Overview
EN ISO 9226:2012 - Corrosion of metals and alloys - Corrosivity of atmospheres - Determination of corrosion rate of standard specimens (ISO 9226:2012) specifies methods to determine corrosion rate using standard metal specimens exposed to outdoor atmospheres. Results (mass loss after one year) are intended as classification criteria for atmospheric corrosivity according to ISO 9223 and can also support informative corrosivity evaluations beyond that scope. The standard covers specimen preparation, exposure, removal of corrosion products and expression of results.
Key topics and technical requirements
- Standard specimens
- Flat rectangular plates, preferably 100 × 150 mm, minimum 50 × 100 mm, thickness ≈ 1 mm.
- Materials: unalloyed carbon steel, zinc (≥ 98.5 %), copper (≥ 99.5 %), aluminium (≥ 99.5 %).
- Specimens must be solvent-degreased and free from pre-existing corrosion products; steel with visible rust should be polished with 120‑grit before degreasing.
- Exposure
- Follow ISO 8565 general exposure requirements.
- Three specimens of each metal are exposed for one year, starting at the beginning of the worst corrosive period (e.g., spring or autumn).
- Measurement and calculation
- Remove corrosion products per ISO 8407 (Annex A gives chemical cleaning procedures).
- Corrosion rate by mass loss: r = Δm / (A · t) expressed in g/(m2·a).
- Thickness reduction rate: r' = Δm / (A · ρ · t) expressed in µm/a; densities for Fe, Zn, Cu, Al are listed in the standard.
- Report all individual values, means and any anomalies affecting results.
- Chemical cleaning
- Annex A provides sample cleaning recipes (e.g., HCl pickling for steel, glycine for zinc, sulfamic acid for copper, phosphoric/chromic mixtures or nitric acid options for aluminium) with cautions about hazardous chemicals.
Applications and who uses it
- Purpose: Characterize atmospheric test sites or service locations by empirical corrosion rates to classify corrosivity categories (ISO 9223) and support corrosion risk assessments.
- Users:
- Corrosion engineers, materials scientists and testing laboratories performing atmospheric corrosion tests.
- Asset owners, infrastructure planners and coatings manufacturers who need site corrosivity data for material selection and maintenance planning.
- Standards bodies and researchers comparing long-term corrosion data (conversion to long-term rates is possible using ISO 9224).
Related standards
- ISO 9223 - Classification, determination and estimation of corrosivity of atmospheres
- ISO 9224 - Guiding values for corrosivity categories
- ISO 8407 - Removal of corrosion products from test specimens
- ISO 8565 - General requirements for atmospheric corrosion testing
Keywords: EN ISO 9226:2012, corrosivity of atmospheres, corrosion rate, standard specimens, ISO 9223, atmospheric corrosivity, corrosion testing, mass loss, exposure, chemical cleaning.
