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What is the Difference Between Cast Iron and Regular Iron?

Regular iron and cast iron are not so different as they are both the same material. The only difference is in some of the properties they possess and the way the metal is shaped. These subtle, yet drastic differences actually mean that each metal type has different uses and applications.

Iron is one of the most widely used metals and is found within the earth’s crust. Here it is sourced from iron ore mines, and the core iron ore metal is then smelted into various types of metals. How the metal is smelted depends on the metal that you want. Each type of iron is manufactured differently and thus the properties and applications of each iron type can differ immensely, such as the differences between cast iron and regular iron.

Regular Iron

So what is regular iron? Regular iron is also known as wrought iron, and it is traditionally smelted at a low temperature for a long period of time. This produces a spongey substance known as bloom. The smelting process is to rid the metal of the impurities, and then the metal is worked on with tools to shape it. The fact that the metal is worked on gives it its name ‘wrought iron’.

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The resultant wrought iron actually has a very small carbon content, less than 1% carbon. It is therefore, incredibly strong and resistant to corrosion. Due to the purity of wrought iron, this metal is able to withstand harsh weather by not rusting.

Cast Iron

This is produced using a similar method. However instead of smelting the metal at a low temperature for a long period of time, this iron is smelted at an incredibly high temperature for a short period of time. This creates a liquid state as a result of the high temperature smelting. As a result, the metal becomes drenched with carbon because of the furnace fuel – approximately 5% compared to the relatively little carbon found in wrought iron.

The liquid metal is then poured into casts to mould the metal into the required shape, as opposed to being hammered into shape. The fact that the metal is poured into casts gives it the name ‘cast iron’. Also because cast iron isn’t treated for a sustained period of time, like that of wrought iron, it isn’t as pure.

Finally the high carbon content actually makes this metal much more rigid and, even at hot temperatures, which is just as well because it is often used for cooking. However because it isn’t as pure, it can rust much easier compared to wrought iron and as a result it is often known as ‘brittle iron’.

When it comes to the uses of wrought and cast iron, there are marked differences. Mainly this is to do with the fact that cast can be shaped using moulds and so can be moulded into any shape that is needed. This therefore makes it a very useful metal for cookware and outdoor appliances. Whereas wrought iron is often used for shapes that are simple and easy to produce such as drains or garden gates.