Creep strength of austenitic stainless steels for boiler applications

Sandström, Rolf

doi:10.1533/9780857097323.1.127

Cited by 9 publications

(6 citation statements)

References 34 publications

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“…Various other austenitic stainless steels with Cr contents varying from 18 to 30% have been studied and used for boiler applications. 20 Nickel-based alloys with Cr contents varying between 18 and 25%, such as Inconel 740 and Inconel 617, have also been investigated for use in boiler components. 35 As this article mainly focuses on the WW in SCPC plants, corrosion models are developed for high-chromium iron and nickel alloys in this work.…”

Section: Corrosion Modelmentioning

confidence: 99%

“…TP304H, Super304H, TP347H, etc., are some of the austenitic steels of the 18Cr− 8Ni type used in boiler components. 20 There is ample work in the open literature focusing on corrosion of components like WWs, superheaters, reheaters, and air preheaters in subcritical and supercritical coal-fired power plants. 21−26 In most of these studies, either a sample of the ex-service component is collected during plant shutdown and using techniques like SEM and XRF, microanalysis and elemental analysis are conducted.…”

Section: Introductionmentioning

confidence: 99%

“…For temperatures between 650 and 700 °C, austenitic steels and nickel-based alloys are often used. TP304H, Super304H, TP347H, etc., are some of the austenitic steels of the 18Cr–8Ni type used in boiler components . There is ample work in the open literature focusing on corrosion of components like WWs, superheaters, reheaters, and air preheaters in subcritical and supercritical coal-fired power plants. − In most of these studies, either a sample of the ex-service component is collected during plant shutdown and using techniques like SEM and XRF, microanalysis and elemental analysis are conducted. ,, In other studies, alloys were exposed to synthetic coal-fired power plant environments in laboratory experiments. ,, In these laboratory studies, generally, the alloy is exposed to a corrosive gas environment for a certain period, and the corrosion layer built up on the metal surface is measured.…”

Section: Introductionmentioning

confidence: 99%

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Hot Corrosion Monitoring in Boilers Using a Nonlinear Estimator and Electrochemical Noise-Based Corrosion Sensors

Somayajula,

Bhattacharyya,

et al. 2023

Ind. Eng. Chem. Res.

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A kinetic model is developed to calculate the thickness of the corrosion scale formed due to hot corrosion in the waterwall section of a boiler in coal-fired power plants. The proposed model is validated by using the data collected from an operating industrial boiler and using a novel electrochemical noisebased corrosion sensor. As corrosion dynamics are significantly slow compared to the dynamics of temperature and gaseous species concentration, a multiscale model is developed where datadriven models are developed for algebraic states that affect the corrosion rate. The novel corrosion sensors can be costly and may be infeasible to place at all locations, especially due to the high temperature and harsh operating conditions in the waterwall section. This paper investigates opportunities for corrosion estimation by placing sensors for the algebraic state variables, the measurement of which is comparatively more mature and considerably cheaper than that of the corrosion sensors. To this end, a nonlinear estimator is investigated. Unlike many systems that are represented by differential-only or differential algebraic equations, in this particular system, differential equations do not affect the algebraic states but the algebraic states affect the differential states. For nonlinear state estimation of this specific class of differential algebraic equation system, a modified unscented Kalman filter algorithm is developed. The performance of the estimation algorithm is evaluated with different configurations of the sensor network by simulating the boiler with various operating conditions, as expected during load-following operation.

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Section: Corrosion Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hot Corrosion Monitoring in Boilers Using a Nonlinear Estimator and Electrochemical Noise-Based Corrosion Sensors

Somayajula,

Bhattacharyya,

et al. 2023

Ind. Eng. Chem. Res.

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“…The solute atoms interact with dislocations, which will reduce the creep rate. So, a factor f sol is taken into account for the creep rate [9,11,23]:…”

Section: Solid Solution Hardeningmentioning

confidence: 99%

“…Q sol is taken as the maximum interaction energy between different alloying elements and dislocations. The interaction energy of different elements with dislocations can be expressed as (in J mol −1 ) [9,11,23]:…”

Section: Solid Solution Hardeningmentioning

confidence: 99%

Application of Fundamental Models for Creep Rupture Prediction of Sanicro 25 (23Cr25NiWCoCu)

Sandström

2019

Crystals

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Creep rupture prediction is always a critical matter for materials serving at high temperatures and stresses for a long time. Empirical models are frequently used to describe creep rupture, but the parameters of the empirical models do not have any physical meanings, and the model cannot reveal the controlling mechanisms during creep rupture. Fundamental models have been proposed where no fitting parameters are involved. Both for ductile and brittle creep rupture, fundamental creep models have been used for the austenitic stainless steel Sanicro 25 (23Cr25NiWCoCu). For ductile creep rupture, the dislocation contribution, solid solution hardening, precipitation hardening, and splitting of dislocations were considered. For brittle creep rupture, creep cavitation models were used taking grain boundary sliding, formation, and growth of creep cavities into account. All parameters in the models have been well defined and no fitting is involved. MatCalc was used for the calculation of the evolution of precipitates. Some physical parameters were obtained with first-principles methods. By combining the ductile and brittle creep rupture models, the final creep rupture prediction was made for Sanicro 25. The modeling results can predict the experiments at long-term creep exposure times in a reasonable way.

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The Role of Fundamental Modeling

Sandström

2024

Springer Series in Materials Science

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The difference between empirical and basic modeling and its significance is explained. The types of basic models that have been possible to develop and that are describe in the book are summarized. The starting point is a basic model for the dislocation density that is used to derive expression for tensile and creep properties. It is described how the accuracy of the basic models can be verified. For the creep models it is described that they are applicable over a wide range of temperatures and stresses that is of great value to identify operating mechanisms.

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Creep strength of austenitic stainless steels for boiler applications

Cited by 9 publications

References 34 publications

Hot Corrosion Monitoring in Boilers Using a Nonlinear Estimator and Electrochemical Noise-Based Corrosion Sensors

Hot Corrosion Monitoring in Boilers Using a Nonlinear Estimator and Electrochemical Noise-Based Corrosion Sensors

Application of Fundamental Models for Creep Rupture Prediction of Sanicro 25 (23Cr25NiWCoCu)

The Role of Fundamental Modeling

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