<p>To promote the replacement of the highly polluting conventional hot-dip galvanizing process with hydrogen reduction-based acid-free hot-dip galvanizing technology, this study investigates the interface between the porous hydrogen-reduction layer and the flux AND the interface between the porous hydrogen-reduction layer and galvanizing bath. Scanning electron microscopy, electron probe microanalysis, and Thermo-Calc software were employed to examine the effects of flux time and galvanizing time on the interfacial state of the porous iron layer. The results demonstrate that the porous iron layer is destroyed when the galvanizing time significantly exceeds the flux time, whereas part of the porous iron layer is retained in the opposite scenario. When the galvanizing time reaches 30&#xa0;seconds, the residual galvanizing aid at the interface is completely consumed; in contrast, a substantial amount of galvanizing aid remains under other conditions. The penetration of the galvanizing aid into the inner layer of porous iron leads to the formation of flaky <i>Γ</i>₂ at the galvanizing interface, which is identified as the primary cause of the curling and detachment of the porous iron layer from the substrate. Furthermore, Fe₂Al₅ forms between the galvanized liquid and the outer layer of porous iron, while Fe₄Al₁₃, characterized by coarse grains, is loosely distributed at the interface between the galvanized layer and the matrix.</p> Graphical Abstract <p></p>