| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a laser lap welding method for a surface-coated metallic material as represented by a galvanized steel sheet which has appearance with little welding defects due to zinc vapor and which enables a lap joint to be obtained that is superior in corrosion resistance and joint performance. SOLUTION: The metallic material 2 on the laser irradiation side is irradiated with a first laser beam 1 that has a penetration depth d 0.60-0.95 times the thickness t of the material 2, thereby forming a projection 2a on the back surface of the material and producing a gap G between the superimposed surfaces. Then, a second laser beam is emitted in the range of 4 mm in the width direction around the irradiation line of the first laser beam, melting and welding the superimposed metallic materials together.</p> |
