| 摘要 |
PURPOSE:To decrease component segregation and to obtain a steel material which is free from detects by inclusions by producing a low-C steel contg. Si at the controlled ratio, introducing Fe-Mn and Al thereto in the stage of tapping to adjust the quantity of free oxygen then adding Ti to the molten steel and casting continuously the same. CONSTITUTION:The molten steel contg. <=0.20% C and <=0.05% Si is produced in a converter. The Fe-Mn is introduced to the molten steel according to the target Mn of the product and further the Al is introduced thereto at <=0.5kg/molten steel (t) in the stage of tapping. Such molten steel is treated by a vacuum degassing treatment or dis oxidation by Alor by combining the dis oxidation by other alloy elements to adjust the free oxygen in the molten steel to 50-150ppm. The Ti is added to the molten steel subjected to such adjustment so as to be incorporated therein at 0.003-0.020% in a tundish and thereafter the molten steel is continuously cast. The low-C steel material contg. <=0.20% C, <=0.05% Si, <=1.0% Mn and <=0.003% Al is obtd. by the above-mentioned method. The steel material has no Al2O3 inclusion, is free from surface and internal defects and is stable in quality. |
