Angle iron is a long strip of steel that is perpendicular to each other and forms an angle. There are equilateral angle steel and unequal angle steel. The two sides of an equilateral angle are equal in width. Its specifications are expressed in millimeters of side width x side width x side thickness. For example, "∟30×30×3" means an equilateral angle steel with a side width of 30 mm and a side thickness of 3 mm. It can also be indicated by the model number, which is the centimeters of the side width, such as ∟3#. The model does not indicate the size of different side thicknesses in the same model, so fill in the side width and side thickness dimensions of the angle steel in the contract and other documents, and avoid using the model to indicate it alone. The specifications of hot-rolled equilateral angle steel are 2#-20#. Angle steel can be composed of various stress components according to different needs of the structure, and can also be used as a connector between components. Widely used in various building structures and engineering structures, such as beams, bridges, transmission towers, lifting and transportation machinery, ships, industrial furnaces, reaction towers, container racks and warehouses.