| 摘要 |
PURPOSE: To provide a method for manufacturing steel for non-oriented magnetic steel sheet with superior magnetic properties by simultaneously controlling a basicity and a terminal oxygen amount in converter and P concentration in the bubbling process and injecting proper quantities of Fe-P according to a proper injection time point according to an amount of arrived oxygen in the secondary refining. CONSTITUTION: In a method for manufacturing steel for non-oriented magnetic steel sheet comprising a converter refining process, a bubbling process and a secondary refining process performed in a degassing treatment facility, the method comprises a step of injecting subsidiary raw materials in to a converter during the converter refining process such that a basicity £(%CaO)/(%SiO2)| is maintained to 5.5 or more and a terminal oxygen amount is maintained to 600 ppm or more; a step of controlling content of £P| to 0.020% or less in the bubbling process; and a step of injecting 1.52 to 2.0 kg/molten steel to n of Fe-(25 to 30%)P in to the degassing treatment facility at a time point between decarburization starting time and 5 minutes after starting decarburization in case that an oxygen amount contained in arrived molten steel is 600 ppm or more, injecting 1.52 to 2.0 kg/molten steel to n of Fe-(25 to 30%)P in to the degassing treatment facility at a time point between 5 minutes and 7 minutes after starting decarburization in case that the oxygen amount contained in the arrived molten steel is between 500 ppm and 600 ppm, injecting 1.52 to 2.0 kg/molten steel to n of Fe-(25 to 30%)P in to the degassing treatment facility at a time point between 7 minutes and 9 minutes after starting decarburization in case that the oxygen amount contained in the arrived molten steel is between 400 ppm and 500 ppm, and injecting 1.52 to 2.0 kg/molten steel to n of Fe-(25 to 30%)P in to the degassing treatment facility at a time point between 9 minutes after starting decarburization and 3 minutes before starting deoxidization in case that the oxygen amount contained in the arrived molten steel is between 400 ppm or less in the secondary refining process. |
