Where do you think steel comes from? If you thought that it was simply lying around on the earth's surface like other metals, you’re wrong! Do you want to know how this iron-carbon alloy is made? Find out below.
You might have wondered what metal your kitchen pans are made of, or what the can that your tuna fish comes in is made from. Look no further: the answer is steel! Countless items that furnish our everyday lives are made from this material and it is essential for our economy and society.
Steel is made from an iron-carbon alloy, but it’s possible to add elements that enhance specific properties for greater hardness, malleability, or durability.
High-temperature furnaces are used to smelt the metal and ensure it alloys correctly with other components. There are two principal ways of producing steel in use today:
Iron is mined and extracted in raw form, known as iron ore, and taken to a blast furnace where it is smelted, separating off the impurities such as nitrogen, sulfur and excess carbon, to produce what’s known as pig iron. This is then heated at a high temperature and other alloying elements, including carbon, are added to the mixture to produce different grades of steel. The alloy is then subjected to a molding and cooling stage.
Ferrous scrap, sourced from discarded iron and steel products, is sorted and shredded, before being taken to a large melting furnace at temperatures as high as 1,600°C. One of the by-products of this process is slag, used as an aggregate in civil construction works. The molten steel is poured into molds and proceeds to the cooling stage.
According to the World Steel Association, around 70% of the steel manufactured today is produced using the basic oxygen furnace method, which blows oxygen through molten pig iron to lower the carbon content of the alloy, resulting in low-carbon steel. Worldsteel explains that, “the industry has been hard at work, improving the efficiency of its operations; producing a ton of steel today takes 40% less energy than it did in 1960.”