Deformation and Fracture Strength of Cu-5%Al Alloy Subjected to Tension-Compression Fatigue

Abstract

Fatigue deformation and fracture strength have been studied by tension-compression fatigue tests of Cu-5%Al alloy on the assumption that the damage accumlation can be shown by Coffin’s formula. The discussion of the fatigue strength is supported by the microscopic observation on the slip lines. The results obtained are as follows: (1) The relation between maximum value σ₀ of cyclic stress and number N of stress cycles to failure is derived as α^m(σ₀^m\barn−σ_f^m\barn)N=C for σ₀>σ_f(=7.8×10⁷ Pa), where α, C, m and \barn are 5.59×10⁻³⁹ Pa^−\barn, 9.32×10⁻², 2.32 and 4.43, respectively. This relation is confirmed by the fatigue tests. (2) The slip lines made in one cyclic stress decrease with the increase of the number of stress cycles.