Deoxidation method of low-carbon low-silicon steel hot-rolled steel plate

Abstract

The invention relates to a deoxidation method for a low-carbon low-silicon steel hot-rolled steel plate, and belongs to the technical field of steel smelting. The deoxidation method of the low-carbon low-silicon steel hot-rolled steel plate comprises the following steps: when converter blowing is carried out to the end point and 1 / 4 of converter tapping is carried out, carbon powder is added for molten steel shallow deoxidation; adding silicon iron to carry out molten steel shallow deoxidation before 3 / 4 of tapping; and after tapping is completed, argon blowing stirring is conducted, and then aluminum blocks are added for molten steel deep deoxidation. The smelting cost of the low-carbon low-silicon steel hot-rolled steel plate is reduced while the oxygen content in the molten steel is reduced. Meanwhile, the silicon content in the molten steel is kept stable, and the risk of exceeding the standard is avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steel smelting, and particularly relates to a deoxidation method for low-carbon low-silicon steel hot-rolled steel plate. BACKGROUND

[0002] Low-carbon low-silicon steel is a kind of metal material with low carbon and low silicon content, the carbon content is <0.08%, and the silicon content is 1.0%~4.5%. This material not only has high strength and toughness, but also has good weldability and corrosion resistance, and therefore is widely used in the fields of automobile manufacturing, bridge construction, petroleum chemical industry and the like.

[0003] The traditional converter steelmaking process is to pour the molten iron from the blast furnace into the converter, and then to load the scrap steel according to a certain proportion, and then to lower the oxygen lance to blow oxygen smelting according to a certain oxygen supply, lance position and slagging system. When the blowing endpoint is reached, the lance is lifted and the furnace is emptied, the temperature is measured and the composition is analyzed, and if the molten steel temperature and composition reach the target value range, the molten steel is tapped. Otherwise, the oxygen lance is lowered for supplementary blowing. In the tapping process, deoxidizing agents and alloys are added to the ladle for deoxidation and alloying. Then, the molten steel is sent to the refining process for refining or the continuous casting process for pouring.

[0004] Tapping deoxidation and alloying is an important step in the converter steelmaking process. The commonly used method is to add carbon powder, silicon iron, aluminum block and other types of deoxidizing agents to 1 / 3 of the molten steel for deoxidation. The excessive silicon, aluminum and added manganese and other alloying elements in the molten steel belong to alloying elements. For low-carbon low-silicon steel hot-rolled steel plate (SPHC), because low carbon (C≤0.06%) and low silicon (Si≤0.03%) are required, the traditional process mainly uses the method of adding aluminum blocks for deoxidation during tapping, and the average consumption of aluminum blocks is 2.0 kg / ton. The traditional deoxidation method has the following disadvantages: first, the deoxidation cost is high, and special deoxidizing agents need to be added. If low-cost deoxidizing agents such as carbon powder or silicon iron are added, it is easy to cause the molten steel to increase in carbon and silicon, so it needs to be used carefully. Second, during tapping, due to the slagging and other reasons, it is easy to cause the silicon content to exceed the standard. SUMMARY

[0005] In view of the problems of high deoxidation cost and easy silicon content exceeding the standard in the existing deoxidation process, the present application provides a deoxidation method for low-carbon low-silicon steel hot-rolled steel plate to solve the above problems.

[0006] The technical scheme of the present application is as follows: A deoxidation method for low-carbon low-silicon steel hot-rolled steel plate, comprising the following steps: The converter is blown to the endpoint, and carbon powder is added at 1 / 4 of the converter tapping for shallow deoxidization of the molten steel; silicon iron is added before 3 / 4 of the tapping for shallow deoxidization of the molten steel; after the tapping is completed, argon blowing is performed for stirring, and then aluminum blocks are added for deep deoxidization of the molten steel. The specific steps are as follows: (1) converter blowing to the end, temperature sampling meets the requirements of tapping, then tapping; ladle open to the furnace, open the bottom blowing argon 30s in advance to prevent the bottom blowing argon open late, causing the bottom blowing gas brick to block the cold steel; (2) the furnace is inverted and tapped, and carbon powder is added to perform shallow deoxidization of the molten steel, and silicon iron is added in the later stage of tapping to perform medium deoxidization; (3) after tapping is completed, argon blowing is performed for 1 min to allow the carbon powder and silicon iron added into the molten steel to fully perform deoxidization reaction, and then aluminum blocks are added to perform deep deoxidization and alloying of the molten steel; (4) sampling can be performed at the argon station after 2 min of argon blowing, and according to process requirements, the ladle is lifted to the refining or directly fed into the machine at the argon station.

[0007] Further, the amount of carbon powder is 0.16-0.17 kg / ton based on the tapping amount.

[0008] Further, the amount of silicon iron is 0.16-0.17 kg / 6 tons based on the tapping amount.

[0009] Further, the amount of aluminum blocks is 1.5 kg / ton based on the tapping amount.

[0010] Further, in step (1), the temperature at the end of converter blowing is controlled at 1630-1650℃; and the carbon content is ≤0.05%.

[0011] Further, when the carbon content is <0.05%, carbon powder is added; and for each 0.01% reduction in the carbon content of the molten steel, 0.1 kg / ton of carbon powder is added based on the tapping amount.

[0012] Further, the time for blowing argon is 1-2 min.

[0013] The beneficial effects of the present application are: The present application provides a low-cost smelting method for low-carbon low-silicon steel hot-rolled steel plates, which reduces the smelting cost of low-carbon low-silicon steel hot-rolled steel plates while reducing the oxygen content in the molten steel. At the same time, the silicon content in the molten steel remains stable, avoiding the risk of exceeding the standard. DETAILED DESCRIPTION

[0014] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0015] Embodiment 1 A method for deoxidizing a low-carbon and low-silicon steel hot-rolled steel plate, comprising the following steps: (1) After the converter blowing is finished and the temperature sampling meets the tapping requirements, the tapping is performed, and the tapping amount is 120 tons; the end point temperature is 1630°C, and the end point carbon content is 0.05%; (2) The ladle is opened to the furnace, and the bottom argon blowing is started 30 seconds in advance to perform the ladle argon blowing emptying, so as to avoid the bottom argon blowing gas opening being late and causing the bottom argon blowing gas permeable brick to be blocked by the cold steel; (3) The furnace is inverted and tapped, and when the tapping amount is about 30 tons, 20 kg of carbon powder is added to perform the molten steel shallow deoxidation operation; (4) When the tapping amount is about 40 tons, 20 kg of ferrosilicon is added to perform the molten steel deoxidation; (5) After the tapping is completed, the argon blowing is performed at 500 NL / min for strong stirring for 1 min, so that the carbon powder and the ferrosilicon added into the molten steel fully perform the deoxidation reaction, and then 180 kg of aluminum blocks are added to perform the molten steel deep deoxidation and alloying; (6) After the argon blowing is performed at 500 NL / min for strong stirring for 1 min, the argon flow is adjusted to 300 NL / min, the ladle is opened to the argon blowing station after the aluminum blocks are added, the argon blowing is performed for 2 min, the bottom argon blowing flow is adjusted to 50 NL / min, the temperature sampling is performed at the argon station, and according to the process requirements, the ladle is lifted to the refining or directly fed to the wire at the argon station.

[0016] According to the deoxidation chemical reaction formula: C+O=CO, in theory, 20 kg of carbon powder is added into 120 tons of the converter, and 26.7 kg of oxygen content can be removed. That is, 222 ppm of O content. The hot-rolled steel plate end point carbon is considered to be 0.05%, according to the carbon oxygen product, 500 ppm of [O] is considered in the average tapping, and 278 ppm of [O] is left after the carbon powder deoxidation. According to Si+2O=SiO2, the silicon content in the ferrosilicon is considered to be 75%, and 20 kg of ferrosilicon can remove 20 kg of O content in the molten steel, that is, 167 ppm of [O] content. C, Si total deoxidation 389 ppm, and the residual oxygen in the molten steel is 111 ppm. In this way, the carbon powder shallow deoxidation and the ferrosilicon medium deoxidation are performed, C and Si are fully involved in the deoxidation reaction, and the molten steel is not increased in carbon and silicon. According to the reaction 2Al+3O=Al2O3, if 389 ppm of aluminum is used for deoxidation, 0.44 kg / ton of aluminum blocks are needed. According to the unit price of the aluminum block 18144 yuan / ton, the carbon powder 1783 yuan / ton, and the ferrosilicon 5869 yuan / ton, the ton steel cost saving can reduce the cost: 0.44 kg / ton x 18144 yuan / ton-0.17 kg / ton x 1783 yuan / ton-0.17 kg / ton x 5869 yuan / ton=6.7 yuan / ton.

[0017] Example 2 A method for deoxidizing a low-carbon and low-silicon steel hot-rolled steel plate, comprising the following steps: (1) After the converter blowing to the end, the temperature sampling meets the tapping requirements, then the tapping is carried out, and the tapping amount is 120 tons; the end point temperature is 1630℃, and the end point carbon content is 0.02%; (2) The ladle is opened to the furnace, and the bottom argon blowing is started 30s in advance to carry out the ladle argon blowing emptying, so as to avoid the bottom argon blowing gas opening late, causing the bottom argon blowing gas brick to be blocked by the cold steel; (3) The furnace is reversed and tapped, and when the tapping amount is about 30 tons, 56kg of carbon powder is added to carry out the steel shallow deoxidation operation; (4) When the tapping amount is about 40 tons, 20kg of ferrosilicon is added to deoxidize the steel; (5) After the tapping is completed, the argon blowing is 800NL / min strong stirring for 1min, so that the carbon powder and ferrosilicon added into the molten steel fully carry out the deoxidation reaction, and then 180kg of aluminum block is added to carry out the steel deep deoxidation and alloying; (6) After the argon blowing is 500~800NL / min strong stirring for 1min, the argon flow is adjusted to 400NL / min, the ladle is opened to the argon blowing station after the aluminum block is added, the argon blowing is carried out for 2min, the bottom argon blowing flow is adjusted to 80NL / min, the temperature sampling is carried out at the argon station, and according to the process requirements, the ladle is lifted to the refining or directly fed into the wire at the argon station.

[0018] The ton steel cost saving can reduce the cost: 0.44kg / ton x 18144 yuan / ton-0.46kg / ton x 1783 yuan / ton-0.17kg / ton x 5869 yuan / ton=6.2 yuan / ton.

[0019] Comparative example According to the method of patent CN101914652A, the deoxidation treatment is carried out, (1) After the converter blowing to the end, the temperature sampling meets the tapping requirements, then the tapping is carried out, and the tapping amount is 120 tons; the end point temperature is 1630℃, and the end point carbon content is 0.02%; (2) The ladle is opened to the furnace, and the bottom argon blowing is started 30s in advance to carry out the ladle argon blowing emptying, so as to avoid the bottom argon blowing gas opening late, causing the bottom argon blowing gas brick to be blocked by the cold steel; (3) The furnace is reversed and tapped, and when the tapping amount is about 30 tons, 56kg of carbon powder is added to carry out the steel shallow deoxidation operation; (4) When the tapping amount is about 40 tons, 20kg of ferrosilicon is added to deoxidize the steel; (5) After the tapping is completed, the argon blowing is 800NL / min strong stirring for 1min, so that the carbon powder and ferrosilicon added into the molten steel fully carry out the deoxidation reaction, and then 180kg of aluminum block is added to carry out the steel deep deoxidation and alloying; (6) After the argon blowing is 500~800NL / min strong stirring for 1min, the argon flow is adjusted to 400NL / min, the ladle is opened to the argon blowing station after the aluminum block is added, the argon blowing is carried out for 2min, the bottom argon blowing flow is adjusted to 80NL / min, the temperature sampling is carried out at the argon station, and according to the process requirements, the ladle is lifted to the refining or directly fed into the wire at the argon station.

[0020] 0.235kg / ton x 18144 yuan / ton-0.16kg / ton x 1783 yuan / ton=2 yuan / ton=4.0 yuan / ton Test example The molten steel before and after deoxidation of Examples 1 to 2 and Comparative Example was detected, and the specific results are shown in Table 1.

[0021] Table 1 - Detection results

[0022] Although the present application has been described in detail by preferred embodiments, the present application is not limited to this. Various equivalent modifications or replacements of the embodiments of the present application can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications or replacements shall be within the scope of the present application. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or replacements, which shall be within the protection scope of the present application.

Claims

1. A method of deoxidizing a low-carbon low-silicon steel hot-rolled steel sheet, characterized by, It comprises the following steps: Converter blowing to the end, converter tapping 1 / 4 to add carbon powder for molten steel shallow deoxidation; before tapping 3 / 4, add ferrosilicon for molten steel shallow deoxidation; after the completion of tapping, argon stirring, then add aluminum block for molten steel deep deoxidation.

2. The deoxidation method of a low-carbon low-silicon steel hot-rolled steel sheet according to claim 1, characterized by, The specific steps are as follows: (1) The converter blowing to the end, temperature sampling to meet the tapping requirements, then tapping; ladle open to the furnace, 30s in advance to open bottom blowing argon for ladle argon emptying, to prevent the late opening of bottom blowing argon, resulting in bottom blowing gas brick cold steel blockage; (2) Tapping, see steel flow to add carbon powder for molten steel shallow deoxidation, add ferrosilicon for medium deoxidation in the later stage of tapping; (3) After the completion of tapping, argon stirring for 1min, let the residual carbon powder, ferrosilicon added in the molten steel fully deoxidize, then add aluminum block for molten steel deep deoxidation and alloying; (4) After 2min of argon blowing, sampling can be carried out at the argon station, according to the process requirements, the ladle is lifted to the refining or directly fed into the machine at the argon station.

3. The deoxidation method of a low-carbon low-silicon steel hot-rolled steel sheet according to claim 2, characterized by, The amount of carbon powder is 0.16~0.17kg / ton based on the tapping amount.

4. The deoxidation method of a low-carbon low-silicon steel hot-rolled steel sheet according to claim 2, characterized by, The amount of ferrosilicon is 0.16~0.17kg / 6 tons based on the tapping amount.

5. The deoxidizing method of a low-carbon low-silicon steel hot-rolled steel sheet according to claim 2, characterized by, The amount of aluminum block is 1.5kg / ton based on the tapping amount.

6. The deoxidizing method of a low-carbon low-silicon steel hot-rolled steel sheet according to claim 2, characterized by, In step (1), the temperature at the end of converter blowing is controlled at 1630~1650℃; the carbon content is ≤0.05%.

7. The deoxidizing method of a low-carbon low-silicon steel hot-rolled steel sheet according to claim 2, characterized by, When the carbon content is <0.05%, increase the carbon powder; for every 0.01% reduction in carbon content of the molten steel, increase the carbon powder by 0.1kg / ton based on the tapping amount.

8. The deoxidizing method of a low-carbon low-silicon steel hot-rolled steel sheet according to claim 2, characterized by, The time of argon blowing is 1~2min.

Images