Fatigue Assessment of Precorroded AlSi9Cu3 Specimens Incorporating Short Crack Propagation

Abstract

This study investigates the fatigue behavior of AlSi9Cu3 aluminum die-cast alloy after exposure to accelerated corrosive conditions. It underscores the significant impact of minor localized corrosion imperfections on fatigue strength and presents a numerically efficient method for fatigue assessment based on fracture mechanics principles. Fatigue tests under rotary bending load showed a 34% reduction in long-life fatigue strength for precorroded surfaces compared to polished ones. Numerical simulations, which treated the precorrosion as a single crack-like surface imperfections, provided good estimates of fatigue life, when using the mean corrosion depth as initial flaw depth. Variations in the assessed fatigue strengths for different flaw geometries and sizes ranged from 13.7% above to 22.2% below the experimental values. The findings underscore the importance of incorporating short crack propagation, particularly for small corrosive defects, in fatigue assessments to enhance accuracy and ensure component reliability and safety when corrosion-induced imperfections are present.