S355 steel is a structural steel grade commonly used in construction and engineering. It is known for its high strength and good weldability, making it suitable for various applications, including bridges, buildings, and machinery. The "S" in S355 stands for structural, while the number indicates the minimum yield strength of 355 megapascals. This steel grade is part of the European Standard EN 10025, which specifies hot-rolled products of structural steels. S355 steel is available in different forms, such as plates, sections, and bars, and can be further categorized into S355JR, S355J0, and S355J2, depending on their impact resistance and other properties.