Influence of Bending Radius and Heat-Affected Zones on the Bending Performance of High-Strength Thin-Walled Structures Formed by Laser-Assisted Robotic Roller Forming

Laser-assisted robotic roller forming (LRRF) is a robot-based forming process that bends metal sheets by a universal forming roller with the synchronous aid of laser heating. Previous investigations have proved that LRRF has the ability to form ultrahigh strength steels to channel sections with a sharp bending radius. In this study, LRRF was applied to form dual-phase steels to hat-shaped beams by sequential flanging, and the bending performance of the thin-walled structures was compared with that formed without laser heating by means of three-point bending tests. The experimental results show that the LRRF process is capable of promoting the peak force, mean force, and apparent stiffness of thin-walled structures by 14.5%, 12.7%, and 140%, respectively. Smaller bending radii and laser-induced heat-affected zones (HAZ) were observed in the hat-shaped beams formed by LRRF. To account for the improvements in bending performance, finite element simulation considering bending radius and laser-induced HAZ was performed. It is found that the small bending radius has a greater influence on the bending performance, especially the apparent stiffness of thin-walled structures formed by LRRF, in comparison to the laser-induced HAZ. The findings of this research provide an excellent solution for forming advanced high-strength steels to thin-walled structures with sharp bending radii and the synergistic enhancement of bending properties via the LRRF process.