Characterization of Tensile Deformation of Hot Stamped Boron Steel Tailor-Welded Blanks

Hot-stamping technology has evolved from single-thickness components to differential-thickness tailor-welded blanks (TWBs). This study investigates the tensile deformation behavior of equal-thickness (1.2/1.2t) and differential-thickness (1.2/1.8t) hot-stamped TWBs using CAE and Digital Image Correlation (DIC). Results show high consistency between simulations and experimental data. The 1.2/1.2t and 1.2/1.8t TWBs exhibit distinct deformation mechanisms. In 1.2/1.2t specimens, both sides undergo uniform deformation before strain localizes in the necking zone. Conversely, deformation in 1.2/1.8t TWBs is primarily concentrated in the 1.2t section. The 1.8t side experiences very limited deformation and remains elastic even as the thinner side reaches fracture. Furthermore, the Gauge Length (GL) significantly influences measured elongation. A longer GL averages localized necking deformation over a larger span, underestimating the material's actual elongation capacity, particularly when spanning the nearly undeformed 1.8t region. To accurately reflect true elongation of the material, measurements should exclude regions with limited deformation. These findings provide critical insights for the automotive industry in evaluating the ductility of hot-stamped TWB components.