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Within this work, NaCl particle induced corrosion of electrolytically zinc coated, skin-passed steel and especially the influence of the skin-pass texture was investigated. Skin-passing is a wet-rolling procedure that applies a texture on the sample surface to improve the mechanical properties and to enhance the optical appearance of applied coatings.Samples were studied in-situ and ex-situ using Raman spectroscopy and optical microscopy in a self-designed 3D-printed weathering cell. Raman imaging and spectral correlation function were applied ex-situ to obtain more detailed information about the product distribution after drying the sample. Complementary information was obtained using SEM and EDX mapping. [ABSTRACT FROM AUTHOR]

Abstract: Press hardening of hot-dip-galvanized steel sheet yields an innovative product with high strength and reduced weight with drastically increasing industrial importance. This process results in an austenitisation of the steel and a conversion of the 10μm Zn layer into a 20μm thick coating consisting of zinc saturated α-iron and Γ-FeZn-phases. A 5-times longer protection is found in cyclic corrosion tests. The mechanism is a combination of the increase of the coating thickness, cathodic protection and the barrier properties of simonkolleite in the corrosion products. Simonkolleite-Zn5(OH)8Cl2, hydrozincite-Zn5(CO3)2(OH)6 and akaganeite-β-FeOOH were identified as corrosion products by XRD, FT-IR and Raman spectroscopy. [Copyright &y& Elsevier]

The formation and evolution of corrosion products on zinc galvanized press-hardened steel during various atmospheric tests were studied. A high protective ability of the coating containing Zn-Fe intermetallics was shown. The composition models of the soluble and stable corrosion products were calculated. A significant effect of barrier corrosion products on corrosion resistance, especially simonkolleite, hydrozincite and dawsonite, was demonstrated. Exposure to constant high relative humidity resulted in the largest mass loss due to the accelerated formation of akaganeite. On the contrary, the presence of sulphates caused formation of additional barrier corrosion products and almost a threefold drop in mass loss. • Composition of corrosion products was quantified based on a proposed model. • 98 % of oxidized metal ions were built into stable corrosion products. • Main corrosion products were simonkolleite, hydrozincite, dawsonite and akaganeite. • Corrosion products protectiveness increased with a ratio of total to metal ion mass. • Presence of sulphate anions significantly decreased the corrosion rate. [ABSTRACT FROM AUTHOR]

Highlights: [•] ZnMgAl material was significantly more affected than GI, and in the range of the Galfan coating. [•] An obvious pH effect was underlined in low CO2 conditions. [•] Layered double hydroxide and simonkolleite were mainly formed on ZnMgAl coating in the absence of CO2. [•] Hydroxycarbonate and simonkolleite were dominating in ambient air, as for GI. [ABSTRACT FROM AUTHOR]