Are you curious about the differences between pig iron and wrought iron? Do you know how to differentiate between the two?
If not, you’re not alone!
Many people are unaware of the nature and performance differences between these two types of iron.
In this blog post, we’ll explain the distinctions between pig iron and wrought iron, including their carbon content, properties, and uses.
So, whether you’re a metalworking enthusiast or just interested in learning something new, keep reading to discover the fascinating world of pig iron and wrought iron.
1. Pig iron
Generally, pig iron refers to an iron alloy with a 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 below 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 smelt 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 of more than 2%.
- Wrought iron has a carbon content of less than 0.04%.
- Steel has a carbon content of 0.05% to 2%.
1. Wrought iron properties
Wrought iron, also known as pure iron, has a soft texture, high plasticity and ductility, making it easy to deform and can be drawn into wire. However, it has low strength and hardness, making it easy to forge and weld. Due to these properties, it is not widely used.
Pure iron is primarily used as electrical material due to its high permeability and can be used in various iron cores. It is also used as a raw material for high-grade alloy steel.
However, pure iron is rarely used as a structural material due to its soft texture and low strength.
2. Pig iron properties
Pig iron has a high carbon content. It is hard and wear-resistant with good castability, but it is also brittle and has almost no plasticity, making it unable to be forged.
Based on the form of carbon in pig iron, it can be classified into three types: steelmaking pig iron, casting pig iron, and nodular cast iron.
(1) Steelmaking pig iron has carbon in the form of iron carbide, and its section appears white, commonly referred to as white iron. This type of pig iron is hard and brittle and is primarily used as a raw material for steelmaking.
(2) Cast pig iron has carbon in the form of flake graphite, and its fracture is gray, commonly referred to as 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 anti-positional strength, making it unable to be forged or rolled, and is only used to manufacture castings such as machine tool beds and iron pipes.
(3) Nodular cast iron has carbon in the form of spherical graphite, which gives it mechanical properties that are closer to steel and are much better than gray iron. It has excellent casting, cutting, wear resistance, and a certain level of elasticity, making it widely used in the manufacture of high-grade castings like crankshafts, gears, pistons, and various mechanical parts.
(4) Additionally, 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 alloy pig iron to the steelmaking process can improve the properties of steel.