A588 Standard Specification for Grade B Weathering Steel

The ASTM A588 specification is the standard specification for high-strength low-alloy structural steels with a minimum yield point up to 50 ksi, resistant to atmospheric corrosion, and suitable for applications requiring strength and durability. The required ASTM G101 corrosion resistance index must be 6.0. Structural steel is used in welded, riveted, and bolted structures and shall employ standard welding procedures appropriate to the grade of steel and the intended use or service.

Grade B Weathering Steel is a finely distributed and low alloy steel, which contains elements such as copper, chromium, nickel, and phosphorus. It resists atmospheric corrosion, and because of its high resistance to oxidation and salt spray, it has excellent weldability and forming characteristics for outdoor structures.

The atmospheric corrosion resistance of this steel in most environments is substantially better than that of carbon steels with or without copper addition. When properly exposed to the atmosphere, this steel can be used bare (unpainted) for many applications. The elements of Weathering Steel are summarized below:

• Copper - Copper increases the corrosion resistance of steel and promotes the formation of a protective layer of rust.

• Chromium - Chromium increases the corrosion resistance and hardness of steel.

• Nickel - Nickel helps to form a protective layer on the surface of steel.

• Phosphorus - Phosphorus helps to increase the corrosion resistance of steel.

Grade B Weathering Steel plates and sheets perform substantially better than other carbon steels when exposed to atmospheric elements. The advanced characteristics of these plates and sheets, such as the high strength, low alloy and atmospheric corrosion resistance, make them suitable for purposes such as bolted, riveted, or welded structures.

Class B weathering steels, when properly exposed to the atmosphere, are significantly more resistant to atmospheric corrosion than carbon steels such as A572-50 with or without copper additions. This steel is economical to use and provides excellent performance in environments often filled with corrosive materials, harsh chemicals and heavy pollution. The physical properties of Grade B weathering steel are unrivaled, making it the perfect steel for any application that needs to last for many years.