Tailor-welded blanks of different thickness ratios effects on forming limit diagrams

In this paper, the objective is to study the thickness ratio effects of TWBs on forming limit diagrams (FLDs). Tailor-welded blanks (TWBs) of the same material but with different thickness combinations were welded together to form a single part before the formability tests. Thus, SPCC steel sheets of thickness 0.5, 0.6, 0.8 and 1.0 mm were studied and combined to form TWBs of different thickness ratios of 2 (0.5/1.0 mm), 1.67 (0.6/1.0 mm) and 1.25 (0.8/1.0 mm). An Nd:YAG laser was used to weld the tailor-made blanks before the formability tests of the uniaxial tensile test and the Swift test. The experimental findings show that TWBs of different dimensions and radii of cut-off yield different major strain and minor strain values of the FLD. The uniaxial tensile tests show that there are no significant differences between the tensile strengths of TWBs and their relative base metals. In addition, the FLDs of the TWBs indicate that both the level of the forming limit curves and the minimum major strain value decreases as the thickness ratio increases. This implies that the higher is the thickness ratio, the lower is the formability of the TWBs.