Understanding of localized corrosion mechanism of lean-duplex stainless in alkaline soltuiion is a key issue on construction and civil engineering industry, because the growing use and application of SS in those sectors. Duplex stainless steel improves the lifetime in service of reinforced concrete structures (RCS), thus combining good corrosion and mechanical properties. This research work studied corrosion behavior of duplex stainless steel rebars RCS: LDSS 2001, AISI 2304 and AISI 2205. Corrosion testing was performed in alkaline media under high chloride content conditions, [Cl^–]= 4; 6 and 8%. Results allowed to elucidate chloride threshold on localized pitting corrosion, passive layer chemistry and electrochemical behaviour, for different duplex stainless steels reinforcements. The evolution with time of corrosion potential (E_corr) and polarization resistance (R_p) was studied. Polarization resistance and time constant (τ) were obtained by potentiostatic pulse technique.

Duplex stainless steel reinforcements revealed pitting corrosion after 6 months exposure in high chloride contained alkaline solutions (pH>12). Despite of pitting corrosion, a very low corrosion risk was found for duplex stainless steel used.