Overview
EN ISO 15349-2:2021 specifies an infrared absorption method after combustion in an induction furnace (with preheating) for the determination of low carbon content in unalloyed steel. Published by CEN and identical to ISO 15349-2:2021, the standard applies to carbon mass fractions from 0.0003 % to 0.009 %, and supersedes the 2003 edition. The method converts sample carbon to CO₂/CO by high-temperature combustion in an induction furnace and measures evolved gases by infrared absorption to quantify carbon.
Key topics and technical requirements
- Scope and range: Applicable to unalloyed steels with very low carbon content (0.0003–0.009 %).
- Principle: Pre‑heating at low temperature followed by combustion in an induction furnace in a stream of high‑purity oxygen, with carbon measured as CO₂/CO by infrared absorption.
- Reagents and gases: Requires analytical-grade reagents and oxygen ≥ 99.95 % (volume fraction); water free from CO₂ for preparation.
- Accelerators and sample aids: Common accelerators include copper, tungsten–tin mixtures, iron, tungsten or nickel; specified cleaning and heat treatments for accelerator materials (e.g., copper plates heated 450–600 °C before use) are described.
- Calibration: Calibration is performed using sucrose standard solutions or calcium carbonate, with procedures for preparing calibration solutions and establishing calibration curves.
- Procedure elements: Sampling and test portion preparation, blank tests, pre‑treatment, combustion, and calculation of results are specified to ensure traceable, repeatable carbon analysis.
- Normative references and precision: The standard references ISO laboratory glassware and sampling standards and includes updated precision data from inter-laboratory testing.
Applications and users
EN ISO 15349-2:2021 is primarily used for:
- Steel producers and mills performing quality control on low-carbon unalloyed steels.
- Metallurgical and materials testing laboratories requiring reliable carbon quantification at trace levels.
- Certification bodies and inspection labs involved in conformity assessment and specifications compliance.
- R&D and failure analysis where precise low-carbon measurement affects material properties.
Practical benefits include validated trace-level carbon determination for process control, acceptance testing, product certification, and research into material behavior tied to ultra-low carbon content.
Related standards
- ISO 15349 series (other parts addressing carbon analysis methods)
- ISO 648, ISO 1042 (laboratory glassware)
- ISO 3696 (water for analytical use)
- ISO 14284 (sampling and preparation of steel and iron for chemical analysis)
Keywords: EN ISO 15349-2:2021, low carbon determination, unalloyed steel, infrared absorption, induction furnace, carbon analysis, sucrose calibration, oxygen purity.
