A mechanically welded structure comprising a first flat and thin metallic structural element extending in a plane and delimited by a straight edge on one side, and a second metallic structural element welded to the straight edge of the first structural element, or welded to an intermediate element connected to the straight edge and inserted between the first and second structural elements, the second structural element exerting, at least one point of the straight edge, a force resolving into at least one component extending in said plane perpendicularly to the straight edge, wherein the first structural element has a stress-relieving slit extending parallel to the straight edge and situated facing the point at which said force is exerted.