High-temperature fatigue cavitation in a copper alloy

Abstract

The process of intergranular fatigue cavitation at 500°C in a copper-base alloy (CDA 638) has been studied in low-frequency tension/compression cycling. The focus has been upon the role of grain size over the range 16–330 μm average dia. Specimens were also cut transverse and parallel to the rolling direction to investigate the influence of anisotropy. Fatigue life seems to be determined by a damage parameter based upon crack length at coarse grain sizes (50–330 μm) and upon void linkage at fine grain sizes (16–50 μm). The idea that failure is largely controlled by the ease of final crack propagation is emphasized by the anisotropic behaviour-material cut transverse to the rolling direction exhibited a markedly reduced life owing to the coplanarity of boundaries in the rolling direction which facilitated linkage.