Overview
ISO 1352:2021 - Metallic materials - Torque-controlled fatigue testing specifies standardized conditions for performing torsional, constant‑amplitude, nominally elastic stress fatigue tests on metallic specimens. The standard covers testing by applying a pure couple (torque) about the specimen’s longitudinal axis, typically at ambient or elevated temperature in air. It describes specimen forms, preparation, apparatus, test procedures and reporting for specimens of circular and tubular cross-section. Component testing and low‑cycle torsional tests under angular‑displacement control are excluded.
Key topics and technical requirements
- Test scope and exclusions: Applies to nominally elastic, constant‑amplitude torque-controlled torsional fatigue; excludes component/specialized tests and low‑cycle angular‑displacement fatigue leading to failure in a few thousand cycles.
- Specimen geometry and preparation: Detailed guidance on form, dimensions, machining, surface condition, sampling, marking, dimensional checks and storage for circular and tubular specimens.
- Apparatus and alignment: Requirements for torsional fatigue testing machines, torque cells, grips, alignment verification and axial force control. Annexes provide methods for machine alignment verification and measuring uniformity of torsional strain/stress.
- Test procedure: Mounting, frequency, sinusoidal constant‑amplitude waveforms, application of torque, calculation of nominal torsional (shear) stress, temperature control for elevated‑temperature tests, and failure/termination criteria. Ambient tests are normally performed between 10 °C and 35 °C.
- Data, uncertainty and reporting: Test plan elements (stress ratios, objectives such as fatigue life, fatigue strength or full S–N / Wöhler curves), recording and cycle counting, measurement uncertainty estimation and standardized test reporting. Annexes cover presentation of results and uncertainty estimation.
Applications and who uses this standard
- Materials and mechanical testing laboratories performing torsional fatigue characterization of metallic materials.
- Engineers developing S–N (Wöhler) curves, fatigue life predictions and material selection for rotating or torsion‑loaded parts (e.g., shafts, fasteners, springs), where pure torsion data are required.
- Quality assurance and product development teams in automotive, aerospace, heavy machinery and manufacturing industries that require repeatable, comparable torque‑controlled fatigue data.
- Standards bodies and test equipment manufacturers for machine verification and calibration guidance.
Related standards
- ISO 554 - Standard atmospheres for conditioning/testing (environmental control)
- ISO 23788 - Verification of alignment of fatigue testing machines
- ISO 12107 - Statistical methods for fatigue data (referenced for data presentation)
ISO 1352:2021 is essential for obtaining consistent, comparable torsional fatigue data on metallic materials using torque‑controlled methods, supporting reliable fatigue design and material assessment.