A square tube is a hollow, square-sectioned light-gauge, thin-walled steel pipe, also known as cold-formed steel section. It is a type of steel with a square cross-section shape and size, made by cold bending steel strip or coil, which is hot-rolled or cold-rolled, into the desired shape and then welded using high-frequency welding. In addition to the increased wall thickness, hot-rolled extra-thick-walled square tubes also have corner dimensions and edge straightness that meet or exceed those of resistance-welded cold-formed square tubes. Square tubes are categorized by their applications, including structural square tubes, decorative square tubes, construction square tubes, and mechanical square tubes, among others.

Q235 steel is a common carbon structural steel. Common carbon structural steel, also known as general plate, is a type of steel material. "Q" signifies the yield limit of this material, with the following "235" indicating the yield value, approximately 235MPa, and the tensile strength ranges from 375 to 500MPa. The yield value decreases with the increase in material thickness. Due to moderate carbon content, it boasts good comprehensive properties, with well-coordinated strength, ductility, and welding capabilities, making it widely applicable.