Effect of anodizing on high cycle fatigue behaviour of cast AlSi8Mg-T6 alloy

The work investigates the effect of anodizing on the high cycle fatigue behaviour of a high-quality cast Aluminium (AlSi8Mg-T6) alloy. Tensile and fatigue tests are carried out on both non-anodized and anodized specimens in order to highlight the differences in tensile and fatigue responses. In addition, roughness measurements, fracture surfaces analyses, metallography, instrumented micro-indentation and scanning electron microscope (SEM) inspections are performed in order to investigate the interplay between the presence of an anodic layer and the fatigue life of anodized specimens. It is demonstrated that, after anodizing, AlSi8Mg-T6 specimens shows a deterioration of the fatigue performance at medium–low stress amplitudes (130 and 110 MPa). In addition, fracture surface analysis reveals that the presence of the anodic layer modifies the fatigue crack initiation and early growth mechanisms. The manuscript paves the way for an accurate fatigue design of anodized, cast AlSix components.