I believe many people don’t know how to distinguish pig iron from wrought iron.
Let me tell you the difference between pig iron and wrought iron.
1. Pig iron
Generally refers to iron alloy with the carbon content of 2 ~ 6.69%.
Also known as cast iron.
In addition to carbon, pig iron also contains silicon, manganese and a small amount of sulfur and phosphorus.
It can be cast but not forged.
2. Wrought iron
It is relatively pure iron refined from pig iron.
Carbon content is below 0.02%, also known as wrought iron and pure iron.
Pure iron requires a very low content of impurity elements such as carbon, phosphorus and sulfur.
It is difficult to smelt, and the manufacturing cost is much higher than pig iron and steel.
The main difference between pig iron, wrought iron and steel lies in the carbon content.
Iron with a carbon content of more than 2% is called pig iron;
Iron with a carbon content of less than 0.04% is called wrought iron;
Iron with a carbon content of 0.05 ~ 2% is called steel.
1. Wrought iron properties
Cooked iron is very soft, has good plasticity, and good ductility, is easy to deform, can be pulled into wire, has low strength and hardness, is easy to forge and weld, and is not widely used.
Pure iron is mainly used as electrical material with high permeability and can be used in various iron cores.
It is also used as raw material for high-grade alloy steel.
Pure iron is rarely used as a structural material because of its soft texture and low strength.
2. Pig iron properties
Pig iron contains a lot of carbon.
Pig iron is hard, wear-resistant, and has good castability, but pig iron is hard and brittle, has almost no plasticity, and cannot be forged.
According to the different forms of carbon in pig iron, it can be divided into steelmaking pig iron, casting pig iron, and nodular cast iron.
(1) The carbon in steel-making pig iron mainly exists in the form of iron carbide, and its section is white, which is usually called white iron.
This pig iron is hard and brittle.
It is generally used as raw material for steelmaking.
(2) The carbon in cast pig iron exists in the form of flake graphite, and its fracture is gray, which is usually called gray iron.
Because graphite is soft and has a lubricating effect, cast pig iron has good cutting, wear resistance and casting properties.
However, its anti-positional strength is not enough, so it can not be forged and rolled.
It can only be used to manufacture various castings, such as casting various machine tool bed seats, iron pipes, etc.
(3) The carbon in nodular cast iron exists in the form of spherical graphite.
Its mechanical properties are much better than gray iron and are close to steel.
It has excellent casting, cutting, wear resistance and certain elasticity.
It is widely used in manufacturing high-grade castings such as crankshaft, gear, piston and a variety of mechanical parts.
(4) In addition, there is pig iron with a particularly high content of silicon, manganese, nickel or other elements, called alloy pig iron, such as ferrosilicon and ferromanganese, which are commonly used as raw materials for steelmaking.
Adding some alloy pig iron in steelmaking can improve the properties of steel.