Institutional RepositoryThis is a postprint version of the following published document:A. Bautista (et al.). HI GHLIGHTS• 5 corrugated stainless steel grades are studied in chloride contaminated mortars.• Ecorr and E IS are used for monitoring, and polarizations tests are also carried out • Spo ntaneous corrosion only appears in low Ni austenitic 520430 at partial immersion.• 532205 duplex does not show any sign of corrosion even at anodic high polarizations. ABSTRA C T Keywords: Stainless steel Steel reinforced mortar EISMortar sampl es reinforced with 5 different corrugated stainless steels were tested for 9 years in 2 differ ent conditions: partial immersion (P I) in 3. 5% NaC l, and chloride addition to the mortar and exposure to high relative humidity (H R H) . The monitoring during the exposures was carried out with corrosi on potential (Ecorr) and electrochemical impedance spectroscopy (E IS) measurements. A year before finishing (after 8 years of exposure), the reinforced mortar samples were anodically polarised to obtain more infor mation about the pitting resistance of the passi ve layers formed under the different conditions. The last year of exposure was established to study the pr ogress or repassivation of the pits. The P I is the most aggressive testing condition and it causes low intensity corrosion in 520430 austenitic stainless steel after 7 years of exposure. The 532205 duplex stainless steel shows very good corrosion behaviour.

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a b s t r a c tStainless steels are formed by either hot working (HW) or cold working (CW) when used as reinforcement for concrete structures. The influence of the forming process on the corrosion behaviour is analyzed in depth in the present work. CW and HW corrugated bars of austenitic AISI 304L and 316L, and duplex SAF 2205 grades are studied. The electrochemical behaviour of the corrugated surface and the core of these materials are characterized by Mott Schottky analysis and polarization curves. Tests are carried out in both carbonated and non carbonated Ca(OH) 2 solutions. The microstructure and local mechanical properties of these materials are also analysed by means of universal hardness (UH) measurements to complete available information. The results prove that the surface of corrugated bars is far more likely to suffer corrosion than the core of the same material. The corrosion probability and the morphology of the attack induced in corrugated surfaces by anodic polarization clearly differ in HW and CW bars.

The selective corrosion of the phases comprised in four duplex stainless steels (DSS) is studied in acid media (H2SO4 + HCl solutions). The work considers traditional UNS S32205 grade as well as other economical‐advantageous grades (UNS S32001 and UNS S32304). The samples of the lean DSS come from bars formed by hot working (HW), while those of the S32205 come both from HW bars and bars obtained by cold working. The amount of strain‐induced martensite in the austenitic phase of DSS that the processing has induced is highly dependent on the DSS composition. The change in the relative corrosion resistance of the different phases comprised in the microstructure with the potential is considered. The influence of the composition of the DSS is discussed. It has been checked that, at potentials close to the corrosion potential (Ecorr), the corrosion of the ferritic phase is more favored than that of the austenite. Increasing potentials in the anodic activation region tends to favor the selective corrosion of the austenite. The trend to selective dissolution is less marked for the least alloyed DSS. The strain‐induced martensite in the austenitic phase exhibits a corrosion resistance clearly higher than that of the ferrite at Ecorr or potentials close to Ecorr. The possible influence of TiN precipitates in the corrosion development is also analyzed.