The two main categories of fabricated steel are plain-carbon and alloy steels. You might be wondering what the fundamental differences between them are. Let’s now talk about alloy steel.

Alloy steels with suitable alloy compositions have greater hardenability than plain-carbon steel and, thus, can provide high strength and good toughness in thicker sections. Their alloy contents may also provide improved heat and corrosion resistance. Alloy steels are normally heat treated to further improve their performance as an engineered material.

Steels used for building construction (Table 1) use standard ASTM identification numbers beginning with A and then two, three or four numbers. These designations are different than the four-number AISI steel grades (Table 2) commonly used for general fabrication steels.