GB780326A - Improvements in and relating to metallic arc welding electrodes - Google Patents

Abstract

In a flux-coated electrode for metallic arc welding the binder in the coating mixture is constituted by a metallic fluoride in the form of a precipitated paste which is free from soluble compounds present in the reaction resulting in the precipitation, the electrode when coated being dried to expel the water from the coating. An alkaline earth, e.g. calcium or magnesium, fluoride is preferably used; it may be prepared by the reaction in water between the alkaline earth chloride and soluble alkali metal fluoride when the alkaline earth metal fluoride is obtained in colloidal form, this being the preferred form. The flux-coating mixture in paste form is extruded on to the core wire or the core wire is dipped into the paste to produce the coated electrode which is then dried at a temperature of 200 DEG -400 DEG C. A coating composition given by way of example contains, by weight:- Precipitated colloidal calcium fluoride paste 5-55 per cent; calcium carbonate 5-55 per cent; ferro-manganese 2-15 per cent; ferro-silicon 2-15 per cent; titanium oxide 1-10 per cent; felspar or glass powder 1-20 per cent; with or without, ferro-titanium 5-10 per cent.