GB833925A - A process and apparatus for the vacuum treatment of steel or steel alloy - Google Patents

Abstract

833,925. Vacuum degassing. BOCHUMER VEREIN FUR GUSSSTAHLFABRIKATION A. G. Nov. 19, 1957 [Dec. 12, 1956], No. 36023/57. Class 72 [Also in Group XXII] Steel is vacuum treated by allowing it to fall through a plurality of stages at different pressures. In an upper stage at a pressure between 10 and 500 mm. Hg it is heated by an electric arc and then conveyed in vacuo to a lower stage at a pressure between 5 and 10<SP>-3</SP> mm. Hg. As shown (Fig. 1) steel may flow from ladle 1 between electrodes 10<SP>11</SP>, 11<SP>11</SP> and 10<SP>1</SP>, 11<SP>1</SP>, divergence of the stream being restricted by current in coil 25, accumulates in vessel 14 so as to form a seal between vacuum chambers 4 and 6, being heated by arcs 10, 11 and 12, and then flow into the empty ladle below. In a modification (Fig. 3), the metal may be treated with desulphurizing or dephosphorizing agents in a small electric furnace with a hearth 17, additions being made to the metal under the arcs by an airlock device 21<SP>1</SP> or to the metal, separated from the arcs by a partition wall 18, by device 21. The metal flows into intermediate vessel 14 and then into a ladle or a continuous casting device 30 with air locks 32, 33, 34. In another modification (Fig. 4, not shown) the metal flows through an outlet in the hearth the rate of flow being restricted by current in a coil around the outlet which produces eddy currents in the liquid steel. A further modification includes three vacuum chambers in two of which there are arc furnaces the out-flow from which is controlled by the eddy current method.