Understanding the corrosion behaviour of laser directed energy deposition-based additive manufacturing built Inconel 718 under acidic environments

Abstract

This paper presents an investigation on the electrochemical corrosion behaviour of Laser Directed Energy Deposition (LDED)-based additive manufacturing built Inconel 718 (IN718) for the first time in various acidic environments (2 M HNO<inf>3</inf>, 2 M HCl and 2 M H<inf>2</inf>SO<inf>4</inf>). Open circuit potential reveals that corrosion is more active in HCl, and Tafel extrapolation shows that the corrosion rate (CR) is maximum in HCl and minimum in HNO<inf>3</inf>. Potentiodynamic polarization studies conducted on the samples reveal active–passive behaviour of IN718 and show that pitting potential is maximum in HCl. Cyclic polarization studies reveal localized pitting behaviour in HCl, with no signs of pitting corrosion in HNO<inf>3</inf> and H<inf>2</inf>SO<inf>4</inf>, which is further confirmed using Scanning Electron Microscopy. The estimated CR for IN718 is lower than the acceptable CR for nickel-based alloys (4 mpy) in all acidic environments under investigation. The study paves the way for potential deployment of LDED built IN718 components under various corrosive environments. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.