On twist springback in advanced high-strength steels

The sheet metal components made of advanced high-strength steel (AHSS) become fairly attractive in reducing weight and enhancing operational performance of products. However the corresponding forming process often generates more severe springback. This paper aims to investigate the behavior of twist springback in advanced high strength sheet components, where a twist rail was considered and the corresponding die and measurement tool were developed. Finite element model of the twist rail was first validated through a try-out test and then is used to carry out a parametric study on the twist springback. The results lead to an in-depth understanding of how the design and process parameters, such as transition ratio of cross-section width, corner angle, drawbead depth and material strength grade, affect the twist springback, thereby providing some insights into sensitivity analysis for the design of products and corresponding processes.

► Understand twist springback behaviour for advanced high strength steels (DP and TRIP). ► Torsional moment and stiffness of sheet parts determines twist springback. ► Derive Sensitivity of various design and process parameters to twist springback. ► Explore effects of cross-section width ratio, corner angle, drawbead and materials.