The difference between steel and iron

The main difference between steel and iron is the difference in carbon content.

There are two types of iron: pig iron and wrought iron. They are also distinguished by the difference in carbon content.

Usually called wrought iron with a carbon content of less than 0.02%, pig iron with a carbon content of more than 2.11% to 4.3%, and steel in the middle.

The content of carbon determines the performance of iron. High carbon content, high hardness and poor ductility.

Pig iron

Pig iron is hard, wear-resistant and has good castability, but pig iron is brittle and cannot be forged.

According to the form of carbon in pig iron, it can be divided into: white iron, gray iron and ball milled cast iron.

White iron: It exists in the form of iron carbide, its cross section is white, and it is usually called white iron. This kind of pig iron is hard and brittle, and is generally used as a raw material for steelmaking.

Gray iron: Carbon exists in the form of flake graphite, and its fracture is gray, usually called cast iron. Because graphite is soft and has a lubricating effect, cast pig iron has good cutting, wear resistance and casting properties. But its tensile strength is not enough, so it cannot be forged and rolled and can only be used to make cast products. Such as various machine bed bases, iron pipes, etc.

Ball-milled cast iron: Carbon exists in the form of spherical graphite, which has excellent casting, cutting and wear resistance. It has a certain degree of flexibility and is widely used in the manufacture of high-grade castings such as crankshafts, gears, pistons, and various mechanical parts.

Wrought iron

Wrought iron is relatively pure iron refined from pig iron. The carbon content is below 0.02%. Wrought iron is soft, has good plasticity, good ductility, can be drawn into wire, has low strength and hardness, and is easy to forge and weld.

The purpose of wrought iron: one is used as an electromagnetic material, because wrought iron has a higher magnetic permeability and can be used for various iron cores. One is used as a deep-drawing material because it can be punched into extremely complex shapes.

Beautiful crafts made of wrought iron.

Steel

Steel is the most common form in our lives.

Steel is between pig iron and wrought iron, and is also called carbon steel. Carbon steel not only has good plasticity, but also steel products have excellent physical and chemical applications such as high strength, good toughness, high temperature resistance, corrosion resistance, easy processing, impact resistance, and easy extraction. Performance, so it is widely used.

According to the carbon content of carbon steel, steel can also be divided into: low carbon steel, medium carbon steel and high carbon steel.

As the carbon content increases, the hardness of carbon steel increases and the toughness decreases.

Steel is smelted from pig iron through high-temperature calcination and other processes in a steelmaking plant. The carbon and oxygen in it react to form carbon dioxide, thereby reducing the carbon content in iron and becoming steel.

In order to meet more needs and improve the performance of steel, on the basis of smelting carbon steel, steel made by adding some alloying elements, such as chromium steel, manganese steel, chromium-manganese steel, and chromium-nickel steel. This kind of steel is also called alloy steel.