Predicted life of P91 steel for cyclic high temperature service

Pohja, Rami; Holmström, Stefan; Auerkari, Pertti; Nurmela, Asta

doi:10.1080/09603409.2017.1383710

Cited by 3 publications

(4 citation statements)

References 7 publications

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“…Cyclic thermal creep and creep-fatigue interaction are possible causes of the damage and failure of high-temperature components under cycling loading. Intensive efforts have recently been undertaken to study the role of the high-temperature cyclic behaviour on creep strength enhanced 9%Cr steels [19][20][21][22][23][24][25][26][27][28][29][30][31][32]. The effect of hold time and stress ratio at a constant temperature on cyclic creep properties of advanced 9%Cr steels was investigated in most of these studies.…”

Section: Introductionmentioning

confidence: 99%

Creep behaviour and microstructure evolution of advanced creep-resistant 9%Cr martensitic steels under cyclic thermal loading

Sklenička¹,

Kuchařová²,

Svoboda³

2018

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The effect of cyclic thermal loading on the creep behaviour and microstructure evolution of three creep strength enhanced 9%Cr ferritic-martensitic steels (P91, P92 and E911) was investigated. The temperature cycles consisted of cooling the specimen after creep exposure from the creep testing temperature of 600 • C to room temperature and then heating it up again to the creep testing temperature. Standard creep tests at the same creep testing temperature were carried out simultaneously for comparison. The results of the thermal cycled and standard creep tests showed no detrimental effect of intermittent heating on the creep behaviour of the specimens during the cycled tests. Microstructural investigations revealed no substantial differences in the types and chemical compositions of precipitating phases for the specimens after standard or cyclic creep in the three steels examined. There is no reason to expect substantially different creep behaviour for specimens experiencing standard or cyclic creep, provided that the specimens possess similar microstructures.

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Section: Introductionmentioning

confidence: 99%

Creep behaviour and microstructure evolution of advanced creep-resistant 9%Cr martensitic steels under cyclic thermal loading

Sklenička¹,

Kuchařová²,

Svoboda³

2018

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“…This process evens out the cavity distribution until the locally increasing density or other factors start to override so that additional cavity growth will appear from interaction and coalescence of cavities [21]. The coalescence will first promote the appearance of string-like oriented cavitation, typically along boundaries that are perpendicular to the maximum tensile principal stress, or like in welds, to the weakest material zone [11][12][13][14][15]. The cavities will concentrate on the same grain boundaries from the very beginning, so that the appearance of oriented cavitation is also a function of cavity density and not only of the distribution in terms of orientation with respect to the stress state.…”

Section: Nucleation and Growth Of Creep Cavitation Damagementioning

confidence: 99%

“…In welded ferritic steels, the susceptible region for cavity formation is often the Type IV region of the heat affected zone (HAZ) [9][10][11][12][13][14][15][16][17]. Figure 2(a-b) show examples of in-service creep damage in the HAZ of X20 steel, in the form of scattered and orientated creep cavities.…”

Section: Nucleation and Growth Of Creep Cavitation Damagementioning

confidence: 99%

“…The decreasing opportunities to baseload operation and increasing need to support intermittent renewable supply have resulted in new patterns of accumulating damage. Therefore, it is challenging to reliably detect and evaluate the leading damage so that its progression and impact can be accurately characterised for life prediction [3][4][5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Modelling for Creep Cavitation Damage and Life of Three Metallic Materials

Pohja

Auerkari

Vilaça

2022

Materials at High Temperatures

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Metallic structures operating at high temperatures can have creep as a life-limiting mechanism. The limit can arise by nucleation and growth of creep cavities that eventually merge becoming the leading damage of the fracture mechanisms. Understanding and modelling for creep cavitation can therefore help in prediction of structural safety and condition of such structures. The present paper will introduce a new model to predict creep cavitation damage so that the associated creep strain is also modelled out of the predictive expression without losing accuracy in the time to critical damage and corresponding residual life. The model was verified for OFHC copper, low-alloy 0.5CMV steel and higher-alloy X20 steel, to cover a wide range of polycrystalline metals and their microstructures. The new model performed as well as or better than the classical approach which requires access to measured strain. The model was applied to predict creep cavitation damage from time, stress and temperature as predictive variables.

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