The effects of strength ratio on the forming limit diagram of tailor-welded blanks

In the present study, the influences of strength ratio (SR) are studied on the formability and forming limit diagram (FLD) of tailor-welded blanks (TWBs). AISI 340, St 12 and St 14 steel sheets with equal thickness of 1 mm were used as different kinds of steel to make TWB with different SR. TWBs were obtained by CO2 laser welding of different steel sheets. Limit strength ratio (LSR) is introduced as a new useful factor to predict the FLD of TWB with different SR. Results of this research show that with increasing of difference of TWB's SR and LSR, formability and the level of FLD will decrease. By SR increasing, limit dome height decreases and some defects such as weld line movement increase. The experimental findings show that the SR of TWB can effect on the position of fracture in the TWB products.