Grade 45 refers to a specific classification of steel used in construction and manufacturing. It is characterized by its yield strength of 450 megapascals (MPa) and is commonly used in structural applications. This grade of steel is known for its good weldability and machinability, making it suitable for various engineering projects. In the context of the European standard, Grade 45 is often associated with S355 steel, which is widely used in building bridges, buildings, and other infrastructure. Its strength and durability make it a preferred choice for heavy-duty applications, ensuring safety and reliability in construction.