FINITE-ELEMENT ANALYSIS OF HEAT-FLOW IN DUAL-BEAM LASER WELDED TAILORED BLANKS

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 radi ation heat transfer are considered. The simulation results show that w elding with a dual-beam system to induce preheating reduces cooling ra tes effectively. The cooling rate in the thin blank is observed to be slightly higher than that in the thick blank at a given temperature. F or example, at 650 degrees C, 2 mm away from the weld centerline, the cooling rates are calculated to be 362 degrees C/sec and 373 degrees 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 interbeam spacing of 1 cm, the cooling rates reduce to 212 degrees C/ sec and 228 degrees C/sec in the thick and thin blanks, respectively. Experiments undertaken for verification show close correlation between the simulation and experimental results.