Influence of solution annealing and aging treatments on the electrochemical behavior of duplex stainless steel

Abstract

Duplex stainless steels are broadly employed in harsh environments because of their excellent combination of mechanical strength and corrosion resistance. But, exposure to temperatures near 475 °C can trigger microstructural degradation within the ferritic phase, which results in development of chromium enriched and Iron enriched nanophases. This transformation is known to cause embrittlement and significantly diminish corrosion resistance, affecting the durability. In this experimental study, the electrochemical performance of duplex stainless steel thermally aged at 475 °C was systematically evaluated, with emphasis on pitting corrosion resistance in both aerated 3.5 weight percent sodium chloride solution and carbon dioxide‐saturated simulated oilfield brines. Electrochemical techniques were used to measure pitting breakdown potentials, while x‐ray photoelectron spectroscopy was employed to characterize the passive film and investigate chloride ion incorporation. Results reveal a significant decline in corrosion resistance associated with thermally induced embrittlement. These outcomes emphasize need of carefully considering thermal exposure effects when deploying duplex stainless‐steel components in service environments prone to aging.