ArcelorMittal S.A.
Method for butt laser welding two metal sheets

Abstract:

A method for butt laser welding two metal sheets (2, 4) includes providing a first metal sheet (2) and a second metal sheet (4) and butt welding the metal sheets (2, 4) along a direction of welding. The butt welding step includes simultaneously emitting a first front laser beam (12) creating a first front spot (18) at the intersection with the first metal sheet (2), and generating a first front keyhole (19) in the first metal sheet (2) at the first front spot (18); a second front laser beam (14) creating a second front spot (20) at the intersection with the second metal sheet, and generating a second front keyhole in the second metal sheet (4) at the second front spot (20); and a back laser beam (16) creating a back spot (22) on the first and second metal sheets (2, 4), and generating a back keyhole (23A) in the first and second metal sheets (2, 4) at the back spot (22). The first and second front laser beams (12, 14) and the back laser beam (16) are configured in such a manner that at each moment in time, a solid phase region (25) and/or a liquid phase region (13, 23B) of the metal sheets (2, 4) remains between the first front keyhole (19) and the back keyhole (23A) and between the second front keyhole and the back keyhole (23A).