Influence of Ni and Cu on Oxide-Scale Structure of Steel

Abstract

Oxide scales exert important effects on the surface quality of steel products. In hot rolling processes in the steel industry, the heterogeneous structure of oxide scales, such as an uneven scale/steel interface, causes surface defects. For steels containing Ni, the structure of oxide scales at the scale/steel interface is characteristic and complicated. Consequently, this study focuses on Ni and Cu, which are nobler than Fe, and investigates their effects on the structure of oxide scales of steels. Fe-10mass%Ni and Fe-10mass%Cu alloys were oxidized at 1000 or 1200°C in an atmosphere of 10%O2+20%H2O+70%N2 for 1800 s. In all cases, uneven scale/steel interfaces were observed because both Ni and Cu are nobler than Fe. Furthermore, different structure of oxide scales was formed at the scale/steel interface between the Fe-Ni and Fe-Cu alloys depending on the alloys’ solid solubility limit to austenite.