Damage relaxation in cyclic strained stainless steel

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

Improved endurance in fatigue tests with intermediate holds and annealing to roughly simulate steady state normal operation between fatigue transients in nuclear power plant (NPP) components has been reported [1]. Similar effect is expected in plant components - e.g. in a pressurized water reactor (PWR) surge line or in pressurizer spray lines. Quantification of this effect is a topic of continued research on fatigue performance of niobium stabilized austenitic stainless steel. Holds affect cyclic stress strain response. Stress amplitude, tensile mean stress and apparent elastic modulus are increased immediately after a hold, while decreased by cycles in between. A decrease of volume is measured during hot holds at zero external stress and a stress is generated, when applying a constant temperature hold in strain control. This all suggest cyclic accumulation of lattice defects and recovery during holds. Recovery may occur through thermally activated dislocation migration together with diffusion, grouping and annihilation of lattice defects. A mechanism informed explanation and thermodynamic model is sought for to improve transferability of laboratory data to real plant components and accuracy of fatigue usage assessment. Anticipated mechanisms behind gradual changes in material responses are discussed in relation to quantitative effects of holds.
Original languageEnglish
Title of host publicationBaltica X
Subtitle of host publicationInternational Conference on Life Management and Maintenance for Power Plants
EditorsPertti Auerkari
PublisherVTT Technical Research Centre of Finland
Number of pages12
ISBN (Electronic)978-951-38-8436-9, 978-951-38-8435-2
Publication statusPublished - 2016
MoE publication typeA4 Article in a conference publication
EventBALTICA X - International Conference on Life Management and Maintenance for Power Plants - Cruise, Helsinki-Stockholm, Finland
Duration: 7 Jun 20169 Jun 2016

Publication series

NameVTT Technology
PublisherVTT
Volume261
ISSN (Electronic)2242-122X

Conference

ConferenceBALTICA X - International Conference on Life Management and Maintenance for Power Plants
Abbreviated titleBaltica X
CountryFinland
CityHelsinki-Stockholm
Period7/06/169/06/16

Fingerprint

Stainless steel
Fatigue of materials
Crystal defects
Strain control
Recovery
Pressurized water reactors
Austenitic stainless steel
Niobium
Nuclear power plants
Durability
Elastic moduli
Thermodynamics
Annealing
Temperature

Cite this

Solin, J. (2016). Damage relaxation in cyclic strained stainless steel. In P. Auerkari (Ed.), Baltica X: International Conference on Life Management and Maintenance for Power Plants VTT Technical Research Centre of Finland. VTT Technology, Vol.. 261
Solin, Jussi. / Damage relaxation in cyclic strained stainless steel. Baltica X: International Conference on Life Management and Maintenance for Power Plants. editor / Pertti Auerkari. VTT Technical Research Centre of Finland, 2016. (VTT Technology, Vol. 261).
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Solin, J 2016, Damage relaxation in cyclic strained stainless steel. in P Auerkari (ed.), Baltica X: International Conference on Life Management and Maintenance for Power Plants. VTT Technical Research Centre of Finland, VTT Technology, vol. 261, BALTICA X - International Conference on Life Management and Maintenance for Power Plants, Helsinki-Stockholm, Finland, 7/06/16.

Damage relaxation in cyclic strained stainless steel. / Solin, Jussi.

Baltica X: International Conference on Life Management and Maintenance for Power Plants. ed. / Pertti Auerkari. VTT Technical Research Centre of Finland, 2016. (VTT Technology, Vol. 261).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

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T1 - Damage relaxation in cyclic strained stainless steel

AU - Solin, Jussi

PY - 2016

Y1 - 2016

N2 - Improved endurance in fatigue tests with intermediate holds and annealing to roughly simulate steady state normal operation between fatigue transients in nuclear power plant (NPP) components has been reported [1]. Similar effect is expected in plant components - e.g. in a pressurized water reactor (PWR) surge line or in pressurizer spray lines. Quantification of this effect is a topic of continued research on fatigue performance of niobium stabilized austenitic stainless steel. Holds affect cyclic stress strain response. Stress amplitude, tensile mean stress and apparent elastic modulus are increased immediately after a hold, while decreased by cycles in between. A decrease of volume is measured during hot holds at zero external stress and a stress is generated, when applying a constant temperature hold in strain control. This all suggest cyclic accumulation of lattice defects and recovery during holds. Recovery may occur through thermally activated dislocation migration together with diffusion, grouping and annihilation of lattice defects. A mechanism informed explanation and thermodynamic model is sought for to improve transferability of laboratory data to real plant components and accuracy of fatigue usage assessment. Anticipated mechanisms behind gradual changes in material responses are discussed in relation to quantitative effects of holds.

AB - Improved endurance in fatigue tests with intermediate holds and annealing to roughly simulate steady state normal operation between fatigue transients in nuclear power plant (NPP) components has been reported [1]. Similar effect is expected in plant components - e.g. in a pressurized water reactor (PWR) surge line or in pressurizer spray lines. Quantification of this effect is a topic of continued research on fatigue performance of niobium stabilized austenitic stainless steel. Holds affect cyclic stress strain response. Stress amplitude, tensile mean stress and apparent elastic modulus are increased immediately after a hold, while decreased by cycles in between. A decrease of volume is measured during hot holds at zero external stress and a stress is generated, when applying a constant temperature hold in strain control. This all suggest cyclic accumulation of lattice defects and recovery during holds. Recovery may occur through thermally activated dislocation migration together with diffusion, grouping and annihilation of lattice defects. A mechanism informed explanation and thermodynamic model is sought for to improve transferability of laboratory data to real plant components and accuracy of fatigue usage assessment. Anticipated mechanisms behind gradual changes in material responses are discussed in relation to quantitative effects of holds.

M3 - Conference article in proceedings

T3 - VTT Technology

BT - Baltica X

A2 - Auerkari, Pertti

PB - VTT Technical Research Centre of Finland

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Solin J. Damage relaxation in cyclic strained stainless steel. In Auerkari P, editor, Baltica X: International Conference on Life Management and Maintenance for Power Plants. VTT Technical Research Centre of Finland. 2016. (VTT Technology, Vol. 261).