White cast iron is a hard and brittle form of cast iron.

It gets its name because the fracture surface appears white due to the presence of cementite (Fe₃C).

Definition

White Cast Iron

White cast iron is a type of cast iron in which carbon is present in the combined form as iron carbide (cementite).

Microstructure

• Carbon exists as cementite (Fe₃C)

• No free graphite

• Fracture surface appears white and crystalline

Properties

Important characteristics:

• Very hard

• Very brittle

• High wear resistance

• Difficult to machine

Uses

White cast iron is used in applications requiring high wear resistance, such as:

• Crushing machinery

• Mill liners

• Grinding balls

• Rolling mill rolls

Exam Points

• Carbon form → cementite (Fe₃C)

• Fracture surface → white

• Hardest type of cast iron