Effect of a Hybrid Pumice-Portland Cement Extract on Corrosion Activity of Stainless Steel SS304 and Carbon Mild Steel A36.

The change in the corrosion activities of SS304 and the carbon steel A36 were studied during their exposure for 30 days to hybrid pumice-Portland cement extract (CE), to simulate the concrete-pore environment. The ionic composition and the initial pH (12.99) of the CE were influenced by the reduction of Portland cement (PC) content, volcanic pumice oxides and alkaline activators. Because of the air CO2 dissolution, the pH decreased and maintained a constant value ≈ 9.10 (established dynamic ionic equilibrium). The CE promoted the passivation of both steels and their free corrosion potential (OCP) reached positive values. On the surfaces, Fe and Cr oxides were formed, according to the nature of the steel. Over the time of exposure, the presence of chloride ions in the pumice caused a localized pitting attack, and for carbon steel, this fact may indicate an intermediate risk of corrosion. The chloride effect was retarded by the accumulation of SO42- ions at the steel surfaces. Based on electrochemical impedance (EIS), the polarization resistance (Rp) and the thickness of the passive layers were calculated. Their values were compared with those previously reported for the steels exposed to CEs of Portland and supersulfated cements, and the hybrid cement was considered as a PC "green" alternative.

Atmospheric corrosion of carbon steel: Results of one-year exposure in an andean tropical atmosphere in Colombia.

In this study was examined the response of carbon steel to atmospheric corrosion after one-year exposure in Valle de Aburrá, a subregion located in northwestern Colombia. The study involved the assessment of material mass loss and corrosion rate, the characterization of atmospheric aggressiveness, and the analysis of the morphology and composition of corrosion products in five different sites. Climatological and meteorological factors were assessed by testing for chloride content, sulfur dioxide levels, and time of wetness (TOW). The analysis of corrosion products was conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. Based on corrosion rates, two sites exhibited a more aggressive environment, with a corrosivity category of C3, while the remaining sites were categorized as C2. The study confirmed the presence of lepidocrocite and goethite phases on the surface of carbon steel at all test sites. Data analysis revealed that both the TOW and the industrial activity significantly influence the corrosion of this metal.

Performance of Anticorrosive Paint Systems for Carbon Steel in the Antarctic Marine Environment.

This study evaluated the behavior of three paint systems exposed to the Antarctic marine environment for 45 months compared to a control of uncoated carbon steel with a determined corrosion rate. At the study site, all environmental conditions, solar radiation, and the concentration of environmental pollutants (Cl- and SO2) were evaluated. The paint systems differed in terms of the primer and top coat. Coated samples were studied before and after exposure. They were evaluated visually and using SEM to determine adhesion, abrasion, and contact angle; using the Evans X-Cut Tape Test; using ATR-FTIR spectroscopy to analyze the state of aging of the top layer; and using electrochemical impedance spectroscopy (EIS) for coat protection characterization. The corrosion rate obtained for steel was 85.64 µm year-1, which aligned with a C5 environmental corrosivity category. In general, the evaluation in the period studied showed the paint systems had good adhesion and resistance to delamination, without the presence of surface rust, and exhibited some loss of brightness, an increase in the abrasion index, and a decrease in the percentage of reflectance due to aging. EIS showed good protection capability of the three coating schemes. In general, this type of paint system has not previously been evaluated in an extreme environment after 45 months of exposure to the environment. The results showed that the best behavior was found for the system whose top layer was acrylic-aliphatic polyurethane.

Corrosion Activity of Stainless Steel SS430 and Carbon Steel B450C in a Sodium Silicate Modified Limestone-Portland Cement Extract.

Stainless steel SS430 and carbon steel B450C were exposed for 30 days to the aqueous extract of sodium silicate-modified limestone-Portland cement as an alternative for the partial replacement of the Portland cement clinker. The initial pH of 12.60 was lowered and maintained at an average of 9.60, associated with air CO2 dissolution and acidification. As a result, the carbon steel lost its passive state, and the corrosion potential (OCP) reached a negative value of up to 296 mV, forming the corrosion layer of FeO, and FeOOH. In the meaning time, on the stainless steel SS430 surface, a passive layer of Cr2O3 grew in the presence of FeO, Fe2O3 and Cr(OH)3 corrosion products; thus, the OCP shifted to more positive values of +150 mV. It is suggested that a self-repassivation process took place on the SS430 surface due to the accumulation of alkaline sulfates on the interface. Because of the chloride attack, SS430 presented isolated pits, while on B450C, their area was extended. The quantitative analysis of EIS Nyquist and Bode diagrams revealed that the Rp of the corrosion process for SS430 was 2500 kΩcm2, ≈32 times lower in magnitude than on B450C, for which the passive layer tended to disappear, while that on SS430 was ≈0.82 nm.

Corrosion Activity of Carbon Steel B450C and Stainless Steel SS430 Exposed to Extract Solution of a Supersulfated Cement.

Carbon steel B450C and low-chromium stainless steel SS430 were exposed for 30 days to supersulfated "SS1" cement extract solution, considered as a "green" alternative for partial replacement of the Portland cement clinker. The initial pH of 12.38 dropped since the first day to 7.84, accompanied by a displacement to more negative values of the free corrosion potential (OCP) of the carbon steel up to ≈-480.74 mV, giving the formation of γ-FeOOH, α-FeOOH and Fe2O3, as suggested by XRD and XPS analysis. In the meantime, the OCP of the SS430 tended towards more positive values (+182.50 mV), although at lower pH, and XPS analysis revealed the presence of Cr(OH)3 and FeO as corrosion products, as well the crystals of CaCO3, NaCl and KCl. On both surfaces, a localized corrosion attack was observed in the vicinity of local cathodes (Cu, Mn-carbides, Cr-nitrides, among others), influenced by the presence of Cl- ions in the "SS1" extract solution, originating from the pumice. Two equivalent circuits were proposed for the quantitative analysis of EIS Nyquist and Bode diagrams, whose data were correlated with the OCP values and pH change in time of the "SS1" extract solution. The thickness of the corrosion layer formed on the SS430 surface was ≈0.8 nm, while that on the B450C layer was ≈0.3 nm.

Atmospheric corrosion maps as a tool for designing and maintaining building materials: A review.

Atmospheric corrosion maps can be used to conduct a fast and graphical assessment of material deterioration in specific geographic environments. These maps are a key tool for selecting the most adequate materials in terms of corrosion resistance, maintenance, and cost-efficiency in outdoor constructions. Several studies have evaluated the effects of environmental factors and pollutants on building materials at local, regional, national, and international levels. However, not enough atmospheric corrosion maps are readily available, possibly due to the complexity of the variables that should be considered to construct them, which include weather, meteorological, and pollution-related factors that vary in space and time. This article presents a thorough literature review of atmospheric corrosion maps published between 1971 and 2021 mainly indexed in the Scopus database. It is complemented with a detailed review of books, journals, and projects by research centers that focuses on the methodologies, parameters, and tools that have been used to construct said maps. Most of the available maps are outdated, which highlights the need for new maps that reflect recent global changes in atmospheric pollution and temperature that can intensify metal deterioration in some places.

Anodic electrodissolution: a low-cost alternative for carbon steel sample preparation for quantification of metals by ICP-MS.

A fast and low-cost method using electrolysis for sample preparation of carbon steel present in weld electrodes aiming to achieve quantification of heavy metals by inductively coupled plasma mass spectrometry (ICP-MS) was developed. Conditions of the electrolysis, such as pH and electrical charge were investigated to improve the solubility and concentration of the analytes in the electrolyte. The method showed high reproducibility, with a relative standard deviation (RSD) of less than 3.05%, and the recovery from 88.6 to 108.9% for the analytes demonstrates the accuracy of the developed method.

Finite Element Modeling of Hot Rolling of 1075 Carbon Steel Process with Variable Cross Section.

Currently, it is common to use steel poles for applications in livestock and agriculture. In this work, finite element analysis of five hot rolling passes for the manufacture of farm poles using 1075 carbon steels from recycled railway material was developed. The steel industry in Mexico imports products from other countries or from companies specialized in metallurgy at an excessive cost. To be more competitive and save costs, companies seek the reutilization of existing resources such as the railway 1075 steel, which has good mechanical properties. SFTC DEFORM-3D software was used to model five hot rolling passes considering a variable cross section railway profile. The effect of rolling speed and temperature were considered to analyze flow behavior. Rolling loads were also determined.

The influence of the marine Bacillus cereus over carbon steel, stainless corrosion, and copper coupons.

The present study evaluated the influence of the marine bacteria Bacillus cereus Mc-1 on the corrosion of 1020 carbon steel, 316L stainless steel, and copper alloy. The Mc-1 strain was grown in a modified ammoniacal citrate culture medium (CFA.ico-), CFA.ico- with sodium nitrate supplementation (NO3-), and CFA.ico- with sodium chloride supplementation (NaCl). The mass loss and corrosion rate were evaluated after the periods of 7, 15, and 30 days. The results showed that in CFA.ico- and CFA.ico- medium added NO3- the corrosion rates of carbon steel and copper alloy were high when compared to the control. Whereas the medium was supplemented with NaCl, despite the rates being above the averages of the control system, they were considerably below the previous results. In general, the corrosion rates induced by Mc-1 on 316L coupons were below the results compared to carbon steel and copper alloy. When analyzing the corrosion rate measurements, regardless of the culture medium, the corrosion levels decreased consistently after 15 days, being below the levels evaluated after 7 days of the experiment. Our analyses suggest that B. cereus Mc-1 has different influences on corrosion in different metals and environmental conditions, such as the presence of NO3- and NaCl. These results can help to better understand the influence of this bacteria genus on the corrosion of metals in marine environments.

Zinc-Layered Hydroxide Salt Intercalated with Molybdate Anions as a New Smart Nanocontainer for Active Corrosion Protection of Carbon Steel.

The use of smart nanocontainers to store corrosion inhibitors in coatings significantly increases the efficiency and durability of the coating, providing active corrosion protection. Here we report the synthesis of a zinc-layered hydroxide salt (LHS) and its use as a novel nanocontainer for this purpose, storing the corrosion inhibitor molybdate in the interlayer region of the LHS. Layered zinc hydroxide molybdate (ZHM) was obtained by anion-exchange reactions using layered zinc hydroxide acetate (ZHA) as a precursor, obtained by alkaline coprecipitation. The release behavior of molybdate from the ZHM nanocontainers in aqueous NaCl solution (0.05 mol/L) was evaluated using UV-vis absorption spectroscopy. The molybdate release from the ZHM nanocontainers was realized by the anion-exchange mechanism, where chloride anions replaced intercalated molybdate anions. The release was fast in the first minutes of exposure, followed by a controlled release afterward, reaching about 35% of cumulative amount of released molybdate after 30 days of exposure. The anticorrosion effect provided by the ZHM nanocontainers for carbon steel was investigated by electrochemical impedance spectroscopy. The steel substrate was coated with an epoxy resin loaded with ZHM nanocontainers (5 wt %) and immersed in an NaCl solution (0.05 mol/L) to evaluate the active mechanisms of inhibition and the anticorrosion properties of the loaded coating in comparison with a neat coating (blank). The coating loaded with ZHM nanocontainers presented the best corrosion protection performance, exhibiting an increase of RC (coating resistance) with the immersion time and superior RP (polarization resistance) for all the measured periods, compared to the blank. This effect is a consequence of the double mechanism of protection provided by the ZHM nanocontainers: (i) stimulus-response release of molybdate and its active inhibition in the scratched region by the formation of an insoluble protective film, simultaneously with (ii) removal of the corrosive chloride species from the medium.

"Self arranged Cactis" as new goethite morphology from the natural corrosion process of SAE 1020 carbon steel.

A new morphology of goethite aggregates (α-FeOOH) obtained through the natural corrosion process of 1020 carbon steel parts exposed to weathering was found. Micrographies obtained by SEM reveal micro and nanostructures with forms of nanosquares, microparticles, nanowires inside microparticles and the unpublished structure of "Self arranged Cactis", all varying between 115 nm and 8 µm. The molecular structure of goethite was characterized by FTIR and elemental analysis of EDX converged with the obtained data. The average corrosion rate for 1020 carbon steel in the weathering was 1.7592 mpy. The data obtained in this work will contribute to the understanding of the corrosion process of 1020 carbon steel, one of the most used in civil construction, as well as in material sciences, where iron oxides are widely used in metallurgy, catalysis and adsorption, and the domain of morphology is fundamental for each application.

Water-soluble carboxymethylchitosan used as corrosion inhibitor for carbon steel in saline medium.

Biodegradability and ecotoxicity of products used in oil industry are of great relevance and corrosion inhibitor could not be an exception. In earlier reports, chitosan and some derivatives were evaluated as corrosion inhibitors at acid pH, mainly due to polymer solubility. An eco-friendly corrosion inhibitor with water solubility in all pH range should be ideal, as well as that could act under the high salinity of oil field environment. Thus, herein is presented the performance of a water-soluble carboxymethylchitosan (CMC) as corrosion inhibitor in presence of chlorides (3.5% NaCl) in 1020 carbon steel, without any addition of acid or base. CMC showed good properties as corrosion inhibitor in media containing Cl-, and behaved as an anodic inhibitor. CMC exhibited inhibitory efficiency of about 80% and 67%, according to Tafel curve and electrochemical impedance, respectively, which was attributed to chemisorption mechanism (ΔGads ≈ -45 kJ/mol).

The influence of surface microbial diversity and succession on microbiologically influenced corrosion of steel in a simulated marine environment.

To explore how a succession of bacteria grown on steel coupons in a marine environment can influence their corrosion process, we designed a microcosm in laboratory to evaluate corrosion kinetics and microbial diversity over 30 days. The results described a clear influence of corrosion by a succession of different bacterial groups. During the initial period, 2-7 days, a sharp increase in the rate of corrosion was detected accompanied by the presence of Alteromonadaceae, Vibrionaceae, Oceanospirillaceae, Rhodobacteraceae, Rhodospirillaceae and Flavobacteriaceae bacteria families. After 15 days, representatives of families Piscirickettsiaceae and Pseudomonadaceae were also described, accompanied by a continuous corrosion process over the coupons. After 30 days, there was a sudden change in the profile of the bacteria present on the steel coupons, with a prevalence of Halomonadaceae family species, and establishment and continuity of the corrosion process by the biofilm grown on the coupons. The results describe differences in microbial diversity over the time, highlighting certain bacterial lithotrophic species that persisted for most of the experiment, through a complex association between bacteria and metal surfaces, which can be a new starting point for development and maintenance of a favorable microenvironment to accelerate corrosion processes.

Electrochemical analysis of the corrosion inhibition properties of L-leucine and trypsin complex admixture on high carbon steel in 1 M H 2 SO 4 solution / Análisis electroquímico de las propiedades de inhibición de la corrosión de la mezcla de L-leucina y complejo de tripsina sobre acero de alto contenido de carbono en solución 1 M de H 2 SO 4 / Análise eletroquímica das propriedades de inibição da corrosão da mistura de L-leucina e complexo de tripsina em aço de alto carbono em solução 1 M de H 2 SO 4

Abstract Corrosion inhibition of biodegradable chemical compounds (L-leucine and trypsin complex) on high carbon steel in 1 M H2SO4 acid media was evaluated with potentiodynamic polarization technique, weight loss analysis, open circuit potential measurement, optical microscopy, and ATR-FTIR spectroscopy. Data obtained showed the mixture has a maximum inhibition efficiency of 82.4% and 90.08% from the electrochemical tests with mixed type inhibition properties. The addition of the mixture shifts significantly the corrosion potential of the steel to passivation values from open circuit potential measurement. Results from thermodynamic calculations indicated chemisorption adsorption mechanism according to Langmuir, Freundlich, and Frumkin isotherms coupled with correlation coefficients of 0.9994, 0.9651 and 0.8834. Statistical analysis showed exposure time to be the most significant variable responsible for corrosion inhibition. Identified functional groups of the compound from ATF-FTIR spectroscopy were adsorbed completely on the carbon steel surface from observation of the decreased peak intensity. Optical microscopy images of the inhibited and uninhibited steel surfaces contrast each other with due to the presence of macro-pits and porous oxide on the uninhibited steel.

Resumen Se evaluó la inhibición de la corrosión por parte de compuestos químicos biodegradables (complejo de L-leucina y tripsina) sobre acero de alto contenido de carbono en H2SO4 1 M a través de técnica de polarización potenciodinámica, análisis de pérdida de peso, medición de potencial de circuito abierto, microscopía óptica y espectroscopia ATR-FTIR. Los datos obtenidos mostraron que la mezcla tiene una eficacia de inhibición máxima de 82,4% y 90,08%, a partir de las pruebas electroquímicas con propiedades de inhibición de tipo mixto. La adición de la mezcla cambia significativamente el potencial de corrosión del acero a los valores de pasivación de la medición del potencial de circuito abierto. Los resultados de los cálculos termodinámicos indicaron un mecanismo de adsorción por quimisorción de acuerdo con las isotermas Langmuir, Freundlich y Frumkin, acopladas con coeficientes de correlación de 0,9994; 0,9651 y 0,8834, respectivamente. El análisis estadístico mostró que el tiempo de exposición es la variable más importante en la inhibición de la corrosión. Los grupos funcionales de la mezcla, identificados mediante espectroscopía ATF-FTIR, fueron completamente adsorbidos en la superficie de acero al carbono; esto se dedujo a partir de la observación de la disminución de la intensidad de pico. Las imágenes de microscopía óptica de las superficies de acero inhibidas y desinhibidas contrastan entre sí, debido a la presencia de macro-pozos y óxido poroso en el acero desinhibido.

Resumo Foram feitos estudos de inibição da corrosão de compostos químicos biodegradáveis ccomplexo de L-leucina e tripsina) em aço de alto conteúdo de carbono em meio de H2SO4 1 M, estes foram avaliados com técnica de polarização potenciodinâmica, análise de perda de peso, medição de potencial de circuito aberto, microscopia óptica e espectroscopia ATR-FTIR. Os dados obtidos mostram que a mistura tem uma eficiência de inibição máxima de 82,4% e 90,08% dos testes eletroquímicos com propriedades de inibição do tipo misto. A adição da mistura desloca significativamente o potencial de corrosão do aço para valores de passivação da medição de potencial de circuito aberto. Os resultados dos cálculos termodinâmicos indicam o mecanismo de adsorção de quimisorção de acordo com as isotermas de Langmuir, Freundlich e Frumkin, juntamente com coeficientes de correlação de 0,9994; 0,9651 e 0,8834 respectivamente. A análise estatística mostrou que o tempo de exposição é a variável mais significativa da inibição da corrosão. Os grupos funcionais identificados pela espectroscopia ATF-FTIR foram completamente adsorvidos na superfície do aço ao carbono, de acordo com a observação da intensidade de pico diminuída. As imagens de microscopia óptica das superfícies de aço inibidas e desinibidas contrastam entre si devido à presença de macro-poços e óxido poroso no aço desinibido.

Microestructura y propiedades mecánicas del Acero AISI 1016 calibrado procesado por ECAP / Microstructure and mechanical properties of cold drawn AISI 1016 steel processed by ECAP / Microestrutura e propriedades mecânicas do aço AISI 1016 calibrado processado por ECAP

Se utilizó el proceso de presión en canal angular de sección constante para deformar un acero de bajo carbono calibrado, con el fin de evaluar microestructura y propiedades mecánicas. A su vez, se identificó la posibilidad de mejorar propiedades más allá del proceso de calibrado. El material utilizado fue un acero de bajo carbono calibrado de composición 0.16 % C, 0.8 % Mn, 0.2 % Si, 0.02 % P, 0.012 % S y balance Fe. El proceso se realizó a temperatura ambiente con cuatro pasadas usando la ruta Bc, con una deformación equivalente de ∼0.6 en cada pasada. Se estudió la evolución de la estructura antes y después de la deformación usando microscopía electrónica de barrido y difracción de rayos X y se evaluaron las propiedades mecánicas de microdureza y resistencia a la tensión. Se encontró un aumento leve de las propiedades mecánicas al aumentar el número de pasadas en el proceso. Los análisis mostraron cambios en la estructura ferrítica-perlítica original a través del refinamiento de los granos de ferrita y la deformación de la perlita.

Low carbon cold drawn steel was deformed using equal channel angular pressing to evaluate its mechanical properties and microstructure, while assessing the possibility of improving properties beyond the cold drawn process. We used low carbon cold drawn steel with a composition of 0.16% C, 0.8% Mn, 0.2% Si, 0.02% P, 0.012% S and Fe balance. The process was carried out at room temperature and four passes at route Bc with a deformation of ∼0.6 in each pass. Using scanning electron microscopy and x-ray diffraction, we evaluated the evolution of the structure before and after deformation as well as the mechanical properties of microhardness and tensile strength. A slight increase in the mechanical properties occurred when the number of passes was increased. There were changes in the original ferritic-pearlitic structure with the refinement of ferrite grains and pearlite deformation.

Utilizou-se o processo de pressão em canal angular de secção constante para deformar um aço de baixo carbono calibrado, com a finalidade de avaliar microestruturas e propriedades mecânicas. Assim, identificou-se a possibilidade de melhorar propriedades para além do processo de calibração. O material utilizado foi um aço de baixo carbono calibrado com a seguinte composição 0.16% C, 0.8% Mn, 0.2% Si, 0.02% P, 0.012% S e balance Fe. O processo realizou-se à temperatura ambiente com quatro passos utilizando a rota Bc, com uma deformação equivalente de ∼0.6 em cada passo. Estudou-se a evolução da estrutura antes e depois da formação utilizando microscopia electrónica de varrimento e difracção de rayos X e avaliaram-se as propriedades mecânicas de microdureza e resistência à tensão. Encontrou-se um aumento ligeiro das propriedades mecânicas ao aumentar o número de passos no processo. As análises mostraram alterações nas estruturas ferrítica-perlítica original a através do refinamento dos grãos de ferrita e a deformação da perlita.

Mechanical resistance of carbon and stainless steel hand instruments used in a reciprocating handpiece.

AIM: The manual files are still widely used for initial canal negotiation prior the use of nickel-titanium shaping instruments, to determine working length and to verify patency. A mechanical glide path can be performed using manual files with handpieces, such as M4 Handpiece (SybronEndo, USA) that allows a 30°/30° reciprocating motion. The Pathfinders (SybronEndo, USA) are hand files designed to negotiate complex canals, made from stainless steel (SS) or carbon steel (CS) alloys. The aim of this in vitro study was to compare cyclic fatigue resistance of these two different types of manual Pathfinder instruments used in a M4 reciprocating handpiece in double curved artificial canals. MATERIALS AND METHODS: Manual instruments designed for glide path (size #9 ISO .02 taper) made from different alloys were selected: Group SS -stainless steel Pathfinders (Sybron Endo) and Group CS - carbon steel Pathfinders size K2 (Sybron Endo). Ten instruments of each group were tested for resistance to cyclic fatigue with a reciprocating M4 handpiece inside an artificial S-shaped canal; the time to fracture was recorded for each file and data were statistically analyzed (ANOVA). RESULTS: Mean values (and SD) were 527 (± 89) seconds for the CS instruments and 548 (± 104) seconds for the SS files. No significant differences were observed between groups (p=0,062). CONCLUSIONS: According to the results, both carbon and stainless steel instruments presented similar fatigue resistance when used with M4 reciprocating handpiece in double curved canals.