CN109604338B - Manufacturing method for reducing width of hairline defect at edge of hot-rolled pipeline steel - Google Patents
Manufacturing method for reducing width of hairline defect at edge of hot-rolled pipeline steel Download PDFInfo
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- CN109604338B CN109604338B CN201811542049.4A CN201811542049A CN109604338B CN 109604338 B CN109604338 B CN 109604338B CN 201811542049 A CN201811542049 A CN 201811542049A CN 109604338 B CN109604338 B CN 109604338B
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- 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
- B21B1/46—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 metal immediately subsequent to continuous casting
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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
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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
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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
- B21B37/76—Cooling control on the run-out table
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B41/00—Guiding, conveying, or accumulating easily-flexible work, e.g. wire, sheet metal bands, in loops or curves; Loop lifters
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
- B21B45/08—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing hydraulically
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Abstract
The invention discloses a manufacturing method for reducing the width of hairline defects at the edge of hot-rolled pipeline steel, which comprises the following steps: adopting a continuous casting billet with an edge part in a blunt angle shape; heating the continuous casting billet to a target heating temperature; discharging the continuous casting billet and descaling; carrying out fixed-width side pressing on the continuous casting billet; carrying out multi-pass rough rolling on the continuous casting billet, and covering and preserving heat after rough rolling; finish rolling of the continuous casting billet; cooling the continuous casting billet to a target cooling temperature; and rolling the manufactured strip steel into a steel coil. The invention has the beneficial effects that: the width of the hot-rolled pipeline steel edge hairline can be obviously reduced, the product quality problem caused by the edge hairline can be basically eliminated, and the yield and the production efficiency of downstream users are improved.
Description
Technical Field
The invention belongs to the technical field of surface treatment of hot-rolled pipeline steel products, and particularly relates to a manufacturing method for reducing the width of hairline defects at the edge of hot-rolled pipeline steel.
Background
The hot-rolled pipeline steel plate coil is widely used for petroleum and natural gas transmission, is a basic project of national energy artery, is generally delivered by a hot-rolled raw coil, and is manufactured by a downstream user in a spiral submerged arc welding mode, the edge part hairline of the hot-rolled pipeline steel produced by the conventional process is generally wide (10-25 mm), so that the cutting amount is increased or the hairline cannot be removed by the downstream user in the using process, on one hand, the using difficulty of the client is increased, the yield is reduced, and the cost is increased; on the other hand, the product quality problem caused by hairline defects can be judged to be useless, and even serious safety accidents such as pipeline explosion and the like can be caused. Therefore, the reduction of the hairline width has important significance for improving the product yield and the product quality and ensuring the service safety of the product.
It is believed that the reasons for the generation of the hair lines are mainly caused by the fact that the temperature of the steel strip edge is low due to two-dimensional heat transfer during rolling, the plasticity is poor, and the part of the steel strip edge in the thickness direction is partially flattened to the surface of the steel plate during the metal rolling process, and a schematic diagram is shown in fig. 1. Therefore, the width of the hairline at the edge of the hot-rolled strip steel is reduced mainly from two aspects: 1) reducing the total compression ratio from the casting blank to a finished product; 2) the characteristic of large temperature drop at the edge part in the strip steel rolling process is improved, and more metal in the thickness direction of the casting blank is promoted to flow to the rolling direction.
Through retrieval, prior to the application of the invention, Chinese patent with application publication number CN 107096795A discloses a manufacturing method for reducing edge defects of hot-rolled strip steel. The method only changes the method for optimizing rough rolling load distribution and reducing vertical roll cooling water, reduces edge temperature drop to reduce edge defects, and is seen from the implementation effect: the edge defect judgment amount is only reduced by 60%, and the defect reduction degree is not specifically quantified, so that the aim of effectively controlling the edge hairline defect cannot be achieved. In addition, the chinese patent with application publication No. CN 106734370a discloses a method for preventing edge portions of a wide-specification steel plate from being folded, which is to adopt a liquefied gas spray gun to perform chamfering cleaning for the steel plate with a width-to-width ratio (finished product width/casting blank width) of not less than 1.5 in the rolling of the wide and thick plate, on one hand, the method is only suitable for the production of the wide plate (the width-to-width ratio of hot-rolled strip steel is not more than 1.0), and on the other hand, manual cleaning is adopted, so that the efficiency is low, the labor cost is high, and the working environment is severe.
Disclosure of Invention
The invention aims to provide a method for reducing the width of the hairline defect at the edge of hot-rolled pipeline steel, which can control the hairline width to be less than 5mm in order to overcome the defects of the prior art.
The technical scheme adopted by the invention is as follows: a manufacturing method for reducing the width of the hairline defect at the edge of hot-rolled pipeline steel comprises the following steps:
step one, adopting a continuous casting blank with an edge part in a shape of a blunt horn;
step two, heating the continuous casting billet to a target heating temperature;
step three, discharging the continuous casting billet and descaling;
step four, performing fixed-width side pressing on the continuous casting billet;
step five, performing multi-pass rough rolling on the continuous casting billet, and covering and preserving heat after rough rolling;
step six, finish rolling of the continuous casting billet;
and step seven, cooling the continuous casting slab to a target cooling temperature of 500-600 ℃.
Step eight, rolling the manufactured strip steel into a steel coil.
According to above-mentioned scheme, in step one, the obtuse angle of continuous casting billet limit portion is 125~ 135.
According to the scheme, in the third step, the two side parts of the continuous casting billet are shielded while the continuous casting billet is descaled.
According to the scheme, the arc width fixing machine is adopted for fixing the width, and the unilateral side pressure of the arc width fixing machine on the continuous casting billet is less than 20 mm.
According to the scheme, in the fifth step, the total compression ratio of rough rolling is less than 70 percent
According to the scheme, in the step five, 7-pass reversible rolling is adopted, wherein descaling water is removed during 1 st, 3 rd, 5 th and 7 th passes of rolling, and the reduction ratios of the passes are respectively 30%, 25%, 15%, 10%, 8% and 4% of the total reduction ratio of rough rolling.
According to the scheme, in the sixth step, a 7-stand finishing mill is adopted for finish rolling, wherein the loop tension of the front 4 stands is 4-8 MPa.
According to the scheme, in the second step, the target heating temperature is 1210-1250 ℃.
According to the scheme, in the seventh step, the target cooling temperature is 500-600 ℃.
The invention has the beneficial effects that:
1) the width of the edge hairline of the hot-rolled pipeline steel can be obviously reduced, the product quality problem caused by the edge hairline can be basically eliminated, and the yield and the production efficiency of downstream users are improved;
2) the whole process adopts mechanical control, the additional labor cost is not increased, the working environment is good, and the product quality is stable;
3) the existing production process and control method are not changed, and the method is suitable for large-scale stable production;
drawings
FIG. 1 is a schematic diagram showing a mechanism of generating an edge hairline of a conventional hot rolled strip.
FIG. 2 is a schematic view of the obtuse angle slab of the present invention.
FIG. 3 is a schematic view of the arc-shaped constant width press of the present invention.
Detailed Description
For a better understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
A manufacturing method for reducing the width of the hairline defect at the edge of hot-rolled pipeline steel specifically comprises the following steps:
step one, changing the shape of the edge of a continuous casting blank from a right-angle shape into an obtuse-angle shape by adopting an arc continuous casting blank, wherein the obtuse angle is 125-135 degrees, as shown in figure 2; meanwhile, the width of the continuous casting billet is ensured to exceed the width of the finished strip steel by 50 mm;
step two, heating the continuous casting slab to a target heating temperature by using a walking beam type heating furnace, wherein the temperature is 1210-1250 ℃;
thirdly, removing scale from the continuous casting billet out of the heating furnace, and shielding the edges on two sides of the continuous casting billet while removing the scale;
step four, performing fixed-width side pressing (specifically: H is more than or equal to H) on the continuous casting billet by using an arc-shaped fixed-width pressing machine, and simultaneously, enabling the unilateral side pressing quantity to be less than or equal to 20mm, as shown in figure 3;
step five, multi-pass rough rolling of the continuous casting slab: the rough rolling adopts multi-pass reversible rolling; in the embodiment, 7-pass rolling is adopted, wherein descaling water is started during the 1 st, 3 rd, 5 th and 7 th-pass rolling, and the total reduction ratio of rough rolling is less than or equal to 70%; the reduction ratios of the passes are respectively 30%, 25%, 15%, 10%, 8% and 4% of the total reduction ratio of the rough rolling. Covering and insulating the rough rolling by using a roller way insulating cover immediately;
step six, finish rolling of the continuous casting slab: after the tongues of the continuous casting slabs are cut off, the continuous casting slabs enter a multi-stand finishing mill for finish rolling, in the embodiment, a 7-stand finishing mill F1-F7 is adopted, wherein the loop tension F of the front 4 stands is 4-8 MPa;
step seven, cooling: and after finishing the finish rolling, cooling the continuous casting slab to a target temperature by adopting a laminar cooling system, wherein the temperature is 500-600 ℃.
And step eight, rolling the manufactured strip steel into a steel coil by adopting a coiler.
The working principle of the invention is as follows:
1) the shape of the edge of the continuous casting billet is changed from the traditional right-angle shape into the obtuse-angle shape, so that the radiating speed of the edge in the rolling process can be obviously reduced, the phenomenon that the deformation is uneven due to low surface temperature and poor plasticity of the edge to form wider flattening and widening is reduced, and the hairline width is reduced; meanwhile, the obtuse angle continuous casting blank is adopted to reduce the thickness of the edge part of the original casting blank, the total compression ratio is reduced, and the degree that the metal in the plate thickness direction is turned flat to the upper surface of the steel plate is obviously reduced;
2) after the slab is discharged from the furnace, the edge part belongs to a two-dimensional heat transfer area and is cooled at a high speed, so that the edge part is shielded in the descaling process, the temperature drop speed of the edge part can be effectively reduced, and the width of the hairline at the edge part of the strip steel is reduced;
3) the right-angle width fixing machine is replaced by the arc-shaped width fixing machine, the edge part of the obtuse-angle continuous casting billet is further pressed into a circular arc shape by mainly utilizing the chamfering function of an arc-shaped die, the heat dissipation speed in the subsequent rolling process is reduced, and the temperature of the edge part is improved; meanwhile, the side pressure of the fixed width is limited to be less than or equal to 20mm, if the side pressure is too large, the edge metal bulge is high, the thickness of the plate blank before rolling is increased, the flattening and widening degree is further intensified, and the hairline width of the strip steel is increased;
4) after the billet is rolled out, the heat preservation roller way is covered, and the temperature drop of the edge part in the traveling process of the billet is relieved;
5) the rough rolling adopts multiple passes, which is beneficial to the more metal in the plate thickness direction to flow to the rolling direction; the rough rolling total compression ratio is controlled to be below 70%, so that the problem that the temperature drop of the edge part in the rough rolling stage is large, if the total compression ratio is too large, metal in the thickness direction of a plate blank is more easily extended to the width direction in the rolling process, and the width of the finished product hairline is increased due to the fact that the metal is flattened and expanded; meanwhile, the rough rolling reduction distribution is adjusted to a high-temperature section, mainly because the temperature difference between the edge part and the center part is small, the metal is more easily promoted to flow towards the rolling direction. The thickness of the rough rolled intermediate slab is designed to be 58 to 60mm in order to retain as much metal in the thickness direction as possible to the finish rolling compression.
6) The loop tension of the front frames of the finishing mill is properly increased, and the flow resistance in the rolling direction is reduced by utilizing the tensile stress action of metal in the thickness direction during the rolling with the belt tension, so that the flattening and widening amount is reduced.
Examples 1 to 10 steel strips were produced using different continuous casting slabs and using two methods (the conventional production method and the production method according to the present invention), respectively, and the quality of the two steel strips was evaluated. The parameters of the continuous casting slab in each example are shown in table 1; the main process parameters in each example are shown in table 2.
TABLE 1 continuous casting slabs and finished products in the examples
| Examples | Width/mm of continuous casting billet | Thickness/mm of continuous casting slab | Shape of continuous casting billet | Finished product width/mm |
| 1 | 1250 | 230 | Obtuse angle | 1200 |
| 2 | 1300 | 230 | Obtuse angle | 1250 |
| 3 | 1400 | 230 | Obtuse angle | 1350 |
| 4 | 1650 | 230 | Obtuse angle | 1600 |
| 5 | 1600 | 230 | Obtuse angle | 1550 |
| 6 | 1800 | 230 | Obtuse angle | 1750 |
| 7 | 1350 | 230 | Obtuse angle | 1300 |
| 8 | 1500 | 230 | Obtuse angle | 1450 |
| 9 | 1600 | 230 | Obtuse angle | 1550 |
| 10 | 1400 | 230 | Obtuse angle | 1350 |
TABLE 2 Main Process parameters of the examples
TABLE 3 Effect of the examples
| Examples | Pre-hair line width/mm | After application-hairline width/mm |
| 1 | 15 | 3 |
| 2 | 16 | 3 |
| 3 | 12 | 2 |
| 4 | 13 | 1 |
| 5 | 10 | 0 |
| 6 | 15 | 2 |
| 7 | 18.5 | 3.5 |
| 8 | 19 | 4 |
| 9 | 18 | 4 |
| 10 | 20 | 5 |
The width of hairline of the steel strip obtained by the conventional method and the manufacturing method according to the present invention is shown in table 3. As can be seen from table 3, with the manufacturing method of the present invention, the width of the edge burr of the hot rolled line steel strip was greatly reduced, and the rate of quality variation was reduced from 9% to 0% (in 2017, the rate of quality variation due to the excessive width of the edge burr of the line steel occurred in the wu steel, which was 9.01%. after 2018, no quality problems due to this problem occurred). The method for reducing the width of hot rolled steel strip according to the present invention is applicable to all hot rolled steel strips and is not limited to the products listed in the examples.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the embodiments, it will be apparent to those skilled in the art that modifications can be made to the technical solutions described in the above-mentioned embodiments, or equivalent substitutions of some technical features, but any modifications, equivalents, improvements and the like within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims (3)
1. A manufacturing method for reducing the width of the hairline defect at the edge of hot-rolled pipeline steel is characterized by comprising the following steps:
step one, adopting a continuous casting blank with an obtuse angle at the edge part, wherein the obtuse angle of the edge part of the continuous casting blank is 125-135 degrees;
step two, heating the continuous casting billet to a target heating temperature;
step three, discharging the continuous casting blank for descaling, and shielding the edges on two sides of the continuous casting blank while descaling the continuous casting blank;
step four, performing fixed-width side pressing on the continuous casting billet, and adopting an arc-shaped fixed-width machine to fix the width, wherein the single-side pressing amount of the arc-shaped fixed-width machine on the continuous casting billet is less than 20 mm;
step five, performing multi-pass rough rolling on the continuous casting billet, and covering and preserving heat after rough rolling; the multi-pass rough rolling adopts 7-pass reversible rolling, wherein descaling water is used during the 1 st, 3 rd, 5 th and 7 th passes, and the reduction ratios of the passes are respectively 30%, 25%, 15%, 10%, 8% and 4% of the total reduction ratio of the rough rolling; the total compression ratio of rough rolling is less than 70 percent;
step six, finish rolling of the continuous casting billet;
step seven, cooling the continuous casting slab to a target cooling temperature of 500-600 ℃;
step eight, rolling the manufactured strip steel into a steel coil.
2. The manufacturing method for reducing the width of the flaw of the edge hairline of the hot rolled pipeline steel according to claim 1, wherein in the sixth step, the finish rolling is performed by using a 7-stand finishing mill, and wherein the loop tension of the first 4 stands is 4 to 8 MPa.
3. The manufacturing method for reducing the width of the hairline defect at the edge of the hot rolled pipeline steel as claimed in claim 1, wherein the target heating temperature in the second step is 1210-1250 ℃.
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| CN111633026B (en) * | 2020-05-21 | 2022-07-22 | 武汉钢铁有限公司 | Control method for reducing linear defects at edge of hot-rolled medium-high carbon alloy steel |
| CN111889510A (en) * | 2020-06-29 | 2020-11-06 | 山西太钢不锈钢股份有限公司 | Stainless steel strip production method for reducing side turn line width of hot rolled steel strip |
| CN112474801B (en) * | 2020-11-09 | 2022-05-17 | 江苏省沙钢钢铁研究院有限公司 | Wide and thick plate with small trimming loss and production method thereof |
| CN112496034B (en) * | 2020-11-30 | 2022-03-22 | 山西太钢不锈钢股份有限公司 | Method for reducing straight crack width of stainless steel strip edge |
| CN112958625B (en) * | 2021-01-28 | 2023-02-21 | 广西南南铝加工有限公司 | Preparation method of aluminum alloy ultra-wide plate |
| CN114669608A (en) * | 2022-03-31 | 2022-06-28 | 湖南华菱涟钢特种新材料有限公司 | A method for controlling edge defects of hot rolled medium and high carbon steel |
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| JPH06269841A (en) * | 1993-03-18 | 1994-09-27 | Sumitomo Metal Ind Ltd | Manufacture of hot rolled steel sheet excellent in surface properties |
| CN102699028B (en) * | 2012-02-24 | 2015-03-04 | 宝山钢铁股份有限公司 | Method for eliminating linear edge defects of hot-rolled low-carbon steel |
| CN103484643B (en) * | 2013-08-23 | 2015-04-15 | 安阳钢铁股份有限公司 | Method for preventing hot rolling edge fractures in oriented silicon steel |
| CN103831412B (en) * | 2014-02-26 | 2017-01-18 | 钢铁研究总院 | Production method for controlling straight crack defect of surface edge of medium-thick plate |
| CN207479193U (en) * | 2017-11-03 | 2018-06-12 | 南京净环热冶金工程有限公司 | A kind of constructional device of continuous casting blank temperature the Uniform Control |
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