Shaped square tube is a hollow square section steel tube, also called steel refrigerated bending section. The special-shaped square tube is a section steel with a square cross-section shape and size made by hot-rolled or cold-rolled strip steel or coiled plate as a blank, formed by cold bending, and then by high-frequency welding. Except for the thickening of the wall thickness of the hot-rolled extra-thick wall square pipe, the corner size and edge flatness reach or exceed the level of the resistance welded cold-formed square pipe.