Pitting corrosion study at the built and substrate region of hybrid additive-manufactured Al-Si-Mg alloys

¹ Centre for Nanoengineering and Advanced Materials (CeNAM), School of Mining, Metallurgy and Chemical Engineering, University of Johannesburg, Johannesburg, 2092, South Africa
² Department of Chemical and Materials Engineering, University of South Africa, P.O. Box 392, Florida 1709, South Africa
³ Department of Mechanical and Mechatronic Engineering, Cape Peninsula University of Technology, Cape Town, South Africa.
⁴ Department of Mechanical and Industrial Engineering, University of Johannesburg, Doornfontein Campus, Johannesburg 2028, South Africa

^* Corresponding author: samsoniumdare@gmail.com

Abstract

Hybrid Additive Manufacturing (HAM) of Al-Si-Mg alloys results in distinct microstructural variations at the built-substrate interface, influencing electrochemical behavior and overall performance. This study investigates the characteristics and corrosion response of as-received built-substrate HAM Al-Si-Mg alloys through microstructural and electrochemical analysis. Thorough microstructural evaluation was carried out using scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), to determine grain morphology and phase distribution in the built and substrate zones. Open circuit potential (OCP), cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were employed to assess corrosion resistance and pitting susceptibility in natural seawater. The findings provide insights into the role of interfacial microstructure on corrosion susceptibility, contributing to the optimization of HAM-processed Al-Si-Mg alloys for enhanced performance in engineering applications. The outcome revealed that the substrate area showed a refined microstructure with enhanced corrosion resistance in contrast to the built. Also, this study gives a vital understanding of the corrosion behaviour of each region of HAM Al-Si-Mg alloys, which is important for service reliability and structural integrity in aerospace and marine applications.