Analysis of Phase Precipitation in Sanicro 25 Austenitic Steel after Ageing

Sroka, M.; Zieliński, A.; Golański, G.

doi:10.12693/aphyspola.135.207

Cited by 3 publications

(3 citation statements)

References 15 publications

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“…Therefore, adding Cu to austenitic heat‐resistant steels can cause a high‐temperature strengthening effect by inducing nanosize Cu‐rich phase precipitation. [ 36,38 ]…”

Section: Resultsmentioning

confidence: 99%

“…[31b,37] Therefore, adding Cu to austenitic heat-resistant steels can cause a high-temperature strengthening effect by inducing nanosize Cu-rich phase precipitation. [36,38] Figure 11b shows the special morphology of the precipitation phase with the form of a short rod or cross star shape, which is rich in Nb, Cr, and N elements according to EDS mapping. This indicates that it is a Z phase with a tetragonal crystal structure and chemical formula NbCrN.…”

Section: Microstructure Analysismentioning

confidence: 99%

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Microstructure and Oxidation Behavior of C‐HRA‐5 Austenitic Heat‐Resistant Steel in Air at the Temperature Range of 650–750 °C

Jia,

Li,

et al. 2024

Adv Eng Mater

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This study investigates the oxidation behavior and microstructure characterization of C‐HRA‐5 (i.e., a new austenitic heat‐resistant steel) in the air at temperatures ranging from 650°C to 750°C over a 1000‐hour duration. The oxidation behavior and mechanism were analyzed using gravimetric evaluation, thermodynamic analysis, microscopic morphology, and microstructure characterization. The results indicate that the oxidation behavior follows a parabolic law at each temperature. With increasing the temperature, the oxide film gradually grows and transforms from small lump particles to strips and needles, eventually covering the entire substrate surface over time. Moreover, long‐term oxidation exposure promotes the formation of various phases, including M23C6, σ, MX, Z, nano‐sized Cu‐rich, and Laves phases, within the metallic substrate. Considering potential applications in new generation power plants, this study provides a solid foundation to disclose the possible oxidation of C‐HRA‐5 austenitic heat‐resistant steel at high temperatures.This article is protected by copyright. All rights reserved.

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“…Therefore, adding Cu to austenitic heat‐resistant steels can cause a high‐temperature strengthening effect by inducing nanosize Cu‐rich phase precipitation. [ 36,38 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Microstructure Analysismentioning

confidence: 99%

Microstructure and Oxidation Behavior of C‐HRA‐5 Austenitic Heat‐Resistant Steel in Air at the Temperature Range of 650–750 °C

Jia,

Li,

et al. 2024

Adv Eng Mater

View full text Add to dashboard Cite

show abstract

“…Solution strengthening and precipitation strengthening constitute the primary techniques for strengthening the characteristics of such steel or alloys. These techniques entail the addition of alloy elements to impart M 23 C 6 , MX, Laves, and Z phases, as well as Cu-rich precipitates [ 5 , 6 , 7 , 8 ]. Sanicro 25 steel is considered an excellent engineering material that can be used in the high-pressure and high-temperature environments of high-efficiency power stations [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Precipitate Evolution in 22Cr25NiWCuCo(Nb) Austenitic Heat-Resistant Stainless Steel during Heat Treatment at 1200 °C

Yang

Pan³

et al. 2021

Materials

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In this study, 22Cr25NiWCuCo(Nb) heat-resistant steel specimens with high Cr and Ni contents were adopted to investigate the effect of Nb content on thermal and precipitation behavior. Differential scanning calorimetry profiles revealed that the melting point of the 22Cr25NiWCuCo(Nb) steel specimens decreased slightly with the Nb content. After heat treatment at 1200 °C for 2 h, the precipitates dissolved in a Nb-free steel matrix. In addition, the Z phase (CrNb(C, N)) and MX (Nb(C, N), (Cr, Fe)(C, N), and NbC) could be observed in the Nb-containing steel specimens. The amount and volume fraction of the precipitates increased with the Nb content, and the precipitates were distributed heterogeneously along the grain boundary and inside the grain. Even when the heat treatment duration was extended to 6 h, the austenitic grain size and precipitates became coarser; the volume fraction of the precipitates also increased at 1200 °C. The Z phase, rather than the MX phase, became the dominant precipitates at this temperature.

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The influence of the temperature on the mechanical properties of Sanicro 25 steel

Sroka

2021

IOP Conf. Ser.: Mater. Sci. Eng.

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Austenitic steel 22Cr25NiWCoCu (Sanicro 25) is one of the newest and most promising steels for use in supercritical and ultra-supercritical power units. High resistance of Sanicro 25 steel to corrosion and oxidation in the steam atmosphere at up to 700 °C is ensured by chromium content at 21.5-23.5 wt%. Also, higher chromium content provides less mass decrement during high-temperature corrosion at 700 °C. Currently, the Sanicro 25 steel is characterised by the highest creep strength among the commercially used creep-resistant stainless steels. In this work, the study of precipitation processes and microstructure stability in the delivery state and after the ageing process in time up to 20,000 h at 750 °C was performed. Identification of secondary phases was performed using electron diffraction on thin films using transmission electron microscopy and X-ray phase composition analysis. Long-term ageing depending on time and temperature showed that there are four secondary phases in Sanicro 25: M23C6, MX, NbCrN, σ-phase and Cu_rich. The precipitation and increase in the size of secondary phase particles during ageing results in a decrease in matrix saturation with alloying elements, which leads to a reduction in hardening by solid solution mechanism. These processes and effects result in changes in mechanical properties. The alloy overageing effect observed for the ageing temperature of 750 °C results in obtaining strength properties similar to those of the steel in the as-received condition.

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Analysis of Phase Precipitation in Sanicro 25 Austenitic Steel after Ageing

Cited by 3 publications

References 15 publications

Microstructure and Oxidation Behavior of C‐HRA‐5 Austenitic Heat‐Resistant Steel in Air at the Temperature Range of 650–750 °C

Microstructure and Oxidation Behavior of C‐HRA‐5 Austenitic Heat‐Resistant Steel in Air at the Temperature Range of 650–750 °C

Precipitate Evolution in 22Cr25NiWCuCo(Nb) Austenitic Heat-Resistant Stainless Steel during Heat Treatment at 1200 °C

The influence of the temperature on the mechanical properties of Sanicro 25 steel

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