GB791176A - Alternating current arc-welding process - Google Patents

Abstract

791,176. Welding by fusion. UNION CARBIDE CORPORATION. Feb. 20, 1956 [March 15, 1955], No. 5236/56. Addition to 709,533. Drawings to Specification. Class 83 (4). In alternating current arc welding with a fusible metal electrode and a shielding gas consisting of a mixture of 0.1-50 per cent oxygen and argon or helium, a high-frequency potential is superimposed on the welding current and the latter is of such intensity as to transfer metal across the arc in the form of a spray. The high frequency is 2-6 megacycles and welding current frequencies of 60 and 240 cycles are referred to. When welding mild steel plate with a steel electrode containing up to 2 per cent total of carbon, manganese and silicon, the minimum welding current to produce spray type transfer is 65,500 amperes per square inch of electrode, whereas when welding stainless steel consisting of up to 0.08 per cent carbon, up to 2 per cent manganese, up to 1 per cent silicon, 17-19 per cent chromium, 9-12 per cent nickel and at least ten times as much cobalt as carbon with an electrode containing up to 0.08 per cent carbon, up to 2 per cent manganese, up to 1 per cent silicon, 18-20 per cent chromium and 8-11 per cent nickel the minimum current density is 68,300 amperes per square inch. In both cases the shielding gas is 95 per cent argon, 5 per cent oxygen. For welding refractory metals such as titanium using a titanium electrode, a very small amount of oxygen is used, but when welding speed is more important than quality, e.g. when welding rimmed steel with a rimmed steel electrode, 20-50 per cent oxygen is used.