GB782927A - Improved process for butt-welding metal parts and suitable insert for carrying out said process - Google Patents

Abstract

782,927. Welding by fusion. GENERAL DYNAMICS CORPORATION. Jan. 10, 1955 [Jan. 11, 1954; April 26, 1954; Dec. 10, 1954], No. 724/55. Class 83 (4). The adjacent edges of two metal parts 10, 11 Fig. 4, are butt welded by causing them to abut a. consumable metal insert 15 and displacing a welding torch along one face of the insert, the shape and composition of which are selected in such a manner that the amount of heat provided by the torch completely melts the insert and produces a weld having an almost smooth surface 53, Fig. 5, on the side of the parts 10, 11 opposite to that to which the heat is applied. The parts 10, 11 may be stainless-steel pipes and the material for the insert, which may be formed by milling out oppositely disposed sectors from a weld rod, may be selected by reference to a metallurgical diagram to produce a weld deposit containing 4 to 8 per cert ferrite. Air is dispelled from the interior of the pipes by an inert gas such as argon, and the insert tack welded at points such as 37. To melt the insert and cause it to fuse with the lips 16, 17 of the parts 10, 11 a root pass is made with an argon or helium shielded non-consumable electrode of tungsten or thoriated tungsten connected to the negative side of a D.C. source, the arc being held stationary until the initial weld puddle has an elliptical contour when the electrode is moved steadily, and preferably with a weaving motion, around the circumference of the weld channel 35. The puddles successively formed in this way are acted upon by surface tension, capillary action and adhesion to take up the shape shown in Fig. 5. The joint is completed by filling in the channel 35 with a number of cover passes, such as 56 to 58, made with a consumable electrode. The cross-sectional area of the rib 25, Fig. 12, of the insert and that of the flange 26 should have a ratio within the range of 0.1 to 1.5 while the dimensions should be in accordance with the formulµ W = r/k and h = r/k<SP>1</SP>, the value of k being greater than 0.6 and less than 3 and that of k<SP>1</SP> being greater than 0.5 and less than 3. The flange portion 26 may be of polygonal shape and the rib portion 25 shaped to suit straight chamfers on the edges to be joined.