Overview
EN ISO 11782-1:2008 / ISO 11782-1:1998 specifies guidance for laboratory corrosion fatigue testing of metals and alloys in aqueous or gaseous environments using cycles-to-failure methods. Adopted by CEN without modification, it describes the test principle, specimen design, environmental and stressing considerations, apparatus, procedure and reporting needed to determine fatigue behaviour when corrosion and cyclic loading act together. The document complements ISO 11782-2 (crack propagation testing) and references ISO 7539-1 for stress-corrosion test guidance.
Key topics and technical requirements
- Test principle: Subject series of specimens to cyclic loading in a corrosive environment at progressively lower alternating stresses to determine fatigue strength at N cycles or an effective fatigue limit.
- Specimen types & geometry:
- Plain, notched, cylindrical and flat (plate/sheet) specimens; rotating-bend and axial designs are covered.
- Recommended dimensional rules: test-section length > 3× diameter/width; transition fillet radius ≥ 8× test-section diameter/width; gripped-end area ≧ 4× test-section area.
- Minimum preferred circular cross-section diameter: 5 mm.
- Loading modes: axial stressing, plane bending, rotating beam, alternate torsion, combined stresses.
- Stress definitions & metrics: stress amplitude, mean stress, stress ratio (R), S–N diagrams, fatigue strength at N cycles, fatigue notch factor (Kf) and stress concentration factor (Kt).
- Specimen handling & measurement:
- Dimensional measurements for area accuracy to within 0.02 mm.
- Indelible identification (stamping) and desiccated storage after cleaning to avoid pre-test corrosion.
- Notched and size effects: Procedures to evaluate notch sensitivity, fatigue notch factor and material notch sensitivity (q). Acknowledges specimen size effects on fatigue results.
- Environment & interpretation: Emphasises that fatigue life data are valid only when test conditions (material, environment, loading) parallel service conditions; engineering judgment required when extrapolating.
Practical applications and users
- Who uses it: Materials engineers, corrosion specialists, fatigue test laboratories, R&D teams, coatings developers, and quality/control personnel in aerospace, automotive, marine, energy and infrastructure sectors.
- Why use it:
- Compare corrosion fatigue resistance of alloys, surface finishes or coatings.
- Provide S–N data for design criteria where cyclic stress and corrosive environments coincide.
- Evaluate influence of notches, residual stresses or specimen size on fatigue life.
- Limitations: Results are directly applicable only when test and service environments are equivalent; otherwise apply engineering judgment or complementary testing.
Related standards
- ISO 11782-2 - Corrosion fatigue testing: crack propagation using precracked specimens.
- ISO 7539-1 - Stress corrosion testing: general guidance on testing procedures.
Keywords: corrosion fatigue testing, cycles to failure, S–N diagram, fatigue strength, notch sensitivity, stress ratio, specimen design.
