Influence of draw restraining force on the springback in advanced high strength steels

Abstract

Abstract Draw beads are used in sheet metal forming processes to regulate material flow and achieve higher quality in the parts. The draw beads impose draw restraining force on the blank which eliminates defects such as wrinkling, tearing and reduces springback. In a draw-bend test, the draw restraining force is imitated by the back force applied through a hydraulic ram. As the back force increases, large strain is induced which reduces springback tendency. This study evaluates the influence of back force on the springback behavior in advanced high strength steel (AHSS). Three grades of dual-phase steel, namely DP600, DP800, DP980, are used with normalized back forces ranging from 0.5 to 1.1. The springback decreases as the back force increases. Anticlastic curvature as well as curl radius has significant influence on the springback behavior of dual phase steels.