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This work analyzes the premature corrosion failure of a welded AISI 304 stainless steel (SS) pipe network in well water (WW) for 6 months. Laboratory tests were performed to analyze the corrosion behavior and to identify and distinguish the genera of bacteria. Pipe specimens were analyzed using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy,open circuit potential, cyclic potentiodynamic polarization, and electrochemical impedance spectroscopy. Physicochemical properties of WW in the AISI 304 SS pipe presented a positive Langelier saturation index, indicating the formation of corrosion scales. In welded 304 austenitic SS, the chromium depletion both in HAZ and in weld-metal leads to preferential anodic dissolution. The biofilm electrochemical activity produces oxygen concentration cells and the acid metabolic products induce preferential MIC, thus leading to pit formation on the HAZ of the weld. Biodiversity analysis of bacteria by next generation sequencing was carried out in corroded AISI 304 SS pipes and different genera of bacteria were identified.

In this work, the corrosion performance of a new developed high-entropy alloy (HEA) of the composition AlCrFeMnTi (at. %) was studied. The corrosion testing of the AlCrFeMnTi HEA was carried out in 2.5 M NaOH, 0.6 M NaCl, and in 0.5 M HSO. The correlation between the microstructure, elemental composition, density, hardness, and corrosion resistance of the new developed AlCrFeMnTi HEA was investigated. The impedance response showed protective corrosion behavior for the neutral and acidic pH, while the alkaline environment led to a passivity breakdown due to dissolution of Al forming Al(OH). The outcome of the presented study suggests that new developed HEA is suitable to be used in industrial environments with a neutral and acidic pH.

The corrosion inhibition mechanism of soluble phosphates on steel reinforcement embedded in mortar fabricated with ordinary Portland cement (OPC) are reviewed. This review focuses soluble phosphate compounds, sodium monofluorophosphate (NaPOF) (MFP), disodium hydrogen phosphate (NaHPO) (DHP) and trisodium phosphate (NaPO) (TSP), embedded in mortar. Phosphate corrosion inhibitors have been deployed in two different ways, as migrating corrosion inhibitors (MCI), or as admixed corrosion inhibitors (ACI). The chemical stability of phosphate corrosion inhibitors depends on the pH of the solution, HPO ions being stable in the pH range of 3-6, the HPO in the pH range of 8-12, while the PO ions are stable above pH 12. The formation of iron phosphate compounds is a thermodynamically favored spontaneous reaction. Phosphate ions promote ferrous phosphate precipitation due to the higher solubility of ferric phosphate, thus producing a protective barrier layer that hinders corrosion. Therefore, the MFP as well as the DHP and TSP compounds are considered anodic corrosion inhibitors. Both types of application (MCI and ACI) of phosphate corrosion inhibitors found MFP to present the higher inhibition efficiency in the following order MFP > DHP > TSP.

The corrosion behavior of austenitic Fe–Mn–Al–Cr–C twinning-induced plasticity (TWIP) and microband-induced plasticity (MBIP) steels with different alloying elements ranging from 22.6–30 wt.% Mn, 5.2–8.5 wt.% Al, 3.1–5.1 wt.% Cr, to 0.68–1.0 wt.% C was studied in 3.5 wt.% NaCl (pH 7) and 10 wt.% NaOH (pH 14) solutions. The results obtained using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques, alongside optical microscopy analysis, revealed pitting as the dominant corrosion mechanism in high-Mn TWIP steels. An X-ray diffraction analysis of the surface revealed that the main corrosion products were hematite (Fe2O3), braunite (Mn2O3), and hausmannite (Mn3O4), and binary oxide spinels were also identified, such as galaxite (MnAl2O4) and jacobsite (MnFe2O4). This is due to the higher dissolution rate of Fe and Mn, which present a more active redox potential. In addition, a protective Al2O3 passive film was also revealed, showing enhanced corrosion protection. The highest corrosion susceptibility in both electrolytes was exhibited by the MBIP steel (30 wt.% Mn). Pitting corrosion was observed in both chloride and alkaline solutions.

[EN] Steel reinforcing bars are often coated with rusts formed during service in reinforced concrete (RC) structures. Rust layers growing on steel rebars induce expansive stresses and cause cracking on cover concrete. This study uses steel corrosion rate results measured on reinforced concrete buildings of more than 50 years of age located in marine environments and considers the pressure generated by the volume expansion of corrosion product layers to calculate the service life of the RC structures using a numerical simulation, estimat-ing the time to corrosion cracking of the concrete cover. Akaganeite, goethite, lepidocrocite, hematite, magnetite and maghemite were identified by X-ray diffraction as crystalline phase constituents of the rust layers., [ES] Los refuerzos corrugados de acero embebidos en hormigón, presentan con frecuencia una capa de herrumbre formada durante la vida en servicio de las estructuras de hormigón armado (EHA). Las capas de óxido, productos de corrosión, que crecen en los refuerzos de acero inducen tensiones expansivas y causan el agrietamiento del recubrimiento de hormigón. El presente estudio utiliza los resultados de la velocidad de corrosión del acero corrugado, medidos en edificios de más de 50 años, construidos con hormigón armado, ubicados en ambientes marinos. El estudio considera la presión generada por la expansión de volumen de las capas de productos de corrosión para calcular la vida útil en servicio de las EHA utilizando una simulación numérica, estimando el tiempo hasta la fisuración por corrosión del recubrimiento de hormigón. Akaganeita, goethita, lepidocrocita, hematita, magnetita y maghemita fueron identificadas por difracción de rayos X, como constituyentes de las fases cristalinas de las capas de óxido.

Steel rebars of structures exposed to cyclic loadings and marine environments suffer an accelerated deterioration process by corrosion fatigue, causing catastrophic failure before service life ends. Hence, stainless steel rebars have been emerging as a way of mitigating pitting corrosion contribution to fatigue, despite the increased cost. The present study proposes a corrosion fatigue semiempirical model. Different samples of rebars made of carbon steel, 304L austenitic (ASS), 316L ASS, 2205 duplex (DSS), 2304 lean duplex stainless steels (LDSS), and 2001 LDSS have been embedded in concrete and exposed to a tidal marine environment for 6 months. Corrosion rates of each steel rebar have been obtained from direct measurement and, considering rebar standard requirements for fatigue and fracture mechanics, an iterative numerical model has been developed to derive the cycles to failure for each stress range level. The model resulted in a corrosion pushing factor for each material, able to be used as an accelerating coefficient for the Palmgren-Miner linear rule and as a performance indicator. Carbon steel showed the worst performance, while 2001 LDSS performed 1.5 times better with the best cost-performance ratio, and finally 2205 DSS performed 1.5 times better than 2001 LDSS.

A new predictive 3D FEM model is proposed using the corrosion damage function by measuring the concrete cover crack width, which is a function of the free concrete cover depth, the steel rebar diameter, the mechanical properties of the concrete, and the length of the anodic zone. A significant aspect to evaluate service lifetime conditions in corroded reinforced concrete structures (RCSs) is the concrete cover crack width. Surface cracks originate due to the pressure exerted by the volume expansion of the corrosion products and oxide layer formed on the rebars. In this work, concrete cover crack width on corroded RCS is analyzed by means of finite element method allowing a corrosion damage model to be proposed. The model obtained was used to find a theoretical relationship between the dissolved steel (corrosion process) and the concrete cover crack width. The results were validated using three experimental data sets from the literature: two corrosion case studies in natural environments and one work covering accelerated corrosion in laboratory test conditions. All the beams were exposed to the simultaneous action of flexural stresses and corrosion. A good correlation was observed between the model and the experimental results, thus supporting reliability of the analytical process and validation of the proposed corrosion damage model.

The corrosion behavior of the sulphuric-anodized AA2099 using two different current densities, 0.19 or 1.0 A·cm−2, with two different sealing treatments in H2O and 6 wt.% Na2Cr2O7 at 95 °C was studied in 3.5 wt.% NaCl and 10 vol.% H2SO4 solutions. The AA2099 is widely used in aeronautical applications, thus it is essential to present good corrosion performance in chloride and acid rain environments. The surface morphology of the anodized film was characterized by scanning electron microscopy (SEM), the electrochemical corrosion behavior was studied using electrochemical impedance (EIS), and finally characterization of the surface chemical composition was revealed by X-ray photoelectron spectroscopy (XPS). It was found the 6 wt.% Na2Cr2O7 sealing treatment imparts a more homogeneous and compact passive layer, and tends to increase the charge transfer resistance, thus improving the corrosion behavior of the anodized AA2099.

A new predictive 3D FEM model is proposed using the corrosion damage function by measuring the concrete cover crack width, which is a function of the free concrete cover depth, the steel rebar diameter, the mechanical properties of the concrete, and the length of the anodic zone. A significant aspect to evaluate service lifetime conditions in corroded reinforced concrete structures (RCSs) is the concrete cover crack width. Surface cracks originate due to the pressure exerted by the volume expansion of the corrosion products and oxide layer formed on the rebars. In this work, concrete cover crack width on corroded RCS is analyzed by means of finite element method allowing a corrosion damage model to be proposed. The model obtained was used to find a theoretical relationship between the dissolved steel (corrosion process) and the concrete cover crack width. The results were validated using three experimental data sets from the literature: two corrosion case studies in natural environments and one work covering accelerated corrosion in laboratory test conditions. All the beams were exposed to the simultaneous action of flexural stresses and corrosion. A good correlation was observed between the model and the experimental results, thus supporting reliability of the analytical process and validation of the proposed corrosion damage model.

The corrosion behavior of the sulphuric-anodized AA2099 using two different current densities, 0.19 or 1.0 A·cm, with two different sealing treatments in HO and 6 wt.% NaCrO at 95 °C was studied in 3.5 wt.% NaCl and 10 vol.% HSO solutions. The AA2099 is widely used in aeronautical applications, thus it is essential to present good corrosion performance in chloride and acid rain environments. The surface morphology of the anodized film was characterized by scanning electron microscopy (SEM), the electrochemical corrosion behavior was studied using electrochemical impedance (EIS), and finally characterization of the surface chemical composition was revealed by X-ray photoelectron spectroscopy (XPS). It was found the 6 wt.% NaCrO sealing treatment imparts a more homogeneous and compact passive layer, and tends to increase the charge transfer resistance, thus improving the corrosion behavior of the anodized AA2099., Efecto del tratamiento de sellado en el comportamiento frente a corrosión de la aleación anodizada de aluminio-litio AA2099. El comportamiento frente a corrosión de la aleación de aluminio AA2099 anodizado en solución de H2SO4, aplicando dos densidades de corriente diferentes, 0,19 o 1,0 A·cm−2, con dos tratamientos de sellado diferentes en H2O y en Na2Cr2O7 (6% peso) a 95 °C, se ha estudiado en disoluciones de NaCl (3,5% peso) y de H2SO4 (10% vol). La aleación AA2099 se usa ampliamente en aplicaciones aeronáuticas, por tanto, se requiere que presente un buen comportamiento frente a la corrosión en ambientes de cloruro y lluvia ácida. La morfología de la superficie de la película anodizada se caracterizó por microscopía electrónica de barrido (MEB), se estudió el comportamiento frente a corrosión electroquímica empleando la impedancia electroquí-mica (EIS), y finalmente la caracterización de la composición química de la superficie se reveló por espectros-copía de fotoelectrones de rayos X (XPS). Se encontró que el tratamiento de sellado con Na2Cr2O7 (6% peso), genera una capa pasiva más homogénea y compacta, y tiende a aumentar la resistencia a la transferencia de carga, mejorando así el comportamiento frente a corrosión del AA2099 anodizado.

A new predictive 3D FEM model is proposed using the corrosion damage function by measuring the concrete cover crack width, which is a function of the free concrete cover depth, the steel rebar diameter, the mechanical properties of the concrete, and the length of the anodic zone. A significant aspect to evaluate service lifetime conditions in corroded reinforced concrete structures (RCSs) is the concrete cover crack width. Surface cracks originate due to the pressure exerted by the volume expansion of the corrosion products and oxide layer formed on the rebars. In this work, concrete cover crack width on corroded RCS is analyzed by means of finite element method allowing a corrosion damage model to be proposed. The model obtained was used to find a theoretical relationship between the dissolved steel (corrosion process) and the concrete cover crack width. The results were validated using three experimental data sets from the literature: two corrosion case studies in natural environments and one work covering accelerated corrosion in laboratory test conditions. All the beams were exposed to the simultaneous action of flexural stresses and corrosion. A good correlation was observed between the model and the experimental results, thus supporting reliability of the analytical process and validation of the proposed corrosion damage model.

Thermo-mechanical processed (TMP) TWIP steels with high-Mn content and different amounts of Cr, Fe-30Mn-5Al-0.5C-(x)Cr, were studied using cyclic potentiodynamic polarization (CPP), optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) in a deaerated 0.1 M NaCl solution. Additionally, X-ray photoelectron spectroscopy (XPS) was used to analyse the chemical composition of the passive film generated potentiostatically on TMP specimens in the deaerated 0.1 M NaCl solution. The results indicate a beneficial effect of Cr additions on the passivity of TWIP steels. However, a high content of Cr seemed to cause a phase-segregation process reducing the corrosion resistance properties of the material. The results also indicate that TMP enhances corrosion attack.

In this study, ternary ecological concrete (TEC) mixtures were produced with partial substitution of the ordinary Portland cement (OPC) by 10%, 20%, and 30% of sugar cane bagasse ash (SCBA) and silica fume (SF); a control mixture (100% OPC) was prepared according to ACI 211.1 standard. The studied TEC specimens were reinforced with AISI 304 stainless steel and AISI 1018 carbon steel rebars. TEC reinforced specimens were immersed in two different electrolytes, a control (DI-water) and 3.5 wt.% MgSO4 solution, for 180 days. The electrochemical corrosion was monitored by corrosion potential (Ecorr) according to ASTM C-876-15 standard, and the linear polarization resistance (LPR) technique using ASTM G59 standard. The Ecorr and current density icorr results show that AISI 304 stainless steel rebars have a high corrosion resistance, with icorr values below 0.1 µA/cm2, which is interpreted as a level of negligible corrosion. The best corrosion performance was found for the TEC mixture made with a 20% addition of blend of sugar cane bagasse ash-silica fume (SCBA-SF) to the OPC.