Effect of Annealing and Hot Rolling on the Low-Cycle Fatigue Behavior of Al–7Ca Eutectic Alloy

Aluminum alloys based on the Al–Ca eutectic are a new class of materials that exhibit excellent casting properties, high corrosion resistance, low density and, unlike traditional Al–Si alloys, are easily deformed. However, the fatigue strength characteristics of Al–Ca alloys have not been studied. Considering that fatigue strength is a critical characteristic of any structural material, this gap must be addressed. In this study, using a dynamic mechanical analyzer, the low-cycle bending fatigue tests were carried out for Al–7Ca eutectic alloy in different conditions. The commercial Al–11Si alloy as-cast was taken as a reference material. It was found that in as-cast conditions, the fatigue strength of the Al–7Ca alloy at N_f = 2 × 10⁴ cycles (S_Nf) was inferior to that of the Al–11Si alloy, whereas in the high-stress range, the fatigue life of the Al–7Ca and Al–11Si alloys was the same. Annealing had little effect on fatigue properties. Hot rolling significantly increased the fatigue resistance of the Al–7Ca alloy: S_Nf of the hot-rolled alloy was more than 2 times higher than that of the as-cast alloy. The hot-rolled Al–7Ca alloy had an outstanding combination of high yield strength, relative elongation and fatigue strength. The influence of aluminum alloys’ microstructure on the fatigue resistance characteristics and fracture mechanisms was analyzed.