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Steel is one of the most widely used metals in the modern world. It’s cheap, strong and incredibly versatile. With worldwide production running at approximately 750 million tonnes per year, steel is the second most mass-produced commodity next to cement.stainless Melbourne steel Fabrication
Steel is completely recyclable and requires relatively little energy to produce. Due to the efforts of the steel industry, energy consumption and carbon dioxide emissions are less than half of what they were in the 1960s. This makes steel very environmentally friendly and sustainable.
Products made of steel are too numerous to list here but include: railroads, oil and gas pipelines, skyscrapers, elevators, subways, bridges, automobiles, ships, knives and forks, razors and surgical instruments. Steel is everywhere!
The History of Iron
Iron is the fourth most abundant element, making up more than 5% of the earth’s crust.
The production of iron by humans started in around 2000 BC in south-west or south-central Asia. This marked the beginning of the Iron Age which saw the widespread replacement of bronze with iron for tools and weapons. During this era, wrought iron was produced by blacksmiths who would heat the iron and hammer out impurities over an anvil. The resulting iron was tough but malleable.
In the Middle Ages, a new type of iron was developed using higher temperatures. This was known as cast iron, which was harder than wrought iron but more brittle.
Iron formed the material basis of human civilization for over three thousand years until the mass production of steel in 1870 AD.
The Composition of Steel
Steel is an alloy of iron and carbon. It can contain small quantities of silicon, phosphorus, sulfur and oxygen.
The carbon content of steel is between 0.08 to 1.5 percent. This makes it harder than wrought iron but not as brittle as cast iron. Steel has a unique balance of hardness, flexibility and tensile strength. It’s more durable and holds a sharper edge better than the softer wrought iron. At the same time it resists shock and tension better than the more brittle cast iron.
How Is Steel Made?
To make steel, iron ore is heated and melted in furnaces where the impurities are removed and carbon added.
Today, most steel is made using one of two processes:
- Blast Furnace
- Electric Arc Furnace (EAF)
Steel is an alloy, which is a mixture of two or more metallic elements. Metals are divided into two different types: ferrous and non-ferrous. Ferrous metals contain iron. Steel is an example of a ferrous metal. Non-ferrous metals include aluminum, copper, and titanium.
By itself, iron ore usually has many impurities, such as silica, phosphorus, and sulfur. These impurities weaken iron. The process of making steel involves removing the impurities from iron and adding carbon to give steel its incredible strength.
Metal can be extracted from ore by heating it to extremely high temperatures until it melts. This process is known as smelting. Historians believe steel has been produced in rudimentary furnaces for thousands of years.
The invention of blast furnaces and other technological improvements in the 17th through 19th centuries led to higher quality steel that could be mass-produced. Today, most steel plants use a production process called basic oxygen steelmaking (BOS).
In large BOS furnaces, high-purity oxygen is blown through molten iron ore. The oxygen combines with impurities to form oxides that either burn off or form a by-product, called slag, which can be skimmed off the surface of the molten iron. Other chemical cleaners, called fluxes, are also added to remove impurities.
Other elements can then be added to create the exact type of steel desired. Carbon is the most common additive. It’s used to create high-strength carbon steel. Another popular additive is chromium, which can be added to make stainless steel that’s very resistant to rust.
Steel is one of the most common building materials in the world, because of its high strength and relatively low cost to produce. Each year, steel plants produce more than 1.3 billion tons of steel that gets used in various ways, such as building materials, ships, automobile frames, bridges, appliances, weapons, and machines.
What is steel made of?
Iron, the major elemental component of steel, is one of the most plentiful elements in the earth’s crust. All steel alloys are primarily iron and 0.002–2.1 % carbon by weight. In this range, carbon bonds with iron to create a strong molecular structure. The resulting lattice microstructure helps achieve certain material properties, like tensile strength and hardness, that we rely on in steel.
Although all steel is made of iron and carbon, different types of steel contain different percentages of each element. Steel can also include other elements like nickel, molybdenum, manganese, titanium, boron, cobalt, or vanadium. Adding different elements to the “recipe” for a steel alloy affects its material properties. The method of manufacture and treatment of the steel further enhances those abilities.
One notable group of steel alloys contain chromium. All such alloys are known commonly as stainless steel.
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