Effect of cobalt on the corrosion resistance of low alloy steel in sulfuric acid solution

This study examines the effect of cobalt addition on the corrosion resistance of low alloy steel in a 10 wt.% sulfuric acid solution at room temperature. All specimens show passive behaviors over the potential range, 0.5–1.55 VSCE, and the passive current density decreased with increasing Co addition. The Co-containing steels also show higher polarization resistance and lower corrosion rate. The beneficial effect of Co is attributed to the formation of a uniform and continuous rust layer due to an interaction between Co and other elements such as Fe, O and S.

► The corrosion rate decreased with increasing Co content ranging from 0 to 0.1 wt.%. ► Surface analyses showed that the addition of Co created a thick and uniform rust layer. ► The interaction between Co and Fe and other elements improved the formation of a continuous and adherent rust layer.