Graphitization factor

Factor for assessment of the graphitization tendency in cast iron materials (see Cast iron).

Depending on the iron composition and the cooling rate (wall thickness) the tendency for solidification occurs subsequent to the stable system (gray solidification, see iron-carbon phase diagram).
The Laplanche diagram highlights that the graphitization factor K is essential for solidification (the graphitization tendency for normal conditions shall apply).
Alloying elements have a strong influence, with chromium, vanadium and partly also molybdenum increasing the tendency for white solidification, and copper and nickel decreasing this tendency.

Additional references:
Graphite form
Structure formation of cast iron
Edge hardness, Chill