Yb:YAG laser welding of TRIP780 steel with dual phase and mild steels for use in tailor welded blanks

Abstract: Advanced high strength steels (AHSS) are essential to meet the demands of safety and fuel efficiency in vehicles. In this paper, we present the results of laser welding of two AHSS steels, TRIP780 and DP980. A 2kW Trumpf TRUDISK 6002® Yb:YAG laser beam was utilized to join 1mm thick TRIP780 with 1.5mm thick DP980 and 1mm thick mild steel. Optical metallography was used to characterize the weld profile and microstructures. Microhardness, tensile and fatigue tests were performed to evaluate the mechanical properties. Results indicate that the laser welds exhibit excellent strength and hardness with minimal defects which are attributed to the high beam quality, disk type of laser. In addition, there is a distinct effect of pre-straining of TRIP780 steels on the energy absorption. [Copyright &y& Elsevier]