1987 年 36 巻 405 号 p. 597-603
The impact fatigue tests for oxygen-free copper and high strength copper were carried out at various temperatures between 100 and 250°C as well as at room temperature. The fatigue strength and plastic deformation due to cyclic creep under impact tensile loads were analyzed in consideration of temperature-dependence and static tensile properties.
The impact fatigue strength was found to be expressed by the formula of σ(NfT)m0=D0, where m0 and D0 are the material constants for impact fatigue strength at each high temperature Tθ(K). The values of m0 and D0 depended on the temperature and were expressed by the formulas of m0=m0*+m1*(Tθ-273) and D0=D0*exp(Q/kTθ).
The behavior of cyclic creep plastic deformation was expressed by a formula including only plastic strain εp and normalized number of cycles N/Nf, which is independent of impact stress σ, duration time T and temperature Tθ. The values of m0, D0 and main material constants (a1, a2), which appear in the formula expressing the cyclic deformation, had distinct relationships with the ultimate strength σB, reduction of area φ and elongation δ in static tension. Impact fatigue strength and cyclic creep plastic deformation at high temperatures can be well estimated through these relationships from the static tensile properties at room temperature.