Unit 15.1: Properties of Wrought Iron

Wrought iron is one of the purest forms of commercial iron.
It contains very low carbon and small amounts of slag fibers, which give it unique mechanical properties.

Wrought iron was widely used before the development of mild steel, but today it is mainly used for decorative and special applications.

2. Definition

Wrought Iron

Wrought iron is a nearly pure form of iron containing less than about 0.08% carbon and small amounts of slag.

3. Composition of Wrought Iron

Typical composition:

The slag fibers are distributed throughout the metal and improve certain properties.

4. Structure

The structure of wrought iron contains:

• Pure iron matrix

• Fine slag fibers (iron silicate)

These slag fibers give wrought iron a fibrous structure, which improves toughness.

5. Important Properties of Wrought Iron

1. High Ductility

Wrought iron can be easily drawn into wires and thin sheets.

2. Good Toughness

It can absorb shock and vibration without breaking easily.

3. Excellent Corrosion Resistance

It has better resistance to rusting than ordinary steel.

4. Good Weldability

Wrought iron can be easily welded and forged.

5. Good Malleability

It can be hammered or rolled into shapes without cracking.

6. Low Strength

Compared to steel, wrought iron has lower tensile strength.

7. Fibrous Fracture

Due to slag fibers, the fracture surface shows a fibrous appearance.

6. Advantages of Wrought Iron

• Easy to forge and weld

• Good corrosion resistance

• Tough and ductile

• Can withstand repeated shock loads

7. Disadvantages

• Low strength compared to steel

• Cannot be hardened by heat treatment

• Costly production process

• Largely replaced by mild steel

8. Applications

Wrought iron is used in:

• Decorative gates and railings

• Chains

• Rivets and bolts

• Pipes

• Agricultural equipment

• Historical structures and ornamental work

9. Important Exam Points

Very important points for JE / AE / Diploma mechanical exams:

• Wrought iron contains less than 0.08% carbon

• It has a fibrous structure due to slag

• It has good corrosion resistance and ductility

• It cannot be hardened by heat treatment

10. Quick Comparison