Exploring the mechanism of stress-induced passive layer degradation in additively manufactured Ni-Fe-Cr-based alloy 718

This study explores the formation and degradation mechanisms of the passive layer on laser powder bed fusion (L-PBF) processed Ni-Fe-Cr-based alloy 718 using high-resolution submicron analysis and microcapillary electrochemical techniques. The findings provide new insights into passive layer breakdown under tensile loading, revealing the influence of microstructural characteristics, dislocation distribution, and mechanical stresses. Tensile loading caused oxide layer cracking near cell boundaries with higher dislocation density. Detachment of the oxide layer from the matrix created voids, allowing aggressive ions to penetrate, promoting crevice corrosion. Cell boundaries remained mostly intact, as metallic particles within the surface oxide layer. • External loading causes oxide layer rupture adjacent to cell boundaries. • Metallic cell boundaries within the oxide layer suggest higher corrosion resistance. • Voids form between the metal and oxide layer promoting aggressive ion penetration. • Crevice corrosion occurs as a result of void coalescence beneath the oxide layer.