The mechanical properties of cast iron depend largely on the form, size and distribution of graphite. The polished (unetched) section is examined under the microscope and graphite is classified by form (I–VI), distribution (A–E) and size class. For ductile (spheroidal graphite) iron, nodularity is also determined.
The test is performed with a method accredited by TÜRKAK under TS EN ISO/IEC 17025 (ISO 945-1 visual analysis, ISO 945-2 image analysis); results are issued as an accredited test report.
Determined Values
- Graphite form, distribution and size
- Nodularity (%) and nodule count (ductile iron)
- Matrix structure after etching: pearlite / ferrite ratio
Applied Standards
- ISO 945-1 – Microstructure of cast irons, graphite classification by visual analysis
- ISO 945-2 – Microstructure of cast irons, graphite classification by image analysis
- ISO 16060 – Spheroidal graphite cast iron, nodularity assessment (reference charts)
Specimens and Reporting
The specimen is cut, mounted, ground, polished and, where needed, etched with a suitable reagent in our laboratory (ASTM E3). Examination is done with a metallurgical microscope and image analysis software; results are reported with scaled micrographs.