Corrosion Resistance of 2205 Duplex Stainless Steel in Sulfuric Acid Solutions

The corrosion resistance of 2205 duplex SS in H2SO4 was investigated and compared with the conventional 316L SS and 20R steel by the conventional weight loss method together with the measurement of potentiodynamic polarization curves and electrochemical impedance spectroscopy.The results showed that the order of corrosion resistance to H2SO4 from high to weak was 2205>>316L>20R;the orders of influence of H2SO4 concentration and temperature from high to low was 20R>316L>2205.As T≤40 ℃,the corrosion velocity of 2205 duplex SS was zero,indicating non-corrosion in H2SO4 for 2205 duplex SS with a corrosion evaluation of level 1.As the temperature increased to 60 ℃ and the concentration of H2SO4 was up to 30%,the corrosion velocity of 2205 duplex SS increased greatly to 27.026 mm/a,indicating obvious corrosion in H2SO4 for 2205 duplex SS with a corrosion evaluation of level 10.The higher content of Cr in 2205 duplex SS was contributed to the much enhanced corrosion resistance because it can reduce the passivation potential and enhance the ability to damage repairing of passivation film.