Steel is not naturally found in abundance but is rather an artificial creation, an alloy. Alloy is a metal that is made after combining two metals together for greater strengthening or resistance properties. If steel is an alloy, what is it made of? Let’s find out.
It is an alloy of iron and carbon, two naturally occurring metals with minute quantities of silicon, sulfur, oxygen, and phosphorus. In this mix, the carbon quantity ranges up to 2%. Steel has better strength, resistance, and fracture compared to other forms. Stainless steels are resistant to corrosion as well as oxidation with an addition of 11% chromium.
Steel has high tensile strength and is low in budget, making it a suitable choice for buildings, infrastructure, ships, tools, weapons, etc.
What is the need to make alloys?
The main reason why alloys are preferred compared to regular metals is their enhanced corrosion resistance ability. Pure metals are more susceptible to chemicals than alloys increasing their longevity.
What Is Steel Made of?
The base of Steel – Iron
Steel is majorly made of iron, a polycrystalline structure, meaning it has crystals joint at boundaries. According to the temperature, it can take 2 forms which are:
- Body-centered cubic
- Face centered cubic
The allotropic interactions with alloys give steel its unique abilities.
Carbon
Carbon constitutes about 2.14% of the entire weight. The carbon content is responsible for enhancing the alloy’s extra qualities, which makes it better than the pure metal.
How Is Steel Made?
Steel is the most used metal in this day and age. It is strong, costs low, and versatile. It comes second in the list of most mass-produced items, the first being cement. Iron ore is heated and melted in the furnace first, and impurities are removed, then carbon is added.
Two processes are used to make steel which are:
- Blast furnace
- Electric arc furnace
What is A Blast Furnace, and How is Steel Made in It?
A blast furnace was an invention of Henry Bessemer. He deduced a way of making steel via blowing air in the molten iron for its oxidation and separation of impurities. A blast furnace is a huge steel shell cylinder lined with a heat-resistant brick in modern times.
The ore of iron, limestone, and coke is put in it; they gradually sink to the bottom, increasing the temperature as they go. In the upper half, gas from the coke burning releases oxygen from the iron ore. On the other hand, at the bottom, limestone reacts with the impurities, forms a slag, and pushes them out.
In the deepest pit, the temperatures reach 3000 F. The slag floats on top and is drained off, and steel is collected from the tap hole.
Electric Arc Furnace
This method yields high-quality steels alloyed with metals. However, this process is also beneficial for making ordinary nonalloy steels. There are differences between the two processes. EAF does not require hot metal. Instead, scrap steel is recycled. It is dropped into the EAF from an overhead crane till the furnace is fully filled. The lid is then placed and shut.
On the lid are electrodes that are dipped in the furnace, which produces electricity, generating heat and melting the scrap. The slag and steel are then separated.