Overview
EN ISO 4829-1:2018 specifies a laboratory spectrophotometric method for the determination of total silicon in steel and cast iron using the reduced molybdosilicate reaction. Part 1 of the series covers silicon mass fractions between 0.05 % and 1.0 %. The method defines the chemical principle, reagents, apparatus, sampling, analytical procedure, calibration and reporting requirements for reliable silicon measurement in ferrous materials.
Key topics and technical requirements
- Principle: dissolution of a test portion, fusion of acid-insoluble residue with sodium peroxide, formation of oxidized molybdosilicate (yellow) and selective reduction to a blue complex with ascorbic acid; final spectrophotometric measurement at about 810 nm.
- Applicable range: 0.05 % to 1.0 % silicon (mass fraction).
- Reagents and quality control:
- Use reagents of recognized analytical grade and grade 2 water (ISO 3696); avoid ion-exchange demineralized water because of colloidal silica.
- Fresh preparation and storage of reagent solutions in polypropylene or PTFE containers; caution about moisture uptake by reagents in glass bottles.
- Key reagents include sodium peroxide for fusion, sodium molybdate, potassium permanganate, ascorbic acid, oxalic acid and controlled acid mixtures.
- Procedure essentials:
- Defined sample dissolution and treatment of insoluble residues.
- Preparation of calibration solutions and establishment of a calibration curve.
- Blank tests, spectrophotometric measurements and calculation of silicon content.
- Interference control: addition of oxalic acid and increase of sulphuric acid concentration to suppress interferences from phosphorus, arsenic and vanadium.
- Documentation: requirements for expression of results, precision data, and test reporting are included.
Applications and users
This standard is intended for:
- Metallurgical and chemical analysis laboratories performing silicon determination in steels and cast irons.
- Quality control and compliance testing in steel mills, foundries and metal component manufacturers.
- Research laboratories and certification bodies needing standardized, repeatable methods for alloy composition control.
Practical benefits include consistent, reproducible silicon assay for process control, specification compliance and material certification.
Related standards
- ISO 14284 - Sampling and preparation of samples for chemical composition determination.
- ISO 3696 - Water for analytical laboratory use (grade 2).
- ISO 648, ISO 1042 - Laboratory glassware (pipettes, volumetric flasks).
- EN/ISO 4829 series - other parts for different silicon ranges or alternative procedures.
Keywords: EN ISO 4829-1:2018, silicon determination, reduced molybdosilicate spectrophotometric method, steel and cast iron analysis, spectrophotometry, silicon 0.05–1.0%.
