Back (Cast Iron)

Graphite degeneration: White irradiation in GJS | Damage case with brittle cleavage fracture

Chemical designationGJS
StateWeißeinstrahlung
Etching3% 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