Nodular cast iron is also called ductile cast iron or spheroidal graphite iron.

In this type, graphite appears as spherical nodules instead of flakes.

This improves the strength and ductility of the material.

Definition

Nodular Cast Iron

Nodular cast iron is a cast iron in which graphite exists in the form of spherical nodules due to the addition of magnesium or cerium.

Production

Small amounts of magnesium or cerium are added to molten iron.

These elements change graphite structure from flakes to spherical nodules.

Properties

Important properties include:

• High tensile strength

• Good ductility

• High toughness

• Good impact resistance

• Good machinability

Uses

Nodular cast iron is widely used in:

• Crankshafts

• Gears

• Automobile components

• Pipes

• Heavy machinery parts

Exam Points

• Graphite form → spherical nodules

• Also called ductile cast iron

• Produced by adding magnesium

Important Comparison (Very Common in Exams)

Quick Revision Summary

Grey Cast Iron

• Graphite flakes

• Grey fracture

• Good damping capacity

White Cast Iron

• Carbon as cementite

• White fracture

• Very hard and brittle

Malleable Cast Iron

• Produced by heat treating white iron

• Contains temper carbon

• Good ductility

Nodular Cast Iron

• Graphite in spherical nodules

• High strength and toughness

• Also called ductile iron