Steel, an alloy of iron and carbon, is by far the most commonly manufactured material in the world. The abundance of its two primary components, the comparatively low cost of producing it, accompanied by its impressive range of mechanical properties, have made steel a fundamental part of society’s industry and infrastructure.

View a second image of medium carbon steel.

There are thousands of varieties of steel, but based solely on chemical composition only three major groups of steel exist: low-alloy steels, high-alloy steels, and carbon steels. Of the three, carbon steel, which is the product resulting from approximately 90 percent of all steel production, is the most widely utilized. Carbon steel is also the most vulnerable to corrosion and, therefore, typically used in either unexposed applications or covered with a protective coating.

The carbon steels are subdivided into low, medium, and high grades based on the percentage of carbon they contain. High carbon steels contain greater amounts of carbon, and are, therefore, the hardest. However, low carbon steels have the advantage of being more ductile. Medium carbon steels, which are usually 0.2 to 0.49 percent carbon, can be heat treated to have a good blend of the favorable qualities of both and are popular for their combination of strength and ductility.