Evaluation of particle size distributions of precipitates in a 9% chromium steel using energy filtered transmission electron microscopy

Hättestrand, Mats; Andrén, Hans-Olof

doi:10.1016/s0968-4328(00)00086-x

Cited by 91 publications

(73 citation statements)

References 7 publications

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“…1) Especially, precipitation strengthening effect of MX carbonitride is important because its coarsening rate is small and fine particle size is maintained for long-term. [2][3][4] Many researches have been conducted on features and role of MX carbonitrides. 2,[5][6][7][8][9][10] A possibility of further improvement in creep strength by controlling MX carbonitride has been also investigated.…”

Section: Introductionmentioning

confidence: 99%

Phase Equilibrium between Austenite and MX Carbonitride in a 9Cr-1Mo-V-Nb Steel

et al. 2005

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Precipitation behavior during normalizing heat treatment has been investigated on a 9Cr-1Mo-V-Nb steel. Heterogeneously distributed spherical MX (MϭNb, V, Cr and XϭC, N) carbonitride particles and platelet M 3 C (MϭFe, Cr) carbide were observed in the as normalized condition. Number of the precipitates decreased with increasing normalizing temperature and no precipitates was observed after normalizing at 1 250°C. Although the size of M 3 C was almost constant independent of normalizing temperature, that of MX increased with increase in normalizing temperature up to 1 200°C. For MX carbonitride, not only size, but also composition of metallic elements was influenced by normalizing temperature. Since equilibrium composition of MX carbonitride depends on temperature, MX particle with non-equilibrium composition dissolves and precipitation of it takes place with its equilibrium composition at the normalizing temperature. A phase field diagram of NbX-VX quasi binary system in a 9Cr-1Mo-V-Nb steel was experimentally determined. It has been supposed that precipitation of M 3 C takes place during cooling from normalizing temperature in the surrounding area of MX particles where the concentration of niobium and vanadium in matrix is poor.KEY WORDS: ferritic creep resistant steel; 9Cr-1Mo-V-Nb steel; MX carbonitrides; cementite; phase equilibrium; precipitation behavior; two-phase separation; normalizing.quency vacuum induction furnace. The ingot was heated to 1 150°C for 1.5 h and hot rolled in a range of temperatures from 1 150°C to 900°C into bar with a diameter of 16 mm. Normalizing heat treatment conditions are shown in Table 2, together with prior austenite grain size number and Vickers hardness in the as normalized condition. Normalizing heat treatments were performed for 600 s in a range of temperatures from 1 050 to 1 250°C and for 3 600 s at 1 100 and 1 200°C, followed by air cooling. Prior austenite grain size of the steel coarsened with increase in normalizing temperature, but hardness of about HV400 was almost the same independent of normalizing temperature. Presence of d-ferrite was not detected for all the normalizing temperatures investigated.Distribution of precipitates was observed on carbon extracted replica under Field Emission Transmission Electron Microscope (FE-TEM). Each precipitates were analyzed by Energy Dispersion X-ray Spectroscopy attached to FE-TEM (TEM-EDS). Mechanically polished specimen surface was etched in a saturated solution of picric acid in ethyl alcohol with 1 % hydrochloric acid (Villela's reagent). The carbon was deposited on the etched surface, and the carbon film was detached from the specimen surface in a Villela's reagent. The carbon extracted replica was cleaned in ethyl alcohol and collected on copper grids for TEM examination. Precipitates were identified by means of X-ray diffraction analysis on an electrolytically extracted residue. Figure 1 shows a TEM micrograph of the carbon extracted replica prepared from the steel in the as received condition. Figure 1(b) is a high...

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Section: Introductionmentioning

confidence: 99%

Phase Equilibrium between Austenite and MX Carbonitride in a 9Cr-1Mo-V-Nb Steel

et al. 2005

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“…3 The subtraction of the characteristic background contribution from the postedge region in EELS result yields an elemental map that may be regarded as quantitative in nature. 3,4 The ratio of In and Ga elemental maps obtained by the earlier method, multiplied by a correction factor to account for the differing inelastic scattering cross sections involved, produces an atomic-ratio map ͑In/Ga ratio͒ which is selfnormalizing for both thickness and elastic effects. In addition, plural scattering deconvolution techniques may be applied to improve the quantitative accuracy of calculated elemental maps and the TEM thickness problem was corrected using the corresponding t/ map calculated from the low-loss data.…”

mentioning

confidence: 99%

Response to “Comment on ‘Effect of growth interruptions on the light emission and indium clustering of InGaN/GaN multiple quantum wells’ ” [Appl. Phys. Lett. 81, 3100 (2002)]

Cho

Lee

Sharma

et al. 2002

Applied Physics Letters

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“…The calculated volume fraction of Laves-phase at 923 K is about 0.58%, which is far lower than the upper limit of 0.95% in this study. The experimental results provided by Dimmler et al [16] and Hättestrand et al [13] also showed that the precipitated volume fraction of Laves-phase in steel P92 aged for 10000 h at 923 K is close to 1.0%. The calculated value is obtained at equilibrium which the Z-phase [Cr（V,Nb）N] forms and fully replaces the MX [（V,Nb）(C,N)] carbonitride, however, no Z-phase is observed during aging at 923 K up to 8000 h. Danielsen [17]have reported observed quantity of Z-phase is still low in P92 steel even after being exposured at 923K for 31000 h. Thus, the …”

Section: Quantitative Results Of the Laves-phasementioning

confidence: 83%

“…Energy filtered transmission electron microscope (EFTEM) offers this similar capability and has been proved to be very useful when applied to 9-12% Cr steel [12], however, this method is not suitable for Laves-phase because of its large precipitate size, only a small number of the specimen area can be observed in one TEM image, and yields poor statistics [13].…”

Section: Sem-bsementioning

confidence: 99%

Laves-phase evolution during aging in 9Cr-1.8W-0.5Mo-VNb steel for USC power plants

Wang

et al. 2015

Materials Chemistry and Physics

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-Laves-phase precipitation and coarsening of tungsten strengthened 9% Cr steel under thermal aging at 923K up to 8000 h was reported in this paper, where the information of the evolution of mean particle size, the number density, the volume fraction of Laves-phase precipitates and the partition coefficients of W and Mo in the matrix over the aging time were determined. The change of hardness over time was also measured. The main results of this investigation were: 1) Laves-phase nucleates and grows rapidly on grain boundaries and lath boundaries within the first 1,500 h of aging time; 2) the coarsening of Laves-phase is much faster than that of M 23 C 6 carbides, meanwhile it demonstrates the two stages characteristics and kinetics of Laves-phase nucleation and growth which were determined experimentally; 3)The precipitation of Laves-phase produces a pronounced matrix depletion of W and Mo atoms; and 4) The precipitated Laves-phase gives rise to weaker precipitation strengthening in comparison with M 23 C 6 carbides, and causes the loss of hardenss and creep strength due to the Corresponding author. Tel.: +86 13554693820; fax: +86 02768772253. E-mail address: wxue2011@whu.edu.cn (Xue Wang) 2 depletion of Mo and W from the solid solution. This paper contributes to the knowledge of kinetics of Laves-phase precipitation and coarsening, as well as understanding the creep damage broadly.

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Evaluation of particle size distributions of precipitates in a 9% chromium steel using energy filtered transmission electron microscopy

Cited by 91 publications

References 7 publications

Phase Equilibrium between Austenite and MX Carbonitride in a 9Cr-1Mo-V-Nb Steel

Phase Equilibrium between Austenite and MX Carbonitride in a 9Cr-1Mo-V-Nb Steel

Response to “Comment on ‘Effect of growth interruptions on the light emission and indium clustering of InGaN/GaN multiple quantum wells’ ” [Appl. Phys. Lett. 81, 3100 (2002)]

Laves-phase evolution during aging in 9Cr-1.8W-0.5Mo-VNb steel for USC power plants

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