CN114535310A - Method for controlling shape of low-carbon bainite steel - Google Patents
Method for controlling shape of low-carbon bainite steel Download PDFInfo
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- CN114535310A CN114535310A CN202210182759.0A CN202210182759A CN114535310A CN 114535310 A CN114535310 A CN 114535310A CN 202210182759 A CN202210182759 A CN 202210182759A CN 114535310 A CN114535310 A CN 114535310A
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- carbon bainite
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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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Abstract
A method for controlling the shape of low-carbon bainite steel aims to solve the problems of high cold straightening rate and low shape qualification rate of the existing low-carbon bainite steel in the production process of medium plates. According to the invention, the plate shape is accurately improved from the aspects of casting blank heating uniformity, finish rolling plate shape control, pre-straightening force, Mulpic head and tail shielding edge shielding, hot straightening force and the like, the cold straightening rate of the low-carbon bainite steel is ensured to be lower than 2%, the process cost is reduced, the plate shape saving cost is reduced, and the unevenness of the low-carbon bainite steel is controlled within 3 mm/m.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and relates to a method for controlling the shape of a low-carbon bainite steel plate.
Background
The shape control is an important index for measuring the production level of the medium plate, and the good shape control can improve the qualification rate and the yield of the steel plate. Under the current severe steel market situation, the control level of the shape of the steel plate is improved, and the defects of the shape of the steel plate are reduced, so that the method is an important means for reducing the production cost of enterprises and improving the competitiveness of the enterprises. With the rapid development of medium plates, the technologies of controlled cooling after rolling, on-line quenching and ultra-fast cooling are effectively popularized and applied, and low-carbon bainite steel becomes an inevitable development trend of the steel industry. Due to the fact that the ultra-fast cooling control parameters are more, various factors comprehensively influence the ultra-fast cooling control parameters, the cooling along the longitudinal direction, the transverse direction and the thickness direction of the steel plate cannot achieve the expected effect, complex thermal stress change is caused, and the problem of plate shape defects formed on the steel plate is finally shown.
The low-carbon bainite steel belongs to medium-temperature transformation steel, the final cooling temperature is generally lower than 550 ℃, the cooling speed is higher, and the low-carbon bainite steel has internal stress after certain cooling and mainly has three problems: firstly, the head and tail deformation resistances of the low-carbon bainite steel after rolling are different, the head and tail plate shapes of the steel plate mother plate are deteriorated, and the plate shape defects are larger for a production line which is not provided with a pre-straightening machine; secondly, the final cooling temperature of the low-carbon bainite steel is low, the internal stress of the steel plate is complex and difficult to control, and the plate shape defects of convex, concave, raised head and tail, pot shape and the like appear after cooling; thirdly, when the online quenching temperature is reduced to be below 200 ℃, the hot straightener can not be used for straightening, all plate-shaped defects can only be rescued or changed in size through heat treatment, the production cost is seriously improved, and the yield is reduced.
The low-carbon bainite steel produced by the prior art of medium plate factories is mainly improved in hot-rolled plate shape by controlling the modes of finish rolling, roll bending, roller stringing, cooling water proportioning, straightening and the like, and the method is single. The existing low-carbon bainite steel plate shape control level can not meet the requirement of rapid development of the manufacturing industry, for example, the unevenness requirement of steel for bridge structures is controlled within 3mm/1 m. Therefore, a new production process is needed to improve the control level of the shape of the low-carbon bainite steel plate.
Disclosure of Invention
The invention aims to provide a method for controlling the shape of low-carbon bainite steel, which aims to solve the problems of high cold straightening rate and low shape qualification rate of the existing low-carbon bainite steel in the production process of medium plates. The technical scheme of the invention is as follows:
a method for controlling the shape of a low-carbon bainite steel plate comprises the following process steps:
(1) controlling a hearth of the heating furnace: the temperature difference between the upper part and the lower part of the hearth is controlled to be 20-40 ℃, and the temperature of the upper hearth is 10-20 ℃ higher than that of the lower hearth;
(2) the rolling force of the final pass of finish rolling is less than or equal to 50000kN, the last pass adopts high-pressure water of a rack to remove phosphorus, and the rolling speed is less than or equal to 4.5 m/s;
(3) after rolling, passing through a pre-straightening machine, wherein the straightening force is 20000-25000 kN, and the straightening speed is 1.0-2.0 m/s;
(4) the head and tail shielding is started for 1-3 groups, and the edge shielding is 20-40 mm;
(5) and (3) thermal straightening control: and (3) straightening the head and the tail of the mother board at 0-500 mm at a low speed, wherein the straightening speed is 0.5-1.5 m/s, and the straightening force of the hot straightening is 35000-45000 kN.
The invention has the following effects: according to the invention, the plate shape is accurately improved from the aspects of casting blank heating uniformity, finish rolling plate shape control, pre-straightening force, Mulpic head and tail shielding edge shielding, hot straightening force and the like, the cold straightening rate of the low-carbon bainite steel is ensured to be lower than 2%, the process cost is reduced, the plate shape saving cost is reduced, and the unevenness of the low-carbon bainite steel is controlled within 3 mm/m. The production method is simple, saves the process cost, has good plate shape, and is suitable for mass production.
Detailed Description
The present invention will be further described with reference to the following examples.
The first embodiment is as follows:
the method for controlling the plate shape of the 17.5mm low-carbon bainite steel pipeline steel L485M comprises the following process steps:
(1) controlling a hearth of the heating furnace: the temperature difference between the upper part and the lower part of the hearth is controlled to be 35 ℃, and the temperature of the upper hearth is 16 ℃ higher than that of the lower hearth;
(2) the final pass of finish rolling has the rolling force of 42000kN, and the final pass adopts high-pressure water of a frame to remove phosphorus, and the rolling speed is 4.2 m/s;
(3) after rolling, passing through a pre-straightening machine, and straightening force: 22000kN, and the straightening speed is 1.6 m/s;
(4) the head and tail are shielded and opened for 2 groups, and the edge part is shielded by 25 mm;
(5) and (3) controlling thermal straightening: and the head and the tail of the mother board are straightened at 350mm by adopting low speed, the straightening speed is 0.8m/s, and the straightening force of hot straightening is 38000 KN.
The product quality detection result is as follows: : the cold straightening rate is only 0.56 percent, and the unevenness of the steel plate is 2 mm/m.
The second embodiment:
the plate shape control method of the steel Q500qE for the 12mm low-carbon bainite steel bridge structure comprises the following process steps:
(1) controlling a hearth of the heating furnace: the temperature difference between the upper part and the lower part of the hearth is controlled to be 32 ℃, and the temperature of the upper hearth is 17 ℃ higher than that of the lower hearth;
(2) the final pass of finish rolling has the rolling force of 41500kN, and the final pass adopts high-pressure water of a frame to remove phosphorus, and the rolling speed is 4.0 m/s;
(3) after rolling, passing through a pre-straightening machine, and straightening force: 23000kN, straightening speed 1.2 m/s;
(4) the head and tail are shielded and opened by 3 groups, and the edge part is shielded by 36 mm;
(5) and (3) thermal straightening control: the head and the tail of the mother board are straightened at low speed of 450mm, the straightening speed is 0.8m/s, and the straightening force of the hot straightening is 43500 kN.
The product quality detection result is as follows: the cold straightening rate is only 1.1 percent, and the unevenness of the steel plate is 2.5 mm/m.
Claims (1)
1. A method for controlling the shape of a low-carbon bainite steel plate is characterized by comprising the following process steps:
(1) controlling a hearth of the heating furnace: the temperature difference between the upper part and the lower part of the hearth is controlled to be 20-40 ℃, and the temperature of the upper hearth is 10-20 ℃ higher than that of the lower hearth;
(2) the rolling force of the final pass of finish rolling is less than or equal to 50000kN, the last pass adopts high-pressure water of a rack to remove phosphorus, and the rolling speed is less than or equal to 4.5 m/s;
(3) after rolling, passing through a pre-straightening machine, wherein the straightening force is 20000-25000 kN, and the straightening speed is 1.0-2.0 m/s;
(4) the head and tail shielding is started for 1-3 groups, and the edge shielding is 20-40 mm;
(5) and (3) thermal straightening control: and (3) straightening the head and the tail of the mother board at 0-500 mm at a low speed, wherein the straightening speed is 0.5-1.5 m/s, and the straightening force of the hot straightening is 35000-45000 kN.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210182759.0A CN114535310B (en) | 2022-02-27 | 2022-02-27 | Plate shape control method for low-carbon bainite steel |
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| CN202210182759.0A CN114535310B (en) | 2022-02-27 | 2022-02-27 | Plate shape control method for low-carbon bainite steel |
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| CN114535310A true CN114535310A (en) | 2022-05-27 |
| CN114535310B CN114535310B (en) | 2023-07-14 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101086051A (en) * | 2007-07-12 | 2007-12-12 | 济南钢铁股份有限公司 | Non-tempering easy-welding super strong steel and its production method |
| CN101096738A (en) * | 2006-06-26 | 2008-01-02 | 舞阳钢铁有限责任公司 | Steel plate with low welding crack sensitivity and production method thereof |
| CN105057402A (en) * | 2015-07-17 | 2015-11-18 | 河北钢铁股份有限公司邯郸分公司 | Hot straightening method for low-carbon bainite steel plate with thickness of 25 mm |
| CN107058898A (en) * | 2017-03-31 | 2017-08-18 | 河钢股份有限公司邯郸分公司 | A kind of Q690D low-carbon bainite steels and its production method |
| CN108296285A (en) * | 2018-02-01 | 2018-07-20 | 湖南华菱湘潭钢铁有限公司 | A kind of milling method of ultralow-carbon bainite steel plate |
-
2022
- 2022-02-27 CN CN202210182759.0A patent/CN114535310B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101096738A (en) * | 2006-06-26 | 2008-01-02 | 舞阳钢铁有限责任公司 | Steel plate with low welding crack sensitivity and production method thereof |
| CN101086051A (en) * | 2007-07-12 | 2007-12-12 | 济南钢铁股份有限公司 | Non-tempering easy-welding super strong steel and its production method |
| CN105057402A (en) * | 2015-07-17 | 2015-11-18 | 河北钢铁股份有限公司邯郸分公司 | Hot straightening method for low-carbon bainite steel plate with thickness of 25 mm |
| CN107058898A (en) * | 2017-03-31 | 2017-08-18 | 河钢股份有限公司邯郸分公司 | A kind of Q690D low-carbon bainite steels and its production method |
| CN108296285A (en) * | 2018-02-01 | 2018-07-20 | 湖南华菱湘潭钢铁有限公司 | A kind of milling method of ultralow-carbon bainite steel plate |
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