Corrosion performance of additively manufactured bimetallic aluminum alloys

Abstract

Abstract To restore defected AA2618 alloy molds, remanufacturing of the damaged areas using AlSi10Mg alloy through laser powder bed fusion (L-PBF) technique is proposed. This study in particular focuses on the corrosion characteristics of the fabricated L -PBF AlSi10Mg / cast AA2618 bimetal structure in aerated 3.5\xa0wt.% NaCl electrolyte with respect to the individual alloys. The L -PBF AlSi10Mg side of the bimetal sample was characterized with a superior corrosion response and the highest passive film stability compared with the cast AA2618 side and the dissimilar sample (prepared from the interface region), ascribed to its homogeneous microstructure, containing a very fine network of eutectic Si embedded in a fine grained and supersaturated α-Al matrix. The overall corrosion performance of the dissimilar sample was found to be between the cast AA2618 and L -PBF AlSi10Mg part, with no sign of macro-galvanic corrosion effect between the dissimilar alloys. The heavily precipitated microstructure of the cast AA2618 alloy, particularly the anodic Al2CuMg phase and cathodic Fe-containing intermetallics versus the Al-matrix, dictated the inferior corrosion properties of the cast sample and the cast side of the dissimilar sample.