| Tailor-welded blank (TWB) with different thickness ratio plays an important role in the lightweighting technology of automobile industry. Problems, such as weld line movement and reduction of its formability, are always occurred in the application and production of TWBs. And these problems result in the bad quality and performance of the TWB products. Thanks to the different thickness combination of the basic materials, it is impossible to find out the demerits in the process of mould designing and manufacturing. Therefore, it is meaningful to take the study on formability of TWBs.This paper studies the formability of cold rolled steel of GMW2M—ST—S made in USA. In the paper, mechanical analyzing of dome forming, finite element method (FEM) analyzing and physical dome test are carried out. Firstly, mechanical models of dome forming of TWBs with different thickness ratio and different weld line shapes are established. By analyzing the mechanical models, the paper hands out the parameters of thickness ratio and radius of curved weld line, which can impact the dome forming of TWBs. Secondly, by study the results of linear weld line TWBs of FEM and its dome test, the regulations of formability and weld line movement under different thickness ratio and different position of the weld line layout, are put forward, and then the dome test of linear weld line TWB is set up to testify the FEM results. Thirdly, dome tests of TWBs with different thickness ratio, different width of blanks and different curved weld lines are carried out to find out the performances of nonlinear weld line TWBs. With the FEM modeling for the curved weld line TWBs, the paper makes the comparison of linear and nonlinear weld line TWBs, which can help to offer the reference for the engineering application. Finally, the paper tells some further study directions of TWBs. The paper gets the regulations on the formability of TWBs of thickness ratio, weld line position and weld line radius.
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