KR100920580B1 - Method for manufacturing high-carbon hot rolled steel sheets having excellent quality of surface - Google Patents

Method for manufacturing high-carbon hot rolled steel sheets having excellent quality of surface Download PDF

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KR100920580B1
KR100920580B1 KR1020020078647A KR20020078647A KR100920580B1 KR 100920580 B1 KR100920580 B1 KR 100920580B1 KR 1020020078647 A KR1020020078647 A KR 1020020078647A KR 20020078647 A KR20020078647 A KR 20020078647A KR 100920580 B1 KR100920580 B1 KR 100920580B1
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steel sheet
cooling
rolling
hot rolled
rolled steel
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KR1020020078647A
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KR20040051691A (en
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류재화
이주동
김영구
심성철
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주식회사 포스코
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B21B2001/225—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length by hot-rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B2015/0057—Coiling the rolled product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2261/00—Product parameters
    • B21B2261/20—Temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2275/00—Mill drive parameters
    • B21B2275/02—Speed

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Metal Rolling (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

본 발명은 자동차 부품 또는 공구 등에 사용되는 고탄소 열연강판의 제조방법에 관한 것이다.The present invention relates to a method for producing a high carbon hot rolled steel sheet used in automobile parts or tools.

이 열연강판의 제조방법은 탄소함량이 0.4중량% 이상인 고탄소 슬라브를 열간압연하고, 냉각대에서 다수개의 냉각 뱅크로 냉각수를 주수한 후, 권취하는 열연강판의 제조방법에 있어서, 상기 열간압연시 열간 마무리압연 입측온도를 900~950℃로 제어하며, 상기 냉각대에서 냉각수를 주수하는 냉각 뱅크의 수는 다음의 관계,The method for manufacturing a hot rolled steel sheet is a method of manufacturing a hot rolled steel sheet in which a hot carbon slab having a carbon content of 0.4 wt% or more is hot rolled, water is poured into a plurality of cooling banks in a cooling zone, and then wound. Hot finish rolling entrance temperature is controlled to 900 ~ 950 ℃, the number of cooling banks for pouring coolant in the cooling zone is the following relationship,

냉각 뱅크수 ≤ -11.6 + 0.016Te + 0.006Vr Cooling Bank Number ≤ -11.6 + 0.016T e + 0.006V r

(여기서, Te: 마무리 압연이 종료된 강판의 에지부 온도(℃), Vr: 압연속도(mpm)) (T e : edge temperature (° C.), V r : rolling speed (mpm) of the finished steel sheet after finishing rolling)

를 만족하도록 제어하는 것을 포함하여 이루어진다.Control is made to satisfy.

이 열연강판은 마무리압연 입측온도를 적절히 제어하고 마무리압연후 강판의 에지부 온도와 압연속도를 고려하여 냉각 뱅크수를 적정하게 제어함으로써, 스케일 결함과 에지균열의 발생을 억제하여 고탄소강의 실수율 및 작업성을 향상시키는 효과가 있다.The hot rolled steel sheet controls the temperature of the finish rolling side properly and controls the number of cooling banks in consideration of the edge temperature and the rolling speed of the steel sheet after finishing rolling, thereby suppressing the occurrence of scale defects and edge cracks, thereby reducing the error rate of high carbon steel. It is effective to improve workability.

열연강판, 고탄소, 스케일, 에지균열Hot Rolled Steel, High Carbon, Scale, Edge Crack

Description

표면품질이 우수한 고탄소 열연강판의 제조방법{Method for manufacturing high-carbon hot rolled steel sheets having excellent quality of surface} Method for manufacturing high-carbon hot rolled steel sheets having excellent quality of surface}             

도 1은 열간압연 제조설비의 개략도1 is a schematic diagram of a hot rolling facility

도 2는 냉각대의 구조를 나타내는 개략도2 is a schematic view showing the structure of a cooling stand.

도 3은 산화온도와 스케일 두께와의 관계를 나타내는 그래프3 is a graph showing the relationship between oxidation temperature and scale thickness

도 4는 마무리압연 입측온도와 스케일 결함 등급간의 관계를 나타내는 그래프
4 is a graph showing the relationship between finish rolling input temperature and scale defect grade.

*도면의 주요부분에 대한 부호의 설명** Description of the symbols for the main parts of the drawings *

1.....가열로 5.....마무리압연 출측 압연기 1 ..... Furnace 5 ..... Finishing Rolling Mill

2.....조압연기 6.....냉각대 2 ..... Cold rolling mill 6 ..... Cooling rack

3.....스케일 제거 장치 7.....권취기 3 ..... descaler 7 ..... winder

4.....마무리압연 입측 압연기
4 ..... finishing rolled rolling mill

본 발명은 자동차 부품 또는 공구 등에 사용되는 고탄소 열연강판에 관한 것으로, 보다 상세하게는 마무리압연 입측온도와 냉각 뱅크수를 제어함으로써 스케일 결함과 에지균열을 억제하는 표면품질이 우수한 고탄소 열연강판의 제조방법에 관한 것이다.
The present invention relates to a high-carbon hot-rolled steel sheet used in automobile parts or tools, and more particularly, to a high-carbon hot-rolled steel sheet having excellent surface quality that suppresses scale defects and edge cracking by controlling the finish rolling input temperature and the number of cooling banks. It relates to a manufacturing method.

고탄소 강은 탄소함량이 0.4중량% 이상인 강으로, 자동차 부품이나 공구 등에 주로 사용되고 있다. 고탄소 강을 이용하여 최종제품을 제조하는 방법은 연속주조된 슬라브를 열간압연하여 열연강판을 만든 후에 산세 공정에서 스케일을 제거한 다음, 소둔과 냉간압연을 거쳐 냉연강판을 만들고, 이후 열처리후에 도금 등을 행하는 것으로 이루어진다.High carbon steel is a steel having a carbon content of 0.4% by weight or more, and is mainly used for automobile parts and tools. The method of manufacturing the final product by using high carbon steel is hot-rolled continuous slab to make a hot rolled steel sheet, then the scale is removed in the pickling process, and then cold-rolled steel sheet through annealing and cold rolling, and then plated after heat treatment It consists of doing

고탄소 열연강판에 요구되는 특성으로는 우수한 표면품질이 있다. 상기 표면품질이 우수하기 위해서는 산세성 및 도금성을 고려하여 스케일 결함이 없어야 하고, 냉간압연 시에 판파단이 발생되지 않기 위해 에지균열이 없어야 한다. 그러나, 통상의 고탄소열연강판 제조방법에서는 고탄소강이 열간변형 저항이 크기 때문에 압연온도를 높이게 되며 이로 인해 스케일 결함이 많이 발생된다. 또한, 온도가 높은 강판을 냉각하기 위해 냉각대에서 냉각수를 많이 뿌려 강판 에지부가 과냉됨으로써 에지균열이 자주 발생되는 문제점이 있다.
Characteristics required for high carbon hot rolled steel sheet have excellent surface quality. In order to have excellent surface quality, there should be no scale defect in consideration of pickling property and plating property, and there should be no edge cracking in order to prevent plate breakage during cold rolling. However, in the conventional high carbon hot rolled steel sheet manufacturing method, the high carbon steel has a large hot deformation resistance, thereby increasing the rolling temperature, which causes many scale defects. In addition, there is a problem that the edge cracks are frequently generated by spraying a lot of cooling water in the cooling zone to cool the steel sheet having a high temperature, thereby overcooling the steel sheet edge portion.

본 발명은 상기한 종래기술의 문제점을 해결하기 위한 것으로, 고탄소강의 열간압 연시에 마무리압연 입측온도를 적절히 조정하여 스케일 결함의 발생을 억제하고, 에지부의 과냉을 억제하기 위해 마무리 압연후의 에지부 온도와 압연속도를 고려하여 냉각대에서 냉각수량을 제어함으로써 표면품질을 향상시킨 고탄소 열연강판의 제조방법을 제공하는데, 그 목적이 있다.
The present invention is to solve the above problems of the prior art, the edge portion after finishing rolling in order to suppress the occurrence of scale defects by appropriately adjusting the finish rolling side temperature during hot rolling of high carbon steel, and to suppress the supercooling of the edge portion It is an object of the present invention to provide a method for manufacturing a high carbon hot rolled steel sheet having improved surface quality by controlling the amount of cooling water in the cooling zone in consideration of temperature and rolling speed.

상기한 목적을 달성하기 위한 본 발명은, 탄소함량이 0.4중량% 이상인 고탄소 슬라브를 열간압연하고, 냉각대에서 다수개의 냉각 뱅크로 냉각수를 주수한 후, 권취하는 열연강판의 제조방법에 있어서, 상기 열간압연시 열간 마무리압연 입측온도를 900~950℃로 제어하며, 상기 냉각대에서 냉각수를 주수하는 냉각 뱅크의 수는 다음의 관계,In the present invention for achieving the above object, in the method for producing a hot rolled steel sheet is hot-rolled high carbon slab having a carbon content of 0.4% by weight or more, and after the cooling water is poured into a plurality of cooling banks in the cooling table, In the hot rolling, the hot finishing rolling entrance temperature is controlled to 900 to 950 ° C., and the number of cooling banks to cool the cooling water in the cooling zone is as follows.

냉각 뱅크수 ≤ -11.6 + 0.016Te + 0.006Vr Cooling Bank Number ≤ -11.6 + 0.016T e + 0.006V r

(여기서, Te: 마무리 압연이 종료된 강판의 에지부 온도(℃), Vr: 압연속도(mpm)) (T e : edge temperature (° C.), V r : rolling speed (mpm) of the finished steel sheet after finishing rolling)

를 만족하도록 제어하는 것을 포함하여 이루어진다.
Control is made to satisfy.

이하, 본 발명에 대하여 상세하게 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

본 발명은 고탄소 열연강판의 스케일 두께에 미치는 마무리압연 입측온도의 영향을 조사하여 스케일 결함이 발생되지 않는 마무리압연 입측온도를 설정하고, 취성이 강한 베이나이트의 생성을 억제할 수 있는 550℃ 이상의 에지부 온도를 확보하기 위해 마무리압연을 마친 강판의 에지부 온도와 압연판 속도를 고려하여 냉각수량을 적절히 제어하는데 특징이 있다.
The present invention investigates the effect of the finish rolling entrance temperature on the scale thickness of the high carbon hot rolled steel sheet to set the finish rolling entrance temperature at which no scale defects occur, and is capable of suppressing formation of brittle strong bainite at 550 ° C. or more. In order to secure the edge temperature, it is characterized in that the amount of cooling water is properly controlled in consideration of the edge temperature of the finished steel sheet and the rolling plate speed.

도 1은 열연강판의 제조설비를 나타내는 개략도로서, 도 1에서 알 수 있듯이 열연강판의 제조설비는 가열로(1), 조압연기(2), 스케일 제거 장치(3), 마무리압연 입측 압연기(4), 마무리압연 출측 압연기(5), 냉각대(6) 및 권취기(7)로 구성된다. 이중에서 냉각대(6)는 도 2와 같이 다수개의 냉각 뱅크가 강판의 상하부에 구비되어 있다.FIG. 1 is a schematic view showing a manufacturing facility of a hot rolled steel sheet. As shown in FIG. 1, a manufacturing facility for a hot rolled steel sheet includes a heating furnace 1, a rough rolling mill 2, a scale removing device 3, and a finish rolling side rolling mill 4. ), The finish rolling side rolling mill 5, the cooling stand 6 and the winding machine 7. In the cooling stand 6, a plurality of cooling banks are provided in the upper and lower parts of the steel sheet as shown in FIG.

열연강판의 제조시 가열로, 조압연 공정에서 스케일이 생성되지만 마무리압연 전의 스케일 제거 장치(3)에 의해 스케일이 제거되기 때문에 문제가 되지 않는다. 하지만, 마무리압연 공정에는 스케일 제거 장치가 없기 때문에 마무리압연 공정에서 스케일이 두껍게 생성되면 압연중에 파괴되어 스케일 결함이 발생하게 된다.In the production of the hot rolled steel sheet, the scale is generated in the rough rolling process, but the scale is removed by the descaling device 3 before the finish rolling. However, since there is no scale removing device in the finish rolling process, when the scale is thickly produced in the finish rolling process, it is destroyed during rolling and scale defects are generated.

마무리압연 공정에서 발생되는 스케일 두께는 마무리압연 입측온도와 밀접한 관계가 있는데, 상기 스케일 두께와 마무리압연 입측온도(산화온도)의 상관관계는 도 3과 같다. 도 3은 탄소함량이 0.8중량%인 고탄소강을 이용하여 스케일 두께와 마무리압연 입측온도간의 상관관계를 나타내는 그래프로서, 도 3에 나타난 바와 같이 마무리압연 입측온도가 950℃를 초과하면 스케일 두께가 급격히 증가됨을 알 수 있다. 또한, 도 3에서 알 수 있는 바와 같이 마무리압연 입측온도가 낮을수록 스케일 결함은 크게 감소되지만, 마무리압연 입측온도가 900℃ 미만이면 마무리압연 중에 압연성이 불량하여 강판에서 파단이 발생하는 경우가 발생되었다. 따라서, 마무리 압연 입측온도는 900~950℃로 제한하는 것이 바람직하다.
The scale thickness generated in the finish rolling process is closely related to the finish rolling entrance temperature, and the correlation between the scale thickness and the finish rolling entrance temperature (oxidation temperature) is shown in FIG. 3. FIG. 3 is a graph showing a correlation between scale thickness and finish rolling entrance temperature using high carbon steel having a carbon content of 0.8% by weight. As shown in FIG. 3, when the finish rolling entrance temperature exceeds 950 ° C., the scale thickness rapidly increases. It can be seen that the increase. In addition, as can be seen in Figure 3, the lower the finish rolling entry temperature, the scale defects are greatly reduced, but if the finish rolling entrance temperature is less than 900 ℃ the rollability is poor during the finish rolling, the fracture occurs in the steel sheet It became. Therefore, it is preferable to limit finish rolling side temperature to 900-950 degreeC.

마무리압연을 마친 열연강판은 냉각대(6)에서 냉각될 때 에지부의 과냉에 의해 에지균열이 발생하게 된다. 상기 에지균열을 억제하기 위해서는 강판 에지부에 취성이 강한 베이나이트 조직의 생성을 억제해야 되는데, 이를 위해서는 냉각후 에지부의 온도를 550℃ 이상으로 확보해야 한다. 상기 냉각후 에지부의 온도는 냉각수 주수량에 의해 결정되며, 주수량은 냉각대(6)의 냉각 뱅크의 개폐수에 의해 결정된다. 따라서, 냉각후 강판의 에지부의 온도를 550℃ 이상으로 확보하기 위한 주수량 조건 즉, 냉각뱅크의 개폐수를 결정하여야 한다. 그런데, 강판의 냉각에는 냉각전 강판의 에지부 온도(마무리 압연이 종료된 강판의 에지부 온도)와 압연속도(강판의 이동속도)도 영향을 미친다.The hot rolled steel sheet after finishing rolling is subjected to edge cracking due to the subcooling of the edge portion when the hot rolled steel sheet is cooled in the cooling table 6. In order to suppress the edge cracking, it is necessary to suppress the formation of the brittle bainite structure at the edge of the steel sheet. The temperature of the edge portion after the cooling is determined by the amount of cooling water to be supplied, and the amount of water is determined by the opening and closing water of the cooling bank of the cooling table 6. Therefore, the main water quantity condition, that is, the opening and closing number of the cooling bank, to secure the temperature of the edge portion of the steel sheet after cooling to 550 ° C. or higher should be determined. By the way, the cooling of the steel sheet also affects the edge temperature (the edge temperature of the steel sheet after finishing rolling) and the rolling speed (moving speed of the steel sheet) of the steel sheet before cooling.

본 발명에서는 마무리 압연이 종료된 강판의 에지부 온도와 압연속도의 영향을 고려하여 냉각후 강판의 에지부 온도를 550℃로 할 수 있는 냉각 뱅크의 개폐수를 결정하기 위하여 이들의 상관관계를 조사하였고, 그 결과는 하기 관계식 1과 같다.
In the present invention, considering the influence of the edge temperature and the rolling speed of the steel sheet after the finish rolling is completed, the correlation is investigated in order to determine the number of opening and closing of the cooling bank that can make the edge temperature of the steel sheet after cooling to 550 ℃ The result is shown in Equation 1 below.

[관계식 1][Relationship 1]

냉각 뱅크수 ≤ -11.6 + 0.016Te + 0.006Vr Cooling Bank Number ≤ -11.6 + 0.016T e + 0.006V r

(여기서, Te: 마무리 압연이 종료된 강판의 에지부 온도(℃), Vr: 압연속도(mpm))
(T e : edge temperature (° C.), V r : rolling speed (mpm) of the finished steel sheet after finishing rolling)

상기 관계식 1은 마무리 압연이 종료된 강판의 에지부 온도(Te)를 일정하게 유지한 채 압연속도와 냉각 뱅크수의 상관관계를 구한 다음, 다시 압연속도(Vr)를 일정하게 유지한 채 마무리 압연이 종료된 강판의 에지부 온도(Te)와 냉각 뱅크수의 상관관계를 구하고, 이들을 중회귀 분석하여 얻은 것이다.The relational expression 1 is obtained by obtaining a correlation between the rolling speed and the number of cooling banks while maintaining the edge temperature (T e ) of the steel sheet after finishing rolling is constant, and then again maintaining the rolling speed (V r ) The correlation between the edge temperature (T e ) and the number of cooling banks of the steel sheet after finishing rolling was obtained, and these were obtained by performing a multiple regression analysis.

예를들어, 마무리 압연이 종료된 강판의 에지부 온도가 800℃이고 압연속도가 600mpm 인 경우, 이를 상기 관계식 1에 대입하면 냉각 뱅크수가 4.8개 이하로 계산된다. 따라서, 냉각대에서 4개 이하의 냉각 뱅크를 개방하여 강판에 냉각수를 주수하면 냉각후 강판의 에지부 온도가 550℃ 이상이 확보되어 에지균열이 발생되지 않는다.
For example, in the case where the edge temperature of the steel sheet after finishing rolling is 800 ° C. and the rolling speed is 600 mpm, the number of cooling banks is calculated to be 4.8 or less by substituting this in Equation 1. Therefore, when four or less cooling banks are opened in the cooling zone and the cooling water is poured into the steel sheets, the edge temperature of the steel sheets after the cooling is ensured at 550 ° C. or more so that edge cracking does not occur.

이하, 실시예를 통하여 본 발명을 보다 상세하게 설명한다.Hereinafter, the present invention will be described in more detail with reference to Examples.

[실시예 1]Example 1

본 실시예는 마무리압연 입측온도가 스케일 결함에 미치는 영향을 알아보기 위한 것이다.This embodiment is to determine the effect of the finish rolling entrance temperature on the scale defect.

탄소함량이 0.8중량%인 공석강을 두께가 230mm인 슬라브로 제조한 후, 1210℃로 가열한 다음 하기 표 1과 같은 마무리압연 입측온도로 마무리 열간압연하고, 650℃에서 권취하여 두께 2.3mm의 열연강판을 제조하였다. 상기와 같이 제조된 열연강판의 표면을 눈으로 관찰하여 강판의 스케일 결함 등급을 분류하였으며, 그 결과는 하기 표 1 및 도 4와 같다. After manufacturing a vaccinated steel with a carbon content of 0.8 wt% into a slab having a thickness of 230 mm, it was heated to 1210 ° C. and then hot rolled to a finish rolling entrance temperature as shown in Table 1 below, and wound at 650 ° C. to a thickness of 2.3 mm. A hot rolled steel sheet was prepared. The surface of the hot-rolled steel sheet manufactured as described above was visually classified to classify the scale defect grade of the steel sheet, and the results are shown in Table 1 and FIG. 4.                     

Figure 112002041092484-pat00001
Figure 112002041092484-pat00001

상기 표 1과 도 4에 나타난 바와 같이, 마무리압연 입측온도가 낮아짐에 따라 스케일 결함 등급은 향상됨을 알 수 있다. 본 발명의 범위를 만족하는 마무리압연 입측온도를 갖는 발명재(1~2)는 결함 등급이 2 이하로 아주 양호한 표면품질을 얻을 수 있었다. 하지만, 마무리압연 입측온도가 너무 높은 비교재(1~2)는 결함 등급 3 이상의 불량한 표면품질을 나타내었으며, 마무리압연 입측온도가 너무 낮은 비교재(3)은 표면품질은 우수하지만 압연온도가 너무 낮아 통판성이 불량하여 판파단이 발생하는 등 압연성이 크게 저하되었다.
As shown in Table 1 and Figure 4, it can be seen that the scale defect grade is improved as the finish rolling entrance temperature is lowered. Inventive materials 1 to 2 having a finish rolling entrance temperature satisfying the scope of the present invention were able to obtain a very good surface quality with a defect grade of 2 or less. However, the comparative materials (1 ~ 2) having a high finish rolling entry temperature showed poor surface quality of defect grade 3 or higher. The comparative material (3) having a low finish rolling entrance temperature was too good in surface quality but rolling temperature was too high. Low rollability, such as poor sheet flowability and sheet breakage.

[실시예 2] Example 2                     

본 실시예는 고탄소 열연강판의 에지균열에 미치는 냉각대의 냉각 뱅크수의 영향을 알아보기 위한 것이다.This embodiment is to determine the influence of the number of cooling banks of the cooling zone on the edge crack of the high carbon hot rolled steel sheet.

탄소함량이 0.8중량%인 공석강을 두께 230mm의 슬라브로 제조한 후, 1210℃로 가열한 다음 940℃의 마무리압연 입측온도로 마무리 열간압연하고, 하기 표 2와 같은 냉각 뱅크수로 냉각한 다음 권취하여 두께 2.3mm의 열연강판을 제조하였다. 이때 마무리압연 후 강판의 에지부 온도는 800℃이고 압연속도는 600mpm이었으며, 냉각 뱅크 1개당 분당 주수량은 6000리터였다.After preparing a vaccinated steel with a carbon content of 0.8% by weight into a slab having a thickness of 230 mm, it was heated to 1210 ° C. and then hot rolled to a finish rolling entrance temperature of 940 ° C., followed by cooling with the number of cooling banks as shown in Table 2 below. It wound up and manufactured the hot rolled steel plate of thickness 2.3mm. At this time, after finishing rolling, the edge temperature of the steel sheet was 800 ° C., the rolling speed was 600 mpm, and the amount of main water per minute per cooling bank was 6000 liters.

상기와 같이 제조된 열연강판의 에지균열 발생여부를 관찰하였으며, 그 결과는 하기 표 2와 같다.
It was observed whether the edge crack generation of the hot-rolled steel sheet prepared as described above, the results are shown in Table 2.

Figure 112002041092484-pat00002
Figure 112002041092484-pat00002

본 실시예의 마무리 압연이 종료된 강판의 에지부 온도와 압연속도를 수학식 1에 대입하여 계산하면, 냉각 뱅크수가 4.8 이하를 만족하여야 한다.When the edge temperature and the rolling speed of the steel sheet after finishing rolling of the present embodiment are calculated by substituting Equation 1, the number of cooling banks must satisfy 4.8 or less.

상기 표 2에 나타난 바와 같이, 본 발명의 수학식 1에서 제시하는 냉각 뱅크수를 만족하는 발명재(3~4)는 에지균열이 발생하지 않았고, 수학식 1에서 제시하는 냉각 뱅크수를 벗어난 비교재(4~5)는 에지균열이 발생한 것을 알 수 있다.
As shown in Table 2, the invention material (3 ~ 4) that satisfies the number of cooling banks shown in the equation (1) of the present invention did not have edge cracks, compared to the number of cooling banks shown in the equation (1) It can be seen that the ashes 4 to 5 have edge cracks.

상술한 바와 같이, 본 발명은 마무리압연 입측온도를 적절히 제어하고 마무리압연후 강판의 에지부 온도와 압연속도를 고려하여 냉각 뱅크수를 적정하게 제어함으로써, 스케일 결함과 에지균열이 없는 고탄소 열연강판을 제공하여 고탄소강의 실수율 및 작업성을 향상시키는 효과가 있다.As described above, the present invention is a high-carbon hot-rolled steel sheet free of scale defects and edge cracks by appropriately controlling the finish rolling entrance temperature and appropriately controlling the number of cooling banks in consideration of the edge temperature and the rolling speed of the steel sheet after finishing rolling. It provides the effect of improving the error rate and workability of high carbon steel.

Claims (1)

탄소함량이 0.4중량% 이상인 고탄소 슬라브를 열간압연하고, 냉각대에서 다수개의 냉각 뱅크로 냉각수를 주수한 후, 권취하는 열연강판의 제조방법에 있어서, 상기 열간압연시 열간 마무리압연 입측온도를 900~950℃로 제어하며, 상기 냉각대에서 냉각수를 주수하는 냉각 뱅크의 수는 다음의 관계,In the method of manufacturing a hot rolled steel sheet which hot-rolls a high carbon slab having a carbon content of 0.4% by weight or more, and pours coolant through a plurality of cooling banks in a cooling zone, the hot finish rolling entrance temperature during the hot rolling is 900. The number of cooling banks for controlling cooling water at the cooling zone in the cooling zone is as follows. 냉각 뱅크수 ≤ -11.6 + 0.016Te + 0.006Vr Cooling Bank Number ≤ -11.6 + 0.016T e + 0.006V r (여기서, Te: 마무리 압연이 종료된 강판의 에지부 온도(℃), Vr: 압연속도(mpm)) (T e : edge temperature (° C.), V r : rolling speed (mpm) of the finished steel sheet after finishing rolling) 를 만족하도록 제어하는 것을 포함하여 이루어지는 표면품질이 우수한 고탄소 열연강판의 제조방법.Method of manufacturing a high carbon hot rolled steel sheet having excellent surface quality comprising controlling to satisfy.
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