| 摘要 |
PURPOSE: A laser welding method for a three-layered steel sheet is provided to improve the bending strength of welded portions by controlling the output and speed of a laser beam to form bead forming portions along one side of a welding line in a reinforcing plate. CONSTITUTION: A laser welding method for a three-layered steel sheet comprises the steps of: forming bead forming portions(B) protruded by phase transformation of metal along one side of a welding line on the front surface of a reinforcing plate(23) corresponding to the rear surface of an outer plate(21), loading the outer and reinforcing plates and an inner plate(22) on a jig(30) so that the rear surface of the reinforcing plate contacts the front surface of the inner plate, clamping the plates on the jig by overlaying the outer plate to the front surface of the reinforcing plate so that a gas discharge gap is formed between the outer and reinforcing plates, and laser welding the plates through a laser beam of a key hole welding area along a welding line of the outer plate formed of a galvanized plate. |
