Overview
ISO/TR 945-2:2011 - Microstructure of cast irons - Part 2: Graphite classification by image analysis is an ISO Technical Report that illustrates methods for two‑dimensional characterisation of graphite form and size in cast irons using image analysis. It is informative (a Technical Report) and does not prescribe a single standard mathematical description of graphite shapes but provides procedures, examples and a means to compare image‑analysis results with traditional visual analysis (ISO 945-1).
Key topics and technical scope
- Purpose: Show what is possible with graphite classification by image analysis and suggest future development paths.
- Scope exclusions: Does not apply to lamellar (grey) graphite distributions covered by ISO 945-1.
- Designation system: Graphite is classified by form (Roman numerals I–VI) and size (Arabic numerals 1–8). Examples and photomicrographs are provided in Annexes A and B.
- Two‑dimensional metrics: Definitions include maximum Féret diameter, roundness, perimeter and graphite content rate.
- Sampling & sample preparation: Emphasises agreed sampling locations, careful sectioning, grinding and polishing, and examination in the un‑etched condition to preserve graphite features.
- Binary image preparation: Covers microscope illumination, filters, camera requirements, exposure/brightness settings and image capture workflow. Recommends choosing magnification to measure at least ~20 graphite particles per field and a minimum image resolution of 1 pixel/µm.
- Measurement, reporting and acceptance: Describes procedures to measure particle form/size, prepare test reports and a proposed procedure to compare image analysis with visual analysis (ISO 945-1).
Practical applications and users
ISO/TR 945-2:2011 is valuable for:
- Foundries and quality‑control labs implementing graphite classification by image analysis.
- Metallographers and materials engineers performing microstructure characterization of cast irons.
- R&D teams developing or validating image‑analysis software and workflows for graphite quantification.
- Purchasing and inspection agreements where image‑based assessment is agreed between manufacturer and buyer.
- Failure analysis and process improvement where quantitative graphite form/size data support decisions.
Benefits include reduced subjectivity versus visual methods, more reproducible graphite metrics, and a documented comparison route back to visual classification.
Related standards
- ISO 945-1 - Graphite classification by visual analysis (complementary reference).
- ISO 16112 - Provides a mathematical description of graphite form referenced in the report.
Keywords: ISO/TR 945-2:2011, graphite classification by image analysis, microstructure of cast irons, graphite form and size, image analysis, metallography, sample preparation.
