Carburisation of ferritic Fe–Cr alloys by low carbon activity gases

Gheno, Thomas; Monceau, Daniel; Zhang, Jianqiang; Young, David J.

doi:10.1016/j.corsci.2011.05.013

Cited by 155 publications

(80 citation statements)

References 22 publications

(40 reference statements)

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“…• C, the chromium content (22 at % Cr) of Ni-20Cr alloy is close to N (1) Cr and higher than N (2) Cr . As a result, this alloy should exhibit marginal behavior in terms of chromia formation but succeed in maintaining the chromia layer once it emerges.…”

Section: Discussionmentioning

confidence: 99%

“…The chromium content (32.6 at % Cr) of Ni-30Cr alloy is slightly higher than N (1) Cr , so marginal behavior could be expected. This was in fact evidenced by a continuous Cr 2 O 3 band formed at the oxide scale base (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…10f leads to the estimate k p ≈ 1.7 × 10 −14 cm 2 /s. Calculated values of N (1) Cr and N (2) Cr are summarized in Table V, along with the underlying data. It is seen that both N (1) Cr and N (2) Cr are predicted to vary inversely with oxidation temperature.…”

Section: Discussionmentioning

confidence: 99%

“…According to Wagner's theory, this critical concentration of chromium, N (1) Cr , required to form external rather than internal oxide can be estimated from the equation:…”

Section: Discussionmentioning

confidence: 99%

“…Exposed to this atmosphere, the chromia-forming steels which are used successfully in air, undergo breakaway oxidation and carburization. [1][2][3][4] In addition, increased operating temperatures to improve boiler heat efficiency are desirable to meet continuously increasing energy demand, e.g. in advanced ultra-supercritical power generation.…”

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confidence: 99%

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Temperature Effect on Oxidation Behavior of Ni-Cr Alloys in CO₂Gas Atmosphere

Xie

Zhang

Young

2017

J. Electrochem. Soc.

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Model Ni-Cr alloys containing 5, 10, 15, 20, 25 and 30 wt% Cr were oxidized in Ar-20 vol% CO 2 gas mixtures at temperatures of 650, 700 and 800 • C. In general, multi-layered oxide scales were observed on the surface after reaction. With increased alloy Cr content, the oxide structure changed from external NiO, plus intermediate inner oxides and an internal oxidation zone, to forming a thin chromia band at the base of the oxide scale and, at higher Cr levels, an exclusive chromia scale. Increasing temperature accelerated the oxidation kinetics of low chromium-containing alloys, but significantly reduced the oxidation rate of high chromium alloys by promoting formation of the chromia band/scale. The critical Cr concentration required for chromia scale formation and maintenance decreased with increasing temperature, in accord with diffusion theory. Intergranular carbides were formed in high Cr content alloys, indicating elevated carbon activities beneath the oxide scales. In conventional power plants, fossil fuels are burnt in air to generate electricity. This process is of low cost, but can produce a large amount of CO 2 gas, a principal contributor to global warming. To reduce CO 2 emissions, a new technology called oxy-fuel combustion has been developed. In this process, coal is burnt in a mixture of oxygen and recirculated flue gas, so the finally released flue gas consists mainly of CO 2 and water vapor. After condensation of water vapor, sequestering CO 2 gas from the flue gas is relatively easy.Unfortunately, this technology has the potential to exacerbate the corrosion problems encountered in power plants. The CO 2 gas has been found to be very corrosive to the steels of the critical heat exchanging components in boilers, producing severe oxidation and carburization of ferritic-martensitic steels. Exposed to this atmosphere, the chromia-forming steels which are used successfully in air, undergo breakaway oxidation and carburization. [1][2][3][4] In addition, increased operating temperatures to improve boiler heat efficiency are desirable to meet continuously increasing energy demand, e.g. in advanced ultra-supercritical power generation. As a result, the ferritic/martensitic and even austenitic steels currently used in traditional coal-fired power plants will not survive when the operating temperature increases to values higher than 650• C. 5-7 Under these circumstances, nickel-based alloys are alternative candidate materials, owing to their superior creep strength and corrosion resistance at higher temperatures. However, little is known about the corrosion behavior of Ni-based alloys in CO 2 -rich gases at high temperatures.The oxidation of various model Ni-Cr alloys in air and oxygen has been well investigated at temperatures between 800 and 1200• C, [8][9][10][11][12][13] and the oxidation of these alloys in H 2 O-containing environments has also been reported. [14][15][16][17] In air and oxygen environments, it has been generally accepted that binary Ni-Cr alloys with Cr contents lower than 10 wt% oxid...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…According to Wagner's theory, this critical concentration of chromium, N (1) Cr , required to form external rather than internal oxide can be estimated from the equation:…”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Temperature Effect on Oxidation Behavior of Ni-Cr Alloys in CO₂Gas Atmosphere

Xie

Zhang

Young

2017

J. Electrochem. Soc.

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Effect of SO₂ on oxidation of metallic materials in CO₂/H₂O‐rich gases relevant to oxyfuel environments

Huczkowski

Olszewski

Schiek

et al. 2013

Materials & Corrosion

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In an oxyfuel plant, heat exchanging metallic components will be exposed to a flue gas that contains substantially higher contents of CO2, water vapor, and SO2 than conventional flue gases. In the present study, the oxidation behavior of the martensitic steel P92 was studied in CO2‐ and/or H2O‐rich gas mixtures with and without addition of SO2. For this purpose, the corrosion of P92 at 550 °C up to 1000 h in Ar–H2O–SO2, Ar–CO2–SO2, Ar–CO2–O2–SO2 and simulated oxyfuel gas (Ar–CO2–H2O–O2–SO2) was compared with the behavior in selected SO2‐free gases. The oxidation kinetics were estimated by a number of methods such as optical microscopy, scanning electron microscopy with energy and wave length dispersive X‐ray analysis, glow discharge optical emission spectroscopy, X‐ray diffraction as well as transmission electron microscopy. The experimental results revealed that the effect of SO2 addition on the materials behavior substantially differed, depending on the prevailing base gas atmosphere. The various types of corrosion attack affected by SO2 could not be explained by solely comparing equilibrium activities of the gas atmospheres with thermodynamic stabilities of possible corrosion products. The results were found to be strongly affected by relative rates of reactions of the various gas species occurring within the frequently porous corrosion scales as well as at the scale/gas‐ and scale/alloy interfaces. Whereas SO2 addition to Ar–CO2 resulted in formation of an external mixed oxide/sulfide layer, the presence of SO2 in oxyfuel gas and in Ar–H2O–SO2 resulted in Fe‐sulfide formation near the interface between inner and outer oxide layer as well as Cr‐sulfide formation in the alloy. In the latter gases, the presence of SO2 seemed to have no dramatic effect on oxide scale growth rates.

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Effect of pressure on supercritical CO₂ compatibility of structural alloys at 750 °C

Pint

Brese

Keiser

2016

Materials & Corrosion

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Several power generation technologies have interest in employing a supercritical CO2 (sCO2) cycle but relatively little compatibility work has been conducted at the target pressure range of 200–300 bar, particularly at ≥700 °C. With the goal of utilizing lower pressure data sets (especially with controlled O2 and H2O contents), this initial assessment compared the effect of CO2 pressure at 1–300 bar on the compatibility of potential Fe‐ and Ni‐base structural alloys after 500 h exposures at 750 °C. For highly‐alloyed alumina‐ and chromia‐forming alloys, a minimal effect of pressure was observed on the mass change and reaction products, which were similar to those observed in 1 bar dry air, CO2, CO2–0.15%O2 and CO2–10%H2O. After these relatively short exposures, there was no obvious indication of internal carburization and the Cr depletion in the precipitation strengthened Ni‐base alloys (740 and 282) was minimal. In addition to coupons, 25 mm long tensile specimens of alloy 740, 247, 310HCbN, and E‐Brite (Fe–Cr) were exposed in each condition but did not show any detrimental effect of the high‐purity CO2 environments on room temperature tensile properties.

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Carburisation of ferritic Fe–Cr alloys by low carbon activity gases

Cited by 155 publications

References 22 publications

Temperature Effect on Oxidation Behavior of Ni-Cr Alloys in CO₂Gas Atmosphere

Temperature Effect on Oxidation Behavior of Ni-Cr Alloys in CO₂Gas Atmosphere

Effect of SO₂ on oxidation of metallic materials in CO₂/H₂O‐rich gases relevant to oxyfuel environments

Effect of pressure on supercritical CO₂ compatibility of structural alloys at 750 °C

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Carburisation of ferritic Fe–Cr alloys by low carbon activity gases

Cited by 155 publications

References 22 publications

Temperature Effect on Oxidation Behavior of Ni-Cr Alloys in CO2Gas Atmosphere

Temperature Effect on Oxidation Behavior of Ni-Cr Alloys in CO2Gas Atmosphere

Effect of SO2 on oxidation of metallic materials in CO2/H2O‐rich gases relevant to oxyfuel environments

Effect of pressure on supercritical CO2 compatibility of structural alloys at 750 °C

Contact Info

Product

Resources

About

Temperature Effect on Oxidation Behavior of Ni-Cr Alloys in CO₂Gas Atmosphere

Temperature Effect on Oxidation Behavior of Ni-Cr Alloys in CO₂Gas Atmosphere

Effect of SO₂ on oxidation of metallic materials in CO₂/H₂O‐rich gases relevant to oxyfuel environments

Effect of pressure on supercritical CO₂ compatibility of structural alloys at 750 °C