This plate is A36 steel, A36 Steel is a low carbon, structural steel that is widely used in construction, manufacturing, and other industries. It is known for its strength, durability, and relatively low cost. A36 steel contains small amounts of other alloying elements such as manganese, phosphorus, sulfur, and silicon, which help to improve its mechanical properties. It is easy to machine, weld, and form into a variety of shapes, making it a versatile material for a wide range of applications. A36 steel is typically used in the construction of buildings, bridges, and other structures that require a high degree of strength and durability.