Ugitech Research Center

Ugine, France

Ugitech Research Center

Ugine, France
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Monnot M.,Ugitech Research Center | Monnot M.,University Grenoble Alpes | Monnot M.,French National Center for Scientific Research | Nogueira R.P.,The Petroleum Institute | And 10 more authors.
Applied Surface Science | Year: 2017

Thanks to their high corrosion resistance, super martensitic stainless steels are commonly used in the oil and gas industry, particularly in sour environments. Some grades are however susceptible to undergo hydrogen and mechanically-assisted corrosion processes in the presence of H2S, depending on the pH. The martensitic stainless steel EN 1.4418 grade exhibits a clear protective passive behavior with no sulfide stress corrosion cracking when exposed to sour environments of pH ≥ 4, but undergoes a steep decrease in its corrosion resistance at lower pH conditions. The present paper investigated this abrupt loss of corrosion resistance with electrochemical measurements as well as different physicochemical characterization techniques. Results indicated that below pH 4.0 the metal surface is covered by a thick (ca 40 μm) porous and defect-full sulfide-rich corrosion products layer shown to be straightforwardly related to the onset of hydrogen and sulfide mechanically-assisted corrosion phenomena. © 2016 Elsevier B.V.


Monnot M.,Ugitech Research Center | Monnot M.,University Grenoble Alpes | Mantel M.,Ugitech Research Center | Mantel M.,University Grenoble Alpes | And 6 more authors.
European Corrosion Congress, EUROCORR 2015 | Year: 2015

Due to their good corrosion resistance as well as a wide range of mechanical properties, super martensitic stainless steels are generally used in the petrochemical industry. In this context, the super martensitic stainless steel EN 1.4418 (15% Cr, 5% Ni 1%Mo), which exhibits good corrosion and mechanical properties in sour environment, could be an alternative grade to replace EN 1.4542, which presented some stress corrosion cracking problems in service. In this work, corrosion resistance and stress corrosion cracking of 1.4418 have been followed by electrochemical and phys-ical techniques to understand the failure mechanism at low pH. This study focused on laboratory stainless steel heats containing different controlled amounts of Cr, Ni, Mo and various thermal treatments have been performed in order to define carefully the contents of martensite, ferrite and residual austenite. The corrosion mechanisms will be discussed in terms of pitting corrosion potentials, sulfide stress cracking and repassivation processes. Moreover, the effect of H2S on 1.4418 corrosion properties has been correlated to the formation of metallic sulfur, which promotes hydrogen embrittlement. In order to determine the role of this metallic sulfur in the corrosion mechanism, XPS and hydrogen permeation measurements have been realized.


Mesquita T.J.,Ugitech Research Center | Chauveau E.,Ugitech Research Center | Mantel M.,Ugitech Research Center | Nogueira R.P.,Joseph Fourier University
Applied Surface Science | Year: 2013

The objective of this work is to study the effect of Mo additions on film passive properties of three different stainless steels (SS) types (austenitic, ferritic and duplex alloys). A comparison between Mo containing (3 wt% Mo) and free Mo (0 wt% Mo) grades of highly controlled laboratory heats was done considering their passive film formed in different aggressive conditions, from neutral to alkaline pH. The presence of oxidized Mo on the passive layer was confirmed by X-ray photoelectron Spectroscopy (XPS). The presence of Mo within the passive film improved the passivity breakdown potential for the duplex and ferritic SS, but seemed to have no effect for austenitic SS.


Cordoba-Torres P.,Spanish University for Distance Education (UNED) | Mesquita T.J.,Joseph Fourier University | Mesquita T.J.,Ugitech Research Center | Nogueira R.P.,Joseph Fourier University
Electrochimica Acta | Year: 2013

Complex nonlinear-least-squares fitting of impedance data to an equivalent circuit is probably the most intuitive method used to represent the whole electrode impedance from experimental electrochemical impedance spectroscopy data. However, among other questions it has the primary problem of identifying a physically significant model representing the system under examination. In that context it then becomes very suitable the study of other analysis procedures to complement this approach. With regard to constant-phase element (CPE) behavior characterization, direct impedance analysis seems to be a good choice since CPE behavior is explicitly revealed in the high frequency decay of the imaginary component of the impedance. For that reason it is becoming popular among electrochemists who can get the CPE exponent from a simple fit of the imaginary part of the impedance to a frequency power law. There are, however, important limitations to the frequency range employed in this analysis that are commonly ignored. In the case of disk electrodes, geometrical constraints related to the insulating-metal boundary induce current and potential distributions that screen the real underlying CPE behavior in the high frequency domain. On the other hand, for lower frequencies, CPE behavior can also be masked by the effects of diffusion. In this paper we present some methodological considerations taking these effects into account in order to get a more reliable characterization of the CPE behavior from direct impedance analysis. We illustrate these issues with different experimental conditions and show that in many cases deviations can be remedied thanks to a convenient theoretical treatment that allows correct values of CPE parameters to be retrieved. © 2013 Elsevier Ltd.


Mesquita T.J.,Ugitech Research Center | Chauveau E.,Ugitech Research Center | Mantel M.,Ugitech Research Center | Kinsman N.,IMOA International Molybdenum Association | And 7 more authors.
7th European Stainless Steel Conference: Science and Market, Proceedings | Year: 2011

The use of stainless steels (SS) as concrete reinforcement is becoming increasingly popular in coastal and marine constructions in order to prevent corrosion induced by chloride ions penetrating into the concrete. However, the influence of Mo addition on pitting corrosion resistance of these steels is not clearly understood in alkaline chloride conditions even being well stablished the benefictial effect of this element in acidic and neutral environments. Therefore, the understanding of the Mo role on the corrosion resistance of SS in alkaline media is hence of major importance for the setting of optimized alloy composition. The present work aims at studying the effect of Mo addition on pitting corrosion properties of three different stainless steel families (austenitic, ferritic and duplex SS) in alkaline environments (solution simulating a chloride-contaminated-concrete at two alkaline pH values: 10, to simulate carbonated concrete, and 12, to simulate sound concrete). For comparison, an acid (pH=4) and neutral (pH=7) solution were also included in this study and a real cement medium). In order to establish the real role of Mo addition on pitting and passivation properties of the three studied families of SS, the alloy samples were prepared in laboratory under highly controlled conditions. The obtained results were discussed with respect to the influence of Mo addition on pitting potential for industrial alloys (AISI 304, ISI 316, AISI 430, AISI 434, SAF 2304 and SAF 2205) .


Mesquita T.J.,Total S.A. | Chauveau E.,Ugitech Research Center | Monnot M.,Ugitech Research Center | Bouvier N.,Ugitech Research Center
NACE - International Corrosion Conference Series | Year: 2015

The good mechanical properties as well as the large range of corrosion resistance justify the use of super martensitics in oil and gas production fields. Nevertheless with UNS 17400, which is largely used, some in-service failures have occurred. In this context, the super martensitic stainless steel 15Cr5Ni0.8Mo, which has good mechanical and corrosion properties, could be a good candidate to replace it. In this work, different alloying elements are studied with laboratory heats to optimize its chemical composition for oil & gas application. The control of microstructure eliminates residual ferrite and retained austenite as parameters in corrosion behavior. The positive influence of buffer test solution is described and the reinforcement of passive film in non sour medium is explained. Then the influence of H2S on passive film and corrosion mechanism is highlighted, in particular when the gas destabilizes a passive film allowing generalized corrosion. Influence of alloying elements is related to the corrosion mechanism: a positive effect of chromium, molybdenum and copper is observed on corrosion resistance in sulfur medium. The effect of molybdenum on SSC resistance is described. © 2015 by Nace International.


Mesquita T.,Ugitech Research Center | Mesquita T.,Grenoble Institute of Technology | Chauveau E.,Ugitech Research Center | Mantel M.,Ugitech Research Center | And 2 more authors.
Revue de Metallurgie. Cahiers D'Informations Techniques | Year: 2011

The use of stainless steels as concrete reinforcement is becoming increasingly popular in coastal and marine constructions in order to prevent corrosion induced by chloride ions penetrating into the concrete. In these highly aggressive situations, the lean duplex stainless steels have been extensively employed due to their high mechanical and corrosion resistances. However, the influence of Mo addition on pitting corrosion resistance of these steels is not clearly understood in alkaline chloride conditions even if this element is widely associated to an increasing corrosion resistance in acidic and neutral environments. Therefore, understanding Mo mechanism on corrosion resistance in alkaline media is hence of major importance to the setting of optimized alloy composition. The present work aims to study the effect of Mo addition on pitting corrosion properties of lean duplex stainless steels in alkaline environments (concrete). The results are discussed with respect to the influence of Mo addition on pitting potential for two industrial duplex alloys (1.4362 and 1.4462) in several aggressive media mainly in synthetic, chlorinated and carbonated solution simulating concrete pore environments (pH10 solution with carbonates and chlorides ions). In order to establish the real role of Mo addition on lean duplex corrosion and passivation properties, the corrosion behaviors of two specific laboratory lean duplex alloys, which the only difference between then is the amount of Mo (0 and 3% wt. Mo), are also studied. Furthermore, scanning electronic microscopy (SEM) was used to verify which phase of duplex microstructure (ferritic or austenitic) is mostly susceptible to the pit nucleation in these corrosion conditions as the role of Mo is probably different to each simple phase. © EDP Sciences, 2011.


Mesquita T.J.,Ugitech Research Center | Chauveau E.,Ugitech Research Center | Mantel M.,Ugitech Research Center | Mantel M.,Grenoble Institute of Technology | And 2 more authors.
Corrosion Science | Year: 2014

The corrosion properties of two supermartensitic stainless steels were studied in chloride and H2S environments. A comparison between 1.4542 and 1.4418 SS grades was made considering the effects of microstructure, different steps of the heat treatment on the pitting and sulfide stress cracking SSC properties. The SSC limits of 1.4418 were determined in terms of different pH and PH2S conditions. In H2S media, the 1.4418 presented a higher stability and passivation compared to 1.4542. The Electron back-scattering and X-ray diffraction were used to characterize the amount of' retained austenite in the 1.4418 and then its influence on pitting and SSC resistance was investigated. © 2014 Elsevier Ltd.


Mesquita T.J.,Ugitech Research Center | Mesquita T.J.,Grenoble Institute of Technology | Chauveau E.,Ugitech Research Center | Mantel M.,Ugitech Research Center | And 2 more authors.
Revista Escola de Minas | Year: 2013

Corrosion of reinforcement steels, induced by chloride ions penetrating into the concrete, is the main cause of early damage, loss of serviceability and safety of reinforced concrete structures, which can be even more severe in the presence of concomitant concrete carbonation. In order to prevent reinforcement steel corrosion in highly aggressive alkaline environments, the use of stainless steels is becoming increasingly popular in coastal and marine constructions. Although widely used as an increasing corrosion resistance element in acidic environments, the influence of Mo addition on pitting corrosion resistance of stainless steels is not very clear in these conditions. Understanding Mo mechanism on corrosion resistance in alkaline media is hence of major importance, particularly for new lean grades with low Nickel and Molybdenum contents which presents a good balance between the properties required in these applications and the final cost of the material. In this work we will show the effect of Mo addition on pitting corrosion properties of austenitic, ferritic and duplex SS. A comparison between Mo content steels (alloys: 1.4404, 1.4113 and 1.4462) and very low molybdenum contents steels (alloys: 1.4301, 1.4016 and 1.4362) is done considering their pitting corrosion resistance (pitting potential Epit) in different corrosion conditions. The results are discussed with respect to the influence of Mo addition on pitting behaviors for the different stainless steel rebar families in several aggressive media mainly in synthetic, chlorinated and carbonated solution reproducing the real concrete pore environments (pH10 solution with carbonates and chlorides ions).

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