Graphite degeneration: White irradiation in GJS | Damage case with brittle cleavage fracture
Chemical designation | GJS |
---|---|
State | Weißeinstrahlung |
Etching | 3% Nital |
Cementitic white irradiation or white solidification is a metastable solidification in which the carbon forms as cementite (Fe3C) instead of graphite. This makes the component (often locally) significantly harder and more brittle.
Possible causes for this casting defect: rapid cooling (cooling iron) and/or too low Si content.
Micro hardness:
- Cementite: up to 1430 HV0.025
- Perlite: 315 +- 19 HV0.025
- Ferrite: 200 +- 5 HV0.025
Graphite classification (of nodular graphite) according to EN ISO 945-1:2019
- Graphite shape VI
- Guide number for the size range: 3