ASTM A588 is available in 3 grades, A, B, and K.

With the addition of copper, nickel, and chromium alloys, ASTM A588 is specially designed for projects with high exposure to atmospheric conditions. In fact, its advantage over similar steels like A572 is its weathering ability. For that reason, A588 is also known as a weathering steel. The surface oxidation of weathering steel—what gives it its distinctive rusty appearance when unpainted—typically takes six months, but surface treatments can accelerate the oxidation to as little as a few hours.

Because of its strong, innate resistance to corrosion, A588 can be used in its bare, or unpainted, condition.

Q: How is A588 related to Cor-Ten®?

Cor-Ten® is a trade name for atmospheric corrosion resistant steel with the same specifications as A588. As it became more popular over the years, mills began to develop their own versions, at which point ASTM created standard specifications for it, what we now know as A588.