Microstructure, Chemical- and Phase Composition of Sanicro 25 Austenitic Steel After Oxidation in Steam at 700 °C

Rutkowski, Bogdan; Gil, Alain Manuel Chaple; Agüero, Alina; González, Vanessa; Czyrska‐Filemonowicz, A.

doi:10.1007/s11085-017-9824-3

Cited by 12 publications

(12 citation statements)

References 16 publications

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“…The M 23 C 6 precipitates contain mainly Cr, with a minor amount of W. White precipitates on Figure 5 B consist of W, Fe, Cr, and Cu with stoichiometry close to (Fe,Cr,Cu) 2 W. Suo et al also found Laves phase in Sanicro 25 after creep tests [ 15 ] and proposed that the precipitation is promoted by stress.

-Cu precipitates, having the unit cell similar to that of austenite, consist of pure Cu and coagulate with time [ 9 ]. These small precipitates are desirable, to take part in the Orowan strengthening mechanism.…”

Section: Resultsmentioning

confidence: 99%

“…They were ground on abrasive papers with increasing gradation (from 600 to 4000 grit) and polished with diamond pastes (3, 1, 1/4 µm). Afterwards the samples were oxidised at 700 • C for up to 15,000 h. Test setup is described elsewhere [9,10]. Investigations on oxidized samples were performed both on sample surfaces and metallographic cross-sections.…”

Section: Methodsmentioning

confidence: 99%

“…Tungsten contributes to solid solution strengthening, similarly to P92 steel in comparison with the P91 grade [6,7]. Cu further strengthens Sanicro 25 [8], as small, 20-50 nm in size, ε-Cu precipitates, observed after exposure to high temperatures [9].…”

Section: Introductionmentioning

confidence: 90%

“…X-ray diffraction (XRD) measurements in Bragg-Brentano geometry [9], suggest the presence of two oxide phases Cr 2 O 3 and (Fe,X) 3 O 4 , where X = Fe or Cr, clarified by SEM, Figure 3, showing the morphology of the oxide scale surface to be a mixture of two types of structures. Very thin plates are visible in most of the area.…”

Section: After Oxidationmentioning

confidence: 99%

“…Sanicro 25 contains around 22% of Cr, making [15] and proposed that the precipitation is promoted by stress. ε-Cu precipitates, having the unit cell similar to that of austenite, consist of pure Cu and coagulate with time [9]. These small precipitates are desirable, to take part in the Orowan strengthening mechanism.…”

Section: After Oxidationmentioning

confidence: 99%

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Microstructural Characterisation of Austenitic Heat Resistant Sanicro 25 Steel after Steam Oxidation

Rutkowski

2020

Materials

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Microstructural and morphological observations of the surface scale on a high Cr and Ni austenitic heat resistant steel oxidised in water vapour at 700 °C are reported. Analysis of microstructure was carried out by analytical techniques of transmission- and scanning electron microscopy. Investigation of M23C6 nucleated at the interface between matrix and the Z-phase precipitates after exposing to high temperature showed semicoherency between M23C6 and the matrix and no coherency with the Z-phase. Plates developed on the oxide scale surface consist of Cr2O3 crystals separated by amorphous SiO2.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 90%

Section: After Oxidationmentioning

confidence: 99%

Section: After Oxidationmentioning

confidence: 99%

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Microstructural Characterisation of Austenitic Heat Resistant Sanicro 25 Steel after Steam Oxidation

Rutkowski

2020

Materials

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Fireside Corrosion of Heat Exchanger Materials for Advanced Solid Fuel Fired Power Plants

et al. 2021

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To address the challenge of climate change, future energy systems need to have reduced greenhouse gas emissions and increased efficiencies. For solid fuel fired combustion plants, one route towards achieving this is to increase the system’s steam temperatures and pressures. Another route is to co-fire renewable fuels (such as biomass) with coals. Fireside corrosion performance of two candidate superheater/reheater alloys has been characterised at higher heat exchanger surface temperature. Samples of the alloys (a stainless steel, Sanicro 25 and a nickel-based alloy, IN740) were exposed in fireside corrosion tests at 650 °C, 700 °C and 750 °C, in controlled atmosphere furnaces using the ‘deposit recoat’ test method to simulate superheater/reheater exposure for 1000 h. After exposure, the samples were analysed using dimensional metrology to determine the extent and distributions of corrosion damage in terms of surface recession and internal damage. At 650 °C, the stainless steel and nickel-based alloy performed similarly, while at 700 °C and above, the median damage to the steel was at least 3 times greater than for the nickel-based alloy. Optical and electronic microscopy studies were used to study samples’ damage morphologies after exposure. Intergranular damage and pits were found in sample cross sections, while chromium depletion was found in areas with internal damage. For high-temperature applications, the higher cost of the nickel-based alloy could be offset by the longer life they would allow in plant with higher operating temperatures.

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Air Oxidation Behavior of Sanicro-25 with Different Surface Finishes

Rao,

Aishwarya,

Kumar

et al. 2024

J. of Materi Eng and Perform

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Sanicro-25 is a high-temperature material used as the structural material for steam superheaters and reheaters in advanced ultra-supercritical power plants. The air oxidation behavior of Sanicro-25 with various surface roughnesses is being assessed at 650 °C for about 1000 h. Different surface-roughened samples were studied, namely polishing the sample up to diamond finish, grinding up to (80-grit finish and 600-grit finish) and grit blasted. The diamond finish sample showed more weight gain than others, and higher weight gain was observed in the initial oxidation stage. Attributed to different surface preparations leads to defects at different levels, which further alters the diffusion of various elements. The diamond finish sample showed the presence of Cr-rich oxides, and other samples showed the presence of Fe-rich oxides. Smooth surfaces promoted the formation of thick protective oxide scales.

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Microstructure, Chemical- and Phase Composition of Sanicro 25 Austenitic Steel After Oxidation in Steam at 700 °C

Cited by 12 publications

References 16 publications

Microstructural Characterisation of Austenitic Heat Resistant Sanicro 25 Steel after Steam Oxidation

Microstructural Characterisation of Austenitic Heat Resistant Sanicro 25 Steel after Steam Oxidation

Fireside Corrosion of Heat Exchanger Materials for Advanced Solid Fuel Fired Power Plants

Air Oxidation Behavior of Sanicro-25 with Different Surface Finishes

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