ASTM A36 round steel has a tensile strength of 400-550 MPa. This mild steel grade offers excellent weldability and ductility (20% elongation), making it suitable for general structural use-pipes, brackets, and low-stress components. The tensile strength is derived from its chemical composition (0.25% max carbon, 0.40% max manganese) and hot-rolling process, which refines grain structure. It balances affordability and performance, accounting for ~30% of structural round steel usage in North America.