A kind of rh vacuum furnace calcium treatment process method

A treatment method and calcium treatment technology, which is applied in the field of RH vacuum furnace calcium treatment process, 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 and efficient calcium treatment The effect of advanced technology, stable product quality and low production cost

Active Publication Date: 2022-02-25
INST OF RES OF IRON & STEEL JIANGSU PROVINCE +2
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AI Technical Summary

Problems solved by technology

[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.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] In Example 1, the production of ultra-low carbon steel grade cold-rolled substrate steel grade SPHD is taken as an example, the specification of the ladle used is 200t, and the weight of molten steel is 175-185t.

[0030] The mass percentage of the 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 inevitable 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 inevitable impurities. The main indicators of seamless pure calcium wire: iron sheet linear density 160-200g / m, calcium core linear density 60-70g / m, Ca content greater than 98%, and other inevitable impurities.

[0031] The production process is as follows:

[0032] (1) After the molten iron desulfurization treatment, the sulfur content is lower than 0.0050%, and the slag after desulfurization is subjected to slag removal treatment.

[0033] (2) The tapping te...

Embodiment 2

[0040] In Example 2, the production of low-carbon cold-rolled substrate steel grade ST5 is taken as an example, the specification of the ladle used is 200t, and the weight of molten steel is 175-185t.

[0041] The mass percentage of the main chemical components of ST5: 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 inevitable 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 inevitable impurities. The main indicators of seamless pure calcium wire: iron sheet linear density 160-200g / m, calcium core linear density 60-70g / m, Ca content greater than 98%, and other inevitable impurities.

[0042] The production process is as follows:

[0043] (1) After the molten iron desulfurization treatment, the sulfur content is lower than 0.0050%, and the slag after desulfurization is subjected to slag removal treatment.

[0044] (2) The tapping temperature of the co...

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Abstract

This application discloses a RH vacuum furnace calcium treatment process, including KR molten iron pretreatment - converter smelting - RH vacuum refining - slab continuous casting, RH vacuum refining includes decarburization, deoxidation alloying and calcium treatment, decarburization: decarburization Add slag surface deoxidizer to the surface of slag in the middle and later stages of carbonization, the addition amount is 1.0-2.0kg / ton of steel, and modify the ladle slag so that (T.Fe+MnO) in the slag is ≤5wt%; deoxidation alloying: adding alloy and carbon powder for deoxidation alloying; calcium treatment: 5 minutes after the end of deoxidation alloying, start feeding seamless pure calcium wire for calcium treatment. During calcium treatment, raise the pressure of the vacuum chamber to above 200mbar; The chamber pressure drops below 2mbar, and the steel is broken out after 6 minutes of static circulation. In the process method of the present application, the seamless calcium wire is fed after deoxidation alloying, and at the same time, the RH molten steel is used to circulate and stir, so that the distribution of the Ca element in the molten steel is uniform, and the Al 2 o 3 Modification of inclusions; low Ca element oxidation, increased calcium yield, and stable calcium treatment effect.

Description

technical field [0001] The application relates to the technical field of out-of-furnace refining of molten steel, in particular to a process method for calcium treatment in a RH vacuum furnace. Background technique [0002] At present, high-quality cold-rolled substrates have very strict requirements on the morphology, size, quantity and gas content of inclusions in steel. Inadequate control of inclusions can easily lead to the formation of defects such as inclusions, holes, and cracks in the cold-rolled substrate, which seriously affects product performance. The cold-rolled substrate is produced by the RH-LF duplex process, 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-pass process is used, it is not suitable to feed calcium wire due to the high oxygen potential of the slag, and the main type of inclusions in the steel is Al 2 O 3 . [0003] The smelting process routes of col...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21C7/10C21C7/00C21C7/06C22C33/04C22C38/02C22C38/04C22C38/06
CPCC21C7/10C21C7/0006C21C7/0056C21C7/06C22C33/04C22C38/004C22C38/02C22C38/002C22C38/04C22C38/06
Inventor 赵家七周彦召马建超蔡小锋
Owner INST OF RES OF IRON & STEEL JIANGSU PROVINCE
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