KR101182052B1 - Controlling method for surface defection of stainless steel and stainless steel manufactured using the same - Google Patents
Controlling method for surface defection of stainless steel and stainless steel manufactured using the same Download PDFInfo
- Publication number
- KR101182052B1 KR101182052B1 KR1020100136561A KR20100136561A KR101182052B1 KR 101182052 B1 KR101182052 B1 KR 101182052B1 KR 1020100136561 A KR1020100136561 A KR 1020100136561A KR 20100136561 A KR20100136561 A KR 20100136561A KR 101182052 B1 KR101182052 B1 KR 101182052B1
- Authority
- KR
- South Korea
- Prior art keywords
- stainless steel
- steel
- cast
- range
- mold
- Prior art date
Links
Images
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
Abstract
The present invention relates to a method for controlling surface defects of stainless steel that can improve surface defects, and to stainless steels produced using the same.
According to the present invention, during the continuous casting process of stainless steel for producing cast steel from molten steel using a machine, the immersion nozzle in the machine so that the temperature deviation of the center portion and the outer portion in the width direction of the cast steel ranges from 0 ℃ to 5 ℃ Provided are a method for controlling surface defects of stainless steel in which an ejection angle is controlled, and a stainless steel manufactured using the same.
Description
The present invention relates to a method for controlling surface defects of stainless steel and a stainless steel manufactured using the same, and more particularly, to a method for controlling surface defects of stainless steel that can improve surface defects and a stainless steel manufactured using the same.
In general, stainless steel should have a beautiful surface and excellent surface compared to general carbon steel, and therefore, surface defects should be reduced, particularly during continuous casting of stainless steel.
In the molten steel containing a significant proportion of sulfur (S), the surface tension is lowered by the sulfur, and thus tensile stress acts in the width direction of the slab in the mold, thereby causing cracks vertically on the upper surface of the slab.
If the cracks are intensified due to such duty free, it is impossible to make stainless steel products and the entire scrap process is required, so proper continuous casting technology is required.
In particular, the high sulfur-containing martensitic stainless steel is used as a mold for manufacturing high hardness and high strength materials, and thus the demand for using high sulfur-containing martensitic stainless steel having excellent corrosion resistance is increasing. Steel continuous casting technology is required.
It is an object of the present invention to provide a method capable of controlling surface defects of stainless steel.
Another object of the present invention is to provide a stainless steel with improved quality by reducing surface defects.
According to an aspect of the present invention, in the continuous casting process of the stainless steel to manufacture the cast from molten steel using a machine, the temperature deviation of the center and the outer portion in the width direction of the cast in the range of 0 ℃ to 5 ℃ A surface defect control method of stainless steel in which the discharge angle of an immersion nozzle is controlled is provided.
Here, the discharge angle may be controlled in the range of 0 ° to 5 °.
In addition, the casting temperature of the cast can be controlled in the range of 15 ℃ to 25 ℃.
In addition, the molten steel may be manufactured into the cast by being cooled by the primary cooling by the mold in the machine and the secondary cooling by the cooling water supplied from the cooling water supply while descending to the vertical curved shape.
On the other hand, the specific amount of the cooling water supplied in the secondary cooling may be controlled in the range of 0.40l / kg to 0.45l / kg.
Here, the stainless steel is C: 0wt% to 0.07wt%, Cr: 12wt% to 15wt%, Ni: 0wt% to 0.8wt%, Mn: 0wt% to 1.5wt%, P: 0wt% to 0.05wt%, S: 0.1wt% to 0.2wt%, Si: 0wt% to 0.7wt%, N: 0wt% to 0.06wt%, may be martensitic stainless steel comprising the remaining Fe and other unavoidable impurities.
According to another aspect of the invention, C: 0wt% to 0.07wt%, Cr: 12wt% to 15wt%, Ni: 0wt% to 0.8wt%, Mn: 0wt% to 1.5wt%, P: 0wt% to 0.05wt %, S: 0.1wt% to 0.2wt%, Si: 0wt% to 0.7wt%, N: 0wt% to 0.06wt%, and the remaining Fe and other unavoidable impurities. The stainless steel produced by controlling the discharge angle of the immersion nozzle in the machine is controlled so that the temperature deviation of the center portion and the outer portion in the width direction of the cast steel in the continuous casting process of the stainless steel to be produced is in the range of 0 ℃ to 5 ℃.
Here, the discharge angle may be controlled in the range of 0 ° to 5 °.
According to the present invention, it is possible to provide a method for controlling surface defects of stainless steel that can improve surface defects such as cracks in duty free, and stainless steel manufactured using the same.
In addition, by appropriately controlling the secondary cooling during continuous casting to minimize the air gap between the mold and the cast, and to minimize the air gap that is not solved by minimizing the air
1 is a cross-sectional view schematically showing a continuous casting process according to an embodiment of the present invention.
FIG. 2 is a perspective view schematically showing an enlarged immersion nozzle of FIG. 1. FIG.
3 is a cross-sectional view of the immersion nozzle according to an embodiment of the present invention, which is taken along AA of FIG. 2.
4 is a cross-sectional view schematically illustrating the immersion nozzle according to another embodiment of the present invention, which is taken along AA of FIG. 2.
5 is a graph showing the relationship between the discharge angle of the immersion nozzle and the temperature difference in the width direction of the cast steel according to the embodiment of the present invention.
6A is an enlarged photograph of a surface of stainless steel according to a comparative example of the present invention.
Figure 6b is an enlarged photograph of the surface of the stainless steel according to an embodiment of the present invention.
DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention and other matters required by those skilled in the art will be described in detail with reference to the accompanying drawings. However, the present invention may be embodied in various different forms within the scope of the claims, and thus the embodiments described below are merely exemplary, regardless of expression.
In describing the present embodiment, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. It should be noted that the same elements in the drawings are represented by the same reference numerals and symbols as much as possible even though they are shown in different drawings. In addition, the thickness or size of each layer in the drawings may be exaggerated for convenience and clarity of description and may be different from the actual layer thickness or size.
In an embodiment of the present invention, the stainless steel may be martensitic stainless steel, the martensitic stainless steel is C: 0wt% to 0.07wt%, Cr: 12wt% to 15wt%, Ni: 0wt% to 0.8wt% , Mn: 0wt% to 1.5wt%, P: 0wt% to 0.05wt%, S: 0.1wt% to 0.2wt%, Si: 0wt% to 0.7wt%, N: 0wt% to 0.06wt%, remaining Fe and It may contain other unavoidable impurities.
Martensitic stainless steel as an example in the embodiment of the present invention is a stainless steel containing sulfur at a high concentration, the embodiment of the present invention is not limited thereto. Recently, the use of high sulfur-containing martensitic stainless steel with excellent corrosion resistance, which is used as a mold for manufacturing high hardness and high strength materials, has been increasing. Therefore, there is a demand for continuous casting process of high sulfur-containing martensitic stainless steel without cracks.
Duty-free cracking occurs for the first time in the mold, so it is necessary to control the casting temperature. In addition, the cooling characteristics of the secondary cooling during continuous casting is an important factor affecting the surface and internal quality of the cast steel, because the secondary cooling determines the solidification thickness, the temperature gradient in the solidification layer and the strength of the solidification layer. Because. The duty free cracks generated in the cast steel can be controlled according to the conditions of the secondary cooling, and in particular, the small duty free cracks generated in the mold may be deteriorated or reduced according to the conditions of the secondary cooling.
In general, the main cause of the duty-free crack generation is due to the air gap phenomenon between the solidification layer and the mold due to the δ → γ transformation and the hot water level hunting. Thus, conventionally, the use of mold powder and grooved mold with low heat transfer reduced duty free cracking. However, caution is required when casting high sulfur-containing martensitic stainless steel in this way, if the thermal conditions are not optimized, cracks may occur in the duty free and severely lead to accidents during performance such as breakout. In addition, since high sulfur-containing martensitic stainless steel contains a large amount of sulfur, the strength and ductility of the solidified layer tends to be easily cracked in the solidified layer, and the surface tension of molten steel containing a large amount of sulfur is very low. Since the meniscus shape is very inadequate and the mold powder inflow state is bad, it is difficult to solve the crack in duty free, so it is not established as a systematic technique.
In order to solve the above problems, in the embodiment of the present invention, to implement a surface defect control process of stainless steel that can improve the cracks duty-free and proposes a method for providing a stainless steel manufactured using the same as follows.
Hereinafter, a process for controlling surface defects of stainless steel according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.
1 is a cross-sectional view schematically showing a continuous casting process according to an embodiment of the present invention, Figure 2 is a perspective view showing an enlarged immersion nozzle of Figure 1, Figure 3 is a view along the AA of FIG. 4 is a cross-sectional view schematically showing an immersion nozzle according to an embodiment of the present invention, and FIG. 4 is a sectional view schematically showing an immersion nozzle according to another embodiment of the present invention. .
Referring to FIG. 1, the
First,
The
The
On the other hand, while the
According to the embodiment of the present invention, during the continuous casting process of the stainless steel to manufacture the
Duty-free cracking occurs in the
Here, the temperature deviation DT 1 in the width direction of the
[Equation 1]
Width direction temperature deviation of cast steel (ΔT 1 ) = intrinsic melting point of cast metal
1 and 2, the
Referring to Table 2 and Figure 3, as the inclined surface (d1) is formed in the discharge port (27a) of the immersion nozzle (25a) according to an embodiment of the present invention with respect to the parallel plane (w) with the ground as shown in Table 2 Upward (+) discharge angle θ1 is formed.
Referring to Table 2 and Figure 4, as the inclined surface (d2) is formed in the discharge port (27b) of the immersion nozzle (25b) according to another embodiment of the present invention with respect to the parallel surface (w) of the ground as shown in Table 2 A downward (-) discharge angle θ2 is formed.
On the other hand, the primary cooling in the
&Quot; (2) "
Casting temperature (ΔT 2 ) = molten steel temperature-metal intrinsic melting point
Meanwhile, the
Here, the degree of secondary cooling can be represented as a specific quantity (l / kg) that can be calculated by
&Quot; (3) "
S = Q / (V × W × D × G)
Where: S: specific quantity (l / kg), Q: total quantity of secondary cooling stand (l / min), W: slab width (m), D: slab thickness (m), G: density (kg / cu.m ), V: casting speed (m / min).
Comparative example And Example
After preparing the high sulfur-containing martensitic stainless steel (5) containing the main elements in the range as shown in Table 1 below, the casting speed was 1.0mm / min through the above-described continuous casting process, the thickness of 200mm, width 1500mm or more To prepare a cast steel (60).
Hereinafter, with reference to Table 2 and 5 will be described examples and comparative examples of the high sulfur-containing martensitic stainless steel having a composition of Table 1.
Table 2 below, by appropriately adjusting the widthwise temperature deviation (ΔT 1 ) and casting temperature (ΔT 2 ) of the cast steel of high sulfur-containing martensitic stainless steel, by appropriately controlling the specific water amount (l / kg) during secondary cooling Test results of the manufactured examples and comparative examples are shown, and FIG. 5 is a graph showing the relationship between the discharge angle θ of the
As in Examples 1 to 4, the widthwise temperature deviation ΔT 1 of the central portion and the outer portion of the
Here, in Comparative Example 1 was treated with the quantity ratio (l / ㎏) is carried casting temperature being the same conditions as in Example (ΔT 2) If the high to 50 ℃ there by a crack defect caused by duty-free total amount of scrap. As described above, even when the stainless steel was cast by appropriate secondary cooling, crack defects occurred in a duty-free manner when the primary cooling conditions, that is, the casting temperature ΔT 2 was high. The casting temperature (ΔT 2 ) is generally low, but it is difficult to control the temperature below 15 °. Therefore, when the casting temperature is controlled to 25 °, there is an effect of reducing the crack vertically.
When SEM and EPMA were observed on high sulfur-containing martensitic specimens to investigate the components around the cracks, the powder component of the
The
The cause of the duty-free cracking is that the surface tension of the high sulfur-containing martensitic steel molten
According to the present invention, it is possible to provide a method for controlling surface defects of stainless steel that can improve surface defects such as cracks in duty free, and stainless steel manufactured using the same.
In addition, by properly controlling the secondary cooling during continuous casting to minimize the air gap between the mold and the cast, and also to minimize the air gap is not solved by minimizing the air gap casting temperature is 15 ℃ to the intrinsic melting point of the metal By maintaining the temperature in the range of 25 ° C and controlling the widthwise temperature deviation of the cast steel to be in the range of 0 ° C to 5 ° C, it is possible to provide the effect of reducing cracks in the duty free of stainless steel.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the present invention.
5: molten steel 10: ladle
15: shrouding nozzle 20: tundish
25: immersion nozzle 27: discharge port
30: mold 40: cooling water supply device
50: feed roll 100: player
Claims (8)
The discharge angle is a surface defect control method of stainless steel, characterized in that controlled in the range of 0 ° to 5 °.
Casting temperature of the cast steel surface defect control method of the stainless steel, characterized in that controlled in the range of 15 ℃ to 25 ℃.
The molten steel is lowered into a vertical curved shape and cooled by primary cooling by a mold in the machine and secondary cooling by cooling water supplied from a cooling water supply device, thereby manufacturing the surface defects of stainless steel. .
The specific amount of the cooling water supplied from the secondary cooling is controlled in the range of 0.40l / kg to 0.45l / kg surface defect control method of stainless steel.
The stainless steel is C: 0wt% to 0.07wt%, Cr: 12wt% to 15wt%, Ni: 0wt% to 0.8wt%, Mn: 0wt% to 1.5wt%, P: 0wt% to 0.05wt%, S: Surface defect control of stainless steel, characterized in that martensitic stainless steel comprising 0.1wt% to 0.2wt%, Si: 0wt% to 0.7wt%, N: 0wt% to 0.06wt%, remaining Fe and other unavoidable impurities Way.
The discharge angle is stainless steel, characterized in that controlled in the range of 0 ° to 5 °.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020100136561A KR101182052B1 (en) | 2010-12-28 | 2010-12-28 | Controlling method for surface defection of stainless steel and stainless steel manufactured using the same |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020100136561A KR101182052B1 (en) | 2010-12-28 | 2010-12-28 | Controlling method for surface defection of stainless steel and stainless steel manufactured using the same |
Publications (2)
Publication Number | Publication Date |
---|---|
KR20120092738A KR20120092738A (en) | 2012-08-22 |
KR101182052B1 true KR101182052B1 (en) | 2012-09-11 |
Family
ID=46884551
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
KR1020100136561A KR101182052B1 (en) | 2010-12-28 | 2010-12-28 | Controlling method for surface defection of stainless steel and stainless steel manufactured using the same |
Country Status (1)
Country | Link |
---|---|
KR (1) | KR101182052B1 (en) |
-
2010
- 2010-12-28 KR KR1020100136561A patent/KR101182052B1/en active IP Right Grant
Also Published As
Publication number | Publication date |
---|---|
KR20120092738A (en) | 2012-08-22 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6484716B2 (en) | Lean duplex stainless steel and manufacturing method thereof | |
JP2015006695A (en) | Continuous casting mold and continuous casting method of steel | |
CN105624571A (en) | Super-thick steel plate and production technology thereof | |
JP2011218403A (en) | Continuous casting method of steel | |
TWI599416B (en) | Continuous casting mold and continuous casting method of steel | |
JP5999294B2 (en) | Steel continuous casting method | |
JP6947737B2 (en) | Continuous steel casting method | |
CN111363972A (en) | Production method of weathering resistant steel Q355NHD | |
KR101182052B1 (en) | Controlling method for surface defection of stainless steel and stainless steel manufactured using the same | |
CN109689247B (en) | Method for continuously casting steel | |
JP2019171435A (en) | Method of continuous casting | |
CN108380835B (en) | Low-segregation gas valve steel continuous casting billet and manufacturing method thereof | |
TWI656924B (en) | Continuous casting mold and continuous casting method for steel | |
CN113584254B (en) | Method for reducing longitudinal crack incidence rate of ultrahigh carbon steel casting blank | |
JP2024035077A (en) | Continuous casting method for casting mold and steel | |
JP2018069324A (en) | Mold device for continuous casting for steel and manufacturing method of surface layer-modified cast slab using the same | |
JP5423715B2 (en) | Continuous casting method | |
JP3283746B2 (en) | Continuous casting mold | |
JP5626438B2 (en) | Continuous casting method | |
KR100656429B1 (en) | Manufacturing method for roll for rolling | |
JP5397213B2 (en) | Continuous casting method | |
JP2008290136A (en) | Continuous casting method for low carbon high sulfur steel | |
JP2016168610A (en) | Steel continuous casting method | |
JP5817681B2 (en) | Mold for continuous casting of high alloy steel round billet slab and continuous casting method | |
JP2005211916A (en) | High speed continuous casting method for carbon steel |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A201 | Request for examination | ||
E701 | Decision to grant or registration of patent right | ||
GRNT | Written decision to grant | ||
FPAY | Annual fee payment |
Payment date: 20160826 Year of fee payment: 5 |
|
FPAY | Annual fee payment |
Payment date: 20170811 Year of fee payment: 6 |
|
FPAY | Annual fee payment |
Payment date: 20180904 Year of fee payment: 7 |
|
FPAY | Annual fee payment |
Payment date: 20190906 Year of fee payment: 8 |