Fatigue life enhancement of aluminum alloy for aircraft by Fine Particle Shot Peening (FPSP)

Fine Particle Shot Peening (FPSP) enhances fatigue properties of aluminum parts for aerospace compared with conventional shot peening (SP). The features of FPSP process are small ceramic media and high velocity of the media flow. Fatigue life of aluminum alloy obtained by FPSP is around one order of magnitude longer than that by SP. And the superior fatigue property unchanged even after anodize for corrosion protection. FPSP creates fine dimples with small surface roughness and high compressive residual stress at very near surface, while SP forms large dimples and high compressive stress inside of the material. The fatigue crack occurred at the subsurface in case of FPSP, while at the surface in case of SP and machined. The fatigue crack initiation at the subsurface is the reason of superior fatigue life by FPSP.