The carbon content of steel ranges from 0.02% to 2.11%.

The main difference between pig iron, wrought iron and steel lies in the carbon content. Iron with carbon content more than 2% is called pig iron. Iron with carbon content less than 0.05% is called wrought iron; Iron with carbon content between 0.05% and 2% is called steel.

The chemical composition of steel can vary greatly, and steel containing only carbon is called carbon steel or ordinary steel; In actual production, steel often contains different alloying elements, such as manganese, nickel, vanadium, etc., depending on the use.

With the increase of carbon content, the strength and hardness of steel increase, while the plasticity and toughness decrease.

The hardness is maximum when the carbon content is 1.0%. When the carbon content is more than 1.0%, the strength of steel decreases, and the increase of carbon content also reduces the weldability and corrosion resistance of steel, and increases the cold brittleness and aging tendency of steel.

The carbon content of medium carbon steel is generally between 0.25 ~ 0.60%