Effects of Laser Remelting on Salt Spray Corrosion Behaviors of Arc-Sprayed Al Coatings in 3.5% NaCl Sea Environment

Abstract

An arc-sprayed Al coating on S355 steel was remelted using an optical fiber laser. The surface–interface morphologies, chemical elements, distribution, and phases of the obtained Al coating were analyzed using a field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD), respectively. The corrosion morphologies and chemical element distributions of the arc-sprayed Al coating before and after laser remelting (LR) were analyzed using a SEM, and its configured EDS, respectively, and the effects of LR on the salt spray corrosion performance of Al coating were also analyzed. The results show that the porosities and cracks on the arc-sprayed Al coatings are eliminated after LR, which improve the bonding strength between the Al coating and the substrate. The arc-sprayed Al coating is composed of Al phase, while that after LR is composed Al–Fe and AlO4FeO6 phases. The corrosion mechanism of arc-sprayed Al coating is crevice corrosion, while that after LR is pitting corrosion.