Difference in nature
1. Pig iron
Generally, pig iron refers to an iron alloy with carbon content ranging from 2% to 6.69%.
It is also known as cast iron.
In addition to carbon, pig iron contains silicon, manganese and small amounts of sulfur and phosphorus.
It can be cast, but it cannot be forged.
2. Wrought iron
Wrought iron, also known as relatively pure iron or pure iron, is refined from pig iron with a carbon content of less than 0.02%.
To be considered pure iron, it must have very low levels of impurities such as carbon, phosphorus and sulfur.
Wrought iron is difficult to cast and has a higher manufacturing cost compared to pig iron and steel.
The distinction between pig iron, wrought iron and steel lies in their carbon content:
- Pig iron has a carbon content greater than 2%.
- Wrought iron has a carbon content of less than 0.04%.
- Steel has a carbon content of 0.05% to 2%.
Performance difference
1. Properties of wrought iron
Wrought iron, also known as pure iron, has a soft texture, high plasticity and ductility, facilitating deformation and can be drawn into wire. However, it has low strength and hardness, making forging and welding easier. Due to these properties, it is not widely used.
Pure iron is mainly used as an electrical material because of its high permeability and can be used in various iron cores. It is also used as a raw material for high-quality alloy steel.
However, pure iron is rarely used as a structural material due to its soft texture and low strength.
2. Properties of pig iron
Pig iron has a high carbon content. It is hard and wear-resistant, with good moldability, but it is also brittle and has almost no plasticity, which makes it incapable of being forged.
Based on the shape of carbon in pig iron, it can be classified into three types: steelmaking pig iron, cast pig iron and nodular cast iron.
(1) Steel pig iron has carbon in the form of iron carbide, and its section appears white, commonly called white iron. This type of pig iron is hard and brittle and is mainly used as a raw material for making steel.
(2) Molten pig iron contains carbon in the form of flake graphite, and its fracture is gray, commonly called gray iron. Due to the soft and lubricating nature of graphite, cast pig iron has good cutting, wear resistance and casting properties. However, it has insufficient antipositional resistance, making it impossible to be forged or rolled, and is only used to manufacture castings, such as machine tool bases and iron pipes.
(3) Nodular cast iron has carbon in the form of spherical graphite, which gives it mechanical properties closer to steel and much better than gray iron. It has excellent casting, cutting, wear resistance and a certain level of elasticity, making it widely used in manufacturing high-quality castings such as crankshafts, gears, pistons and various mechanical parts.
(4) In addition, there is a type of pig iron with a high content of silicon, manganese, nickel or other elements, known as alloy pig iron, such as ferrosilicon and ferromanganese, which are commonly used as raw materials for steelmaking. Adding pig iron alloy to the steelmaking process can improve the properties of steel.
