Study of formability of tailor-welded blanks in plane-strain stretch forming

In sheet metal forming, failure in the regions of the blank which are subjected to plane-strain deformation is one of the most common modes of failure. Therefore, study of forming limits of tailor-welded blanks (TWBs) deformed under plane-strain stretching is important to avoid failure in stampings of these prewelded composite blanks. In the present work, formability of three different types of tailor-welded blanks (TWBs) has been studied by limiting dome height (LDH) tests in plane-strain deformation mode. In all the three TWB combinations, the effect of weld orientation, with respect to major principal strain on formability, has been studied. It has been found that in TWBs with difference in thickness and properties, the LDH is higher in transverse (weld line parallel to width) cases when compared to longitudinal (weld line parallel to length) cases. The weld properties play a major role in the deformation of longitudinal specimens. But the extent of difference in properties, thickness, and surface characteristics has a strong influence on the location of fracture in transverse specimens. Weld line movement occurs toward thicker/stronger side during stretch forming of TWBs. The maximum weld line movement occurs at the pole, and it is highest in TWBs with difference in thickness. The extent of weld line movement is higher in the transverse samples than in the longitudinal samples.