Abstract
Eleven test steels containing P, Cu, Cr, Ni and Al in various combinations were exposed in the atmosphere, tidal and submerged zones up to 5 years. The results show that in the marine atmosphere Cr and Al are beneficial, and at the tidal zone P, Cr, Ni and Al are effective. The slope of the corrosion-time curves decreases in 0.5year. At the tidal zone, moreover, surface rust, local attack and exposure levels have much influence on the corrosion resistance. On the other hand, in the submerged zone the corrosion resistance is increased by the combined additions of Cu, Cr and Al, and the effect is consistent over the whole exposure period. Strongly adherent, hard and Cu, Cr, Al enriched inner rust next to the base metal is formed on such steels and this inner layer increases cathodic polarization remarkably. These results lead to the conclusion that Cu-Cr-Al steels have a good corrosion resistance in marine environments.
