ISO 22407:2021

Overview

ISO 22407:2021 - "Metallic materials - Fatigue testing - Axial plane bending method" defines standardized conditions and procedures for performing plane bending fatigue tests on an axial machine. It covers constant‑amplitude, force- or displacement‑controlled tests at room temperature (ideally 10 °C to 35 °C) on metallic specimens without deliberately introduced stress concentrations. The standard’s aim is to produce reliable fatigue data such as the relation between applied stress and number of cycles to failure for a given material condition (hardness, microstructure) across various stress ratios.

Key topics and technical requirements

• Test principle: Plane bending on an axial testing machine (constant amplitude), force- or displacement-controlled.
• Specimens: Shapes, preparation and dimensional checks for rectangular and bevelled cross‑section specimens are specified; notched and component testing are excluded from the main specification (guidance for notched specimens is provided in Annex A).
• Environmental control: Tests are performed at room temperature (10–35 °C); where atmospheric control is required ISO 554:1976 applies.
• Apparatus and instrumentation: Requirements for testing machines, force and displacement transducers, cycle counters, anti‑rotation systems and instrumentation for test monitoring.
• Stress calculation and homogeneity: Methods for calculating bending stress for specified cross‑sections and for checking stress homogeneity across the test section.
• Test procedure: Mounting of device and specimen, rate of testing, application of load or displacement, recording of temperature/humidity, failure criteria and test termination.
• Data handling: Presentation of fatigue results, test reporting requirements, and treatment of measurement uncertainty.
• Normative references: ISO 7500‑1 (force calibration/verification) and ASTM E2309/E2309M (displacement verification) are cited.

Applications and who uses it

ISO 22407:2021 is intended for:

• Materials and fatigue testing laboratories conducting standardized fatigue life tests on metallic alloys.
• R&D and product qualification teams in aerospace, automotive, rail and heavy engineering who require comparative fatigue data.
• Quality assurance and certification bodies verifying material performance under bending fatigue.
• Design engineers needing validated S–N (stress vs. cycles) data for life prediction and material selection.

Practical applications include generating S–N curves, comparing heat treatments or surface finishes, and supporting fatigue life assessments for components where bending stresses dominate.

Related standards

• ISO 7500-1 - Calibration and verification of force‑measuring systems for testing machines
• ASTM E2309/E2309M - Verification of displacement measuring systems for material testing machines
• ISO 554:1976 - Specification for climatic/environmental control when required

Keywords: ISO 22407:2021, axial plane bending method, fatigue testing, metallic materials, bending fatigue, stress ratio, S–N curve, specimen geometry, fatigue life.