Patent ID: 6914213

Claim:
A lap welding process for welding, by means of a high-energy-density beam ( 11 ), two metal sheets ( 1 , 2 ) coated with a material that has an evaporation temperature below the melting point of the material of the sheets, characterized in that: the two coated sheets ( 1 , 2 ) are at least partly overlapped; the faces of the two sheets ( 1 , 2 ) in the overlap region are brought into contact with each other; the high-energy-density beam ( 11 ) is split, on the one hand, into a first sub-beam ( 12 ) fully penetrating both coated sheets ( 1 , 2 ) in the overlap region and forming a first weld pool ( 18 ) in this region and, on the other hand, into a partially penetrating second sub-beam ( 13 ) forming a second weld pool ( 19 ), the depth of which is less than the thickness of the upper coated sheet ( 1 ), the second weld pool at least partly overlapping the first weld pool ( 18 ) in order to promote removal of the coating material vapor; an inert gas jet ( 21 ) is directed with a high ejection velocity onto the second weld pool ( 19 ) in order to form a depression ( 22 ) in the surface of the second weld pool ( 19 ), increasing the rate of removal of the coating material vapor; and a hermetically sealed continuous weld bead or seam ( 5 ) is formed along the overlap region by displacement of both sub-beams ( 12 , 13 ) and the inert gas jet ( 21 ), or of both coated sheets ( 1 , 2 ).