New forming limit diagram of laser tailored blank

Abstract

The new forming limit diagram (FLD) of a laser tailored blank, which includes independent forming limit curves (FLCs) of a welded zone and constituent base metals, is introduced. To obtain the forming limits of a welded zone, hemispherical dome tests are performed with various widths of symmetric and asymmetric specimens. Together with the know-how to find specific strain conditions for the FLC of a welded zone, the experimental experience is discussed. The dome height at the fracture associated with various specimen widths in the same and different thickness combinations is also investigated in order to examine the formability of a laser tailored blank. In order to see the reliability and applications for the new FLD, the measured strains of a squared cup drawing and the simulated strains of a door inner panel stamping are compared with their FLDs. The successful prediction of the fracture with a new FLD reveals that the forming limits of a welded zone and constituent base metals should be found separately for the accurate evaluation of the formability and workability of the laser tailored blank.