Patent ID: 6068676
Filing Date: 2000-05-30
Classification: C21C,Y02P

Abstract:
A method of producing steel with a high Cr content, the method including the steps ofmelting a solid metal charge material in a melting crucible using an electric arc to form liquid metals,alloying the melt by adding alloying substances and slag-forming constituents containing silicon,refining the melt for lowering the C content of the melt by adding oxygen,chemically reducing the melt with suitable reduction agents, wherein primarily chromium from the slag is reduced, silicon oxide is formed and the silicon oxide is bound by the slag-forming constituents, wherein process gases are supplied to the meltthe improvement comprisingcarrying out the method steps of melting, alloying, refining and chemically reducing in a melting crucible having a specific reaction volume of 0.4-1.5 m.sup.3 /t steel, and introducing the process gases through bottom nozzles,injecting air or nitrogen simultaneously with the step of melting the solid metal charge material, and, after a liquid sump has formed, injecting a gas mixture of oxygen and inert gas,adding slag-forming constituents and alloying agents, and, subsequently, increasing the injection of oxygen and correspondingly reducing a power of the electric arc, after completion of said addition of said alloying substances and said slag-forming constituents,reducing a quantity of the injected oxygen during the refining step in relation to the inert gas, and carrying out a decarburization with a low formation of chromium slag by increasing the power of the electric arc, andcontrolling injection rates of the process gases in a range of 0.1-3.0 Nm.sup.3 /t/min.