Abstract
Square steel pipes are reshaped from welded round pipes by roll-forming. Pipe end deformation after cutting of the square steel pipe was investigated by experimentation and by three-dimensional finite element simulation. Each direction of the residual stresses composed of longitudinal stress and longitudinal-peripheral shear stress becomes reverse with respect to the outer and inner surfaces. A large opening deformation arises at the back end of the product by the release of those residual stresses. The side part receives bending deformation in the surrounding area of the contact zone with a roll. The residual stresses comprising longitudinal stress and longitudinal-peripheral shear stress increase as a result of the reverse bending deformation downstream of the roll center position. The absolute value of residual stress decreases with decreased initial wall thickness.
