Acicular: A hard, highly wear-resistant metallographic structure with a needle-like appearance, made up of martensite and bainite.
Austenite: A structural constituent formed while the roll solidifies. Because it is unstable at low temperatures, it is not desired in large amounts in the final structure of the roll.
Ferrite: A structural constituent made up mostly of almost pure iron. It is the softest phase of steel.
Pearlite: A structural constituent found in most rolling materials, a fine mixture of ferrite and iron carbide.
Bainite: A structural constituent that increases hardness.
Martensite: Obtained by heat-treating materials that contain alloys such as nickel. It increases the hardness of the material more than bainite does.
Graphite: Free (pure) carbon present in the roll structure as spheres or flakes.
Carbide: Compounds that carbon forms with iron or other metallic elements while the roll solidifies (primary carbide) or during cooling and heat treatment after solidification (secondary carbide).