Overview - EN ISO 9658:2024 (Steel - Aluminium determination, AAS)
EN ISO 9658:2024 is the European adoption of ISO 9658:2024 specifying a flame atomic absorption spectrometric (AAS) method for determining acid‑soluble and/or total aluminium in non‑alloyed steel. The method covers aluminium mass fractions from 0.005 % to 0.20 % and replaces EN 29658:1991. It defines the principle (dissolution, fusion of residues, nebulization into a dinitrogen monoxide–acetylene flame and measurement at the 309.3 nm aluminium line), required reagents, apparatus, sample preparation, calibration and expression of results.
Key topics and technical requirements
- Scope and applicability: Non‑alloyed steels; aluminium content between 0.005 % and 0.20 % (mass fraction).
- Analytical principle: Dissolve test portion in a hydrochloric–nitric acid mixture; fuse acid‑insoluble residues with an orthoboric acid / potassium carbonate mixture; nebulize into a N2O–acetylene flame; measure atomic absorption at 309.3 nm (aluminium hollow‑cathode lamp recommended).
- Reagents and standards: Use analytical grade reagents and purified water (ISO 3696). Specified reagents include hydrofluoric acid, hydrochloric and nitric acids, and a fusion mixture (H3BO3 + K2CO3). Example calibration standards given: 2.0 g/L, 0.20 g/L and 0.020 g/L aluminium solutions.
- Apparatus & consumables: Class A volumetric glassware (ISO 385, ISO 648, ISO 1042), 0.45 µm cellulose nitrate filters, acid‑resistant filter funnels, AAS instrument capable of N2O–acetylene flame operation and hollow‑cathode aluminium lamp.
- Quality and calibration: Procedures for blank tests, calibration-curve preparation, instrument optimization and performance criteria are specified. The standard also includes precision data, test reporting requirements and informative annexes on instrument criteria and interlaboratory data.
Applications and users
This standard is intended for:
- Steel manufacturers and heat‑treatment facilities performing routine chemical analysis and quality control.
- Metallurgical and materials testing laboratories verifying aluminium levels in non‑alloyed steel.
- Inspection and compliance laboratories ensuring conformity with material specifications that limit aluminium content.
- Standards bodies and accreditation assessors referencing method precision, calibration and reporting requirements.
Practical benefits include reliable quantification of aluminium to support process control, acceptance testing, and root‑cause investigations where aluminium affects steel properties (inclusion control, ladle chemistry, deoxidation practice).
Related standards
Normative references cited in EN ISO 9658:2024 include:
Keywords: EN ISO 9658:2024, aluminium in steel, flame atomic absorption spectrometry, AAS, aluminium determination, non‑alloyed steel, 309.3 nm, N2O–acetylene flame.
