Smelting method of cleanliness in excellent low carbon aluminum-killed steel

摘要

PROBLEM TO BE SOLVED: To stably melt/prepare a low carbon aluminum killed steel having a high cleanliness of extremely few oxide-based inclusion by combining a primary refining using a converter with a secondary refining using an RH vacuum degassing apparatus.;SOLUTION: There is provided a method for melting/preparing the low carbon aluminum killed steel containing 0.02-0.06 mass% carbon. In the method, molten steel produced by the converter is tapped into a ladle from the converter while the molten steel is not deoxidized yet, and after tapping the molten steel, a slag modifier containing Al is added onto the slag in the ladle present on the un-deoxidized molten steel at an addition quantity of ≥0.3 kg/t of molten steel per pure Al content and a low grade oxide in the slag is reduced with added Al, then, in the RH vacuum degassing apparatus, dissolved oxygen in the molten steel and the carbon in the molten steel are reacted with each other under reduced pressure without newly supplying the oxygen source into the molten steel to perform decarburization treatment, the decarburization treatment is ended when decarburized quantity of ≥0.015 mass% is secured and the carbon concentration in the molten steel becomes 0.02-0.06 mass%, after that. the molten steel is deoxidized by adding Al to the molten steel under reduced pressure condition.;COPYRIGHT: (C)2012,JPO&INPIT