Production method of ultra-low phosphorus if steel

Abstract

The invention belongs to the field of iron and steel metallurgy, and in particular relates to a method for producing ultra-low-phosphorus IF steel. The method for producing the ultra-low-phosphorus IF steel adopts a carbon-free steel ladle in a whole process, and technological parameters in each working procedure are controlled as follows: a converter endpoint is controlled to be as follows: [C] is 0.04wt%-0.06wt% and [P] is less than or equal to 0.007wt%; the steel tapping temperature is 1640-1660 DEG C; the endpoint oxygen activity is 0.05-0.08%; final slag TFe is 18-22wt%; after ladle refining is completed, the weight content of FeO in liquid steel top slag is 16-20% in percentage by weight, and liquid steel [P] is less than or equal to 0.004% in percentage by weight; in a vacuum refining working procedure: when a[O] in the liquid steel is more than or equal to A, vacuum refining is started, wherein A is equal to 1.3[C]+0.02%. The invention provides the method for producing ultra-low-phosphorus steel which combines converter deep dephosphorization with LF refining dephosphorization; the method can achieve stable production of a finished product of which [C] is less than or equal to 0.003% in percentage by weight and [P] is less than or equal to 0.004% in percentage by weight, and can ensure that the dephosphorization rate reaches more than 94%.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to a production method of ultra-low phosphorus IF steel. Background technique [0002] Phosphorus is one of the long-standing elements in steel. Because it segregates at the grain boundaries of steel, it will make steel "cold and brittle" and deteriorate the welding performance and cold bending performance of steel. Therefore, it is often regarded as a harmful element. It needs to be removed during smelting. For IF steel for automobiles, reducing the phosphorus content can significantly improve the performance of IF steel plates such as secondary processing embrittlement resistance and low-temperature impact toughness of hot-rolled steel plates; therefore, when producing high-quality automotive panel steel, the phosphorus content in the steel will be stably controlled It is particularly important at lower values. [0003] Reports on dephosphorization in steel a...

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Problems solved by technology

[0011] Reference document 9 "a dephosphorization method in IF steel ladle", this method can achieve a good dephosphorization effect by adding a large amount of lime in the LF process and using a large amount of slag to dephosphorize molten steel, but for ultra-low carbon steel Production, adding a large amount of lime will greatly reduce the oxidation of ladle slag, which is not conducive to vacuum decarburization

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