A709 steel plate refers to a high-strength, low-alloy (HSLA) structural steel plate that conforms to the ASTM A709 specification commonly used in bridge construction. A709 provides high tensile and yield strength, making it suitable for various bridge components, such as girders, trusses, and other structural elements.

The different grades of A709 steel plate include:

• Grade 36: This grade has a minimum yield strength of 36 ksi (250 MPa) and is commonly used for bridges with general construction purposes.

• Grade 50: This grade has a minimum yield strength of 50 ksi (345 MPa) and is frequently used in bridges with enhanced atmospheric corrosion resistance.

• Grade 50W: This grade has a minimum yield strength of 50 ksi (345 MPa) and offers improved atmospheric corrosion resistance compared to Grade 50. It is commonly used in bridges where exposure to weather elements is a concern.

• Grade HPS 50W: This grade has a minimum yield strength of 50 ksi (345 MPa) and is characterized by its enhanced toughness and weldability. It is often used in bridges with high-demanding conditions and requirements.

• Grade HPS 70W: This grade has a minimum yield strength of 70 ksi (485 MPa) and provides high strength, excellent toughness, and improved weldability. It is typically used in bridges requiring high-performance materials.