Fractographical analysis of fatigue failed Cu–2.55Ni–0.55Si alloy

•The fatigue behavior of cast and forged Cu–Ni–Si alloy was studied.•Effect of microstructure on the fatigue of modified Cu–2.55Ni–0.55Si cast alloy was discussed.•The fracture tracks varied as a function of the applied σmax. In this study, the fatigue behavior of Cu–2.55Ni–055Si alloy specimens was investigated by fractographical analysis. Fatigue specimens were prepared according to ISO 1099 standard and constant amplitude loading was applied at a stress ratio (R=σmin/σmax) of R=−1. The criterion set for the termination of the fatigue tests was either the fracture of the specimen or the limit of 5E6 fatigue cycles. Tests were carried out at different stress levels to determine the stress-lifetime curve (S–N curve) of the material. The fatigue limit was evaluated at 179MPa. All tested surfaces were examined by scanning electron microscope to characterize the fracture behavior. In general, metal silicides, as well as grain and twin boundaries contributed to crack propagation. The fracture surfaces exhibited typical tracks indicating dimple rupture, intergranular/transgranular rupture and fatigue rupture as a function of the applied σmax.