Prediction of formability of tailor welded blanks by modification of MK model

A new model is proposed to predict the Forming Limit Diagrams (FLDs) of Tailor Welded Blanks (TWBs). This model is derived by modification of the Marciniak and Kuczynski (MK) analysis and imposing the weld constraints to deformation state of each blank at each strain increment. Based on this model, it is possible to predict the strains of both weaker and stronger blanks once necking occurs. By comparison to the experimental results of two laser welded TWBs, it is demonstrated that this model provides a close prediction of FLD of TWBs, when necking occurs far from the weld line at a region out of HAZ (Heat Affected Zone) and close to it so that it is affected by the weld line constraints.

► The MK model is modified for TWBs by considering the constraints applied around the weld line.
► Through comparison with the experimental FLDs of two laser welded TWBs, applicable situations of the model are defined.
► A mechanism of decrease in formability of TWBs by the weld constraints is explained.