Overview
ISO 11845:2020 - Corrosion of metals and alloys: General principles for corrosion testing provides high‑level guidance for performing corrosion tests under conditions of constant immersion. The standard establishes general principles for planning, executing and reporting immersion corrosion tests so results are comparable and relevant to practical service conditions. It applies to a wide range of materials and corrosive media but explicitly excludes detailed stress‑corrosion testing procedures (see ISO 7539).
Key topics and requirements
- Test objectives and comparability: Tests are generally comparative; include reference materials/solutions where possible to benchmark behaviour.
- Specimen preparation and identification: Document chemical composition, fabrication, form, dimensions, surface condition, mechanical properties and any coatings. Clean and degrease using agents that do not alter the surface.
- Sampling and machining: Produce specimens to avoid extra cold work or burrs; remove burrs and protect edges that could bias corrosion behaviour.
- Corrosive medium characterization: Report origin, composition, preparation, pH, redox potential and dissolved gases; analyse unknown media and note impurities.
- Solution-to-surface ratio: Maintain a defined volume-to-surface-area ratio - normally at least 5 mL/cm².
- Specimen surface area: Exposed surface area should normally be ≥ 25 cm² (larger for castings and weld considerations).
- Reproducibility and statistics: Because of scatter in corrosion results, use means of at least three tests per measurement point; each specimen used once.
- Test arrangement and vessel requirements: Avoid galvanic contact between specimens and vessel; use non‑reactive vessel materials; arrange specimens to prevent crevice effects and ensure consistent flow orientation.
- Temperature, agitation and duration: Match test conditions to practical application when possible. Exercise caution with accelerated testing (higher temperature/concentration) - results may not reflect real service behavior.
- Reporting: Record all relevant parameters (materials, medium, temperature, agitation, replenishment, measurement times and evaluation method).
Applications and who uses it
ISO 11845:2020 is used by:
- Materials engineers and corrosion scientists designing immersion corrosion tests
- Test laboratories standardizing procedures and producing comparable corrosion data
- Product developers and quality assurance teams evaluating material selection, coatings and protective systems
- Researchers performing long‑term corrosion studies and comparative material assessments
Practical applications include saltwater immersion tests, chemical process media evaluations, coating performance under immersion, and baseline testing before specialized protocols.
Related standards
- ISO 8044 - Corrosion of metals and alloys: Vocabulary (terms used)
- ISO 8407 - Removal of corrosion products from test specimens
- ISO 7539 (all parts) - Stress corrosion testing (procedures not covered by ISO 11845)
Using ISO 11845:2020 helps ensure immersion corrosion testing is consistent, traceable and applicable to real‑world conditions, improving confidence in material selection and corrosion performance data.