composite shot peening strengthening is 1 mm, which is much deeper than that of shot peening, 0.25 mm. Overall, the strengthening effect of composite shot peening is not ideal. This is because laser shock technology is not easy to implement in the riveting holes of small size. In addition, the strengthening process induced the deformation of the connecting holes, affecting the service performance.