Abstract: Warm tensile tests of B340/590DP dual phase steel and tailor welded blanks (TWBs) are carried out by using the testing machine CMT5205. The flow stress behaviors of base metal and TWBs are investigated in the temperatures range form 550 ℃ to 700 ℃ and strain rates from 0.000 1 s–1 to 0.1 s–1. Stress-strain curves for welding zone are obtained by calculation of equal jigging strain method. The models of base metal and tailor welded blanks are established by the improved model contained softening factor. The results show that the dynamic recovery and dynamic recrystallization occur obviously during warm tensile tests of base metal and TWBs. The flow stress increases with the increase of strain rates and decreases with the increase of temperature. The flow stress predicted by the proposed models well agrees with experimental results, which is reliable.

Key words: Dual phase steel, Flow stress, Tailor welded blanks, Warm tensile