RH vacuum calcification furnace process treatment method
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A treatment method and calcium treatment technology, applied in the field of RH vacuum calcification furnace process treatment, can solve the problems of reducing calcium yield and calcium treatment effect, expensive calcium-containing alloys, and reducing calcium treatment effect, etc., to achieve stable product quality, Low production cost and improved pourability
Active Publication Date: 2020-08-25
INST OF RES OF IRON & STEEL JIANGSU PROVINCE +2
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[0008] First of all, it is expensive to purchase all kinds of calcium-containing alloys that increase the melting point and vaporization point of calcium; secondly, the application range is limited. When this type of calcium-containing alloy is brought into the Ca element, it will also bring other elements into the molten steel, resulting in Contamination of molten steel, each type of calcium alloy can only be applied to the production of steel types containing all the elements in the calcium alloy. In order to avoid this problem, calcium and other oxides are used as modifiers, but Ca is a strong reducing element. After molten steel, at high temperature, Ca first reacts with other oxides wrapped in the modifier and consumes it, reducing the effect of calcium treatment; finally, many studies are mainly on how to improve the yield of Ca in the RH vacuum furnace, due to the RH process Most of the cold-rolled substrate steels produced are low-carbon or ultra-low-carbon steels. The molten steel needs to have sufficient oxygen content for decarburization, so the slag also has a certain degree of oxidation. Although calcium alloys are added in the RH vacuum chamber, there is no need to contact the slag. However, after the RH breakout to the continuous casting process, there is always a slag-gold reaction between molten steel and slag, which will reduce the calcium yield and calcium treatment effect. The oxidative control of slag is also an influencing factor for the temperature RH vacuum calcium treatment effect.
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Embodiment 1
[0029] In Example 1, the refining of ultra-low carbon steel and cold-rolled substrate steel SPHD is taken as an example. The size of the ladle used is 200t, and the weight of molten steel is 175-185t.
[0030] Mass percentage of main chemical components of SPHD: C≤0.015%, Si≤0.03%, P≤0.02%, S≤0.015%, Mn=0.15-0.55%, Al=0.01-0.06%, and Fe and other unavoidable impurity elements . Main components of slag surface deoxidizer: 25%≤Al≤45%, 30%≤CaO≤40%, 5%≤Al 2 o 3 ≤15%, 10%≤CaF 2 ≤15%, and other unavoidable impurities. The main indicators of the seamless pure calcium wire: the linear density of the iron sheet is 160-200g / m, the linear density of the calcium core is 60-70g / m, the Ca content is greater than 98%, and other inevitable impurities.
[0031] The production process is as follows:
[0032] (1) After the molten iron is desulfurized, the sulfur content is lower than 0.0050%, and the slag after desulfurization is subjected to slag removal.
[0033] (2) The tapping temperat...
Embodiment 2
[0041] In Example 2, the refining of low-carbon cold-rolled substrate steel grade ST5 is taken as an example, the size of the ladle used is 200t, and the weight of molten steel is 175-185t.
[0042] ST5 main chemical composition mass percentage: C=0.03-0.08%, Si≤0.03%, P≤0.02%, S≤0.015%, Mn=0.1-0.5%, Al=0.01-0.06%, and Fe and other unavoidable impurity elements. Main components of slag surface deoxidizer: 25%≤Al≤45%, 30%≤CaO≤40%, 5%≤Al 2 o 3 ≤15%, 10%≤CaF 2 ≤15%, and other unavoidable impurities. The main indicators of the seamless pure calcium wire: the linear density of the iron sheet is 160-200g / m, the linear density of the calcium core is 60-70g / m, the Ca content is greater than 98%, and other inevitable impurities.
[0043] The production process is as follows:
[0044] (1) After the molten iron is desulfurized, the sulfur content is lower than 0.0050%, and the slag after desulfurization is subjected to slag removal.
[0045] (2) The tapping temperature of the conve...
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Abstract
The invention discloses an RH vacuum calcification furnace process treatment method. The RH vacuum calcification furnace process treatment method comprises the following steps of KR molten iron pretreatment, converter smelting, RH vacuum refining and slab continuous casting, wherein the RH vacuum refining comprises decarburization, deoxidation alloying and calcium treatment; in the decarburizationprocess, a slag surface deoxidizing agent is added to the surface of furnace slag in the middle and later periods of the decarburization, the adding amount is 1.0-2.0 kg per ton of steel, and the ladle slag is modified to enable the content of (T.Fe + MnO) in the slag to be less than or equal to 5 wt%; in the deoxidation alloying process, an alloy and carbon powder are added for the deoxidation alloying; in the calcium treatment process, a seamless pure calcium wire is started to be fed for calcium treatment 5 minutes after the deoxidation alloying is finished, and the pressure of a vacuum chamber is increased to 200 mbar or above during the calcium treatment; and after the calcium treatment is finished, the pressure of the vacuum chamber is reduced to 2 mbar or below, static circulationis conducted for 6 minutes, and then vacuum breaking tapping is conducted. According to the process method, the seamless calcium wire is fed after the deoxidation alloying, and meanwhile, the Ca element is uniformly distributed in molten steel by utilizing RH molten steel circular stirring, so that the modification of Al2O3 inclusion is realized, the Ca element oxidation amount is low, the calciumyield is increased, and the calcium treatment effect is stabilized.
Description
technical field [0001] The present application relates to the technical field of molten steel refining outside the furnace, in particular to a RH vacuum calcification furnace process treatment method. Background technique [0002] At present, high-quality cold-rolled substrates have very strict requirements on the shape, size, quantity and gas content of inclusions in the steel. Inadequate control of inclusions can easily lead to defects such as inclusions, holes, cracks, etc. in the cold-rolled substrate, which seriously affects product performance. The RH-LF dual process is used to produce cold-rolled substrates, and the inclusions can be treated with calcium. The main type of inclusions in the steel is low-melting calcium aluminate. When the RH single-link process is used, due to the high oxygen potential of the slag, it is not suitable to feed the calcium wire, and the main type of inclusions in the steel is Al 2 o 3 . [0003] The cold-rolled substrate smelting proc...
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