Carbon steel A36 circles are flat round shapes made from a low-carbon hot rolled structural steel alloy containing small amounts of manganese, phosphorus, sulfur, and silicon. This steel is commonly used for general structural purposes like bridges and buildings, as well as for flanges, rings, washers, and other circular components in industrial applications requiring moderate strength, good weldability, and machinability. A36 steel is strong, ductile, and easily weldable, making circular shapes cut from it suitable for manufacturing and fabrication projects.