Research and development into a European code-of-practice for strain-controlled thermo-mechanical fatigue testing

Hähner, P.; Rinaldi, Claudia; Bicego, V.; Affeldt, E.; Brendel, Thomas; Andersson, Henrik; Beck, T.; Klingelhöffer, Hellmuth; Kühn, Hans-Joachim; Köster, Alain

doi:10.1016/j.ijfatigue.2007.01.052

Cited by 98 publications

(127 citation statements)

References 6 publications

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“…The temperature gradient observed is within the requirements of the European code of practice for strain-controlled thermomechanical fatigue testing. [11] The axial strain was measured via an air-cooled, hightemperature, ceramic rod extensometer with 12 mm gauge length. TMF tests were performed under full constraint conditions, meaning that the total strain measured by the extensometer was kept constant.…”

Section: B Test Proceduresmentioning

confidence: 99%

Effects of Holding Time on Thermomechanical Fatigue Properties of Compacted Graphite Iron Through Tests with Notched Specimens

Ghodrat

Riemslag

Kestens

et al. 2012

Metall Mater Trans A

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In cylinder heads of compacted graphite iron (CGI), the heating and cooling cycles can lead to localized cracking due to thermomechanical fatigue (TMF). Traditionally, TMF behavior is studied by thermal cycling of smooth specimens. The resulting number of cycles to failure (N f ) constitutes a single parameter that can be used to predict actual service failures. Nevertheless, there are also some drawbacks of the conventional testing procedures, most noticeably the prolonged testing times and a considerable scatter in test results. To address these drawbacks, TMF tests were performed using notched specimens, resulting in shorter testing times with less scatter. In the case of cast iron, artificial notches do not necessarily change the TMF behavior since the inherent graphite particles behave as internal notches. Using a notch depth of 0.2 mm, the effect of prolonged holding times (HT) on TMF lifetime was studied and a clear effect was found. Extended holding times were also found to be accompanied by relaxation of compressive stresses, causing higher tensile stresses to develop in the subsequent low temperature stages of the TMF cycles. The lifetimes in notched CGI specimens can be predicted by the Paris' fatigue crack growth model. This model was used to differentiate between the individual effects of stress level and holding times on TMF lifetime. Microstructural changes were evaluated by analyzing quantitative data sets obtained by orientation contrast microscopy based on electron backscattered diffraction (EBSD).

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Section: B Test Proceduresmentioning

confidence: 99%

Effects of Holding Time on Thermomechanical Fatigue Properties of Compacted Graphite Iron Through Tests with Notched Specimens

Ghodrat

Riemslag

Kestens

et al. 2012

Metall Mater Trans A

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“…There are numerous conclusions that may be drawn from the discussion presented above, one of which is that, while examining the accumulation of damage in the material of thick-walled pipeline components, one should pay more attention to the fatigue process caused by the synergistic interaction of variable temperatures and stresses at different times (Ref [13][14][15][16][17][18][19][20], for which approximation is possible by a comparison with isothermal fatigue only in some cases. In this case, the results obtained from the study would form the basis for determining the characteristics of this fatigue process.…”

Section: Analysis Of Calculation Resultsmentioning

confidence: 99%

Local Stress-Strain Behavior of a High-Temperature Steam Valve Under Transient Mechanical and Thermal Loading

Marek

Okrajni

2013

J. of Materi Eng and Perform

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The problem of determining stress-strain characteristics in a selected component operating in a power plant is discussed. Steam valve in transient working conditions during a power unit start-up is taken as an example. The aim of the paper is to prove the possibility to use measurements of steam temperature and the temperature of selected points of the investigated elements for defining boundary conditions of the heat transfer problem as well as to verify operative correctness of the elaborated computer models. The essential importance of time-variable and non-uniform temperature field for the course of local stress changes that results in metal fatigue processes is shown. The method of the computer model validation is discussed as the one of important problems which should be solved if we wanted to predict properly the variable temperature field. The problem of materials behavior under mechanical and thermal loading in the selected component has been discussed.

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“…It tries to find the parameter which would describe well the fatigue life and take into account mechanical loads and temperature. The method of determining fatigue life formulated in this way is expected to describe the behavior of materials under thermo-mechanical fatigue [19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

The Attempt of the Low-Cycle Fatigue Life Description of Chosen Creep-Resistant Steels Under Mechanical and Thermal Interactions

Okrajni

Marek

2017

Archives of Metallurgy and Materials

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The study focuses on the problem of determination of low-cycle fatigue properties for the chosen group of creep-resistant steels used in the power and chemical industries. It tries to find the parameter which would describe well the fatigue life and take into account mechanical loads and temperature. The results of LCF tests have been presented in the paper. New parameter P has been introduced. This parameter joins a plastic strain range, a stress range and temperature. The fatigue life has been predicted versus parameter P. The comparison of the predicted and observed values of fatigue life shows the agreement between these values. The method of fatigue life prediction formulated in this way is expected to describe the behavior of materials under thermo-mechanical fatigue.

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Research and development into a European code-of-practice for strain-controlled thermo-mechanical fatigue testing

Cited by 98 publications

References 6 publications

Effects of Holding Time on Thermomechanical Fatigue Properties of Compacted Graphite Iron Through Tests with Notched Specimens

Effects of Holding Time on Thermomechanical Fatigue Properties of Compacted Graphite Iron Through Tests with Notched Specimens

Local Stress-Strain Behavior of a High-Temperature Steam Valve Under Transient Mechanical and Thermal Loading

The Attempt of the Low-Cycle Fatigue Life Description of Chosen Creep-Resistant Steels Under Mechanical and Thermal Interactions

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