CN109663818B - Method for eliminating cracks generated in steel plate rolling process - Google Patents
Method for eliminating cracks generated in steel plate rolling process Download PDFInfo
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- CN109663818B CN109663818B CN201811377262.4A CN201811377262A CN109663818B CN 109663818 B CN109663818 B CN 109663818B CN 201811377262 A CN201811377262 A CN 201811377262A CN 109663818 B CN109663818 B CN 109663818B
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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
- B21B37/28—Control of flatness or profile during rolling of strip, sheets or plates
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Abstract
The invention discloses a method for eliminating cracks generated in a steel plate rolling process, which is particularly suitable for producing a steel plate with the thickness of 15-30 mm. By reasonably setting parameters such as biting speed, rolling process and the like, and combining reasonable pass load distribution, improved descaling method and the like, the generation of cracks of the steel plate in the rolling process is effectively eliminated, and the yield of the steel plate is improved by about 1%.
Description
Technical Field
The invention relates to the technical field of material processing, in particular to a method for eliminating cracks generated in a steel plate rolling process.
Background
The quantity of medium plate steel produced by a wide and thick plate rolling mill is getting larger and larger at present, and the medium plate is widely applied to various fields of national economic construction. The medium plate has a large thickness, so that the compression ratio is small during production, various defects often appear on the surface, and the occupied amount of cracks is the largest among the various surface defects. The crack of the medium steel plate is generally generated from two sources, one is that the plate blank has cracks, and the cracks on the surface of the plate blank cannot be completely rolled and welded during rolling due to a small compression ratio during rolling, so that the cracks appear on the surface of the rolled steel plate; secondly, cracks appear on the surface of the rolled steel plate due to improper process parameter setting or operation in the heating and rolling processes. At present, various documents generally research more slab cracks and solve more methods, while related reports on cracks of steel plates in the rolling process are less, and reports on solving methods are more rare. The cracks generated by the steel plate in the rolling process are large in width and deep in depth, and the steel plate cannot be repaired through polishing generally and can only be solved by cutting off defective parts. This results in a short steel sheet, failure to deliver the contract, and a reduction in the yield of the steel sheet.
The 'production method for eliminating edge defects of hot rolled strip' of patent publication No. CN102101124A provides a method for eliminating edge cracks of hot rolled strip. The method can effectively eliminate the edge defect problem which often occurs in the process of producing Nb-containing steel in the medium and thin slab continuous casting and rolling production line by optimally controlling the whole process. But the method is suitable for the production of medium and thin slab continuous casting and rolling steel strips, is not suitable for the production of wide and thick plates, and does not relate to steel plate cracks generated in the rolling process.
The patent publication "CN 102909333A" an apparatus and method for reducing transverse cracks at the corners of a cast slab "provides a method for controlling transverse cracks at the corners of a cast slab, which is effective in reducing transverse cracks at the corners of a cast slab. But does not relate to cracks generated in the steel plate rolling process.
The patent publication No. CN103008594A 'a method for solving transverse corner cracks of an extra-thick continuous casting billet' provides a method for solving the transverse corner cracks of the extra-thick continuous casting billet, and the transverse corner cracks of the extra-thick continuous casting billet can be effectively controlled. But the method does not relate to how to control the generation of cracks in the steel plate during the rolling process.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a method for eliminating cracks generated in the rolling process of a steel plate, which is particularly suitable for producing the steel plate with the thickness of 15-30 mm.
In order to solve the technical problems, the invention adopts the following technical scheme:
2. a method for eliminating cracks generated in the rolling process of a steel plate comprises the following steps:
s1, adopting idle pass as the last pass in the rough rolling stage, wherein the idle pass is an idle pass;
s2, rolling the plate blank in the rough rolling stage until the initial rolling thickness of the second stage of the steel plate, wherein the final rolling temperature in the rough rolling stage is more than 50 ℃ higher than the initial rolling temperature in the second stage;
s3, the initial rolling thickness of the finish rolling stage is 3-4 times of the thickness of a finished product, the finish rolling stage is used for rolling 8-10 passes, the biting speed of the first two passes of the finish rolling stage is 1.5-1.8 m/S, and the rolling speed is 4.5-5 m/S; the rolling reduction of the first two passes of the finish rolling stage is 10-12 mm, the initial rolling temperature of the finish rolling stage is 910-940 ℃, and the final rolling temperature is 810-830 ℃;
and S4, performing descaling treatment in the first two passes of the second-stage rolling.
Further, the dephosphorization in the step S4 uses a frame to descale.
Further, the descaling process in step S4 is reverse descaling, that is, the steel sheet is descaled by using a rear descaling device when being rolled from front to rear, and is descaled by using a front descaling device when being rolled from rear to front.
Further, the method is applied to producing the steel plate with the thickness of 15-30 mm.
When rolling a wide and thick plate with double stands, the first stage of rolling is generally completed by rough rolling, and the second stage of rolling is completed by finish rolling. And after the first-stage rolling is finished, the intermediate blank swings on a roller way between the rough rolling mill and the finish rolling mill to cool, and the second-stage rolling is started when the temperature is reduced to the second-stage rolling temperature. When the intermediate billet swings and is cooled, a layer of iron scale can be generated on the surface, and the iron scale is removed by spraying water by using a rack descaling device during finish rolling, so that the iron scale is prevented from being pressed into the surface of the steel plate to form a pit during rolling. The method is characterized in that a slab is subjected to head buckling when being rolled by a roughing mill, so that the rolled intermediate slab is subjected to wave generation frequently, in order to avoid pressing iron scales into a steel plate, descaling is performed when the first rolling of finish rolling is performed, descaling water can be gathered at the wave position when the first rolling of a finishing mill is performed, the surface temperature of the intermediate slab is low when the finish rolling starts to be rolled, the peak top of the wave is blackened, severe cracks appear at the peak top of the wave due to low temperature and poor plasticity during rolling, the depth of the cracks is deep, the width is wide, and the thickness of the steel plate after being polished exceeds a standard, so that the steel plate is scrapped. Therefore, the problem of the cracking due to the poor shape and the descaling of the intermediate slab is solved from the aspects of the biting speed and the descaling method at the finish rolling. The faster biting speed and rolling speed are adopted to reduce the contact time of the steel plate and the descaling water and reduce the temperature drop of the surface of the steel plate. The rolling of the previous pass is finished, when the rolling of the next pass is started, a pass interval time exists in the middle, if reverse removal is adopted, even if the wave appears on the surface of the steel plate and is poured black, the steel plate can turn red in the time, the surface temperature is raised, the plasticity is recovered, and therefore cracks can not appear during the rolling again. Because the first two passes of finish rolling are descaled, the first two passes adopt smaller reduction amount which is used for controlling the rolling plate shape, so that the rolled steel plate is straight without wave, thus the descaling of the first two passes has uniform temperature on the surface of the steel plate and no low-temperature area, and no crack appears during rolling.
Compared with the prior art, the invention has the beneficial technical effects that:
1. the method can effectively eliminate the generation of cracks in the rolling process of the wide and thick plate;
2. the method does not need to add other equipment, does not need to add operators, does not need additional investment, and is easy to realize in actual production;
3. the method is simple to operate, is easy to realize in field production operation, and is convenient to popularize and apply.
Detailed Description
The present invention is further described below with reference to examples.
Example 1
Rolling a finished product of a steel plate with the thickness of 15mm, wherein the last pass of the rough rolling stage is an idle pass; the thickness of the plate blank in the rough rolling stage is rolled until the initial rolling thickness in the second stage is 60mm, and the final rolling temperature in the rough rolling stage is 990 ℃. The initial rolling thickness of the steel plate in the second stage is 60mm, the steel plate is rolled for 8 passes in the second stage, the biting speed of the first two passes in the second stage is 1.8m/s, and the rolling speed is 5 m/s; the reduction in the first two passes of the second stage was 10 mm. The second stage is at the beginning rolling temperature of 940 ℃ and the finishing rolling temperature of 830 ℃. And the first two passes of the second stage of rolling use a rack for descaling, and the descaling mode adopts reverse descaling, namely a steel plate is descaled by using a rear descaling device when being rolled from the front to the rear of the machine, and is descaled by using a front descaling device when being rolled from the rear to the front of the machine. The rolled steel plate has good surface quality and no cracks.
Example 2
Rolling a finished product of a steel plate with the thickness of 30mm, wherein the last pass of the rough rolling stage is an idle pass; the thickness of the plate blank in the rough rolling stage is rolled until the initial rolling thickness in the second stage is 90mm, and the final rolling temperature in the rough rolling stage is 1102 ℃. The initial rolling thickness of the steel plate in the second stage is 90mm, the steel plate is rolled for 10 passes in the second stage, the biting speed of the first two passes in the second stage is 1.5m/s, and the rolling speed is 4.5 m/s; the reduction in the first two passes of the second stage was 12 mm. The second stage rolling temperature is 910 ℃, and the finishing temperature is 810 ℃. And the first two passes of the second stage of rolling use a rack for descaling, and the descaling mode adopts reverse descaling, namely a steel plate is descaled by using a rear descaling device when being rolled from the front to the rear of the machine, and is descaled by using a front descaling device when being rolled from the rear to the front of the machine. The rolled steel plate has good surface quality and no cracks.
Example 3
Rolling a finished product of a steel plate with the thickness of 22mm, wherein the last pass of the rough rolling stage is an idle pass; the thickness of the plate blank in the rough rolling stage is rolled until the initial rolling thickness in the second stage is 77mm, and the final rolling temperature in the rough rolling stage is 1089 ℃. The initial rolling thickness of the steel plate in the second stage is 77mm, 9 passes are rolled in the second stage, the biting speed of the first two passes in the second stage is 1.6m/s, and the rolling speed is 4.8 m/s; the reduction in the first two passes of the second stage was 11 mm. The initial rolling temperature of the second stage is 915 ℃, and the final rolling temperature is 817 ℃. And the first two passes of the second stage of rolling use a rack for descaling, and the descaling mode adopts reverse descaling, namely a steel plate is descaled by using a rear descaling device when being rolled from the front to the rear of the machine, and is descaled by using a front descaling device when being rolled from the rear to the front of the machine. The rolled steel plate has good surface quality and no cracks.
Example 4
Rolling a finished product of a steel plate with the thickness of 20mm, wherein the last pass of the rough rolling stage is an idle pass; the thickness of the plate blank in the rough rolling stage is rolled until the initial rolling thickness in the second stage is 68mm, and the final rolling temperature in the rough rolling stage is 1077 ℃. The initial rolling thickness of the steel plate in the second stage is 68mm, 9 passes are rolled in the second stage, the biting speed of the first two passes in the second stage is 1.7m/s, and the rolling speed is 4.7 m/s; the reduction in the first two passes of the second stage was 11.5 mm. The second stage rolling temperature is 920 ℃ and the final rolling temperature is 821 ℃. And the first two passes of the second stage of rolling use a rack for descaling, and the descaling mode adopts reverse descaling, namely a steel plate is descaled by using a rear descaling device when being rolled from the front to the rear of the machine, and is descaled by using a front descaling device when being rolled from the rear to the front of the machine. The rolled steel plate has good surface quality and no cracks.
After the invention is used, the generation of cracks in the rolling process of the wide and thick plate is eliminated, the yield of the steel plate is greatly improved by about 1 percent compared with that before the implementation, and the effect is very obvious.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (1)
1. A method for eliminating cracks generated in the steel plate rolling process is characterized in that a rolled finished steel plate with the thickness of 15mm is obtained, and the last pass of a rough rolling stage is an idle pass; rolling the plate blank until the initial rolling thickness of the second stage is 60mm in the rough rolling stage, wherein the final rolling temperature of the rough rolling stage is 990 ℃; the initial rolling thickness of the steel plate in the second stage is 60mm, the steel plate is rolled for 8 passes in the second stage, the biting speed of the first two passes in the second stage is 1.8m/s, and the rolling speed is 5 m/s; the rolling reduction of the first two passes of the second stage is 10 mm; the second stage is at the beginning rolling temperature of 940 ℃ and the finishing rolling temperature of 830 ℃; and the first two passes of the second stage of rolling use a rack for descaling, and the descaling mode adopts reverse descaling, namely a steel plate is descaled by using a rear descaling device when being rolled from the front to the rear of the machine, and is descaled by using a front descaling device when being rolled from the rear to the front of the machine.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811377262.4A CN109663818B (en) | 2018-11-19 | 2018-11-19 | Method for eliminating cracks generated in steel plate rolling process |
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| CN201811377262.4A CN109663818B (en) | 2018-11-19 | 2018-11-19 | Method for eliminating cracks generated in steel plate rolling process |
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| CN109663818B true CN109663818B (en) | 2021-03-02 |
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Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1034217A (en) * | 1996-07-18 | 1998-02-10 | Nisshin Steel Co Ltd | Arithmetic and control method of forward slip and backward slip in hot rolling mill |
| CN102101124B (en) * | 2009-12-22 | 2014-05-07 | 鞍钢股份有限公司 | Production method for eliminating edge defects of hot-rolled strip steel |
| CN101947549A (en) * | 2010-09-10 | 2011-01-19 | 山东泰山钢铁集团有限公司 | Production technology for inhibiting nickel-saving austenitic stainless steel hot-rolled plate edge crack |
| CN103624088B (en) * | 2013-11-29 | 2015-11-18 | 内蒙古包钢钢联股份有限公司 | Eliminate the method for steel plate tail transverse crack |
| CN106148846B (en) * | 2016-08-19 | 2017-10-31 | 山东钢铁股份有限公司 | A kind of thick-specification high-tenacity X80 pipe fitting steel steel plates and manufacture method |
| CN106987773B (en) * | 2017-05-05 | 2019-02-12 | 内蒙古包钢钢联股份有限公司 | A kind of high strength steel plate and its board-shape control method |
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