Effect of multifunction cavitation on fatigue characteristics of A6061-T6 aluminum alloy rods and estimation of fatigue strength

• MFC generated high compressive residual stress on the surface of aluminum alloy rods. • MFC suppressed the formation of dents on the surface of aluminum alloy rods. • The residual stress relaxation behavior during fatigue tests was revealed. • The fatigue strength of aluminum alloy rods was estimated. The effects of multifunction cavitation (MFC) on the fatigue characteristics of A6061-T6 aluminum alloy rods subjected to a T6 treatment and polished to a mirror finish were examined using rotating bending tests. The MFC technique was able to generate a surface-modified layer having a metallic luster while imparting compressive residual stress and high hardness. In contrast to conventional surface modification techniques using shot particles, such as fine particle peening (FPP), this process also limited the formation of relatively large dents on the rod surfaces. MFC processing was found to increase the fatigue strength and fatigue life of these rods after 10 7 bending cycles. The fatigue lives at low stress amplitudes for specimens treated using MFC were higher than those for materials processed using FPP. However, the latter technique provided a deeper surface-modified layer and more rapid increases in surface hardness. The effectiveness of the MFC process was confirmed by estimating the fatigue strength of the aluminum alloy rods based on assessing residual stress relaxation, surface morphology and surface hardness.