E. Otero

The influence of Cr addition on the corrosion resistance of Fe73.5Si13.5B9Nb3Cu1 metallic glass in SO2 contaminated environments

Abstract The influence of Cr concentration on the corrosion resistance of Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 metallic glass in simulated environments contaminated with SO 2 has been studied (0.1 M Na 2 SO 4 ). The corrosion kinetics has been analysed using direct current electrochemical techniques. Moreover, gravimetric tests were conducted in order to establish the reliability of the data obtained electrochemically. Cyclic polarisation measurements were made to study the possibility of localised corrosion. Every test was determined with the same material in different states: amorphous, nanocrystalline and crystalline. Furthermore, the study has also focused on the modification of the magnetic properties in the material as a result of Cr addition and the exposition to an aggressive medium. These properties mainly depend on the Cr concentration, as well as on the material state (amorphous, crystalline or nanocrystalline).

Corrosion Behavior of 12CrMoV Steel in Waste Incineration Environments: Hot Corrosion by Molten Chlorides

The corrosion resistance of a 12CrMoV alloy incontact with a molten mixture of (52-48)mol.%PbCl2-KCl, similar to that found inwaste incineration plants, has been studied. Thecorrosion kinetics have been analyzed using continuous-currentelectrochemical techniques and electrochemical impedancespectroscopy (EIS). Studies were performed to determinethe influence that temperature and the presence of carbon in the salt have on the corrosion rate.Scanning electron microscopy (SEM) and electron-probemicroanalysis (EPMA) were used as additional analyticaltechniques to analyze the corrosion products in order to elucidate the corrosionmechanism.

Influence of Cr addition on the corrosion resistance and magnetic properties of amorphous Fe73.5Si13.5B9Nb3Cu1 in simulated industrial environments

Abstract The influence of Cr concentration on the corrosion resistance of Fe73.5Si13.5B9Nb3Cu1 amorphous alloy in simulated industrial environments contaminated with SO2 has been studied. The corrosion kinetics have been analysed using DC electrochemical techniques. Moreover, gravimetric tests were conducted to establish the reliability of the data obtained electrochemically. Every test was determined with the same material in different states: amorphous, nanocrystalline and crystalline. Furthermore, the study has also focused on the modification of the magnetic properties (coercive field and saturation magnetisation) in the material as a result of Cr addition and the exposure to an aggressive medium. These properties mainly depend on the Cr concentration, as well as on the material state (amorphous, crystalline, or nanocrystalline).

Influence of the filler material on pitting corrosion in welded duplex stainless steel 2205

In this work, the pitting corrosion resistance of welding duplex stainless steel 2205 was studied. Joints were made using the GMAW process with different fillers: duplex ER 2209 and two austenitic fillers (ER 316LSi and ER 308LSi). The microstructure obtained with the duplex ER 2209 filler is similar to the duplex 2205 base material, but the joints produced with the austenitic fillers cause a decrease of the α/γ phase ratio. In order to evaluate the influence of the filler on the weld, the pitting corrosion resistance was determined by means of an electrochemical critical pitting temperature test, and the mechanical properties by the hardness test. The phase imbalance produced for the different fillers causes variation of the pitting corrosion resistance and the mechanical properties. The variation in the mechanical properties of the material was also studied by means of hardness tests.

Roughness Effect on the Mechanical Properties of Ceramic Materials Measured from Nanoindentation Tests

An experimental study was performed to evaluate the roughness effect on the determination of hardness and Young´s modulus of ceramic materials from nanoindentation tests. Several specimens polished at various stages were tested at different peak load values. Local roughness measurements have been done by means of atomic force microscopy. Results indicate that roughness and size effects are joined. Proportional Specimen Resistant Modified model (PSRM) was applied to avoid the scale effect, isolating the roughness influence. Indentations where the average roughness-elastic displacement ratio is lower than a critical value are needed to get consistent results.

Influence of Chromium Addition on the Corrosion Resistance of Co73.5Si13.5B9Nb3Cu1 Metallic Glass in Sodium Sulfate

Abstract This study addresses the influence of Cr concentration on the corrosion resistance of Co73.5Si13.5B9Nb3Cu1 amorphous material in simulated industrial environments slightly contaminated with SO2 (0.1 M sodium sulfate [Na2SO4]). Anodic polarization measurements were carried out to study susceptibility to passivation. The corrosion kinetics was analyzed using direct current (DC) electrochemical techniques. Every test was carried out with the same material in different states: amorphous, nanocrystalline, and crystalline. The study also focused on changes in the magnetic properties of the material as a result of Cr addition and exposure to an aggressive medium. Corrosion resistance depends mainly on the Cr concentration and the material state (amorphous, crystalline, or nanocrystalline). Both an increase of Cr concentration and nanocrystalline state improved the corrosion resistance.

Pitting and crevice corrosion behaviour of high alloy stainless steels in chloride‐fluoride solutions

The localised corrosion resistance (pitting and crevice corrosion) of two high alloy stainless steels, namely superduplex (SD) and superaustenitic (SA), has been studied in chloride-fluoride solutions at pH values ranging from 2 to 6.5. The pitting potential (Epit) and crevice potential (Ecre) have been calculated for these test media using electrochemical techniques (continuous current). The Critical Pitting Temperature (CPT) and Critical Crevice Temperature (CCT) are in both materials lower then the room temperature. In spite of this fact and due to the high repassivation rate, the resistance of these materials to localised corrosion is high in the tested media. At the highest tested concentration of aggressive anions and pH 6.5 both materials undergo a generalised attack. n n n nLoch- und Spaltkorrosionsverhalten von hochlegierten nichtrostenden Stahlen in Chlorid-Fluorid-Losungen n n n nDer Lokalkorrosionswiderstand (Loch- und Spaltkorrosion) von zwei hochlegierten nichtrostenden Stahlen – ein Superduplex (SD) und ein Superaustenit (SA) – wurden in Chlorid-Fluorid-Losungen bei pH-Werten von 2 bis 6,5 untersucht. n n n nDas Lochkorrosions- (Epit) und Spaltkorrosionspotential (Ecre) wurde in diesen Versuchsmedien mit Hilfe elektrochemischer Techniken bestimmt. Die kritische Lochkorrosionstemperatur (CPT) und die kritische Spaltkorrosionstemperatur (CCT) ist bei beiden Werkstoffen niedriger als die Raumtemperatur. Trotz dieser Tatsache und bedingt durch die hohe Repassivierungsgeschwindigkeit ist der Widerstand dieser Werkstoffe in den untersuchten Medien gegenuber Lokalkorrosion hoch. Bei der hochsten verwendeten Konzentration an aggressiven Anionen und bei einem pH-Wert von 6,5 erleiden beide Werkstoffe einen allgemeinen Angriff.

Characterization of the Corrosion Behavior of a Mg Alloy in Chloride Solution

The influence of the microconstituent phases in the first stages of the corrosion process of the AZ91D Mg-Al alloy in a 3.5 wt% sodium chloride (NaCl) solution was studied at different immersion ti...

Effects of Grit Blasting and Annealing on the High-Temperature Oxidation Behavior of Austenitic and Ferritic Fe-Cr Alloys

Grit blasting (corundum) of an austenitic AISI 304 stainless steel (18Cr-8Ni) and of a low-alloy SA213 T22 ferritic steel (2.25Cr-1Mo) followed by annealing in argon resulted in enhanced outward diffusion of Cr, Mn, and Fe. Whereas 3xa0bar of blasting pressure allowed to grow more Cr2O3 and MnxCr3−xO4 spinel-rich scales, higher pressures gave rise to Fe2O3-enriched layers and were therefore disregarded. The effect of annealing pre-oxidation treatment on the isothermal oxidation resistance was subsequently evaluated for 48xa0h for both steels and the results were compared with their polished counterparts. The change of oxidation kinetics of the pre-oxidized 18Cr-8Ni samples at 850xa0°C was ascribed to the growth of a duplex Cr2O3/MnxCr3−xO4 scale that remained adherent to the substrate. Such a positive effect was less marked when considering the oxidation kinetics of the 2.25Cr-1Mo steel but a more compact and thinner FexCr3−xO4 subscale grew at 650xa0°C compared to that of the polished samples. It appeared that the beneficial effect is very sensitive to the experimental blasting conditions. The input of Raman micro-spectroscopy was shown to be of ground importance in the precise identification of multiple oxide phases grown under the different conditions investigated in this study.

Influence of the heat treatments on the corrosion resistance of a duplex stainless steel manufactured by powder metallurgy

Abstract Duplex austenite-ferrite stainless steels were manufactured by sintering mixtures of austenitic (Type 316L [UNS S31603]) and ferritic (Type 434L) atomized powders. Although different Type ...