Experimental investigation of springback of dual-phase steels

With a view to advancing the use of DP steels in the automotive industry, this research emphasizes the characterization of mechanical behavior and forming of DP sheet steels. Two grades of DP steels were studied, DP 600/300 and DP 600/400. Standard tension tests were used to characterize the mechanical behavior. Properties such as elongation to fracture, strength coefficient, n-value and ultimate tensile strength (UTS) were determined. Moreover, tension-compression tests were also conducted on the two steel grades considered to study the Bauschinger effect. In addition, simple bending experiments were done in directions 0, 45, and 90 degrees to the rolling direction, to examine the effect of rolling direction and material anisotropy on the springback angles in simple forming. Multiple-bend experiments were also conducted to study the effect of reverse yield on the final geometry of the formed part. It was found that the effect of planar anisotropy can be neglected and the influence of the Bauschinger effect on the springback angle is not very significant. Finally, draw-bend experiments were performed. The clamping force or blank-holding-force (BHF) was varied to study its effect on the final springback angles of the part.