The Science Behind Iron and Steel
The most remarkable 19th-century structures globally, including the Statue of Liberty and the Eiffel Tower, were crafted from iron. This is the fourth most common element found in the Earth’s crust, and it’s been widely used for around 6,000 years. Its versatility is what sets it apart from other metals, as well as its affordability and strength. For this reason, iron was a huge player in the industrial revolution, and it’s also a vital element within animal and plant life.
When combined with varying amounts of metal, iron becomes steel, which is a considerably stronger metal. From a steel box section to cutlery, there are a number of things that can be crafted from steel.
Steel is an iron alloy; however, it contains around the same amount of carbon (or slightly more) than wrought iron. Meanwhile, its carbon content is much lower than that of cast iron. Since it’s so useful, steel is often spoken about as if it’s a metal in its own right; however, it’s predominantly made from iron. Moreover, there are thousands of steel types, meaning they can be designed to fulfill a specific purpose. There are four different types of steel, including stainless steel, tool steel, alloy steel, and carbon steel. These names can present confusion, though, as all steels are alloys, and each of them contains carbon.
Making Steel from Iron
As previously mentioned, steel is made from iron; however, there are three stages in the production process. First, is the steel being made from the iron. Second is the treatment to improve steel’s properties. Last is the rolling or shaping of the product.
In order to make steel from iron, several processes need to be completed. These include the following:
- Electric-furnace process– electric furnaces use electric arcs, which are giant sparks, to melt scrap steel or pig iron. Electric furnaces are more controllable, meaning they’re often employed in the creation of higher-specification steels.
- Open-hearth process – this involves metals being burned in a giant fireplace with limestone until they fuse together. Unwanted carbon combines with oxygen, and impurities are removed in the creation of molten steel.
- Basic oxygen process – basic oxygen furnaces are large egg-shaped containers. It rotates from side to side to pour off the completed metal. The air draft in a blast furnace gets replaced with pure oxygen.
Each of the above processes creates liquid steel, which is then cast into ingots (which are large bars that can weigh a few or a few hundred tons). These are then rolled and pressed to make one of three building blocks. These include the following:
- Billets –large bars with small square ends
- Slabs – large bars with rectangular ends
- Blooms – large bars with square ends
Each of these blocks can then be worked and shaped to create a number of products. The standard shaping process is hot rolling; the closeness of the rollers allows for the creation of very thin sheets. These sheets can then be fashioned into any other shape.
As previously mentioned, steel is a very versatile material. As a result, it can be used in the likes of machine tools, cutlery, surgical instruments, jet engines, and more. For instance, most modern buildings contain an inner steel structure. As a result, steel is consumed by electrical appliance manufacturers, food can producers, shipbuilding and automobile industries, the construction industry, and more.
The History of Iron and Steel
From the first use of iron for decoration and ornaments in the Middle East in 4000 BC to the invention of the modern basic oxygen process in 1954, iron and steel has a rich history.