Overview
ISO 16112:2017 - Compacted (vermicular) graphite cast irons - Classification defines a clear, test‑based grading system for compacted (vermicular) graphite cast iron (CGI). The standard specifies five CGI grades based on minimum mechanical properties measured on machined test pieces prepared from separately cast samples, side‑by‑side cast samples, cast‑on samples, or - by agreement - samples cut from a casting. ISO 16112:2017 sets how grades are designated, sampled and tested to ensure consistent material performance for manufacturing and procurement.
Key topics and technical requirements
- Five material grades (ISO 16112/JV/300/S through ISO 16112/JV/500/S) are defined by minimum tensile properties. Example minimum values for test pieces from separately cast samples:
- ISO 16112/JV/300/S: Rm ≥ 300 MPa, Rp0.2 ≥ 210 MPa, A ≥ 2.0%
- ISO 16112/JV/350/S: Rm ≥ 350 MPa, Rp0.2 ≥ 245 MPa, A ≥ 1.5%
- ISO 16112/JV/400/S: Rm ≥ 400 MPa, Rp0.2 ≥ 280 MPa, A ≥ 1.0%
- ISO 16112/JV/450/S: Rm ≥ 450 MPa, Rp0.2 ≥ 315 MPa, A ≥ 1.0%
- ISO 16112/JV/500/S: Rm ≥ 500 MPa, Rp0.2 ≥ 350 MPa, A ≥ 0.5%
- Sample types and designations: suffix “S” indicates properties from separately cast samples; “U” is used for side‑by‑side or cast‑on samples. Samples cut from castings may be used only by purchaser–manufacturer agreement.
- Testing and sampling: tensile testing, hardness testing and microstructure assessment are required. The standard references ISO tensile and hardness test methods and gives detailed sampling rules (frequency, sample types, test unit formation).
- Microstructure and nodularity: graphite form and matrix (ferrite/pearlite) affect properties; Annex B explains nodularity evaluation for CGI.
- Process control: production tests must meet minimums; statistical analysis is recommended to demonstrate process capability. Manufacture and chemistry are left to the producer provided the grade requirements are met.
- Additional provisions: retest rules, heat treatment considerations, and ordering information (designation and special requirements).
Applications and who uses this standard
ISO 16112:2017 is used by:
- Foundries and casting engineers for material specification and quality control
- Design and mechanical engineers specifying CGI components
- Procurement and quality assurance teams setting acceptance criteria
- Test laboratories performing tensile, hardness and microstructure evaluations
Annex C (informative) provides examples of typical applications and property guidance to aid selection of CGI grades for specific component requirements.
Related standards (referenced)
- ISO 6892‑1 - Tensile testing at room temperature
- ISO 6506‑1 - Brinell hardness test method
- ISO 945‑1 - Graphite classification by visual analysis
- ISO/TR 15931 - Designation system for cast irons and pig irons
Keywords: ISO 16112:2017, compacted (vermicular) graphite cast iron, CGI classification, CGI grades, tensile strength, sampling, nodularity, foundry quality control.
