What is the difference between A36 and A588?

A36 and A588 are both grades of steel that have different properties and are used in various applications. Here are the main differences between A36 and A588:

Chemical Composition:

A36: A36 steel is a low carbon steel with carbon content typically ranging from 0.18% to 0.29% by weight. It also contains small amounts of other elements such as manganese, phosphorus, sulfur, and silicon.

A588: A588 steel, also known as weathering steel, contains additional alloying elements like copper, nickel, and chromium. It has a higher level of corrosion resistance compared to A36 due to its composition.

Mechanical Properties:

A36: A36 steel has a minimum yield strength of 36,000 psi (250 MPa) and a tensile strength of 58,000-80,000 psi (400-550 MPa). It exhibits good ductility and can be easily formed, welded, and machined.

A588: A588 steel has a minimum yield strength of 50,000 psi (345 MPa) and a tensile strength of 70,000-95,000 psi (485-655 MPa). Its high-strength properties make it suitable for structural applications, especially in environments prone to atmospheric corrosion.

Corrosion Resistance:

A36: A36 steel does not possess significant corrosion resistance on its own. It may require additional protective coatings or treatments to enhance its resistance to corrosion.

A588: A588 steel is specifically designed for improved corrosion resistance. It forms a protective layer of oxide (patina) on its surface when exposed to atmospheric conditions, which inhibits further corrosion. This makes A588 suitable for outdoor structural applications without the need for additional coatings.

Common Applications:

A36: A36 steel is widely used in general construction, including buildings, bridges, and machinery. It is versatile, cost-effective, and can be easily fabricated and welded.

A588: A588 steel is commonly used in structural applications exposed to outdoor environments such as bridges, buildings, and transmission towers. Its corrosion-resistant properties make it suitable for withstanding atmospheric conditions and reducing maintenance requirements.

The above information provides a general comparison between A36 and A588 but does not cover all possible variations or specific project requirements. When choosing between these grades of steel, it is advisable to consult with a structural engineer or refer to the relevant standards and specifications to ensure the appropriate material selection for your specific application.