Application of an advanced mean-field dislocation creep model to P91 for calculation of creep curves and time-to-rupture diagrams

Riedlsperger, Florian; Krenmayr, Bernhard; Zuderstorfer, Gerold; Fercher, Bernhard; Niederl, Bernd; Schmid, Johannes; Sonderegger, Bernhard

doi:10.1016/j.mtla.2020.100760

Cited by 19 publications

(22 citation statements)

References 59 publications

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“…Dislocation pile-ups have also been proposed to nucleate cavities at grain boundaries [9]. While recent advances in calculating creep curves by modelling dislocations are promising [51], dislocation creep plays only a minor role in the long term creep of power plant components. It is more reasonable to model cavity nucleation and growth by diffusion where diffusional creep is the dominant deformation mechanism.…”

Section: Discussionmentioning

confidence: 99%

Cavity Nucleation and Growth in Nickel-Based Alloys during Creep

2022

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The number of fossil fueled power plants in electricity generation is still rising, making improvements to their efficiency essential. The development of new materials to withstand the higher service temperatures and pressures of newer, more efficient power plants is greatly aided by physics-based models, which can simulate the microstructural processes leading to their eventual failure. In this work, such a model is developed from classical nucleation theory and diffusion driven growth from vacancy condensation. This model predicts the shape and distribution of cavities which nucleate almost exclusively at grain boundaries during high temperature creep. Cavity radii, number density and phase fraction are validated quantitively against specimens of nickel-based alloys (617 and 625) tested at 700 °C and stresses between 160 and 185 MPa. The model’s results agree well with the experimental results. However, they fail to represent the complex interlinking of cavities which occurs in tertiary creep.

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Section: Discussionmentioning

confidence: 99%

Cavity Nucleation and Growth in Nickel-Based Alloys during Creep

2022

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“…Implementation of the presented microstructural and phase data into a recently published mean-field dislocation creep model [ 60 ] is planned.…”

Section: Discussionmentioning

confidence: 99%

Thermodynamic Modelling and Microstructural Study of Z-Phase Formation in a Ta-Alloyed Martensitic Steel

et al. 2021

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A thermokinetic computational framework for precipitate transformation simulations in Ta-containing martensitic Z-steels was developed, including Calphad thermodynamics, diffusion mobility data from the literature, and a kinetic parameter setup that considered precipitation sites, interfacial energies and dislocation density evolution. The thermodynamics of Ta-containing subsystems were assessed by atomic solubility data and enthalpies from the literature as well as from the experimental dissolution temperature of Ta-based Z-phase CrTaN obtained from differential scanning calorimetry. Accompanied by a comprehensive transmission electron microscopy analysis of the microstructure, thermokinetic precipitation simulations with a wide-ranging and well-documented set of input parameters were carried out in MatCalc for one sample alloy. A special focus was placed on modelling the transformation of MX into the Z-phase, which was driven by Cr diffusion. The simulation results showed excellent agreement with experimental data in regard to size, number density and chemical composition of the precipitates, showing the usability of the developed thermokinetic simulation framework.

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“…(1). Latter term has been introduced by Riedlsperger [5] incorporating glide and climb processes. Since both quantities, ρ m and υ eff , result from interactions within the microstructure, we take a closer look at those, see e. Spontaneous annihilation of mobile (e 1 ) and static dislocations (e 2 ) f. Subgrain boundaries produced from static dislocations g. Subgrain growth minus Zener-pinning of boundary precipitates These interactions (a-g) are also integrated into the rate equations for the microstructural evolution of mobile dislocations ρ m , static dislocations ρ s , dislocations within subgrain boundaries ρ b , and subgrain boundaries R sgb ; see Eqs.…”

Section: Creep Model: Our Microstructurally Based Approachmentioning

confidence: 99%

“…( 9), has been deducted by geometrical means [6]. The effective velocity of mobile dislocations v eff includes glide processes as well as climbing of dislocations over precipitates within the subgrain interior [5]. The glide velocity of mobile dislocations υ g considers forward and potential backward movements according to their jump probabilities, which are linked to mechanical and thermal activation [9].…”

Section: Creep Model: Our Microstructurally Based Approachmentioning

confidence: 99%

“…These kinds of models are easily and quickly employed; however, the approaches carry some disadvantages as well: (1) they give little or no insight into the actual underlying physical processes governing the creep rate, and (2) the model parameters cannot be usually determined independently from the creep experiment the model is actually aiming to predict. For these reasons, we choose to focus on a physically based model instead [5], which is a reviewed, corrected, and extended version of the seminal work of Ghoniem [6]. In addition to avoiding the mentioned drawbacks of phenomenological approaches, our physical model has the advantage of including a variety of microstructural elements such as dislocations and subgrain boundaries (SGBs), and their interactions.…”

Section: Introductionmentioning

confidence: 99%

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Microstructurally Based Modeling of Creep Deformation and Damage in Martensitic Steels

Sommitsch¹,

Sonderegger²,

Ahmadi³

et al. 2023

Failure Analysis - Structural Health Monitoring of Structure and Infrastructure Components

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This chapter deals with modeling the microstructural evolution, creep deformation, and pore formation in creep-resistant martensitic 9–12% Cr steels. Apart from the stress and temperature exposure of the material, the input parameters for the models are as-received microstructure and one single-creep experiment of moderate duration. The models provide predictive results on deformation rates and microstructure degradation over a wide stress range. Due to their link to the underlying fundamental physical processes such as classical nucleation theory, Gibbs energy dissipation, climb, and glide of dislocations, etc., the models are applicable to any martensitic steel with similar microstructure to the presented case study. Note that we section the chapter into part 1: creep deformation and part 2: pore formation.

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Application of an advanced mean-field dislocation creep model to P91 for calculation of creep curves and time-to-rupture diagrams

Cited by 19 publications

References 59 publications

Cavity Nucleation and Growth in Nickel-Based Alloys during Creep

Cavity Nucleation and Growth in Nickel-Based Alloys during Creep

Thermodynamic Modelling and Microstructural Study of Z-Phase Formation in a Ta-Alloyed Martensitic Steel

Microstructurally Based Modeling of Creep Deformation and Damage in Martensitic Steels

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