Evaluation of hot cracking susceptibility on laser welded aluminum alloy using coaxially arranged multiple-beam laser

Dual-beam laser welding using an adjustable ring mode (ARM) fiber laser was implemented to evaluate weld bead characteristics and hot cracking susceptibility. An ARM laser with dual beams having diameters of 175 and 450 μm was implemented in the focal position. By controlling the core laser power (700–1800 W) and ring laser power (0–1100 W), respectively, full penetration welds were achieved for a 1 mm-thick Al 6014-T4 alloy even at a high welding speed of 120 mm/s under a total laser power of 1800 W. High welding speed enabled a small molten area and a narrow equiaxed dendrite structure along the bead center, which reduced hot cracking susceptibility.