GB1333541A - Methods of electron-beam welding of thick parts - Google Patents

Abstract

1333541 Welding by fusion MOSKOVSKY ORDENA LENINA ENERGETICHESKY INSTITUT 11 Jan 1972 1152/72 Heading B3R In straight or circumferential seam, vertical position, low voltage (i.e. up to 60 kv) electronbeam welding of metal, e.g. steel, workpiece parts 100 mm. or over thick, workpiece parts (7) (8) held together to present a vertical plane joint are moved relatively to a horizontal electron beam gun 6, vertically grooved shoes 4, 5 are provided to retain melt and form reinforcing beads, and to prevent screening of the beam by liquid metal and vapours the axis of the beam is kept a distance of 2-2À5 beam diameters above the top surface of the molten metal throughout the welding. The beam to molten metal surface distance is provided, at the commencement of the weld, by starting the weld using a hole (12) in a starter piece secured below the workpieces (Fig. 4, not shown) or using workpiece hole (13) in the circumferential welding of Fig. 5 (not shown). The hole (12) or (13) is disposed parallel to the beam, extends 0À7 to 0À8 of the workpiece thickness and, measured vertically, is preferably to 2-2À5 beam diameters. A device 3 is provided for moving the workpieces past a stationary gun. The shoes 4, 5, of high heat conducting metal, e.g. copper, have channels (9) for cooling liquid circulation. The shoe 4 has a top slot (10) for beam passage and molten metal observation. A heat resistant stopper (e.g. asbestos) seals the bead forming groove below the slot (10). If filler wire is used, e.g. for alloying the weld metal, the depths of the bead former grooves in the shoots are increased to accommodate the resulting extra weld metal. In straight seams, welding is terminated by cutting off current during welding on an extension plate, and in circumferential seams, welding is terminated by gradually reducing current during a seam overlap. The specification discloses beam sizes and energy densities, and shoe groove sizes.