Effect of yttrium on the corrosion behaviour of 09CrCuSb alloy in concentrated sulphuric acid

The effect of yttrium on the corrosion behaviour of 09CrCuSb alloy (ND steel) in concentrated sulphuric acid at 383 K has been investigated. The results demonstrate that addition of 0.15 wt.% Y effectively improves the corrosion resistance of such alloy. By observing the surface morphology and cross-section of the scale, it is found that Y addition refines the corrosion product, and improves the adhesion ability between the scale and the matrix. The electrochemical test exhibits a decrease passive currents as well as a higher passive and charge transfer resistance of the Y-modified alloy.

► The presence of alloyed yttrium lowers the corrosion rate of steel in 85% sulphuric acid.
► Yttrium addition helps to keep a fine uniform compact corrosion layer.
► Y addition enhances the adhesion between the corrosion scale and the matrix.
► Yttrium addition increases the electrochemical reaction resistance of 09CrCuSb alloy.