Residual stresses in roll-formed square hollow sections

Residual stresses play a significant role in determining roll-formed members’ behaviour and strength. This paper presents an extensive experimental investigation of the residual stresses in roll-formed square hollow sections. With a total of over 600 readings taken, the residual stresses on outside surface, along thickness direction and inside surface, were analyzed using X-rays diffraction method. The experimental results provide a further understanding of the magnitude and distribution of the residual stresses in roll-formed square hollow sections. The residual stresses on the welding line were found to be the maximum, and through thickness variations of residual stresses came out typically as bi-linear. For the same dimension, the forming process has a significant effect on the distribution of longitudinal residual stresses on the outside surface of square hollow sections.