Abstract: A method of welding at least two sheets using a high energy density radiation beam that preferably is a laser beam or an electron beam for producing a welded lap joint that is substantially completely fused across the width of overlap of the sheets preferably for enabling shaping or forming to be performed such that at least one of the sheets and at least portion of a weld line defined between the overlapped sheets are bent or three dimensionally contoured. In practicing a preferred embodiment of the method, the sheets are overlapped and welded by directing at least one radiation beam toward the overlapped sheets having sufficient power density and for a sufficient amount of time to weld the sheets such that they are substantially completely fused from front to back in the overlap region.

Abstract: A method of welding using a high energy density radiation beam such as an electron beam or preferably a laser beam to weld a pair of sheets using an oblong focused beam spot for reducing the power density of the oblong beam spot to maximize welding speed while minimizing welding defects. The high energy density radiation beam source has a power of at least one kilowatt for achieving Keyhole welding, and a beam delivery system capable of focusing the beam into an oblong spot shape, such as a generally rectangular focused beam spot shape, and directing the beam spot onto at least one of the sheets to weld the sheets. During welding, the beam is focused into an oblong focused beam spot and trained on at least one of the sheets to weld them with the longitudinal axis of the beam spot preferably oriented generally tangent to the weld line, generally parallel to the weld direction, or acutely angled relative to the tangent to the welding direction.

Abstract: A method of welding using a high energy density radiation beam for butt welding a pair of sheets while minimizing and preferably eliminating edge preparation required before welding and the use of filler metal during welding. In preparation for welding, the sheets are placed with edges facing each other in a butt-joint arrangement. To minimize and preferably eliminate edge preparation, surface mismatch is introduced between the sheets with a portion of the edge of the mismatched sheet being above the weld interface of the sheets and preferably exposed to the beam during welding. To further assist flow of molten metal from the mismatched sheet into the weld interface region, the sheets are preferably angled from the horizontal such that the weld interface plane is acutely angled relative to the direction of gravity so that flow of molten sheet material is influenced by gravity.