The American Society for Testing and Materials standardizes, among other things, the composition and mechanical properties of steel. While many forms of steel possess similar compositions, such as A529 and A572, relatively small differences in the quantities of particular elements are enough to make the steels have different mechanical properties, and therefore, different applications.
In terms of chemistry, A529 and A572 have very similar elemental composition. A572 has a carbon content of about .21 percent, a manganese content of 1.35 percent, a phosphorous content of .04 percent, a silicon content of .3 percent and a sulfur content of .05 percent. In comparison, A529 steel has a content of .27 percent, a manganese content of 1.2 percent, a phosphorous content of .04 percent and a sulfur content of .05 percent. Additionally, A529 has copper added (.2 percent) and lacks silicon.
Mechanically, A572 and A529 are very similar. A572 has an ultimate tensile or breaking strength of 60,200 pounds per square inch, a tensile yield strength of 42,100 psi and a shear modulus of 11,600 ksi. A529 possesses an ultimate tensile strength of 72,500 psi, a tensile yield strength of 42,100 psi and a shear modulus of 11,600 ksi. The additional ultimate tensile strength is partly due to the addition of copper and slightly higher carbon content of A572.
With such similar chemistry and nearly identical mechanical properties, A529 and A572 steel are used interchangeably in most applications. Both steels are typically available in plate and bar form. Because both types of steel can be easily welded and riveted, they are typically used in the construction of buildings, bridges and other structures.