Effect of Weld Line Orientation on Formability of Tailor Welded Blank of 22MnB5 at Elevated Temperature

Currently, a tailor-welded blank (TWB) is being applied to hot stamped parts using 22MnB5 for better energy absorption and lightweight construction. In this study, the effect of the weld line orientation on the formability of a TWB of 22MnB5 was investigated using a Nakajima test at an elevated temperature. As a result of the Nakajima test, differences in the dome heights and forming limits were observed between TWBs with weld line orientations of 0 degrees, 45 degrees, and 90 degrees. For the 0 degrees and 45 degrees TWBs, the dome heights and forming limit curves (FLCs) were lower than those of base metals and the 90 degrees TWB because of the deformation concentration in the thinner material. Furthermore, the FLC of the 90 degrees TWB was located between those of the two parent materials because no deformation concentration appeared, and the martensite at the weld was homogeneously austenized during hot stamping. On the basis of the obtained FLCs for the examined materials, fracture was predicted in the hot stamping of a rear side member using a TWB by considering the weld line orientation and weld line movement during stamping.