Corrosion behaviour of sensitized and unsensitized Alloy 900 (UNS 1.4462) in concentrated aqueous lithium bromide solutions at different temperatures

Duplex stainless steels can undergo microstructural changes if they are heated improperly. When that happens, duplex stainless steels are sensitized and intermetallic phases appear. The high Chromium and Molybdenum content promotes the formation of secondary phases as a consequence of the heat treatment. These secondary phases, which are rich in alloying elements, such as Cr and Mo, deplete these elements from the neighbouring phases, leading to a reduction in corrosion resistance. In order to study the influence of the secondary phases on the corrosion parameters, samples of duplex stainless steel, Alloy 900 (UNS 1.4462), have been heated in argon atmosphere at 825 °C for 1 h. The corrosion behaviour of sensitized and unsensitized Alloy 900 has been analyzed in a concentrated aqueous lithium bromide (LiBr) solution of 992 g/L by means of cyclic potentiodynamic curves. Secondary phase presence reduces the pitting potential value of Alloy 900. Besides, the pitting potential decreases with temperature. On the other hand, the corrosion potential and open circuit potential values increase with temperature and sensitization.