Evaluating the effect of aluminum on the corrosion resistance of the structural steels used for marine engineering

The effect of aluminum (Al) on the corrosion resistance of structural steels were evaluated in chlorine-containing conditions by both immersion and neutral cyclic salt spray tests as well as electrochemical measurements. The results showed that the addition of Al had different effects on the corrosion resistance. In neutral cyclic salt spray condition, sufficient oxygen content promoted the formation of stable protective layer of Al compounds. Thus, Al could enhance the compactness of rust layer, repelled the invasion of Cl−, and finally improve the corrosion resistance. However, in immersion condition, the addition of Al increased the electrochemical activity of the matrix and the number of local corrosion sites, leading to the decrease of corrosion resistance.