Steel vs Iron: The Differences Explained

Whether you have such doubts – “I have seen iron and I know steel, but I can’t tell what’s different between them”.

Today, I will show you the difference between steel and iron in detail.

First of all, it should be clear from the concept that iron is an element, while steel is an alloy containing elements such as iron and carbon.

Steel vs Iron: The Differences Explained 1

A little confused?

It seems that elements can’t make things.

Well, in fact, the iron we often use is also an alloy, which is a ferrocarbon alloy composed of iron and carbon.

What’s the difference between steel and iron?

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What makes them different is their carbon content.

First, let’s divide iron into two kinds: pig iron and wrought iron. They are also distinguished by their carbon content.

Look at the table below, and you can see the difference between them.

Iron and steel carbon content table

NameWrought ironSteelPig iron
Carbon content<0.02%0.02%-2.11%2.11%-4.3%

Generally, those with carbon content less than 0.02% are called wrought iron, those with carbon content greater than 2.11% to 4.3% are called pig iron, and steel is in the middle.

The content of carbon element determines the performance of iron.

It can be understood that the more carbon content, the harder the iron is, but the more brittle it is;

On the contrary, it is soft and has good ductility.

Related reading: Pig Iron vs Wrought Iron

Wrought iron

Wrought iron is pure iron refined from pig iron.

The carbon content is below 0.02%, also known as wrought iron and pure iron.

The cooked iron is soft, plastic and ductile, and can be drawn into wire with low strength and hardness.

It is easy to forge and weld.

Use of wrought iron:

One is used as electromagnetic material, because wrought iron has high magnetic permeability, it can be used for various iron cores.

One is used as deep drawing material because it can be pressed into extremely complex shapes.

Look at the beautiful handicrafts.

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Pig iron

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

If the form of carbon in pig iron is divided, pig iron can be divided into white iron, gray iron and ball cast iron.

White iron:

Carbon mainly exists in the form of iron carbide, and its section is white, usually called white iron.

This pig iron is hard and brittle, and is generally used as raw material for steelmaking.

This is a picture of white iron.

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Gray iron:

Carbon exists in the form of flake graphite, and its fracture is gray, usually called cast pig iron.

As graphite is soft and has lubricating effect, cast pig iron has good cutting, wear resistance and casting properties.

However, its tensile strength is not enough, so it can not be forged and rolled, and can only be used to manufacture various kinds, such as casting various machine tool beds, iron pipes, etc.

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Ball cast iron:

Carbon exists in the form of spherical graphite, and its mechanical properties are far better than that of gray iron and close to steel.

It has excellent casting, cutting and wear resistance properties, and has a certain elasticity.

It is widely used to manufacture crankshaft, gear, piston and other advanced castings and a variety of mechanical parts.

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Steel is the most common form in our life.

Steel is between pig iron and wrought iron, also called carbon steel.

Carbon steel not only has good plasticity, but also has excellent physical and chemical application properties such as high strength, good toughness, high temperature resistance, corrosion resistance, easy processing, impact resistance, easy refining, etc., so it is widely used.

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

Related reading: Types of Steel

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

Steel is smelted from pig iron by the steelmaking plant through high-temperature calcination and other processes.

The carbon and oxygen in the steel react to generate carbon dioxide, thus reducing the carbon content in the iron and becoming steel.

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In order to meet more needs and improve the performance of steel, on the basis of smelting carbon steel, some alloy elements are added to the steel, such as chrome steel, manganese steel, chrome manganese steel and chrome nickel steel.

This steel is also called alloy steel.

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