Thermodynamic and kinetic modelling: Creep resistant materials

Hald, John; Korcakova, L.; Danielsen, Hilmar Kjartansson; Dahl, Kristian Vinter

doi:10.1179/174328408x265622

Cited by 18 publications

(5 citation statements)

References 27 publications

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“…Given that austenite has higher affinity for C than α-ferrite, the M23C6 precipitates exist up to 865 °C, and then dissolve into the austenitic matrix. The mass fraction of MX type precipitates was constant till Ac3 temperature, but then gradually decreased with increased temperature and totally dissolved at ~1200 °C [24]. In the present study, the volume fraction of Nb-rich MX increased at ~770 °C, started to decrease rapidly after ~850 °C, then gradually at ~1120 °C till 1260 °C.…”

Section: Thermo-calc Calculationssupporting

confidence: 52%

Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel

Shrestha

Alsagabi

Charit

et al. 2015

Metals

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Grade 91 steel (modified 9Cr-1Mo steel) is considered a prospective material for the Next Generation Nuclear Power Plant for application in reactor pressure vessels at temperatures of up to 650 °C. In this study, heat treatment of Grade 91 steel was performed by normalizing and tempering the steel at various temperatures for different periods of time. Optical microscopy, scanning and transmission electron microscopy in conjunction with microhardness profiles and calorimetric plots were used to understand the microstructural evolution including precipitate structures and were correlated with mechanical behavior of the steel. Thermo-Calc™ calculations were used to support the experimental work. Furthermore, carbon isopleth and temperature dependencies of the volume fraction of different precipitates were constructed.

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Section: Thermo-calc Calculationssupporting

confidence: 52%

Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel

Shrestha

Alsagabi

Charit

et al. 2015

Metals

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“…(It has later been discovered that HCM12 has been unable to live up to expectations. 1 ) The corrosion and oxidation rates are compared to the well known reference alloys X20 and T91 which were exposed at the same time and in the same location as the other steels. The data have been collected in four confidential reports [2][3][4][5] and this paper seeks to highlight some of the interesting results from the investigations.…”

Section: Introductionmentioning

confidence: 99%

Fireside corrosion and steamside oxidation of 9–12%Cr martensitic steels exposed for long term testing

Montgomery

Jensen

Rasmussen

et al. 2009

Corrosion Engineering, Science and Technology

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To obtain long term corrosion and steam oxidation data for the 9-12%Cr ferritic steels, test tube sections have been exposed in Amager 3 and Avedøre 1 coal fired power plants in Denmark (formerly run by ENERGI E2). Thus direct comparisons can be made for T91 and T92 for the 9%Cr steels and X20CrMoV121 and HCM12 for the 12%Cr steels. The test tubes were welded in as part of the existing final superheaters in actual plants and exposure has been conducted over a ten year period (1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005). Compared to the older steel types, T92 and HCM12 utilise tungsten to improve their creep strength. From Avedøre I testing, T91 and T92 can be compared for exposure times up to y48 000 h exposure. From Amager 3 testing, X20, HCM12 and T92 were tested; T92 has been exposed for up to 31 000 h and X20 and HCM12 have had 84 500 h exposure. Tube sections were removed for various exposure durations such that steamside oxidation and fireside corrosion could be investigated with respect to exposure time. The fireside corrosion rate was assessed by oxide thickness and in some cases residual metal thickness. The growth of steamside oxide was assessed by inner oxide thickness. The microstructure and chromium content of the corroded layers has been investigated using light optical and scanning electron microscopy. The fireside corrosion rate for the T92 and HCM12 steels are comparable to those of T91, however X20CrMoV121 has a higher fireside corrosion rate after the longest exposure time. For steamside oxidation, it was HCM12 that revealed high oxidation rates after the longest exposure time.

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“…The lack of diffusion data for γ' and β has previously been troublesome. Hald et al [21] circumvented this by a "labyrinth factor" which took into account the impeded diffusion due to phases other than γ.…”

Section: Introductionmentioning

confidence: 99%

“…Recent attempts to utilize Thermo-Calc and DICTRA for such purposes include Nijdam and Sloof [20] who modeled the β-depletion due to isothermal and cyclic oxidation of a freestanding MCrAlY. Beck et al [16] modeled coating-substrate interdiffusion for NiCoCrAlY coatings; the model was said to be "semi-quantitative" and usable mainly for microstructures low in γ' and β. Hald et al [21] modeled the interdiffusion for an MCrAlY coating; diffusion was only modeled to occur in the γ matrix phase. The lack of diffusion data for γ' and β has previously been troublesome.…”

Section: Introductionmentioning

confidence: 99%

Modeling of microstructural evolution and lifetime prediction of MCrAlY coatings on nickel based superalloys during high temperature oxidation

Yuan

Eriksson

Peng

et al. 2013

Surface and Coatings Technology

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MCrAlY coatings are deposited onto superalloys to provide oxidation and corrosion protection at high temperature by the formation of a thermally grown oxide scale. In this project, the oxidation behaviour of a HVOF CoNiCrAlYSi coating on IN792 was studied for both isothermal oxidation (900, 1000 and 1100 °C) and thermal cycling (100-1100 °C). The microstructural evolution of the CoNiCrAlYSi coatings after oxidation was investigated. It was found that the Al-rich β phase is gradually consumed due to two effects: surface oxidation and coating-substrate interdiffusion. Some voids and oxides along the coating-substrate interface, or inside the coating, were considered to play a role in blocking the diffusion of alloying elements. Based on the microstructural observation, an oxidation-diffusion model, considering both surface oxidation and coating-substrate interdiffusion, was developed by using Matlab and DICTRA software to predict the useful life of MCrAlY coatings.A new concept of diffusion blocking is also introduced into the model to give more accurate description on the microstructural evolution. The results from modeling and the experimentally established composition profiles showed good agreement.

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Thermodynamic and kinetic modelling: Creep resistant materials

Cited by 18 publications

References 27 publications

Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel

Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel

Fireside corrosion and steamside oxidation of 9–12%Cr martensitic steels exposed for long term testing

Modeling of microstructural evolution and lifetime prediction of MCrAlY coatings on nickel based superalloys during high temperature oxidation

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