Method for ultra-deeply dephosphorizing in steel ladle
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A ladle, ultra-low technology, applied in the field of dephosphorization in ladle to ultra-low, can solve problems such as high cost, affecting product performance and quality, and long production cycle
Inactive Publication Date: 2011-02-23
SHANXI TAIGANG STAINLESS STEEL CO LTD
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Problems solved by technology
The current method has a long production cycle and high cost, and cannot meet the requirements of some ultra-low phosphorus steels for the phosphorus content in the finished product to be less than 0.003%, which affects the performance and quality of the product
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Embodiment 1
[0024] This example is carried out on a 180-ton double-blowing converter, and the bottom of the ladle used is equipped with two bottom blowing gas supply devices, and the single bottom gas supply flow rate is up to 700L / min. The smelted steel is 9% Ni. In GB24510-2009, the mass percentage of the finished product components is shown in Table 1.
[0025] Table 1
[0026]
[0027] The rest is Fe and unavoidable impurities.
[0028] The physical and chemical indicators of the lime, fluorite and carbon steel dedusting ash briquette used in this embodiment are as follows:
[0029] a The physical and chemical indicators of lime (mass percentage) are
[0030] CaO 92%; MgO 3.6%; SiO 2 2.1%; P 0.019%;
[0031] S 0.035%; Moisture content 0.2%%; Raw burning + overheating rate 10%;
[0032] The particle size is less than 50mm.
[0033] b Fluorite physical and chemical indicators (mass percentage) are:
[0034] CaF 2 87%; SiO 2 8.9%; P 0.053%; S 0.12%;
[0035] Moisture 0.2%...
Embodiment 2
[0048] This example is carried out on a 180-ton double-blowing converter, and the bottom of the ladle used is equipped with two bottom blowing gas supply devices, and the single bottom gas supply flow rate is up to 700L / min. The smelted steel is DT4C, and the mass percentage of its chemical composition is shown in Table 2 in GB / T6983-2008.
[0049] Table 2
[0050]
[0051] The rest is Fe and unavoidable impurities.
[0052] The physical and chemical indicators of the lime, fluorite and carbon steel dedusting ash briquette used in this embodiment are as follows:
[0053] a The physical and chemical indicators of lime (mass percentage) are
[0054] CaO 93; MgO 3.5; SiO 2 1.9; P 0.015; S 0.043%;
[0055] Moisture content 0.2; raw burning + overheating rate 9.2;
[0056] The particle size is less than 50mm.
[0057] b Fluorite physical and chemical indicators (mass percentage) are:
[0058] CaF 2 86%; SiO 2 6.7%; P 0.051%; S 0.11%;
[0059] Moisture 0.2%; particle...
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Abstract
The invention discloses a method for ultra-deeply dephosphorizing in a steel ladle, which comprises the following steps in turn: (1) blowing in a converter in a normal mode, and before steel tapping of the converter, adding 7 to 9 kilograms of lime, 1.5 to 2.0 kilograms of fluorite and 3 to 5 kilograms of carbon steel dust-free briquette into each ton of molten steel in the steel ladle; (2) when steel is tapped from the converter, keeping the oxygen content of the molten steel less than 0.065 percent and the phosphorus content not more than 0.015 percent, preventing the molten steel from being deoxidized and alloyed, blowing argon at the bottom of the steel ladle and stirring in the whole steel tapping process, and keeping the blowing gas supply strength at the bottom of the steel ladle is 3.0 to 6.0L/min.t; and (3) blocking slag in steel tapping with the slag takeover being not more than 6kg/t and the temperature of the molten steel in the steel ladle not above 1,590 DEG C after the steel tapping, drossing with the slag content of the molten steel not more than 0.2 percent and after the drossing, heating the molten steel, deoxidizing, alloying and refining. When the method for ultra-deeply dephosphorizing in a steel ladle is used, the phosphorus content of the finished steel is as low as less than 0.003 percent.
Description
technical field [0001] The invention relates to a method for dephosphorizing to ultra-low levels in a ladle. Background technique [0002] Phosphorus is an element harmful to the toughness of steel. It can significantly reduce the low-temperature impact toughness of steel and increase the strength and hardness of steel; the segregation of phosphorus in steel is relatively serious, and it is easy to make the local structure of steel abnormal and cause uneven mechanical properties; Phosphorus can also cause corrosion fatigue and weld cracking. Therefore, there are many steel grades that require ultra-low phosphorus content in the finished product, less than 0.003%. [0003] The existing dephosphorization method is as follows: the first step is to put molten iron and steel scrap into the converter according to a certain proportion, blow it according to the normal smelting method of the converter, tap the steel to block the slag, deoxidize and alloy the molten steel in the ladl...
Claims
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Application Information
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