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Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Alliage base nickel, Nickel base alloys, Chrome alliage, Chromium alloy, Cromo aleación, Chromlegierung, Corrosion, Corrosión, Korrosion, Cycle thermique, Thermal cycle, Ciclo térmico, Temperaturverlauf, Effet composition, Composition effect, Efecto composición, Konzentrationseinfluss, Elément alliage, Alloying element, Elemento aleación, Legierungselement, Oxydation, Oxidation, Oxidación, Perte masse, Mass loss, Pérdida masa, Superalliage, Superalloy, Superaléación, Superlegierung, A. Nickel, A. Superalloys, B. Thermal cycling, B. Weight loss, and C. Oxidation

The effect of the addition of less than 1 wt% of Al, Si and Mn on the cyclic oxidation of the Ni-22Cr-14W-2Mo alloy is investigated. The cyclic oxidation experiment is performed between 1150 °C and 400 °C. Al and Si addition reduced the oxidation rate by suppressing the formation of transient oxides. In particular, Al enhanced the adhesion of the oxide scale by forming oxide pegs and a (Cr,Al)2O3 layer. Mn is detrimental to the oxidation resistance by enhancing the formation of NiO, NiCr2O4, and NiWO4. However, the detrimental effect of Mn is suppressed by the addition of Al and Si.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Acier galvanisé, Galvanized steel, Acero galvanizado, Corrosion électrochimique, Electrochemical corrosion, Corrosión electroquímica, Elektrochemische Korrosion, Diffraction RX, X ray diffraction, Difracción RX, Roentgenbeugung, Produit corrosion, Corrosion product, Producto corrosión, Korrosionsprodukt, Réduction chimique, Chemical reduction, Reducción química, Reduktion, A. Electrogalvanized steel, B. X-ray diffraction, C. Corrosion product, C. Oxygen reduction, and C. Self healing

The differences in the reactivity of carbon steel covered or not by a layer of electrochemically synthesed zinc corrosion products were observed in 0.85 M NaCl at different initial pH. The magnitude of the cathodic current /j/ increases in the order: /j(steel/Na2Zn3(CO3)4·3H2O)/

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Acier galvanisé, Galvanized steel, Acero galvanizado, Corrosion atmosphérique, Atmospheric corrosion, Corrosión atmosférica, Atmosphaerische Korrosion, Corrosion effet pile, Galvanic corrosion, Corrosión galvánica, Kontaktkorrosion, Couplage galvanique, Galvanic coupling, Acoplamiento galvánica, Produit corrosion, Corrosion product, Producto corrosión, Korrosionsprodukt, Réduction chimique, Chemical reduction, Reducción química, Reduktion, A. Steel, A. Zinc, B. Polarization, C. Atmospheric corrosion, and C. Oxygen reduction

The reactivity of zinc under synthetic zinc patinas and the galvanic coupling in steel/patina/Zn are studied. Zn5(OH)6(CO3)2 and Na2Zn3(CO3)4·3H2O inhibit zinc anodic dissolution in NaCI, while Zn5(OH)8Cl2 H2O and Zn4(OH)6SO4 nH2O do not. The galvanic current in steel/patina/NaCl/Zn is smaller as compared to steel/NaCl/Zn. The inhibiting effect decreases with time for Na2Zn3(CO3)4·3H2O or Zn4(OH)6SO4 nH2O due to the transformation into Zn(OH)2. In NaHCO3, the polarity between zinc and steel can reverse. The effect of confinement on the cathodic current is stronger than the initial effect of patina which is explained by the instability of the patinas under rapid pH-increase.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Alliage base aluminium, Aluminium base alloys, Corrosion intergranulaire, Intergranular corrosion, Corrosión intergranular, Interkristalline Korrosion, Impédance, Impedance, Impedancia, Microscopie force atomique, Atomic force microscopy, Microscopía fuerza atómica, Trempe et revenu, Quenching and tempering, Temple y revenido, Vergueten, Vitesse refroidissement, Cooling rate, Velocidad enfriamiento, Abkuehlungsgeschwindigkeit, A. Aluminium, B. AFM, B. EIS, B. Polarisation, and C. Intergranular corrosion

The corrosion behaviour of AA7050 on different quench rates and ageing conditions has been studied using immersion tests and complementary techniques like SEM, TEM-EDS and Scanning Kelvin probe force microscopy. The results reveal that overageing temper can effectively reduce corrosion sensitivity caused by peak-ageing treatment. The comparison of corrosion resistance in the over-aged and severely over-aged alloys shows significant dependence of the changes in corrosion resistance with ageing time on quench rate. The results are discussed in terms of the changes in the composition and distribution of precipitates, width of precipitate-free zone and diffusivity of alloying elements.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de matériaux non métalliques, Nonmetallic coatings, Corrosion, Action des agents de corrosion, Corrosion environments, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Composé organique, Organic compounds, Compuesto orgánico, Organische Verbindung, Corrosion atmosphérique, Atmospheric corrosion, Corrosión atmosférica, Atmosphaerische Korrosion, Corrosion filiforme, Filiform corrosion, Corrosión filiforme, Fadenkorrosion, Pression partielle, Partial pressure, Presión parcial, Partialdruck, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, A. Iron, A. Organic coatings, A. Steel, and C. Atmospheric corrosion

An in-situ time-lapse optical microscopy study, using a novel dual-compartment cell is used to gain mechanistic understanding of filiform corrosion (FFC) affecting an organic-coated iron surface. The apparatus allows independent control of environments surrounding the filament head and tail regions. When oxygen-containing environments surround the filament head, an anterior cathodic arc is formed, constraining the filament head electrolyte. When oxygen is removed from the vicinity of the head, FFC propagation rates remain unchanged, although the constraining arc is not present. Maximum propagation is observed when oxygen is available for transport through the filament tail to the rear of the head.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Attache, Fastener, Atadura, Corrosion, Corrosión, Korrosion, Diffraction RX, X ray diffraction, Difracción RX, Roentgenbeugung, Effet composition, Composition effect, Efecto composición, Konzentrationseinfluss, Humidité, Humidity, Humedad, Feuchtigkeit, Perte masse, Mass loss, Pérdida masa, A. Steel, A. Zinc, B. Polarization, B. Weight loss, and B. X-ray diffraction

This paper characterizes the corrosion rate of embedded fasteners as a function of wood moisture content using gravimetric and electrochemical measurements. The results indicated that the corrosion rate increased with moisture content before reaching a plateau. The phases present in the corrosion products, as analyzed using X-ray diffraction, are generally consistent with previous work. Uniform corrosion was observed for all fasteners and all conditions except steel fasteners embedded in water-saturated wood. Data of dependence of corrosion rate on moisture content, presented herein, are necessary to ensure the accuracy of combined hygrothermal/corrosion models used to predict durability of wood structures.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Alliage base magnésium, Magnesium base alloys, Basse température, Low temperature, Baja temperatura, Tieftemperatur, Chlorure de sodium, Sodium chloride, Sodio cloruro, Natriumchlorid, Corrosion, Corrosión, Korrosion, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Microstructure, Microestructura, Mikrogefuege, Passivation, Pasivación, Passivierung, Passivité, Passivity, Pasividad, Passivitaet, Résistance corrosion, Corrosion resistance, Resistencia corrosión, Korrosionsbestaendigkeit, Spectrométrie photoélectron, Photoelectron spectrometry, Espectrometría fotoelectrón, ESCA Spektrometrie, Ségrégation, Segregation, Segregación, Seigerung, Température, Temperature, Temperatura, Temperatur, Traitement thermique, Heat treatment, Tratamiento térmico, Waermebehandlung, A. Magnesium, B. SEM, B. XPS, C. Passivity, and C. Segregation

This paper studies the differences in chemical composition of the oxide surface layers induced by heating in air at 200 °C for time intervals from 5 min up to 60 min on commercial AZ31 and AZ61 magnesium alloys with a view to a better understanding of their protective properties. A strong link was found between the aluminium enrichment observed in the surface of the oxide layer and the decrease in the protective properties of the heat treated AZ31 alloy. In contrast, no significant changes have been observed in the case of the heat treated AZ61 alloy.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Acier bas carbone, Low carbon steel, Acero bajo carbono, Kohlenstoffarmer Stahl, Acier non allié, Carbon steel, Acero no aliado, Unlegierter Stahl, Chlorure, Chlorides, Cloruro, Chlorid, Corrosion, Corrosión, Korrosion, Inclusion non métallique, Non metallic inclusion, Inclusión no metálica, Nichtmetallischer Einschluss, Microstructure, Microestructura, Mikrogefuege, Voltammétrie, Voltammetry, Voltametría, Voltammetrie, A.Chloride-ions, A.Low carbon steel, B.Cyclic voltammetry, C.Corrosion, C.Microstructure, and C.Non-metallic inclusions

The effect of microstructure and inclusions on corrosion of API-5LX60-X100 low carbon steel is examined in acetate buffer solutions (pH 6) containing chloride. Microstructure was varied by preliminary heat treatment resulting in following series: ferrite-pearlite, ferrite-bainite, ferrite-martensite, and demonstrated the minor effect on the active dissolution kinetics, as well as oxide and sulfide inclusions. The current in the passive region and breakdown potential appeared to be sensitive to both types of inclusions and steel microstructure. Voltammetric parameters are listed which correlate with corrosion rate under open circuit and can be used to predict both short- and long-term corrosion behavior.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de métaux et d'alliages, Metallic coatings, Dépôt de matériaux non métalliques, Nonmetallic coatings, Corrosion, Action des agents de corrosion, Corrosion environments, Adhérence, Adhesion, Adherencia, Adhaesion, Affinement grain, Grain refinement, Afino grano, Kornfeinen, Alumine, Alumina, Alúmina, Tonerde, Aluminure, Aluminides, Aluminuro, Composé intermétallique, Intermetallic compound, Compuesto intermetálico, Intermetallische Verbindung, Corrosion, Corrosión, Korrosion, Couche oxyde, Oxide layer, Capa óxido, Oxidschicht, Grosseur grain, Grain size, Grosor grano, Korngroesse, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Microscopie électronique transmission, Transmission electron microscopy, Microscopía electrónica transmisión, Transmissionselektronenmikroskopie, Microstructure, Microestructura, Mikrogefuege, Oxydation, Oxidation, Oxidación, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, A. Metal coatings, B. SEM, B. TEM, B. XRD, and C. Oxidation

To understand the effect of grain refinement on the thermally grown alumina scale adhesion to the metal substrate, two δ-Ni2Al3 coatings, one coarse-grained (~70 μm) and the other ultrafine-grained (generally below ~500 nm), were prepared. The cyclic oxidation in air at 1100 °C shows that the ultrafine-grained (UFG) coating is better oxidation resistant than the coarse-grained (CG) coating due to the formation of a more adherent alumina scale. The latter is intrinsically correlated with the fact that the aluminide grain refinement helps to increase the oxide/metal strength through a route to prevent the formation of large-sized voids at the interface.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Corrosion haute température, High temperature corrosion, Corrosión alta temperatura, Hochtemperaturkorrosion, Haute température, High temperature, Alta temperatura, Hochtemperatur, Joint grain, Grain boundary, Limite grano, Korngrenze, Microstructure, Microestructura, Mikrogefuege, Oxydation, Oxidation, Oxidación, Spectrométrie SIMS, Secondary ion mass spectrometry, Espectrometría SIMS, Sekundaerionenmassenspektrometrie, Superalliage, Superalloy, Superaléación, Superlegierung, Température, Temperature, Temperatura, Temperatur, A. Cobalt, A. Superalloys, B. SIMS, and C. Oxidation

Isothermal oxidation in air was carried out on a γ'-strengthened single crystalline Co―Al―W―B superalloy at 800, 900, and 1000 °C. The absence of grain boundaries leads to inferior oxidation properties at 800 and 900 °C, and improved properties at 1000 °C. compared to a polycrystalline alloy of the same composition. At lower temperatures, grain boundary diffusion is dominant and assumed to be the reason for enhanced B-accumulation in the inner oxide layer and enhanced formation of the protective inner Al2O3 layer. However, at 1000 °C superior oxidation resistance of the single crystalline superalloy can be observed.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Chromate, Chromates, Cromato, Corrosion piqûre, Pitting corrosion, Corrosión superficial, Lochkorrosion, Phénomène transitoire, Transients, Fenómeno transitorio, A. Alloy, A. Aluminium, B. Potentiostatic, and C. Pitting corrosion

The effect of chromate on metastable pitting of AA7075-T651 as determined via potentiostatic polarisation is reported. A systematic study of metastable pitting and its correlation with stable pits was conducted in various concentrations of sodium chromate (Na2CrO4), revealing the metastable pitting rate was able to provide a quantitative metric for pitting corrosion. The size and number of metastable pits decreased significantly in the presence of chromate. The present study is intended as a general baseline for the assessment of future chromate replacement technologies, as elaborated herein.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Acier inoxydable, Stainless steel, Acero inoxidable, Nichtrostender Stahl, Application, Aplicación, Anwendung, Corrosion caverneuse, Crevice corrosion, Corrosión cavernosa, Spaltkorrosion, Eau potable, Drinking water, Agua potable, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Recuit, Annealing, Recocido, Gluehen, Traitement thermique, Heat treatment, Tratamiento térmico, Waermebehandlung, A. Stainless steel, B. Polarization, B. SEM, and C. Crevice corrosion

In this study, the corrosion behaviour of annealed and not annealed AISI 444 ferritic stainless steel in tap water with and without addition of selected concentrations of chloride ions was investigated. Cyclic potentiodynamic macro (large area) and micro (small area) polarization measurements (CPP), salt spray test, SEM and EDS analysis were employed to evaluate the pitting and crevice corrosion susceptibility of annealed and not annealed AISI 444. The results obtained indicate that annealing does not improve the resistance to pitting and crevice corrosion. Moreover, micro CPP indicates local susceptibility to pitting on both annealed and not annealed materials; such susceptibility was not evident from macropolarization tests.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Rupture, Fractures, Propriété mécanique, Mechanical properties, Propiedad mecánica, Corrosion, Corrosión, Korrosion, Fragilisation hydrogène, Hydrogen embrittlement, Fragilización hidrógeno, Wasserstoffversproedung, Hydrogène, Hydrogen, Hidrógeno, Wasserstoff, Interface, Interfase, Grenzflaeche, Maclage, Twinning, Chocleo, Zwillingsbildung, Plasticité, Plasticity, Plasticidad, Plastizitaet, Précipitation, Precipitation, Precipitación, Ausscheidung, Précipité, Precipitate, Precipitado, Ausscheidungsprodukt, Rupture, Ruptura, Bruch, A. Steel, B. Galvanostatic, C. Hydrogen embrittlement, and C. Interfaces

The effect of Ti precipitates on hydrogen embrittlement (HE) was investigated using Ti-free and Ti-bearing TWIP steels through slow tensile tests and thermal desorption analysis. Whereas Ti-free steel did not show the reduction in elongation by hydrogen charging, Ti-bearing steel revealed a great reduction in elongation, indicative of the low resistance to HE. During plastic deformation, hydrogen atoms migrated from grain boundaries and dislocations to twin boundaries for Ti-free steel and to the interfaces of Ti particles for Ti-bearing steel. The low resistance to HE of Ti-bearing steel was due to a ductile to brittle transition near hydrogen-trapped TiN particles.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Fatigue, Rupture, Fractures, Acier non allié, Carbon steel, Acero no aliado, Unlegierter Stahl, Application, Aplicación, Anwendung, Corrosion biochimique, Bacterial corrosion, Corrosión bioquímica, Biologische Korrosion, Corrosion intergranulaire, Intergranular corrosion, Corrosión intergranular, Interkristalline Korrosion, Ethanol, Etanol, Aethanol, Fatigue avec corrosion, Corrosion fatigue, Fatiga con corrosión, Korrosionsermuedung, Fissure fatigue, Fatigue crack, Fisura fatiga, Ermuedungsriss, Fragilisation hydrogène, Hydrogen embrittlement, Fragilización hidrógeno, Wasserstoffversproedung, Hydrogène, Hydrogen, Hidrógeno, Wasserstoff, Industrie pétrolière, Oil industry, Industria petrolera, Erdoelindustrie, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Pipeline, Oleoducto, Propagation fissure, Crack propagation, Propagación fisura, Rissausbreitung, Propriété mécanique, Mechanical properties, Propiedad mecánica, Rupture, Ruptura, Bruch, Réservoir stockage, Storage tank, Tanque almacenamiento, Lagerbehaelter, Stockage, Storage, Almacenamiento, Lagerung, Sulfate, Sulfates, Sulfato, Sulfat, A. Steel, B. SEM, C. Corrosion fatigue, C. Hydrogen embrittlement, C. Intergranular corrosion, and C. Microbiological corrosion

This paper evaluates the effects of microbiologically influenced corrosion (MIC) on fatigue-crack growth of candidate materials useful in expanding bio-ethanol usage, including a storage-tank steel (ASTM A36) and two pipeline steels (API 5L X52 and X70). The microbiological species sampled and cultivated from an ethanol fuel production stream are responsible for both acetic acid and hydrogen sulfide production that lead to significant increases in fatigue-crack growth rate across a wide range of stress-intensity-factor amplitudes (ΔK). The mechanism for increased fatigue damage is hydrogen uptake through adsorption into the steel, which embrittles material ahead of the growing fatigue crack.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Protection contre la corrosion, Corrosion prevention, Anode sacrificielle, Sacrificial anode, Anodo sacrificial, Opferanode, Bactérie sulfatoréductrice, Sulfate-reducing bacteria, Bactéria sulfatorreductora, Corrosion biochimique, Bacterial corrosion, Corrosión bioquímica, Biologische Korrosion, Corrosion piqûre, Pitting corrosion, Corrosión superficial, Lochkorrosion, Impédance, Impedance, Impedancia, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Protection cathodique, Cathodic protection, Protección catódica, Kathodischer Schutz, Protection corrosion, Corrosion protection, Protección corrosión, Korrosionsschutz, A. Aluminium, B. EIS, B. SEM, C. Microbiological corrosion, and C. Pitting corrosion

Corrosion of two sacrificial anodes in marine sediment with and without sulphate-reducing bacteria (SRB) was performed. Weight loss experiments indicated that the corrosion rate of Al-Zn-In-Sn was 2-3 times higher than that of Al-Zn-In-Mg-Ti in the SRB-containing sediment. Electrochemical analysis suggested that the corrosion rates of the two anodes were enhanced substantially by SRB. Surface analysis revealed the localised corrosion of the two sacrificial anodes in abiotic and biotic sediments. The concentration of Al3+ in the surface of the samples immersed with SRB was lower than that of the samples without SRB.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Métaux renforcés par dispersion, Dispersion hardening metals, Corrosion, Action des agents de corrosion, Corrosion environments, Acide nitrique, Nitric acid, Nítrico ácido, Salpetersaeure, Corrosion haute température, High temperature corrosion, Corrosión alta temperatura, Hochtemperaturkorrosion, Couche superficielle, Surface layer, Capa superficial, Oberflaechenschicht, Haute température, High temperature, Alta temperatura, Hochtemperatur, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Microscopie électronique transmission, Transmission electron microscopy, Microscopía electrónica transmisión, Transmissionselektronenmikroskopie, Milieu acide, Acid medium, Medio ácido, Saures Medium, Métal renforcé dispersion, Dispersion strengthened metal, Metal reforzado dispersión, Dispersionsgehaertetes Metall, Passivation, Pasivación, Passivierung, Passivité, Passivity, Pasividad, Passivitaet, Résistance corrosion, Corrosion resistance, Resistencia corrosión, Korrosionsbestaendigkeit, Spectrométrie photoélectron, Photoelectron spectrometry, Espectrometría fotoelectrón, ESCA Spektrometrie, Température, Temperature, Temperatura, Temperatur, A. Steel, B. Polarization, B. TEM, B. XPS, C. High temperature corrosion, and C. Passive films

The passive film compositions and corrosion resistance of 12% Cr and 15% Cr oxide dispersion strengthened (ODS) steels in 3 M HNO3 to 9 M HNO3 was evaluated. The potentiodynamic polarization plots exhibited a shift in corrosion potential, and higher passive current density with increasing HNO3 concentrations. In 12% Cr ODS steel, high corrosion rate was observed in all HNO3 concentrations. However, low corrosion rate observed in 15% Cr ODS steel was attributed to Al2O3 enrichment. The TEM analysis indicated a complex Y2Hf2O7 formation in 15% Cr ODS steel, and this may have a role in suppressing intergranular corrosion attack.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Alliage moulé, Cast alloy, Aleación moldeada, Gusslegierung, Corrosion atmosphérique, Atmospheric corrosion, Corrosión atmosférica, Atmosphaerische Korrosion, Fonderie, Foundry, Fundería, Giesserei, Microscopie électronique transmission, Transmission electron microscopy, Microscopía electrónica transmisión, Transmissionselektronenmikroskopie, Précipitation, Precipitation, Precipitación, Ausscheidung, Précipité, Precipitate, Precipitado, Ausscheidungsprodukt, A. Alloy, A. Magnesium, B. STEM, and B. TEM

The behaviour of Al-Mn precipitates during atmospheric and aqueous corrosion of an AM50 Mg alloy was investigated using site-specific analytical electron microscopy. After air-exposure, localized attack was observed close to Al-Mn precipitates, with the top layer of the intermetallic enriched in Al and O. During immersed corrosion, these precipitates developed protruding domes of corrosion products, with crystalline Mg(OH)2 on top and an inner layer of crystalline MgO. After prolonged immersion, these precipitates showed evidence of preferential Al dissolution, ultimately developing a fragmented interlayer of Mn3O4. This phase transformation is linked to the enhanced hydrogen evolution rates adjacent to these precipitates.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Protection contre la corrosion, Corrosion prevention, Chlorure de sodium, Sodium chloride, Sodio cloruro, Natriumchlorid, Corrosion, Corrosión, Korrosion, Dioxyde de carbone, Carbon dioxide, Carbono dióxido, Kohlendioxid, Impédance, Impedance, Impedancia, Inhibiteur corrosion, Corrosion inhibitor, Inhibidor corrosión, Korrosionsinhibitor, Lanthanide, Lantánido, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Protection corrosion, Corrosion protection, Protección corrosión, Korrosionsschutz, Spectrométrie photoélectron, Photoelectron spectrometry, Espectrometría fotoelectrón, ESCA Spektrometrie, A. Steel, B. EIS, B. SEM, B. XPS, and C. Corrosion inhibition

Praseodymium 4-hydroxycinnamate (Pr(40HCin)3) was investigated as a novel corrosion inhibitor for steel in NaCl solutions, and found to be effective at inhibiting corrosion in both CO2-containing and naturally-aerated systems. Surface analysis results suggest that the corrosion inhibition ability of Pr(4OHCin)3 in the naturally-aerated corrosion system could be attributed to the formation of a continuous protective film. For the CO2-containing system, the corrosion inhibition efficiency of Pr(4OHCin)3 was predominantly because of formation of protective inhibiting deposits at the active electrochemical corrosion sites, in addition to a thinner surface film deposit.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Acier non allié, Carbon steel, Acero no aliado, Unlegierter Stahl, Corrosion, Corrosión, Korrosion, Durcissement, Hardening, Endurecimiento, Haerten, Modélisation, Modeling, Modelización, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété traction, Tensile property, Propiedad tracción, Zugeigenschaft, Résistance mécanique, Strength, Resistencia mecánica, Festigkeit, Résistance traction, Tensile strength, Resistencia tracción, Zugfestigkeit, A. Carbon steel, B. Modeling study, C. Effect of strain, and C. Hardening

Tensile strength tests are performed on small scale corroded specimens, so as to derive their mechanical properties. The specimens were cut from a box girder that was initially corroded in real sea water conditions. As a result of the tensile tests the mechanical properties of the specimens are determined, namely modulus of elasticity, yield stress, tensile strength, resilience, fracture toughness and total uniform elongation. Regression equations are derived for the properties as a function of the degree of corrosion degradation. It is identified that those material parameters are influenced by the severity of corrosion degradation.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Protection contre la corrosion, Corrosion prevention, Carbure de silicium, Silicon carbide, Silicio carburo, Siliciumcarbid, Corrosion, Corrosión, Korrosion, Couche protectrice, Protective layer, Capa protectora, Schutzschicht, Céramique, Ceramic materials, Cerámica, Keramik, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Oxydation, Oxidation, Oxidación, Oxyde de tantale, Tantalum oxide, Tantalio óxido, Tantaloxid, Protection corrosion, Corrosion protection, Protección corrosión, Korrosionsschutz, Revêtement protecteur, Protective coatings, Revestimiento protector, Schutzueberzug, A. Ceramic, A. Tantalum oxide, B. SEM, B. XRD, and C. Oxidation

A TaxHf1_xB2-SiC coating was prepared by in-situ reaction method on SiC coated C/C composites. TaxHf1-- xB2 phase is the form of solid solution between TaB2 and HfB2. Isothermal oxidation behavior at 1773 K and ablation behavior of the coated C/C were tested. TaxHf1-xB2-SiC/SiC coating could protect the C/C from oxidation at 1773 K for 1480 h and ablation above 2200 K for 40 s. During oxidation, oxides of Ta and Hf atoms exist as pinning phases in the compound glass layer consisted of outer Ta-Si-O compound silicate layer and inner SiO2 glass layer, which was responsible for the excellent oxidation resistance.