Square Steel Pipe is usually used in steel structures, structural curtain walls, machinery manufacturing, building materials, shipbuilding, airport, liquid transportation and other fields. Seamless Square Tube is a round tube without joint extrusion, that can be used for liquid delivery. Slotted square pipes can be welded with steel plates and are commonly used in steel structures. Plasticity refers to the ability of a metal material to slow down the plastic deformation (permanent deformation) of a metal shape under loading without damage. Hardness is the ability of a metal material to combine hard and soft. Over-steel is easy to embrittlement, and too soft is non-plastic. Now in square steel pipe detection, the commonly used method is the indentation hardness detection method. Measure the degree of indentation by squeezing the square tube against the rectangular tube. At present, the angle size, corner angle, and straightness of cold rolled square pipe used in steel structure engineering have reached or even exceeded the level of welded square pipe.

Square pipe is a hollow square cross-section light thin wall steel pipe, also known as cold bending steel profile. Now the common material is Q235, and Q235 is divided into B, C, D, and other grades. Seam square pipe is based on Q235 hot or cold rolled strip or coil, and then formed by high-frequency welding, this way is only suitable for square pipe with ordinary requirements. Usually, for better performance, and stronger sealing square pipe, we use seamless round pipe with cold rolled formation. Compared with cold rolled square pipe and hot rolled square pipe, hot rolled super thick wall square pipe is famous for the thickening of the wall, and its hardness value is measured according to the degree of hardness testing. Common methods are Brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC), and Vickers hardness (HV). In fact, solar scaffolds, steel structures, and many mechanical parts operate under cyclic loads. So it is still necessary to carry out regular safety checks. In short, the different uses of the square pipe determine the material of the square tube, and the material of the square tube also produces many different physical and chemical properties.