Angle steel, commonly known as angle iron, is a long steel with two sides perpendicular to each other. There are equal angle steel and unequal angle steel.The width of two sides of an equal angle steel is equal. The specification is expressed in mm of side width × side width × side thickness. Such as “∟ 30 × 30 × 3”, that is to say, equal angle steel with side width of 30mm and side thickness of 3mm. It can also be expressed by model. The model is the centimeter of the side width, such as ∟ 3 × 3. The model does not represent the dimensions of different edge thicknesses in the same model, so the edge width and edge thickness dimensions of angle steel shall be filled in completely in the contract and other documents to avoid using the model alone. The specification of hot rolled equal leg angle steel is 2 × 3-20 × 3.