Fatigue behaviour of Zn–Al casting alloys

Abstract

A series of binary Zn–Al and ternary Zn–Al–Cu alloys were produced by permanent mould casting. The fatigue behaviour of the alloys was examined using a rotating bending fatigue machine, which was designed and built for the present work. The stress–number of cycles to failure (S–N) curves of the alloys were obtained. It was found that both fatigue strength and fatigue life of the binary Zn–Al alloys increased with increasing aluminium content. It was also observed that copper additions of up to 2% increased the fatigue strength of the binary alloys. However, above this level, the fatigue strength of the ternary alloys decreased with increasing copper content. In addition, it was observed that the fatigue strength of the ternary alloys was dependent on their tensile strength, rather than on their hardness. Correlation of the fatigue data showed that Basquin's law can be used to express the fatigue behaviour of these alloys.