Design of heat treatment and magnetic field-assisted machining for microstructure and surface corrosion control in Inconel 718

Abstract

It has been demonstrated that Magnetic Field-Assisted Machining (MAM) has strong potential for improving surface quality and tailoring microstructure in hard-to-machine heat-treatable Inconel 718 (IN718). However, the influence of MAM on corrosion performance of IN718, particularly when coupled with heat treatment (HT) strategies, remains unclear. In this study, IN718 fabricated using laser powder bed fusion (LPBF) was heat treated in air (HT(Air)) and argon (HT(Ar)) atmospheres reported in the literatures, and subsequently finished by Magnetic Field-assisted Polishing (MAP) and Burnishing (MAB). The combined effects of HT and MAM on microstructural evolution were systematically characterized, enabling a comprehensive understanding of the resulting surface corrosion behavior. The results establish a process-structure-property relationship linking HT atmosphere, MAM finishing, and corrosion resistance. The combination of HT(Ar) and MAM, hereafter referred to as HT(Ar) + MAM, results in higher corrosion resistance than the combination of HT(Air) and MAM, hereafter referred to as HT(Air) + MAM. This work provides critical insights into developing a systematic, surface-sensitive post-processing strategy for LPBF-fabricated IN718 and offers practical guidelines for enhancing corrosion resistance through integrated post processing design.