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• Pure Zn and Zn-epoxy powder coatings was prepared by zincate electrodeposition. • The addition of epoxy powder improves microstructures and reduce roughness. • The incorporation of epoxy powder enhances the corrosion resistance. • The incorporation of epoxy powder hinders the hydrogen permeation. • The addition of epoxy powder improves the wear resistance. To improve the corrosion and wear resistance of the coating and reduce the effect of hydrogen penetration on the performance of galvanized steel, Zinc-epoxy powder (EP) composite coatings were prepared by alkaline zincate electrodeposition. The results show that the Zn-6 g/L EP coating has the lowest root mean square roughness of 281.99 A. The incorporation of EP enhances the corrosion resistance of the coating. The Zn-6 g/L EP coating has the largest coating resistance and charge transfer resistance. The incorporation of EP can hinder the hydrogen permeation, which may reduce the hydrogen embrittlement of galvanized steel. Tribological experiment shows that the wear resistance of the composite coating is improved. The friction coefficient and wear scar width of the Zn-12 g/L EP coating is the lowest. [ABSTRACT FROM AUTHOR]

• DL-EPR was used to describe the precipitation of carbides in super Cr13 stainless steel. • The main reason for the decrease in impact toughness is the precipitation of continuous Cr-rich carbides (M23C6) along the interface. • Solution treatment before quenching and tempering treatment can improve the impact toughness. • The impact tough of the steel can be predicted by DL-EPR. Super martensitic stainless steel (SMSS) is characterized by improved mechanical properties and corrosion resistance. However, during production the impact toughness will be significantly reduced under certain heat treatment regimes (tempering at 873 K followed by quenching at 1213 K and tempering at 913 K). Double loop electrochemical potentiokinetic reactivation (DL-EPR) were used to investigate the mechanism for the reduction of impact toughness in this experiment. It was found that the primary cause for the decrease was precipitation of continuously distributed Cr-rich carbides (M 23 C 6) along martensite lath boundaries. The Ra value obtained by DL-EPR is positively correlated with the amount of Cr-rich carbide precipitation. As Ra increases, impact toughness increases first and then decreases rapidly, which indicates that it is reasonable to use Ra to qualitatively predict the impact toughness of the steel. [ABSTRACT FROM AUTHOR]