1. Introduction to the standard
The EN10025-2 standard is issued by the European Committee for Standardization (CEN). It mainly specifies the requirements for hot-rolled structural steel plates and strips. It is suitable for the manufacture of various structural steel products, including steel plates, strips, profiles, etc. It is widely used in construction, bridges, machinery manufacturing, shipbuilding and other industries. The standard defines the chemical composition, mechanical properties, dimensions and tolerances of steel to ensure that the product has the necessary strength, toughness and durability.
2. Chemical composition requirements
The standard has strict requirements for the chemical composition of steel, especially for major alloying elements such as carbon (C), manganese (Mn), silicon (Si), sulfur (S), phosphorus (P), etc. There are detailed provisions. According to different steel grades (such as S235, S275, S355, etc.), the standard requires different upper and lower limits for the chemical composition of steel. These requirements are intended to ensure the mechanical properties and corrosion resistance of steel. For example, the carbon content of S235 is usually less than 0.17%, and the manganese content is usually 0.60% - 0.90%; the carbon content of S275 is usually less than 0.20%, and the manganese content is 0.60% - 0.90%. The standard also makes strict requirements on the content of other elements in steel (such as sulfur and phosphorus) to ensure its corrosion resistance and formability.
3. Mechanical performance requirements
Detailed provisions are made for the mechanical properties of steel (such as tensile strength, yield strength, elongation, impact toughness, etc.), which vary according to different steel grades and uses. Mechanical properties are the key to the application performance of steel, ensuring that it can meet various load conditions in actual use. For example, the tensile strength of S235 steel is 360 - 510MPa, and the yield strength is 235MPa (minimum); the tensile strength of S355 steel is 470 - 630MPa, and the yield strength is 355MPa (minimum). The higher the elongation, the better the plasticity of the steel, and the more complex the processing requirements. For steel used at low temperatures, the impact toughness requirements are higher.
4. Dimension and tolerance requirements
The dimensions and tolerances of steel are also clearly specified to ensure the accuracy and applicability of the product. Common dimensional requirements include: Standard requirements for the thickness of steel plates. The thickness of hot-rolled steel plates can range from 3mm to 400mm, depending on the grade and purpose of the steel. For thicker steel plates, special production processes are usually required; The width of the strip is usually 1000mm to 2500mm, depending on the usage scenario; The length tolerance varies according to different standard grades, and the general tolerance range is ±5mm. The surface of the steel should be flat and smooth to avoid defects such as cracks, folds, and scales. The surface quality requirements directly affect the subsequent processing and welding performance.
6. Heat treatment requirements
Requirements are made for the heat treatment process of steel, especially when manufacturing S355 grade steel. Heat treatment includes annealing, normalizing, quenching and other processes, which are used to adjust the microstructure of steel and improve its mechanical properties. Normalizing is suitable for steel of grade S355 and above, which can improve its toughness and strength; annealing is usually used for thicker steel plates to help remove internal stress and improve the machinability of steel.
7. Surface quality and defect control
The surface quality of steel directly affects subsequent processing and application. The standard imposes strict requirements on the surface quality of steel. There should be no oxide scale or contaminants on the surface of steel, which will affect welding performance and corrosion resistance; the surface of steel should be free of cracks, folds or other serious defects, which will greatly reduce the strength and durability of steel; the surface of steel should be kept as flat as possible to avoid difficulties in subsequent processing due to uneven surface.
