GG 15HC High Carbon Brake disc material and why it is a better Brake
disc material for automotive applications
EBC Brakes Blade Disc

GG15HC as the name implies uses Higher Carbon content during the casting process , approximately DOUBLE the Carbon element content than normal. Carbon content in brake discs ranges from 2 to approximately 4%. GG 15HC is right there at the highest content figure. More Silicone is also added to GG15HC to encourage the formation of GRAPHITE during the cooling process. These graphite flakes add "Plasticity" to the cast iron matrix and are excellent at absorbing shocks and preventing cracks. Whilst the GG 15HC is essentially a "Softer" iron and may wear slightly faster than its harder low carbon counterparts the development of the enemy article CEMENTITE is much reduced in GG 15HC. Cementite is a brittle bi product formed in cooling of the disc material during the casting process. The content of GG15HC is shown below

3.72%C
1.74%Si
0.50%Mn
0.05%P
0.108%S
0.16%Cr
0.24%Cu
0.02%V
0.45%Mo
0.112%Sn
0.0085%La
0.03%Zr

 

This "Grey" cast iron GG15HC has also many other benefits:

1)
The graphite flakes dampen vibrations reducing brake judder and brake noise
 
2)
These graphite flakes also conduct heat very well and therefore reduce thermal distortions
 
3)
The graphite flakes act as mini stress "Focal points" for potential cracking and make this material extremely viable for use on drilled and slotted discs or rotors, drawing the stress energy away from the machined slots or holes and preventing cracks