Corrosion behavior of AlSi10Mg alloys produced by additive manufacturing for automotive

摘要

The selective laser melting (SLM) process is an additive manufacturing 3D printing procedure thatcan be used to create metallic objects layer by layer, designed by a CAD-like drawing project.During the process, the powdered metal is melted by a high-powered laser source allowing toproduce artefacts without the traditional restrictions due to forming and machine processing,reaching the final goal of obtaining near-net-shape objects which require minimal finishingprocess.Among several metallic materials, aluminium alloys, due to their unique combination of lightnesswith good stiffness, strength and easy formability, are good candidates in the new optic of a moreenvironmental-friendly automotive industry. As a matter of facts, they allow to reduce both the carweight and the energy consumption, thus decreasing the pollution. Finally, these alloys also offerrecycling possibility.This study is devoted to the assessment of the effect of anisotropy on the corrosion resistance ofa SLM-3D-printed AlSi10Mg alloy. With this aim, electrochemical measurements have beenperformed on sample surfaces grown both parallel and perpendicular with respect to the printdirection. In addition, the effect of residual stresses on the corrosion properties has been evaluatedby investigating as built and heat-treated samples.Both polarisation curves and Electrochemical Impedance Spectroscopy (EIS) measurements havebeen used to evaluate the corrosion behaviour. Analyses have been carried out in 0.2 M NaCl +0.5 M Na_2SO_4 aerated solution.Surfaces and microstructural characterisations of the alloy have been also carried out on the twodifferent analysed orientations before and after the electrochemical measurements.Preliminary results seem promising and two different corrosion kinetics have been detected as afunction of the grown orientation because of the different porosity and density achieved over thetwo investigated surfaces.