Fretting corrosion mechanisms driven by salt concentration in additively manufactured GH3536 Ni-based superalloy

Purpose To address the limited durability of additively manufactured GH3536 nickel-based superalloys in offshore engineering contact applications, this study aims to systematically investigate the fretting corrosion behavior of the alloy under varying salinity conditions. Design/methodology/approach Fretting corrosion experiments were performed using an Rtec MFT-5000 tribometer coupled with a Modulab electrochemical workstation in a three-electrode system, with an Ag/AgCl electrode as the reference electrode. Findings The results reveal that at a salinity of 1.5% under potentiodynamic polarization, the alloy exhibits a low-friction coefficient, attributed to the formation of a Cr2O3 film with high hardness and favorable lubrication properties. At 3.5% salinity, a dense Cr2O3 passive film forms, which minimizes strain accumulation and effectively suppresses the synergistic interaction between corrosion and wear, resulting in the lowest observed wear rate. In contrast, at 0% and 7.5% salinities, corrosion-wear and crack propagation are exacerbated due to the porosity of the NiO film and the formation of localized corrosion-driven galvanic couples, leading to elevated wear rates. Notably, a moderate concentration of Cl promotes Cr reprecipitation, enhances passive film compactness and stabilizes the wear interface. Originality/value This study provides a foundation for the salinity-adaptive design of additively manufactured components in marine environments.