Materials

• Cementine: hard and brittle, found above the eutectoid point
• Ferrite: soft and ductile, found below the eutectoid point
• Eutectoid point: 0.83% carbon content in steels
• Cast irons develop through >2% carbon content in steel
• White cast irons: low silicone content, thus includes cementite
• Grey cast iron: high silicon content; lesser cementite properties and includes graphite flakes
• The larger the graphite flakes in grey cast irons, the higher the silicon content, this, the lesser cementite-like properties. Larger graphite flakes oftentimes mean ferrite micro-structure
• Since grey cast iron includes graphite flakes/points of weakness, they are worse in tensile strength. To reduce this weakened property, spheroidal graphite is created through adding magnesium and cerium, as cracks are more likely to develop with flaky voids.
• Malleable cast irons consist of:

  • Blackheart malleable cast iron
  • Whiteheart malleable cast iron
  • Pearlitic malleable cast iron
• Temper carbon rosettes are present in both Blackheart and pearlitic MCIs. These are graphite from the cementite breaking down. In Blackheart, these are on a ferrite matrix, in pearlitic, these are on a pearlite matrix