A method for smelting ultra-low carbon steel and a method for continuously casting ultra-low carbon steel

Abstract

The invention provides a method for smelting of ultra-low carbon steel and a continuous casting method for ultra-low carbon steel. The method comprises: (1) employing a converter to perform primary smelting on molten iron or semisteel with a sulfur content of less than 0.015wt%, and then subjecting the molten steel obtained by primary smelting to tapping into ladle; adding a slag material with alkalinity of 4-5 and an SiO2 content of less than or equal to 20wt% during tapping; making the total content of FeO and MnO% in the ladle slag less than or equal to 15wt%; controlling the tapping temperature of the converter at 1600-1700DEG C, the carbon content at a blowing end point at 0.04-0.06wt%, and the oxygen activity at 0.03-0.07wt%; and (2) carrying out decarbonization and deoxidation alloying on the molten steel obtained in step (1) in an RH vacuum device under vacuum conditions in order recurrently, with the carbon content of the molten steel being less than 30ppm under the decarbonization conditions. The method provided by the invention can improve the molten steel quality of ultra-low carbon steel, ensures stable and batch production of IF (interstitial free) steel with a C content of less than 30ppm and deepest decarbonization of less than 6ppm.

Description

technical field [0001] The invention relates to a method for smelting ultra-low carbon steel and a method for continuously casting ultra-low carbon steel. Background technique [0002] Advanced smelting technologies such as BOF blowing + RH vacuum cycle degassing are used to reduce the carbon content in steel (0.005-0.010% by weight), and titanium and niobium elements are added to fix carbon and oxygen elements, thereby obtaining pure steel without interstitial atoms Ferritic steel is interstitial free steel, referred to as IF steel (Interstitial Free Steel). In recent years, due to the increasing requirements for steel quality, higher requirements have been put forward for the carbon content in steel. Some advanced steel mills in the world require that the C content in IF steel be 0.002% by weight. Table 1 below is a typical IF steel. [0003] Table 1 [0004] serial number C (weight%) Si(wt%) Mn(wt%) P (weight%) 1 0.0008 0.017 ...

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Problems solved by technology

[0005] It can be seen from Table 1 that IF steel has strict requirements on carbon content, which is generally controlled below 0.002% by weight, but if the carbon content of the finished product is to be lower, such as making the carbon content less than or equal to 30ppm, the IF steel The comprehensive pass rate will be low, which will restrict the production of ultra-low carbon steel and the development of varieties, and is not conducive to the stable and mass production of ultra-low carbon steel

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