ASTM A709 steel is carbon steel and high-strength low-alloy structural steel used for bridges under the American ASTM standard. It is divided into 6 grades according to its yield strength and its application occasions.
ASTM A709 steel is a low alloy structural steel. Low-alloy structural steel refers to alloy structural steel with a total alloy composition of less than 5%. The carbon content of low-alloy structural steel is similar to that of low-carbon steel, and it is mainly strengthened by a small amount of alloying elements to improve toughness and weldability.
The alloying elements manganese, silicon and molybdenum in ASTM A709 steel can cause solid solution strengthening. The alloying elements vanadium and niobium in ASTM A709 steel refine grain and improve toughness. Molybdenum can improve hardenability, promote the acquisition of bainite structure, and can also improve thermal strength.
ASTM A709 steel is widely used in pressure vessels, chemical equipment, boilers, bridges, vehicles, ships and large steel structures.
