Narrow-face copper plate of rounding crystallizer

Abstract

A working face of the narrow-face copper plate comprises a plane area located in the middle of the copper plate and two rounding areas located on the two sides of the copper plate, the plane area is connected with the rounding areas on the two sides, the first chamfering distance H1 of the rounding areas in the horizontal direction and the second chamfering distance H2 of the rounding areas in the height direction both range from 30 mm to 40 mm, and H1-H2 is smaller than or equal to 5 mm. And the circular arc radius of the fillet area is 40-70mm. According to the narrow-face copper plate of the rounding crystallizer, the stress distribution of the narrow side of a rounding casting blank obtained through continuous casting is changed in the hot continuous rolling rough rolling process, so that metal wrinkles on the narrow side become shallower, serious staggering cannot be generated among the wrinkles, and then even if the copper plate is turned flat to the wide face to form the side turning defect, the product quality is improved. And in combination with the broadening effect and the pickling effect of subsequent finish rolling, the rollover defect can be flattened and pickled away, so that the overall rollover defect is greatly improved and even eliminated, the product metal yield is remarkably improved, and the production cost of a steel mill is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a narrow copper plate of a rounded crystallizer. Background Art

[0002] After hot rolling and pickling, most stainless steel ingots will form one or more "black line" defects parallel to the rolling direction within 5 to 30 mm from the edge. Some are intermittent in length, while others are continuous. The width of a single defect is generally 50 to 200 microns. This defect is usually called "rollover", "straight crack", "narrow crack", "thin line" and so on in the industry. In this article, it is uniformly referred to as rollover defect. The depth of rollover defect is generally 30 to 220 microns.

[0003] During the hot rolling rough rolling process of the ingot, the metal on the narrow side of the edge will wrinkle, and the wrinkles are easy to intertwine. Due to the rolling widening effect, the wrinkles in the middle and later stages of the rough rolling will flatten to the wide edge to form rollover defects. After the fine rolling widening effect and pickling corrosion, some shallow and regular rollover defects will disappear, while other deeper or intertwined defects will remain on the matrix, thus forming hot coil rollover defects. In addition, the larger the distance from the edge to the steel grades with low high temperature strength, such as stainless steel 430 and 0Cr13R, the larger the rollover defect will be. Practice has proved that the occurrence of this defect has nothing to do with the cracks in the corners of the ingot.

[0004] Hot coil rollover defects will not be eliminated with cold rolling and cold pickling. Most of them will be inherited to the final cold rolled product, affecting the user's use. Therefore, the rolling process needs to remove all the defects. After the rollover defects are completely removed, on the one hand, the metal recovery rate will be low, and on the other hand, the width of the hot rolled coil may not be suitable, which will increase the production cost of the steel plant.

[0005] Chinese patent CN201110281520 entitled “A self-contained taper continuous casting slab chamfering crystallizer”, Chinese patent CN201210201520 entitled “A combined slab continuous casting chamfering crystallizer narrow copper plate”, Chinese patent CN201320350661 entitled “A slab continuous casting chamfering crystallizer narrow copper plate”, Chinese patent CN201510583062 entitled “A slab continuous casting chamfering crystallizer narrow copper plate” etc. all provide a continuous casting chamfering crystallizer narrow copper plate. The purpose of these patents is to increase the corner temperature of the ingot during the continuous casting process and prevent the ingot from generating transverse cracks at the corners. The chamfering structures on both sides of the crystallizer are chamfered planes or bevels approximating planes (large arc radius). The authors of the present invention have found through experiments that this chamfered crystallizer with an inverted plane or a nearly flat structure cannot reduce or eliminate the rollover defect of the hot rolled coil when used for stainless steel continuous casting. Instead, it will widen the distance between the defect and the edge of the hot rolled coil, causing the metal yield to be further reduced.

[0006] Chinese patent CN202011373736 entitled “Method for reducing the width of straight cracks on the edge of stainless steel strip” and Chinese patent CN202010225692 entitled “Method for producing stainless steel slabs by a continuous casting machine with an arc chamfered crystallizer” provide methods for improving rollover defects by using an oblique chamfered crystallizer or an arc chamfered crystallizer. However, the authors of the present invention have concluded through experiments that this method is greatly affected by fluctuations in production conditions, and may not only fail to improve the rollover defect, but may worsen the severity of the rollover defect. On the other hand, even if the depth of the rollover defect is improved, the width of the rollover defect from the edge does not change much, and the rollover defect will still be inherited to the cold-rolled product. Summary of the invention

[0007] In order to solve some or all of the technical problems existing in the above-mentioned prior art, the present invention provides a chamfered narrow copper plate of a crystallizer, wherein the working surface of the chamfered narrow copper plate of the crystallizer in contact with the molten steel includes a plane area located in the middle of the copper plate and two chamfered areas located on both sides of the copper plate, the plane area is connected to the chamfered areas on both sides, the first chamfer distance H1 along the horizontal direction and the second chamfer distance H2 along the height direction of the chamfered area are both 30 to 40 mm, and |H1-H2|≤5 mm, and the arc radius of the chamfered area is 40 to 70 mm.

[0008] Furthermore, in the above-mentioned chamfered narrow-surface copper plate of the crystallizer, the flat area and the chamfered areas on both sides are smoothly connected by connecting arcs, and the arc radius of the connecting arc is 5 to 15 mm.

[0009] Furthermore, in the above-mentioned chamfered crystallizer narrow surface copper plate, a flat area cooling water trough and a chamfered area cooling water trough are provided on the back of the copper plate opposite to the working surface. The flat area cooling water trough is perpendicular to the back of the copper plate, and the chamfered area cooling water trough forms an angle of 80 to 89 degrees with the back of the copper plate.

[0010] Furthermore, in the above-mentioned rounded crystallizer narrow copper plate, the width of the cooling water trough in the flat area is 4-6 mm, and the depth is 18-25 mm; the width of the cooling water trough in the rounded area is 4-8 mm, and the depth is 25-35 mm.

[0011] Furthermore, in the above-mentioned rounded crystallizer narrow surface copper plate, a plurality of cooling water holes are arranged on both sides of the copper plate near the rounded corner area, and the diameter of the cooling water holes is 7 to 10 mm.

[0012] Furthermore, in the above-mentioned chamfered crystallizer narrow surface copper plate, the first chamfer distance H1 and the second chamfer distance H2 of the chamfered area are equal, that is, |H1-H2|=0, and the arc of the chamfered area is symmetrical along the oblique 45-degree direction.

[0013] The rounded crystallizer narrow copper plate of the present invention has the following advantages and beneficial effects:

[0014] By applying the rounded crystallizer narrow face copper plate provided by the present invention, the rounded ingot obtained by continuous casting changes the force distribution on the narrow side during the hot rolling rough rolling process, so that the metal wrinkles on the narrow side become shallower, and no serious staggering occurs between the wrinkles. Even if the rollover defect is formed by flattening to the wide face, the rollover defect will be flattened and pickled away in combination with the widening effect and pickling effect of subsequent fine rolling, so that the overall rollover defect is greatly improved or even eliminated, which significantly improves the metal yield of the product and reduces the production cost of the steel plant.

[0015] Moreover, the rounded crystallizer narrow side copper plate of the present invention can be applied on the basis of a conventional continuous casting process, with little modification of the process and equipment and low cost for upgrading and transformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0017] Figure 1 It is a schematic structural diagram of a narrow copper plate of a rounded crystallizer according to the present invention;

[0018] Figure 2 for Figure 1 The enlarged schematic diagram of the middle A part;

[0019] Figure 3 This is a schematic structural diagram of the narrow copper plate of the chamfered crystallizer in Example 1 of the present invention.

[0020] Description of reference numerals:

[0021] 1- plane area, 2- chamfered corner area, 3- cooling water trough in plane area, 4- cooling water trough in chamfered corner area, 5- cooling water hole, 6- connecting arc. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] like Figure 1 and Figure 2 As shown, the working surface of the narrow copper plate of the chamfered crystallizer of the present invention that contacts the molten steel includes a plane area 1 located in the middle of the copper plate and two chamfered areas 2 located on both sides of the copper plate, the plane area 1 is connected to the chamfered areas 2 on both sides, the first chamfer distance H1 along the horizontal direction and the second chamfer distance H2 along the height direction of the chamfered area 2 are both 30 to 40 mm, and |H1-H2|≤5 mm, and the arc radius R of the chamfered area 2 is 40 to 70 mm.

[0024] The narrow copper plate of the chamfered crystallizer of the present invention has a flat area 1 and a chamfered area 2 with an inverted taper from the upper mouth to the lower mouth of the crystallizer in the height direction, so as to match the inverted taper structure of the crystallizer with a large upper mouth and a small lower mouth, thereby adapting to the shrinkage of the ingot during the solidification process and reducing the formation of an air gap between the surface of the ingot and the crystallizer.

[0025] Preferably, in the above-mentioned rounded crystallizer narrow copper plate, the flat area 1 and the rounded areas 2 on both sides are smoothly connected by connecting arcs 6, and the arc radius of the connecting arc 6 is 5 to 15 mm.

[0026] Furthermore, a flat area cooling water trough 3 and a chamfered area cooling water trough 4 are provided on the back of the copper plate opposite to the working surface of the narrow copper plate of the chamfered crystallizer. The flat area cooling water trough 3 is perpendicular to the back of the copper plate, and the chamfered area cooling water trough 4 forms an angle θ of 80 to 89 degrees with the back of the copper plate.

[0027] Preferably, the width W3 of the cooling water groove 3 in the plane area is 4-6 mm, and the depth D3 is 18-25 mm. The width W4 of the cooling water groove 4 in the rounded corner area is 4-8 mm, and the depth D4 is 25-35 mm.

[0028] Furthermore, in order to enhance the cooling effect of the corners, a plurality of cooling water holes 5 are provided on both sides of the copper plate near the rounded corners 2, and the diameter Φ of the cooling water holes 5 is 7-10 mm.

[0029] In the above-mentioned rounded crystallizer narrow copper plate, since the first chamfer distance H1 and the second chamfer distance H2 of the rounded area 2 satisfy |H1-H2|≤5mm, the arc of the rounded area 2 is symmetrical or approximately symmetrical along the oblique 45-degree direction.

[0030] Preferably, in the above-mentioned chamfered narrow copper plate of the crystallizer, the first chamfer distance H1 and the second chamfer distance H2 of the chamfered area 2 are equal, that is, |H1-H2|=0, thereby making the arc of the chamfered area 2 symmetrical along the oblique 45-degree direction.

[0031] The rounded crystallizer narrow copper plate of the present invention is described in detail below in conjunction with the embodiments.

[0032] Example 1

[0033] The rounded crystallizer narrow copper plate provided in Example 1 of the present invention is mainly used for the continuous casting production of ingots with a thickness of 200 mm and a width ranging from 1000 to 2000 mm. The casting machine is a straight arc casting machine. The narrow copper plate is used in conjunction with a parallel plate wide copper plate, and the height of the copper plate is 900 mm.

[0034] like Figure 3 Shown and referenced Figure 1 and Figure 2 The working surface of the narrow copper plate of the chamfered crystallizer in Example 1 includes a flat area 1 and a chamfered area 2. The flat area 1 is located in the middle of the copper plate, and the width L is 146 mm. The chamfered area 2 is located on both sides of the copper plate. The arc radius R of the chamfered area 2 is 60 mm. The first chamfer distance H1 along the horizontal direction and the second chamfer distance H2 along the height direction are both 30 mm, so that the arc of the chamfered area 2 is symmetrical along the oblique 45-degree direction.

[0035] The plane area 1 and the rounded corner areas 2 on both sides are smoothly connected by connecting arcs 6, and the arc radius of the connecting arc 6 is 10 mm.

[0036] A flat area cooling water groove 3 and a chamfered area cooling water groove 4 are provided on the back of the narrow copper plate of the chamfered crystallizer. The flat area cooling water groove 3 is perpendicular to the back of the copper plate, with a width W3 of 5 mm and a depth D3 of 20 mm; the chamfered area cooling water groove 4 forms an angle θ of 88 degrees with the back of the copper plate, with a width W4 of 6 mm and a depth D4 of 30 mm.

[0037] In order to further enhance the cooling effect of the corners, two cooling water holes 5 are respectively opened on both sides of the copper plate near the rounded corner area 2, and the diameter Φ of the cooling water hole 5 is 8 mm.

[0038] Example 2

[0039] A steel plant used the rounded narrow copper plate of the crystallizer in Example 1 of the present invention when continuously casting 430 ingots with a specification of 200mm*1235mm. The cooling water flow rate of the wide copper plate of the crystallizer was 4500L / min, the cooling water flow rate of the narrow copper plate was 580L / min, the water flow rate on the side of the crystallizer was 150L / min, the crystallizer taper was 1.0%, and the pulling speed was 1.25m / min.

[0040] The actual production test of Example 2 proves that through the application of the narrow copper plate of the chamfered crystallizer of the present invention, the cast continuous casting slab with rounded corners has no surface and internal quality problems. After hot rolling and pickling, the hot coil thickness is 3.0 mm. The rollover defects at four positions on both sides and the upper and lower surfaces of the hot coil are checked. It is found that the rollover defects on one side of the upper and lower surfaces have completely disappeared, and only two slight and intermittent rollover defects appear on the other side of the lower surface. The rollover defects are about 10 mm away from the edge. The overall rollover defects are greatly improved compared with the conventional process.

[0041] Example 3

[0042] A steel plant used the rounded narrow copper plate of the crystallizer in Example 1 of the present invention when continuously casting 200mm*1075mm 304 ingots. The cooling water flow rate of the wide copper plate of the crystallizer was 4200L / min, the cooling water flow rate of the narrow copper plate was 500L / min, the water flow rate of the crystallizer side was 150L / min, the crystallizer taper was 1.3%, and the pulling speed was 1.30m / min.

[0043] The actual production test of Example 3 proves that through the application of the narrow copper plate of the chamfered crystallizer of the present invention, the cast continuous casting slab with rounded corners has no surface and internal quality problems. After hot rolling and pickling, the thickness of the hot coil is 2.8 mm. The rollover defects at four positions on both sides and the upper and lower surfaces of the hot coil are checked. Only three slight and intermittent rollover defects appear on one side of the lower surface. The distance between the rollover defects and the edge is about 5 mm. The overall rollover defects are greatly improved compared with the conventional process.

[0044] In summary, by applying the rounded crystallizer narrow copper plate provided by the present invention, the rounded ingot obtained by continuous casting changes the force distribution on the narrow side during the hot rolling rough rolling process, so that the metal wrinkles on the narrow side become shallower, and there will be no serious staggering between the wrinkles. Even if it is subsequently flattened to the wide surface to form a rollover defect, combined with the widening effect and pickling effect of subsequent fine rolling, the rollover defect will be flattened and pickled away, so that the overall rollover defect is greatly improved or even eliminated, significantly improving the metal yield of the product and reducing the production cost of the steel plant. Moreover, the rounded crystallizer narrow copper plate of the present invention can be applied on the basis of the conventional continuous casting process, with small changes in process and equipment and low cost of upgrading and transformation.

[0045] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, the orientation or position relationship indicated by the terms "front", "back", "left", "right", "horizontal direction", "height direction", "length", "width", "thickness", "depth" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of description and simplified description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rounded crystallizer narrow copper plate, characterized in that: The working surface of the narrow copper plate of the chamfered crystallizer in contact with the molten steel includes a plane area located in the middle of the copper plate and two chamfered areas located on both sides of the copper plate. The plane area is connected to the chamfered areas on both sides. The first chamfer distance H1 along the horizontal direction and the second chamfer distance H2 along the height direction of the chamfered area are both 30 to 40 mm, and |H1-H2|≤5 mm. The arc radius of the chamfered area is 40 to 70 mm.

2. The rounded crystallizer narrow copper plate according to claim 1, characterized in that: The plane area and the rounded corner areas on both sides are smoothly connected through a connecting arc, and the arc radius of the connecting arc is 5 to 15 mm.

3. The rounded crystallizer narrow copper plate according to claim 1, characterized in that: The back of the narrow copper plate of the chamfered crystallizer opposite to the working surface is provided with a flat area cooling water trough and a chamfered area cooling water trough, the flat area cooling water trough is perpendicular to the back of the copper plate, and the chamfered area cooling water trough forms an angle of 80 to 89 degrees with the back of the copper plate.

4. The rounded crystallizer narrow copper plate according to claim 3, characterized in that: The width of the cooling water groove in the plane area is 4-6 mm, and the depth is 18-25 mm; the width of the cooling water groove in the chamfered corner area is 4-8 mm, and the depth is 25-35 mm.

5. The rounded crystallizer narrow copper plate according to claim 3, characterized in that: A plurality of cooling water holes are arranged on both sides of the copper plate near the rounded corners, and the diameter of the cooling water holes is 7 to 10 mm.

6. The rounded mold narrow copper plate according to any one of claims 1 to 5, characterized in that: The first chamfer distance H1 and the second chamfer distance H2 of the chamfered corner area are equal, that is, |H1-H2|=0, and the arc of the chamfered corner area is symmetrical along the oblique 45-degree direction.

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