GB1370442A - Welding processes - Google Patents

Abstract

1370442 Welding by fusion GENERAL ELECTRIC CO Ltd 21 Nov 1972 [10 Sept 1971] 42363/71 Heading B3R In the electron-beam welding together of two parts by a glow-discharge cold-cathode gun, an insert is placed between and in contact with said parts prior to welding. As shown, two tubes 1 are welded together end-to-end, with the interposition of an insert 4 by a gun 8. The tubes extending into a gun enclosure 2 through means 3 each of which comprises an inflatable seal 6 and two sets of three equi-spaced tube clamping and centering pins 5. The tube bores are sealed by inflatable bulbs (not shown) which together with the seals 6 are of heat-resistant rubber. The enclosure is, in use, evacuated through a port 7 and argon is introduced through a bleed port 21 to establish an argon atmosphere at approximately 0À1 Torr. The gun 8 comprises an annular, concave innersurfaced, cathode 9 supported by rods 11 sealed by electrically insulating glass seals 12. Coaxially within the cathode there is disposed a curved cross-section anode 13 which has a circular aperture 14 and is rotatable, e.g. at 1 r.p.m., via bevel gears 18, 17, to rotate a beam 22 about the tube joint. The tube axis may be vertical or, as shown, horizontal. In a first example, tubes 1 of 2 inches O.D., 1/8 inch wall thickness, and both of chromium-molybdenum steel are welded together using an insert 4 comprising a ring of 0À188 inch diameter wire flattened to 0À063 inch axial thickness and of an iron alloy consisting of, in weight per cent: Carbon 0À1 max. Manganese 0À75-1À5 Silicon 0À3-0À6 Titanium 0À07-0À10 Chromium 0À75-1À25 Molybdenum 0À4-0À65 Iron balance The insert dioxidants take up oxygen release from the tubes. In a second example, one of the two tubes is of mild steel and the other is of stainless steel comprising, in weight per cent: Carbon 0À08 Silicon 0À80 Manganese 0À80 Chromium 18À0 Nickel 9À3 Titanium 0À5 Iron balance and the insert is either of an iron alloy consisting of, in weight per cent: Carbon 0À1 Silicon 1À3 Manganese 0À8 Nickel 21À5 Chromium 23À5 Iron balance or of a nickel alloy consisting of, in weight per cent: Chromium 16À0 Iron 8À1 Manganese 0À2 Silicon 0À2 Carbon 0À1 Nickel balance.