Effect of surface roughness on rotating fatigue strength of as-built AlSi10Mg produced by laser powder bed fusion

AlSi10Mg samples with as-built surfaces characterized by three levels of increasing roughness were fabricated varying the building orientation by laser powder bed fusion. In particular, the sample axis was oriented at 0°,90°, and 45° with respect to the building direction. It is demonstrated that roughness directly influences the fatigue performance of as-built samples, since cracks initiate at surface notches related to features produced by surface roughness. Rougher surfaces generate higher concentration stress and show lower cyclic properties. Then, the rotating fatigue strength of the samples is non-destructively estimated using Murakami’s square root area parameter model. The equivalent size of the defect was calculated from theroughness parameters Sz and RSm. The model gives a good correlation with the experimental data, and then it can be applied to evaluate the fatigue strength of as-built AlSi10Mg. These results are important for the reliable design in terms of fatigue strength of selective laser-melted AlSi10Mg components.