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The Differences In the Types of Steel

Steel is an alloy containing iron and carbon, and is in use throughout the engineering and manufacturing world today. The wide use of iron can be attributed to its abundance in the earth's crust, while nowadays the mechanical properties it offers ensure it can provide high performance for a vast range of applications. Mixing the iron with various other materials, called alloying elements, produces different types of steel, each designed specifically to enhance a few particular properties.

Carbon Steels
- These are the most common of all steels in use today, accounting for more than 85% of the steel produced and shipped in the United States. The addition of carbon makes the steel harder and stronger, and once the carbon is added the material can be designated as being low, mild or high carbon steel depending on the carbon content (measured as percentage of total volume). In general, carbon steels contain up to about two percent alloying elements along with the iron.
Stainless Steels
- When iron is mixed with another element in efforts to improve its corrosion resistance, it is termed "stainless steel." Most commonly, this is done to improve the aesthetics of the steel. The alloying elements are typically chromium, nickel, molybdenum and titanium, all of which have much greater corrosion resistance than pure iron. Typical chromium content is 10%, while the exact volume of this and the other alloying elements decides which grade the stainless steel is.
Alloy Steels
- Alloy steels are essentially carbon steels with the addition of other chemical elements. Which elements are added depends on the specific application and the particular properties which are to be enhanced, but can include manganese to improve tensile strength, nickel for corrosion resistance, and silicon for ease of hardening. Each material has an American Iron and Steel Institute (AISI) four-digit number that indicates which alloy steel it is.
Tool Steels
- While not a unique type of steel, tool steels are those carbon and alloy steels suitable for use in tools. Typical properties include a high resistance to wear, the ability to operate in elevated temperatures, and obviously higher strength than the material being operated on. What is different about tool steels, however, is that they are always heat treated after manufacture to help develop the desired properties. This consists of heating the steel to temperatures as high as 300 degrees Celsius, before cooling it at a rate which depends on the chemical composition and desired finish.

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