How Is Wrought Iron Made?

What Is Wrought Iron?

All irons and steels are simply irons with different carbon contents. Wrought iron has a very low carbon content. Its fibrous appearance is because of the slag (oxidized metal impurities) in the iron. Wrought iron is now less common than mild steel, which has a similar appearance, though a different carbon content.

The Original Manufacture of Wrought Iron

A few centuries ago, wrought iron was made through the bloomery process. This process included throwing iron ore and charcoal into a forge and burning the mixture, called the bloomery, at a temperature below the melting point of iron. This caused the slag in the ore, which must be removed to harvest the iron at low carbon content, to run out of the forge. However, this did not produce pure wrought iron. The bloom, which was the spongy iron ore produced from the forge, had to be fired again and beat into bars for use by blacksmiths.

The Most Modern Production of Wrought Iron

Although no wrought iron has been commercially manufactured since 1969, the most recent method for its production was the Aston process. In this process, molten steel from a Bessemer converter, which converts high-carbon pig iron to steel through oxidation, is poured into somewhat cooler liquid slag. When the molten steel hits the slag, its impurities are evaporated as gases, and a mass similar to that described above is produced. As in the bloomery process, this mass must be compressed and beaten many times until flat bars of wrought iron are produced.