GB1499192A - Process for welding of thick aluminum and aluminum alloy plates - Google Patents

Abstract

1499192 Welding by fusion KOBE STEEL Ltd 29 Jan 1975 [29 Jan 1974 (2) 30 May 1974 5 Sept 1974 13 Sept 1974 30 Sept 1974 (2)] 3808/75 Heading B3R In a method of butt arc welding together of aluminium or aluminium alloy plates of 20-100 mm thickness, in vertical, horizontalvertical and flat positions, a filling material is inserted into a weld preparation groove, presented by the plates, having a groove side angle less than 30 degrees and TIG welding is effected with a non-consumable electrode (preferably having a flat or rounded tip, Figs. 5(b), (c)), straight polarity D.C. at 300-2000 A, arc length of 0À5-5 mm, arc current density of 10-50 A/mm<SP>2</SP>, and shielding gas at least an inner shield of which comprises at least 50% He. The method is intended to provide a bead in which, as shown in Fig. 4, dimension b exceeds a. The weld preparation may be I, V, U, H, or X. Preferably, the filler is 3-20 mm thickness and of width 1-3 times non-consumable electrode diameter. The gas shielding may comprise the inner shield of at least 50% (e.g. 100%) He and an outer shield, preferably of higher specific gravity than that of the inner shield, e.g. 100% A. In the H joint of Figs. 6(a)-(d), (i) a straight polarity TIG arc at both sides, at 4, penetrates the plate centre, (ii) filler 5 is driven into the groove, the filler being elastic or pre-heated (by flame or induction) to fit any curved surface of the weld at 4, (iii) the filler is subjected to TIG arc to provide a deposited metal 5<SP>1</SP>. Such welding is effected on both sides. The filler may be aluminium alloy, of round, oval, square or rectangular cross-section, and may be zinc plated. The electrode may be tungsten containing thorium and may be woven. Example fillers are slit, to facilitate insertion, Figs. 7(a), (b) (not shown); aluminium foil wrapped fibrous or powdery or granular filler, Figs. 7(c) (d) (not shown); aluminium wrapped separate or combined triangular-section-solid and fibrous or powdery filler, Fig. 7(e) (not shown); solid fillers sandwiching powdery, granular or fibrous filler, Fig. 7 (f) (not shown); and magnesium plated aluminium alloy, Fig. 7(g) (not shown). In Figs. 8(a) (b) (not shown), beads of filler material are inserted by MIG welding. In TIG welding, electrode weaving may be transversely of the seam, and, for a wide groove, in and out of the groove. Weaving is preferably 10-100 cycles/min and less than 100 mm width. In tandem TIG welding with two or more electrodes, the distance between electrodes should be 30-200 mm and the time interval for passing of successive electrodes 4-60 seconds. In Figs. 9(a), (b) (not shown), in horizontalvertical position welding, both horizontal and inclined, initial MIG welding effects fusion of the upper portion of the groove and subsequently TIG welding fuses the lower portion. In vertical or inclined vertical position welding, TIG welding may be effected downwardly or, with upwardly effected MIG, upwardly.