Abstract
In this work, the corrosion of duplex stainless steel (DSS) alloy 2209 alloy in 2 M HCl and 0.6 M NaCl solutions was studied. The effect of adding ~ 0.3% ruthenium (Ru) as an alloying element on the corrosion passivation of DSS in the solutions under investigation was also reported. The work has been performed using conventional gravimetric and electrochemical methods in addition to the electrochemical impedance spectroscopy measurements. The weight-loss data showed that the dissolution of DSS increased with increasing time and that effect remarkably decreased in the presence of Ru in the alloy. The electrochemical tests showed the presence of Ru shifted the corrosion potential in the positive direction and decreased the corrosion current density and both the uniform and pitting corrosion, while increased the polarization resistance of the DSS alloy. Electrochemical impedance spectroscopy revealed that the Ru alloyed DSS had higher surface and polarization resistances. The results together were internally consistent with each other, showing clearly that the presence of Ru in DSS alloy 2209 increases its passivity against corrosion in acidic and neutral chloride solutions.