Anodizing 3D-Printed AlSi10Mg Alloy and Its Fatigue Properties

Two ways of anodizing 3D-printed AlSi10Mg alloy were characterized, and then their fatigue properties were evaluated. Test specimens were fabricated via a laser-powder bed fusion (L-PBF) process followed by machining. Normal and hard anodizing were both conducted in a sulfuric acid bath. The anodized layer was observed using FE-SEM/EDS. Fine Si particles dispersed in the matrix showing web-like patterns were incorporated in the anodized layer. By etching the Si particles away with Keller’s reagent, a characteristic maze-like 3D structure of anodized Al was observed. Then, rotating bending fatigue tests were carried out to evaluate the fatigue strength at 107 cycles. The fatigue strength of the as-machined, normal-anodized and hard-anodized specimens was 106, 100 and 95 MPa, respectively. The fatigue limits were proportional to the surface roughness with higher linearity. By reducing the surface roughness, the fatigue strength of the hard-anodized specimen was improved. This result demonstrates the possibility of improving the fatigue properties of anodized components by reducing their surface roughness. Lastly, a CASS (copper-accelerated acetic acid salt spray) test was conducted, and superior corrosion resistance of the normal- and hard-anodized layers was verified.