ISO 23296:2022

INTERNATIONAL ISO
STANDARD 23296
First edition
2022-01
Metallic materials – Fatigue testing –
Force controlled thermo-mechanical
fatigue testing method
Matériaux métalliques – Essai de fatigue – Méthode d'essai de fatigue
thermomécanique à force contrôlée
Reference number
© ISO 2022
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Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test methods . 4
4.1 Apparatus . 4
4.1.1 Testing machine . 4
4.1.2 Testing machine calibration . 4
4.1.3 Cycle counting . 4
4.1.4 Waveform generation and control . 4
4.1.5 Force measuring system . 6
4.1.6 Test fixtures . 6
4.1.7 Alignment verification . 7
4.1.8 Heating device . 7
4.1.9 Cooling device . 7
4.2 Specimens . 7
4.2.1 Geometry . 7
4.2.2 Specimen preparation . 9
4.2.3 Specimen measurement . 9
4.2.4 Circular or rectangular sections . 9
4.2.5 Sampling, storage and handling . 9
4.2.6 Specimen insertion . . 10
4.2.7 Thermocouple attachment . 10
4.2.8 Spot welding of thermocouples . 10
4.2.9 Heating the specimen . . 11
4.2.10 Cooling the specimen . 11
5 Test preparatory issues .11
5.1 Temperature measurement . 11
5.1.1 General . 11
5.1.2 Temperature control . 11
5.2 Verification of temperature uniformity - Thermal profiling.12
5.2.1 General .12
5.2.2 Maximum permissible temperature variation along the specimen .12
5.2.3 Data recorders .13
5.2.4 Furnace positioning . 13
5.3 Force waveform optimisation . 13
5.4 Temperature force optimisation. 14
5.5 The application of an extensometer to measure maximum and minimum
mechanical strain to observe the effects of ratcheting . 14
6 Test execution .15
6.1 Test start . 15
6.1.1 General .15
6.1.2 Data recording . 15
6.1.3 Test termination . 15
6.1.4 Test validity . 15
6.1.5 During the test. 15
6.2 Test monitoring . 16
6.3 Termination of test. 16
6.3.1 General . 16
6.3.2 Accuracy of control parameters . 16
7 Analysis and reporting .17
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7.1 Validation of analysis software . 17
7.2 Test report . 17
7.2.1 General . 17
7.2.2 Essential information . 17
7.2.3 Additional information . 18
7.2.4 Examination of fracture surface . 18
Annex A (informative) Guidelines on specimen handling and degreasing .20
Annex B (informative) Thermocouple arrangement for a specimen containing a notch
feature .21
Annex C (informative) Thermal imaging for thermal profiling .26
Annex D (informative) Measurement of strain during force controlled TMF testing .27
Annex E (informative) Measurement uncertainty .28
Bibliography .30
iv
Foreword
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