What Is the Chemical Formula of Steel?

By Jack Byrom; Updated April 24, 2017
Weld Steel

The material we call steel is in fact an alloy, a mixture of different metals. The element iron (symbol Fe) makes up a large percentage of all steels, generally composing more than 75 percent of the mix by percent of total mass. Steel is made from iron, and in the process, some element percentages are reduced in the alloy composition (such as carbon and silicon), and other elements (such as chromium, nickel, and tungsten) are added, depending on the type of steel needed.

Low-Carbon Steel

This type of steel is inexpensive and contains less than 0.25 percent carbon, with about 99 percent of the material deriving from iron. Construction I-beams are made of this steel.

High-Carbon Steel

This steel contains 0.60 to 0.99 percent carbon (C), with close to 99 percent iron.

Stainless N Steel

This alloy can be used to make flatware and cutlery, among other things, and often has a composition of 0.18 percent carbon, 18 percent chromium, and 8 percent nickel, with about 74 percent iron.

Hi-Speed Tool Steel

This steel is generally 0.7 percent carbon, 4 percent chromium, 10 percent tungsten, and 1 percent molybdenum, with about 84 percent iron. It is used to make drill bits and saw blades (alloy of Fe, C, Cr, W, and Mo).

Silicon (Electrical) Steel

This steel is used in motors and generators and has a composition of about 0.6 to 5 percent silicon (Si), with one specific steel made of 0.4 percent carbon, 2 percent silicon, and 97.6 percent iron.

About the Author

Jack Byrom has been writing about science since 2002 and has also worked for the American Chemical Society as a technical editor. He received his Bachelor of Arts in environmental science from Capital University and his research there was published by the National Conference on Undergraduate Research (2004) and "Epistimi" (2004). His articles have been published in the "Columbus Free Press" and "Clarity Magazine."