Overview
EN ISO 4947:2020 - "Steel and cast iron - Determination of vanadium content - Potentiometric titration method" - is the CEN-adopted version of ISO 4947:2020. This standard specifies a potentiometric titration method for measuring vanadium in steel and cast iron and is applicable to vanadium mass fractions from 0.04% to 2%. It replaces EN 24947:1991 and is intended for laboratory chemical analysis and quality control in ferrous‑metal production and testing.
Key topics and technical requirements
- Scope and applicability: Analytical method for vanadium in steel and cast iron, usable for 0.04–2.0 % V.
- Analytical principle: Dissolution of a test portion in acids (HCl, HNO3, HF as required to keep tungsten in solution), oxidation with potassium peroxydisulfate, controlled redox manipulations (partial oxidation of chromium, reduction/oxidation steps for vanadium) and potentiometric titration of vanadium with an ammonium iron(II) sulfate standard solution while monitoring potential.
- Reagents: Includes potassium peroxydisulfate, hydrochloric/nitric/hydrofluoric acids, sulfuric and orthophosphoric acids, potassium permanganate, sodium nitrite, sulfamic acid, and potassium dichromate for standardization.
- Apparatus: Ordinary laboratory glassware (class A) and a potentiometric titration device capable of measuring potential differences using platinum‑saturated calomel or platinum Ag/AgCl electrodes (optional electrode introduced in the 2020 edition).
- Sampling and test portions: Follow ISO 14284 for sampling. Recommended test portion masses vary by expected vanadium content:
- ~5 g for 0.04–0.25 % V
- ~2 g for 0.25–1.0 % V
- ~1 g for 1.0–2.0 % V
The vanadium mass in the test portion should be about 2–20 mg.
- Standardization and calculation: Requires potentiometric standardization of the ammonium iron(II) sulfate solution against potassium dichromate; formulae for concentration and result calculation are provided.
- Quality and precision: The 2020 revision re-assessed precision data and clarifies procedural options.
Applications and users
- Quality control and chemical analysis laboratories in steelworks, foundries and independent materials testing labs.
- Metallurgists and process engineers monitoring alloy composition, especially for vanadium-bearing steels (tool steels, high‑strength alloys).
- Compliance testing for procurement, certification, and regulatory purposes where accurate vanadium content measurement is required.
Related standards and references
Keywords: EN ISO 4947:2020, ISO 4947, vanadium determination, potentiometric titration, steel and cast iron analysis, ammonium iron(II) sulfate titration.
