Corrosion and stress corrosion cracking characteristics of 4043 aluminium alloy fabricated through directed energy deposition process

Abstract

Additive manufacturing (AM) has emerged as a crucial element of Industry 4.0. In the pursuit of fabricating lightweight components, AM of aluminium alloys has become the centre of focus in recent years. This study investigates aluminium alloy (ER4043) components fabricated by arc-based directed energy deposition (DED-arc) for their corrosion and stress corrosion cracking (SCC) behaviour in 0.6 M NaCl solution at room temperature. Electrochemical characteristics in 0.6 M NaCl solution were investigated using open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests. Electrochemical results revealed that the DED samples fabricated using a tungsten inert gas (TIG) welder as the energy source demonstrated better resistance against corrosion when compared to those developed through cold metal transfer (CMT) based DED. The prolonged exposure of samples in 0.6 M NaCl facilitated the growth of a stable passive oxide film leading to enhanced corrosion resistance. Slow strain rate tests (SSRT) conducted in air and 0.6 M NaCl solution showed that DED samples are susceptible to SCC. The fractography of the fractured SSRT samples indicated the mode of failure to be intergranular.