Low Cycle Fatigue of Al-Mg-Si Alloys

Abstract

The low cycle fatigue behavior of several age-hardened aluminum alloys with 1% Mg and 1% Si as alloying elements and varying Mn additions of up to 1% was studied. The alloy with the smallest grain size showed the highest strength as well as the highest low cycle fatigue strength. The number of cycles to failure represented by its dependency on strain range did not show any significant differences. However, one could derive from these results that one should try to reduce the number and size of inclusion particles in order to improve fatigue properties. In such a case one can expect that a small grain size of 20 μm diameter, Mn additions of 0.2 to 0.5%, and a polished surface with a roughness below 0.5 μm would be beneficial for low cycle fatigue properties.