Oxidation of ferritic–martensitic alloys T91, HCM12A and HT-9 in supercritical water

Ampornrat, Pantip; Was, Gary S.

doi:10.1016/j.jnucmat.2007.05.023

Cited by 157 publications

(83 citation statements)

References 19 publications

(27 reference statements)

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“…In order to understand the oxidation mechanism of candidate materials under supercritical water environment, the oxidation tests of ferritic-martensitic steels are performed and the effects of SCW temperature and dissolved oxygen on the oxidation rate are analyzed. The diffusion processes in oxide in terms of diffusion species and mechanisms are determined and the structure of the various oxide phases and their formation are understood [5]. In situ electrical and electrochemical measurements during oxidation of ferritic steel P91 and austenitic steel AISI 316L (NG) in ultrasupercritical water (500-700 ∘ C, 30 MPa) have been carried out.…”

Section: Introductionmentioning

confidence: 99%

“…The inner oxide consisted of small equiaxed grains of Fe-Cr spinel oxide Fe 3− Cr O 4 , where (0.7-1) depends on alloy type. The transition layer consisted of grain boundary oxides of chromia and chromite and fine oxide grains of a spinel structure precipitated inside laths [5]. Martinelli et al [12] focused on the growth kinetics simulation of a duplex oxide scale of a Fe-9Cr-1Mo martensitic steel (T91) in static liquid Pb-Bi.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Oxidation Kinetics and Oxide Scale Void Position of Ferritic-Martensitic Steels in Supercritical Water

Sun

Yan

2017

Advances in Materials Science and Engineering

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Exfoliation of oxide scales from high-temperature heating surfaces of power boilers threatened the safety of supercritical power generating units. According to available space model, the oxidation kinetics of two ferritic-martensitic steels are developed to predict in supercritical water at 400 ∘ C, 500 ∘ C, and 600 ∘ C. The iron diffusion coefficients in magnetite and Fe-Cr spinel are extrapolated from studies of Backhaus and Töpfer. According to Fe-Cr-O ternary phase diagram, oxygen partial pressure at the steel/Fe-Cr spinel oxide interface is determined. The oxygen partial pressure at the magnetite/supercritical water interface meets the equivalent oxygen partial pressure when system equilibrium has been attained. The relative error between calculated values and experimental values is analyzed and the reasons of error are suggested. The research results show that the results of simulation at 600 ∘ C are approximately close to experimental results. The iron diffusion coefficient is discontinuous in the duplex scale of two ferritic-martensitic steels. The simulation results of thicknesses of the oxide scale on tubes (T91) of final superheater of a 600 MW supercritical boiler are compared with field measurement data and calculation results by Adrian's method. The calculated void positions of oxide scales are in good agreement with a cross-sectional SEM image of the oxide layers.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Estimation of Oxidation Kinetics and Oxide Scale Void Position of Ferritic-Martensitic Steels in Supercritical Water

Sun

Yan

2017

Advances in Materials Science and Engineering

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“…13) Moreover, increasing the oxide temperature would effectively enhance the diffusion speed of oxygen elements, and increase the heat-activation of iron substrate. The relative agreement between the activate energies for oxidation and that of grain boundary diffusion of oxygen supports an oxidation mechanism based on a short circuit oxygen diffusion to the oxide-metal interface.…”

Section: Resultsmentioning

confidence: 99%

Improvement of Aluminum Erosion Behavior and Corrosion Resistance of AISI H13 Tool Steel by Oxidation Treatment

Chang

Tang

Huang³

2010

ISIJ Int.

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In this work, H13 tool steel was prepared with different oxidation treatments to investigate the effects of oxidation temperature and soaking time. In order to improve erosion and corrosion resistance, this study tested with oxidation temperatures of 560°C, 580°C, and 600°C, and oxidation soaking times of 1 h, 2 h, and 3 h, respectively. Experimental results showed that the oxidation treatment at 600°C and for 3 h is the optimum process. The average thickness of the oxide layer was 9.2 mm. It showed that the oxide layer (Fe 3 O 4 ) can protect and improve the aluminum erosion of H13 steel. The specimens that underwent the oxidative procedure were proven to effectively reduce the ratio of Al-Fe-Si compounds during erosion tests of A380 alloy solution. In addition, the results showed that the oxide layer can enhance polarization resistance, and quickly generate a passivation layer to increase the ability of corrosion resistance.KEY WORDS: H13 tool steel; erosion; corrosion; oxidation; A380 alloy. 569© 2010 ISIJ in order to enhance the erosion rate and weight loss. After removing the aluminum, specimens were cleaned with NaOH to remove any oxide or other residue. The weight loss percentage of erosion test is calculated as follows:Weight loss (%)ϭ(IWϪAW)/IWϫ100 IW is the initial weight, and AW is the weight after erosion test.Corrosion potential analysis adopted three electrodes method. Reference electrode was saturated with silver-silver chloride electrode, auxiliary electrode was a Platinum electrode, and working electrode was connected to the testing specimens. The contact area of specimen was 2.01 cm 2 . Meanwhile, the corrosive solvent used 3.5 wt% NaCl, and was kept at room temperature. The main parameters of corrosion testing included: scanning speed of 0.5 mV s Ϫ1, initial potential of Ϫ1.5 V, and the final potential of 0.5 V. The polarization curve was obtained by Corr-View software for analysis, and compared with different oxidation parameters of the corrosion potential (E corr ) and corrosion current (I corr ). Finally, the polarization resistances (R p ) of different oxidation treatments for AISI H13 tool steel were compared. To evaluate the improvement in erosion and corrosion resistance of AISI H13 tool steel via different oxidation processes, erosion and corrosion tests, XRD and EDS, and microstructure inspections were performed. Figure 3 shows the XRD patterns of H13 tool steel after 560°C 1 h, 2 h, and 3 h of oxidation treatment. As seen, the strongest peak is the original a-Fe structure, in addition, there are two other different crystal structures, Obviously, at the same temperature and different soaking times of oxidation treatment, XRD analysis indicated that two different kinds of oxide layers were provided after oxidation treatments, which are the crystal structures of Fe 3 O 4 and Fe 2 O 3 . The intensity of the original a-Fe gradually decreased as the soaking time of oxidation increased, indicating that increasing the soaking time of oxidation would reduce the proportion of the a-Fe structur...

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“…The previous study indicates that the complex intermetallic layers of FexAlySiz formed on the surface of the H13 metal normally are FeAl4Si, Fe6Al15Si5 and Fe6Al12Si5. 14) Micro-photographic observations of cross sections of O-NH13 specimens, both before and after 4 h erosion tests, are shown in Fig. 5.…”

Section: Methodsmentioning

confidence: 99%

Effects of Post-oxidizing Treatment on Melting Loss and Corrosion Resistance of Gas Nitrided AISI H13 Tool Steel

Chang

Tang

Huang³

et al. 2012

ISIJ Int.

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This study conducted gas nitriding on AISI H13 steels, followed by oxidization treatments at various temperatures (560°C, 580°C, 600°C) and soaking times (1 h, 2 h, 3 h), to investigate the melting loss and corrosion resistance of A380 aluminum alloy. The experimental results indicated that the samples of oxynitriding (post-oxidizing treatment after nitrided) at 580°C for 3 h, 600°C for 2 h and 600°C for 3 h have better ability to resist melting loss due to their thicker oxidized layers. The weight loss rate also showed that they are near zero after a 4 h erosion test. The increasing weight loss rate is relative to the appearance of the FexAlySiz compound. In addition, the difference in corrosion current is closely related to the corrosion rate. A smaller corrosion current will lead to a smaller corrosion rate. As a result, increasing the temperature and soaking time of oxidization is advantageous to the corrosion resistance, and a small variation in corrosion current will result in a significant change to the polarization resistance of corrosion. Consequently, the oxide layer can enhance the polarization resistance, and quickly generate a passivation layer that increases the corrosion resistance ability.

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Oxidation of ferritic–martensitic alloys T91, HCM12A and HT-9 in supercritical water

Cited by 157 publications

References 19 publications

Estimation of Oxidation Kinetics and Oxide Scale Void Position of Ferritic-Martensitic Steels in Supercritical Water

Estimation of Oxidation Kinetics and Oxide Scale Void Position of Ferritic-Martensitic Steels in Supercritical Water

Improvement of Aluminum Erosion Behavior and Corrosion Resistance of AISI H13 Tool Steel by Oxidation Treatment

Effects of Post-oxidizing Treatment on Melting Loss and Corrosion Resistance of Gas Nitrided AISI H13 Tool Steel

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