Carbon content is the main factor that differentiates wrought iron, pig iron, and steel in terms of their properties. Here's a detailed explanation:

1. Wrought Iron:
- Wrought iron is a low carbon iron alloy with a carbon content of less than 0.08%.
- It is primarily composed of iron with small amounts of slag (impurities) and fibers of a tough iron silicate called ferrite.
- Due to its low carbon content, wrought iron is relatively soft, ductile, and malleable.
- It has excellent corrosion resistance, making it suitable for outdoor applications like fences, gates, and decorative items.
- Wrought iron has poor tensile strength and cannot be hardened by heat treatment.

2. Pig Iron:
- Pig iron is an intermediate product obtained during the production of iron from iron ore in a blast furnace.
- It has a high carbon content, typically ranging from 2% to 4%.
- Pig iron also contains impurities like silicon, sulfur, and phosphorus.
- Due to its high carbon content, pig iron is brittle and not suitable for most applications.
- It has a high melting point and is primarily used as a raw material for making steel.

3. Steel:
- Steel is an alloy of iron and carbon, with carbon content typically ranging from 0.2% to 2%.
- It is produced by reducing the carbon content of pig iron through a process called steelmaking, which involves removing impurities and adjusting the carbon content to achieve desired properties.
- The carbon content in steel determines its hardness, strength, and other mechanical properties.
- Low carbon steels (0.2%-0.3% carbon) are relatively soft, ductile, and easily weldable.
- Medium carbon steels (0.3%-0.6% carbon) have higher strength and hardness but reduced ductility.
- High carbon steels (0.6%-2% carbon) are very hard and brittle, suitable for applications like cutting tools or springs.
- Steel can be further alloyed with other elements like chromium, nickel, and manganese to enhance specific properties such as corrosion resistance, heat resistance, or strength.

In conclusion, the properties of wrought iron, pig iron, and steel differ primarily due to their carbon content. Wrought iron has a low carbon content, making it malleable and corrosion-resistant. Pig iron has a high carbon content and is brittle, while steel has varying carbon content, leading to a wide range of mechanical properties.