Most people think that steel is just a pre-set combination of iron and carbon, but did you know there are more than 3,500 different grades of steel? You can compare steel grades by measuring the amount of carbon, additional alloys, and how the manufacturer processes them.
The Four Types of Steel
Authorities grade and categorize steel types into four groups — Carbon, Alloy, Stainless, and Tool. So what are these different types of steel made of, and what are they used for?
Carbon steels only contain trace amounts of elements besides carbon and iron. This group is the most popular of the four grades of steel and it accounts for 90% of steel production.
Carbon Steel has three main subgroups depending on how much carbon is in the metal: Low Carbon Steels/Mild Steels (up to 0.3% carbon), Medium Carbon Steels (0.3–0.6% carbon), and High Carbon Steels (more than 0.6% carbon).
Companies often manufacture these steels in massive quantities since they’re cheap to manufacture and they’re strong enough to use in large-scale construction.
Alloy steels are created by adding additional alloying elements like nickel, copper, chromium, and/or aluminum. Incorporating these elements enhances the steel's strength, ductility, corrosion resistance, and machinability.
Stainless steels contain 10-20% chromium as their alloying element, as well as other elements such as nickel, silicon, manganese, and carbon.
These steels have remarkably high corrosion resistance and are safe to use in outside construction because they have an increased ability to withstand rough weather. They are also widely utilized in electrical equipment. 304 Stainless Steel, for example, is highly sought after for its ability to withstand the elements while keeping electrical material out of harm's way.
While different grades of stainless steel like 304 Stainless Steel have a place in construction, a majority of industries use stainless steel for their sanitary properties. These steels are commonplace in medical equipment, piping, cutting tools, and food processing equipment.
Tool steels, as you can probably guess by the name, excel in cutting and drilling equipment. The secret is the tungsten, molybdenum, cobalt, and vanadium that increases their heat resistance and overall durability. And since they retain their shape under heavy usage, they're the go-to material for most hand tools.
What are the different grades of steel?
Steel grading systems give us a way to categorize steel types based on all the different uses that make them distinct.
For instance, the rate that manufacturers cool steel can impact how strong it is on a molecular level. The amount of time they keep steel at critical temperatures during the cooling process plays an important role as well. In fact, it's possible for two sheets of steel with the same alloy content to have different grades based on their heat-treatment process.
- The ASTM Grading System assigns each metal a letter prefix based on its overall category (“A” is the designation for iron and steel materials), as well as a sequentially assigned number that corresponds with that metal’s specific properties.
- The SAE Grading System uses a four-digit number for classification. The first two digits denote the steel type and alloying element concentration, and the last two digits indicate the carbon concentration of the metal.
Steel grading standards are widely used by scientists, engineers, architects, and government agencies to ensure the quality and consistency of materials. These standards provide a common language to communicate the properties of steel with great specificity, and guide product manufacturers toward proper processing and application procedures.
Mead Metals Makes the Grade
Mead Metals supplies steel at the highest SAE grading standards so you can be sure that your material is durable and long-lasting. No matter your industry or order size, we can provide the right type of steel for your unique project. Contact us to get a quick quote today.