| Abstract Scope |
High-speed steels comprise martensitic matrices reinforced with fine carbide precipitates, exhibiting excellent wear resistance. However, the existence of high fraction of carbide precipitates causes an accelerated anodic dissolution of the martensitic matrix. Recently, we revealed that adding trace Cu significantly improves the corrosion resistance of such steel grades. In this study, to understand the underlying mechanism, we examined the surface evolution of the developed steels during immersion into a sulfuric acid. Using Kelvin probe force microscopy, we demonstrated that the difference in electrochemical potential between the carbide phase and the martensitic matrix, which acts as the driving force of the corrosion reaction, was reduced in the developed steel. Notably, heat-treatment temperature not only reduce the carbide fraction but also enhanced such a surface evolution, associated with surface Cu enrichment. Thus, the lower corrosion rate was obtained after quenching from higher temperatures. |