Comparative experimental study of hot-formed, hot-finished and cold-formed rectangular hollow sections

This paper presents a comparative experimental study on the physical, chemical and mechanical properties of indirectly formed hot-formed, hot-finished and cold-formed structural steel rectangular hollow sections. Characteristic geometrical parameters and chemical compositions are examined to investigate the physical and chemical differences. Tensile test and charpy V-notch impact test are employed to evaluate the difference in strength, ductility and toughness. Further, the residual stress distributions in both transverse and longitudinal directions are measured using the sectioning method and hole-drilling technique. It is found out that although the geometrical parameters and chemical composition of the tested hollow sections are similar, the mechanical properties are significantly different, especially for strength, ductility and residual stress distribution. While the hot-finished and hot-formed sections are often treated equally in design, their mechanical properties and residual stresses distribution are actually different.