Abstract: A blade structure for use in a fluid flow rotary machine wherein the blade profile is thickened within the head region and a cover plate is connected to the head end within the thickened region by means of a substantially loop-shaped welded joint which is made by use of a high-energy beam such as an electron beam applied to the surface of the cover plate. The starting and end portions of the welding run can be overlapped, and the intensity of the welding beam is gradually increased from the starting point of the run to eliminate any swelling effect and is gradually reduced towards the end of the run to prevent crater formation.