Finite Element Analysis of Heat Flow in Dual-Beam Laser Welded Tailored Blanks

Abstract

A two-dimensional moving adaptive finite element analysis is presented for dual-beam laser welded tailored blanks. The phase change effect, temperature dependence of material properties, and convection and radiation heat transfer are considered. The simulation results show that welding with a dual-beam system to induce preheating reduces cooling rates effectively. The cooling rate in the thin blank is observed to be slightly higher than that in the thick blank at a given temperature. For example, at 650°C, 2 mm away from the weld centerline, the cooling rates are calculated to be 362°C/sec and 373°C/sec in the thick (2 mm) and thin (0.8 mm) blanks, respectively, for a welding speed of 1.5 cm/sec and beam power of 900 W on mild steel. For the same welding conditions, but with a preheating power of 400 W and inter-beam spacing of 1 cm, the cooling rates reduce to 212°C/sec and 228°C/sec in the thick and thin blanks, respectively. Experiments undertaken for verification show close correlation between the simulation and experimental results.