Effect of micro-arc oxidation coating defects on fatigue property of Al alloy substrate

Abstract

Ambiguous fatigue failure mechanism of micro-arc oxidation (MAO) coated samples was an urgent issue to be solved. In this paper, the influence mechanism of coating defects on the fatigue property of the samples with thin MAO coating was studied. Based on the stress analysis of the MAO coated 2024-T3 Al alloy, the effect of the MAO coatings produced using 8%, 10%, 15%, and 20% duty cycles on fatigue behavior was discussed. Fatigue fracture and strain under cyclic stress were measured with SEM and extensometer, respectively. The results showed that the maximum cyclic stress affected the initiation of fatigue cracks. With the increase in the external loading, stress variation of the coatings was the critical issue that caused the changes in the fatigue performance under the high and low cyclic stresses. Furthermore, the fatigue failure mechanism of the samples with the thin MAO coatings was revealed. This study provided a method basis for further exploring the fatigue property of the samples with the thick MAO coatings.

Keywords

• Micro-arc oxidation
• Thin coating
• Defects
• Fatigue property