The effect of copper addition on the corrosion resistance of cast duplex stainless steel

Abstract

In this study, the effects of the addition of 3.01% Cu on the corrosion behaviour of cast duplex stainless steel aged for 1 h at different temperatures between 450 and 600 °C was investigated by electrochemical tests in 0.6 M NaCl, 0.3 M H2SO4 and 0.6 M NaCl + 0.3 M H2SO4. A short ageing time increases the hardness and mechanical resistance of the Cu-containing steel by precipitation hardening. Potentiodynamic polarization and electrochemical impedance spectroscopy results show that the effect of Cu addition depends on the media studied. In addition, critical pitting temperature (CPT) measurements revealed that steel with 3.01% Cu has a lower pitting corrosion resistance. On the other hand, for both steels, the short time ageing caused a slight increase in CPT values. Keywords: Cast duplex stainless steel, Copper, Passive film, Pitting corrosion