Overview - ISO 23296:2022 (Thermo‑Mechanical Fatigue, Force‑Controlled)
ISO 23296:2022 specifies a harmonized method for force- or stress-controlled thermo‑mechanical fatigue (TMF) testing of metallic materials. The standard defines the required equipment, specimen geometries and preparation, test execution, monitoring and reporting necessary to determine TMF properties when the mechanical input is controlled by force or stress. It fills a gap where strain‑controlled TMF standards (e.g., ISO 12111, ASTM E2368) are not applicable - for cases where free thermal expansion need not be compensated.
Keywords: ISO 23296:2022, thermo‑mechanical fatigue, TMF testing, force‑controlled, metallic materials, fatigue testing.
Key topics and technical requirements
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Apparatus and calibration
- Requirements for testing machines, force‑measuring systems and calibration (references ISO 7500‑1).
- Verification of alignment and fixtures (reference ISO 23788).
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Waveform and control
- Generation and independent control of simultaneous temperature and force waveforms across the gauge section.
- Cycle counting, waveform optimisation and monitoring of applied force (Fmax, Fmin, Fa, Fm).
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Specimen design and preparation
- Accepted specimen geometries, measurement practices, sampling, storage and handling.
- Guidance on thermocouple attachment, spot welding, and specimen insertion.
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Temperature management
- Heating and cooling device requirements, temperature measurement, control strategies and thermal profiling to ensure uniformity across the gauge length.
- Use of thermal imaging (Annex C) and thermocouple arrangements (Annex B).
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Instrumentation and measurement
- Force measurement, optional extensometer use for strain and ratcheting observation (Annex D).
- Data acquisition, recorder specification, and validation of analysis software.
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Test execution and reporting
- Start-up, monitoring, termination conditions, and test validity checks.
- Required content of test reports, fracture surface examination guidance, and measurement uncertainty (Annex E).
Practical applications and users
ISO 23296:2022 is used to evaluate material durability under combined thermal and mechanical cycling encountered in service environments, for example:
- Aerospace and gas‑turbine components (blades, vanes)
- Power generation and engine parts subjected to cyclic heating/cooling
- Materials development and alloy qualification in R&D labs
- Quality assurance and comparative testing by independent test laboratories and OEMs
Primary users include materials engineers, fatigue test laboratories, component manufacturers, certification bodies and researchers studying high‑temperature cyclic damage mechanisms.
Related standards
- ISO 12111 - Strain‑controlled TMF testing
- ISO 7500‑1 - Calibration and verification of uniaxial testing machines
- ISO 23788 - Alignment verification of fatigue testing machines
- ASTM E2368 - Strain‑controlled TMF guidance
ISO 23296:2022 enables reproducible, comparable force‑controlled TMF test results for metallic materials, supporting design decisions and material selection where combined thermal and mechanical cycling governs fatigue life.