If you’ve ever wondered what the most commonly used metal in the world is, you might be surprised (or unsurprised for that matter) to find out that it’s steel. Steel is strong and widely used. Many objects that you and I interact with on a regular basis are made of steel. Yet, with its popularity and applicability, many people are relatively unaware of steel’s various properties, intricacies, and uses. If that rings true for you, you'll likely find some interesting information in this post.
The Origins of Today’s Steel Alloys
Steel was first made by mining iron ore from the ground, smelting the ore in a furnace to remove impurities, and adding carbon. Today’s steel-making process involves recycling existing steel. Whether it’s mined from the Earth or recycled, steel is a combination of iron and carbon.
As a 100% recyclable material, there is no limit to how many times steel can be reused and repurposed. According to the American Iron and Steel Institute,
“North American steelmaking furnaces consume nearly 70 million tons of domestic steel scrap in the production of new steel… By using steel scrap to make new steel, the North American steel industry conserves energy, emissions, raw materials, and natural resources.”
Plus, recycling steel does not result in a loss of quality or strength.
Steel Groups: Stainless, Carbon, Tool, and Alloy
When you first try to understand steel, it’s easy to end up overwhelmed. And that’s partly because steel is made of four distinct groups. By understanding a bit about these groups, you’ll find the information about steel a bit more digestible. The four groups are stainless, carbon, tool, and alloy, and they are grouped based on chemical composition.
Stainless steel is known for being the most corrosion resistant of the four groups. Stainless steel typically includes chromium, nickel, or molybdenum, with these alloys making up around 11-30 percent of the steel.
Of the four steel groups, stainless steel is the most widely known. It is commonly used in food handling, food processing, medical instruments, hardware, and appliances.
Carbon steel and stainless steel have the same basic ingredients of iron and carbon, but where their composition differs is in alloy content. Carbon steel has under 10.5 percent alloy content. It’s common to see carbon steel broken down into three subcategories: low carbon steel (0.03-0.15% carbon), medium carbon steel (0.25%-0.50% carbon), and high carbon steel (0.55%-1.10% carbon).
As the percentage of carbon increases, the steel becomes harder and more difficult to bend or weld. Low carbon steels are more commonly used due to having lower production costs, greater ductility, and increased ease of use in manufacturing. Low carbon steels are more likely to deform under stress, while high carbon steels are more conducive to breaking under pressure. Low carbon steels are commonly used in auto body panels, bolts, fixtures, seamless tubes, and steel plate.
Tool steels have a carbon content between 0.5% and 1.5%. Tool steel contains other additives, including tungsten, chromium, vanadium, and molybdenum. Tool steels are known for their hardness and their ability to hold a cutting edge at elevated temperatures. This, combined with being resistant to wear and deformation, makes tool steel perfectly suited for use in machining and tool making.
If you’re being technical, steel that falls into any of these four group classifications is an alloy, but that’s not what I’m talking about right here. “Alloy steel” is different from “steel alloys.” So, what is alloy steel? Alloy steel is steel that includes about 5% alloying elements in its composition. These alloying elements can include manganese, chromium, vanadium, nickel, and tungsten. The addition of alloying elements increases overall machinability and corrosion resistance.
Alloy steel is most commonly used to manufacture pipes, especially pipes for energy-related applications. It’s also used in the manufacturing of heating elements in appliances like toasters, silverware, pots and pans, and corrosion-resistant containers.
I hope you have a better understanding of steel in general and the four groups steel is often broken into: stainless steel, carbon steel, tool steel, and alloy steel. If you’d like to learn more about stainless steel, feel free to download a free copy of our steel whitepaper: