A influência da adição de cobre no processo corrosivo do aço duplex 2205

Abstract

This study aimed to evaluate the influence of different copper contents on the corrosion behavior of duplex stainless steel 2205 when exposed to sodium chloride–containing media under different pH conditions, since the literature indicates that the effect of copper on the corrosion resistance of this material does not exhibit a consistent trend as a function of its content. The analyzed samples consisted of duplex stainless steel 2205 without copper addition and with 2 wt.% and 4 wt.% Cu additions. The investigation was carried out at room temperature (25 °C) using electrochemical techniques, including open circuit potential (OCP) monitoring, linear potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS), as well as optical microscopy analyses for metallographic surface evaluation after the tests. The results indicated that decreasing pH increased the aggressiveness of the environment for all samples, promoting shifts in the potential toward more negative values and intensifying localized corrosion. The addition of 2 wt.% Cu proved to be beneficial, especially under more acidic conditions, showing higher electrochemical stability, more noble corrosion potential values, and higher impedance modulus at low frequencies, which are associated with increased stability of the passive film. In contrast, the sample containing 4 wt.% Cu did not show a proportional improvement in corrosion performance, suggesting that higher copper contents may compromise material stability. Overall, the study exhibited a qualitative and quantitative approach, allowing the establishment of relationships between copper content, medium acidity, and the corrosion behavior of duplex stainless steel 2205, providing technical support for the selection and application of this material in aggressive industrial environments.