KR101529189B1 - Method for manufacturing hot rolled coil and method for predicting defect of hot rolled coil edge - Google Patents
Method for manufacturing hot rolled coil and method for predicting defect of hot rolled coil edge Download PDFInfo
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- KR101529189B1 KR101529189B1 KR1020140036901A KR20140036901A KR101529189B1 KR 101529189 B1 KR101529189 B1 KR 101529189B1 KR 1020140036901 A KR1020140036901 A KR 1020140036901A KR 20140036901 A KR20140036901 A KR 20140036901A KR 101529189 B1 KR101529189 B1 KR 101529189B1
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Abstract
Description
The present invention relates to a method for manufacturing a hot-rolled coil and a method for predicting defects at a hot-rolled coil edge.
The continuous casting machine is a machine that is produced in the steel making furnace, receives the molten steel transferred to the ladle by the tundish, and supplies it to the mold for the continuous casting machine to produce the cast steel of a certain size. The continuous casting machine includes a ladle for storing molten steel, a casting mold for forming a tundish and a molten steel that is guided in the tundish first to form a cast slab having a predetermined shape, and a casting member connected to the mold, A plurality of pinch rolls and the like. The molten steel introduced from the ladle and the tundish is formed into a cast slab having a predetermined width, thickness and shape in the mold and is transported through the pinch roll. The slab transported through the pinch roll is cut by a cutter to have a predetermined shape Slabs, blooms, billets, and the like. Slabs, blooms, billets, and the like produced in the continuous casting process are sandwiched between two rotating rolls to form an elongated shape.
A rolling mill is a device for forming a plate material, a bar material or the like through plastic deformation of a material while passing the material between rotating rolls at room temperature or high temperature. A conveyance guide is provided between the rolling mill and the rolling mill to feed the rolling mill to the rolling mill in the next step. The slabs, such as slabs, are rolled and then produced as hot rolled coils.
A related art is Korean Patent Laid-Open Publication No. 2011-0022330 (published on Mar. 07, 2011, a method of reducing surface defects of thin slab hot-rolled coils).
According to an embodiment of the present invention, a method of manufacturing a hot-rolled coil capable of reducing defects at the edge of a hot-rolled coil by predicting edge defects of the hot-rolled coil by measuring the contents of aluminum and nitrogen contained in the molten steel, And a method for predicting a defect in a hot-rolled coil edge portion.
According to an embodiment of the present invention, there is provided a method for measuring the content (%) of aluminum (Al) in molten steel and a content (ppm) of nitrogen (N) A component adjusting step of adjusting the content of aluminum or the content of nitrogen in the molten steel, a thin slab casting step of casting the molten steel into a thin slab by using a funnel type mold, And a production step of producing the hot-rolled coil through a hot-rolling process.
At this time, the component adjustment step includes a prediction step of predicting the defect of the hot-rolled coil edge portion according to the product of the measured content of aluminum and the content of nitrogen, and the product of the content of aluminum and the content of nitrogen If the set value is exceeded, the content of aluminum or the content of nitrogen in the molten steel can be reduced.
Further, in the predicting step, the edge portion defect of the hot-rolled coil can be predicted using the following equation (1).
Y = 0.7545X-1.2117, R 2 = 0.7243 - >
(Where Y is the surface defect rate and X is the product of the aluminum content and the nitrogen content).
The preset value may be 1.6.
According to another embodiment of the present invention, there is provided a method of measuring the content (%) of aluminum (Al) and a content (ppm) of nitrogen (N) in molten steel, a step of measuring the content of aluminum and a content of nitrogen And a prediction step of predicting an edge portion defect of the hot-rolled coil made of the molten steel.
At this time, the predicting step may include predicting the edge portion defect of the hot-rolled coil using the following equation (1).
Y = 0.7545X-1.2117, R 2 = 0.7243 - >
(Where Y is the surface defect rate and X is the product of the aluminum content and the nitrogen content).
According to the embodiments of the present invention, it is possible to estimate the defects at the edge of the hot-rolled coil by measuring the contents of aluminum and nitrogen contained in the molten steel using the hot-rolled coil manufacturing method and the method of predicting the defect portion of the hot- The defects of the edge portion of the hot-rolled coil can be reduced.
1 is a schematic view showing a method of manufacturing a hot-rolled coil according to an embodiment of the present invention;
Fig. 2 shows defects at the edge of the hot-rolled coil; Fig.
3 is a view showing that a precipitate is formed in a form in which Al and N are combined.
4 is a graph showing the edge defect occurrence rate for Al * N;
BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.
The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.
Hereinafter, a method for manufacturing a hot-rolled coil according to the present invention and a method for predicting a defect of a hot-rolled coil edge will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to like And a detailed description thereof will be omitted.
The thin slab method is typically CSP method. In the CSP method, slab thickness is applied to 65mm ~ 50mm. The CSP process is a consistent system from steelmaking to rolling.
1 is a schematic view showing a method of manufacturing a hot-rolled coil according to an embodiment of the present invention.
As shown in Fig. 1, the CSP process includes a thin slab casting step (A) of continuously casting a slab from a molten steel of a tundish via a mold, and a continuous cast slab being heated (hot rolled) And a hot-rolled coil production step (B) for producing a hot-rolled coil through the rolling process.
In this CSP process, the shape of the mold becomes a funnel shape, and the slab is continuously cast. In this process feature, unlike other castors, the slab corner portion is excessively sub-cooled and various defects are generated in the produced hot-rolled coil edge portion.
Fig. 2 is a view showing defects of the edge portion of the hot-rolled coil. Fig. As shown in Fig. 2, the hot-rolled coil edge porosity defect called the lag is generated, and accordingly, a lot of quality loss cost is being spent.
Fig. 3 is a view showing that a precipitate is formed in a form in which Al and N are combined.
As shown in FIG. 3, as the amount of Al and N increases in the edge portion of the hot-rolled coil, precipitates of AlN in the grain boundaries are increased, resulting in an increase in edge defects.
4 is a graph showing an edge defect occurrence rate with respect to Al * N.
As can be seen from Fig. 4, the defect of the hot-rolled coil edge portion increases as the value of Al * [N] increases. Therefore, the method of predicting defects of a hot-rolled coil edge according to the present invention is characterized by a measuring step of measuring a content (%) of aluminum (Al) and a content (ppm) of nitrogen (N) And a prediction step of predicting edge defects of the hot-rolled coil made of the molten steel.
In other words, it is aimed to predict the defect of the hot-rolled coil edge according to the content (%) of aluminum (Al) in molten steel and the content (ppm) of nitrogen (N) and to control the occurrence of defects at the hot- .
At this time, the prediction step includes predicting the edge portion defect of the hot-rolled coil using the following equation (1).
Y = 0.7545X-1.2117, R 2 = 0.7243 - >
(Where Y is the surface defect rate and X is the product of the aluminum content and the nitrogen content).
In the above formula (1), the carbon (C) in the molten steel is 0.02 to 0.06%, the manganese (Mn) is 0.1 to 0.3%, the sulfur (S) is 0.01% 0.01 to 0.07%.
As can be seen from FIG. 4, when the value of Al * [N] is 1.6 or less, it can be seen that defects of the hot-rolled coil edge hardly occur. Therefore, by adjusting the value of Al * [N] in the molten steel to 1.6 or less, defects in the hot-rolled coil edge portion can be significantly reduced.
A method for manufacturing a hot-rolled coil according to another embodiment of the present invention is to manufacture a hot-rolled coil using the method of predicting a defect of the hot-rolled coil edge portion. That is, the method for producing a hot-rolled coil according to the present invention is a method for manufacturing a hot-rolled coil according to the present invention, in which the content (%) of aluminum (Al) and the content (ppm) A component controlling step of adjusting the content of aluminum in the molten steel or the content of nitrogen, a thin slab casting step of casting the molten steel into a thin slab by using a funnel type mold, and a hot rolling step of casting the thin slab And a production step of producing hot-rolled coils.
At this time, the component control step includes a prediction step of predicting the defect of the hot-rolled coil edge according to the product of the content of aluminum and the content of nitrogen measured. When the product of the content of aluminum and the content of nitrogen exceeds the preset value, Reducing the content of aluminum or the content of nitrogen.
In addition, the prediction step includes predicting the edge portion defect of the hot-rolled coil by using the following equation (1) in the same way as the method of predicting the hot-rolled coil edge portion defect.
Y = 0.7545X-1.2117, R 2 = 0.7243 - >
(Where Y is the surface defect rate and X is the product of the aluminum content and the nitrogen content).
In the above formula (1), the carbon (C) in the molten steel is 0.02 to 0.06%, the manganese (Mn) is 0.1 to 0.3%, the sulfur (S) is 0.01% 0.01 to 0.07%.
At this time, when the content of aluminum and the content of nitrogen in the molten steel are adjusted to 1.6 or less, the defect of the hot-rolled coil edge hardly occurs.
The method for predicting defects of a hot-rolled coil edge portion according to the present invention and the method for manufacturing a hot-rolled coil using the same according to the present invention are based on the correlation between the contents of aluminum (Al) and nitrogen (N) The occurrence of defects at the hot-rolled coil edge can be reduced.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.
A: Thin slab casting step
B: Hot-rolled coil production stage
Claims (6)
Depending on the product of the measured aluminum content and the nitrogen content,
A component adjusting step of adjusting the content of aluminum or the content of nitrogen;
A thin slab casting step of casting the molten steel into a thin slab by using a mold of a funnel type; And
And a production step of producing the thin slabs as a hot rolled coil through a hot rolling process,
Wherein the component adjustment step comprises:
And predicting the defect of the hot-rolled coil edge portion according to the product of the aluminum content and the nitrogen content measured,
When the product of the content of aluminum and the content of nitrogen exceeds a preset value, the content of aluminum or the content of nitrogen in the molten steel is decreased,
Wherein,
And predicting an edge portion defect of the hot-rolled coil by using the following equation (1).
Y = 0.7545X-1.2117, R 2 = 0.7243 - >
(Where Y is the surface defect rate and X is the product of the aluminum content and the nitrogen content).
Wherein the predetermined value is 1.6.
And predicting an edge defect of the hot-rolled coil made of the molten steel by using the content of the aluminum and the content of the nitrogen measured,
Wherein,
And predicting an edge portion defect of the hot-rolled coil by using the following equation (1).
Y = 0.7545X-1.2117, R 2 = 0.7243 - >
(Where Y is the surface defect rate and X is the product of the aluminum content and the nitrogen content).
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| Application Number | Priority Date | Filing Date | Title |
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| KR1020140036901A KR101529189B1 (en) | 2014-03-28 | 2014-03-28 | Method for manufacturing hot rolled coil and method for predicting defect of hot rolled coil edge |
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| KR1020140036901A KR101529189B1 (en) | 2014-03-28 | 2014-03-28 | Method for manufacturing hot rolled coil and method for predicting defect of hot rolled coil edge |
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| KR101529189B1 true KR101529189B1 (en) | 2015-06-17 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000005012A1 (en) * | 1998-07-21 | 2000-02-03 | Shinagawa Refractories Co., Ltd. | Molding powder for continuous casting of thin slab |
| KR20060076665A (en) * | 2004-12-29 | 2006-07-04 | 주식회사 포스코 | Refining method for preventing corner crack |
-
2014
- 2014-03-28 KR KR1020140036901A patent/KR101529189B1/en not_active IP Right Cessation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000005012A1 (en) * | 1998-07-21 | 2000-02-03 | Shinagawa Refractories Co., Ltd. | Molding powder for continuous casting of thin slab |
| KR20060076665A (en) * | 2004-12-29 | 2006-07-04 | 주식회사 포스코 | Refining method for preventing corner crack |
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