Abstract: The stretch bending process of a new U-section stainless steel profile with wide flange was investigated by simulation. The causes and corresponding control methods of the main forming defects were studied, and the conclusions were verified by tests. Results show that the main forming defects are the section distortions and low contour accuracy. The section distortions include bottom surface upwarping, sidewall bending, flange warping and section expanding or contracting. The section distortions in the narrow flange side are more serious than that in the wide flange side. The section distortions are mainly caused by the shrinkage of the sidewall during stretch bending, which can be eliminated effectively by reasonable compensation of the profile sidewall height. The low contour accuracy is mainly due to springback, which can be improved to certain extent by adjusting the process parameters, while to modify the die surface based the springback can obviously improve the contour accuracy. Based on the above analyses, defect control methods were proposed and stretch bending tests of a U-section stainless steel pillar with wide flange on a rail vehicle were conducted. Qualified stretch bent parts were achieved, which verify proposed control methods.

Key words: materials synthesis and processing technology, wide flange, U-section, stainless steel, profile stretch bending, defect control