ISO 23296:2025

Overview - ISO 23296:2025 (Force‑controlled TMF testing)

ISO 23296:2025 specifies a harmonized method for force‑controlled thermo‑mechanical fatigue (TMF) testing of metallic materials. The standard covers test objectives, equipment, specimen preparation and the presentation of results required to determine TMF properties under simultaneous thermal and mechanical cycling. It is intended to improve reproducibility and compatibility of force‑controlled TMF data across test laboratories and material studies.

Key topics and technical requirements

• Scope of control: Applies to force‑controlled TMF; both force or stress control modes are accommodated.
• Apparatus and calibration: Requirements for testing machines, calibration of the force‑measuring system, cycle counting, waveform generation/control, fixtures, alignment verification, heating and cooling devices. (See clauses on apparatus and ISO 7500‑1/ISO 23788 references.)
• Specimen requirements: Geometry, preparation, measurement, handling, insertion and thermocouple attachment (including spot welding) are specified to ensure consistent thermal and mechanical response.
• Temperature management: Guidance on temperature measurement, control, thermal profiling and maximum permissible temperature variation along the gauge section. Includes use of data recorders and furnace positioning.
• Waveform and force optimisation: Practical steps for force waveform design and temperature‑force interaction to meet test objectives.
• Instrumentation: Use of extensometers to monitor strain/ratcheting effects, and thermal imaging or thermocouple arrangements for profiling (informative annexes).
• Test execution & reporting: Start/monitoring/termination procedures, data recording, validation of analysis software and essential report contents (including fracture surface examination). Measurement uncertainty guidance is provided in an annex.

Applications and who uses it

ISO 23296:2025 is relevant to:

• Materials and mechanical test laboratories performing TMF characterization.
• Aerospace, power‑generation and turbomachinery manufacturers evaluating components (e.g., blades, vanes) exposed to coupled thermal and mechanical cycles.
• Materials engineers and researchers developing high‑temperature alloys and validating life‑prediction models.
• Quality assurance and certification bodies requiring reproducible TMF fatigue data.

Practical applications include generating force‑to‑life (S–N) TMF curves, assessing damage under service‑like thermal/mechanical phasing, and validating design margins for high‑temperature cyclic loading.

Related standards

• ISO 7500‑1:2018 (calibration/verification of force measurement)
• ISO 23788:2012 (alignment verification of fatigue machines)
• ASTM E2368 and ISO 12111 (strain‑controlled TMF - complementary but different control approach)

Keywords: ISO 23296:2025, thermo‑mechanical fatigue, TMF testing, force‑controlled TMF, metallic materials, fatigue testing, specimen preparation, thermal profiling, extensometer, thermocouple.