Overview
ISO 15350:2000 specifies a routine laboratory procedure for the determination of total carbon and total sulfur in steel and iron using an infrared (IR) absorption method after combustion in an induction furnace. The standard is intended for use in normal production and quality-control operations and is designed to meet the expectations of recognized laboratory accreditation bodies.
Key measurement ranges:
- Carbon: mass fraction from 0.005 % to 4.3 %
- Sulfur: mass fraction from 0.0005 % to 0.33 %
The method can be applied in single-element mode (carbon or sulfur independently) or simultaneous mode (carbon and sulfur concurrently).
Key topics and technical requirements
- Analytical principle: Combustion of sample in oxygen in an induction furnace followed by IR absorption measurement of CO/CO2 (carbon) and SO2 (sulfur).
- Measurement options: Multiple IR detection approaches are described (open-path, diaphragm/capacitor, and closed-loop detectors), all measuring gas-specific IR absorption.
- Sampling and sample prep: Follow ISO 14284 for sampling and ensure test portions are uniform, free of oil/grease and contaminants; solvent cleaning and drying guidance is provided.
- Reagents and materials: Specifies high-purity oxygen (≥ 99.5 %), absorbents (e.g., magnesium perchlorate), inert ceramics and accelerators, and solvent purity limits.
- Apparatus: Commercial C/S determinators with IR source and detector, appropriate ceramic crucibles, and induction furnace; crucibles must be cleaned/treated to avoid blank contamination.
- Calibration & verification: Calibration must use steel and iron certified reference materials (CRMs) traceable to recognized bodies; calibration verification and performance monitoring via statistical process control (SPC) are required.
- Quality & accuracy: Method is intended to conform to good laboratory practice and the accuracy/precision concepts covered in the ISO 5725 series.
- Safety: Warnings on burn risks, oxygen handling, and safe removal of combustion oxygen are emphasized.
Practical applications and users
ISO 15350:2000 is targeted at laboratories and production QC units that require routine, traceable analysis of carbon and sulfur in ferrous materials. Typical users include:
- Steelmakers and foundries (process control, product certification)
- Metallurgical and materials testing laboratories
- Supplier quality and incoming inspection teams
- Accredited testing laboratories implementing routine C/S analysis
- Instrument manufacturers and service providers for combustion IR analyzers
Benefits include fast routine throughput using commercially available analysers, defined calibration/verification practices with CRMs, and integration with SPC for ongoing performance control.
Related standards
Relevant normative and complementary standards referenced within ISO 15350:2000:
Keywords: ISO 15350:2000, infrared absorption method, induction furnace, total carbon, total sulfur, steel and iron, routine C/S analysis, certified reference materials, statistical process control, laboratory accreditation.