CN117583386A - Rolling method of hot rolled patterned steel plate with extremely thin specification of 1.5mm - Google Patents
Rolling method of hot rolled patterned steel plate with extremely thin specification of 1.5mm Download PDFInfo
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- 238000005096 rolling process Methods 0.000 title claims abstract description 205
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 116
- 239000010959 steel Substances 0.000 title claims abstract description 116
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000001816 cooling Methods 0.000 claims abstract description 40
- 238000010438 heat treatment Methods 0.000 claims abstract description 31
- 238000005266 casting Methods 0.000 claims abstract description 18
- 229910000975 Carbon steel Inorganic materials 0.000 claims abstract description 6
- 239000010962 carbon steel Substances 0.000 claims abstract description 6
- 238000005452 bending Methods 0.000 claims abstract description 4
- 238000005098 hot rolling Methods 0.000 claims description 14
- 239000000498 cooling water Substances 0.000 claims description 10
- 238000005461 lubrication Methods 0.000 claims description 9
- 238000007599 discharging Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 15
- 238000004519 manufacturing process Methods 0.000 abstract description 12
- 230000002349 favourable effect Effects 0.000 abstract description 2
- 238000004321 preservation Methods 0.000 description 12
- 229910000746 Structural steel Inorganic materials 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 5
- 238000001953 recrystallisation Methods 0.000 description 5
- 238000010079 rubber tapping Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000009749 continuous casting Methods 0.000 description 3
- 238000010899 nucleation Methods 0.000 description 3
- 230000006911 nucleation Effects 0.000 description 3
- 238000013000 roll bending Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000000889 atomisation Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- 229910000870 Weathering steel Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000005465 channeling Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical group C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000009966 trimming Methods 0.000 description 1
- RMLPZKRPSQVRAB-UHFFFAOYSA-N tris(3-methylphenyl) phosphate Chemical compound CC1=CC=CC(OP(=O)(OC=2C=C(C)C=CC=2)OC=2C=C(C)C=CC=2)=C1 RMLPZKRPSQVRAB-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
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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
- B21B1/22—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
- B21B1/24—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 in a continuous or semi-continuous process
- B21B1/26—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 in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
- B21B27/02—Shape or construction of rolls
- B21B27/021—Rolls for sheets or strips
-
- 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
-
- 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
- B21B37/46—Roll speed or drive motor control
-
- 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
- B21B37/58—Roll-force control; Roll-gap control
-
- 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
- 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
- B21B45/004—Heating the product
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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
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Geometry (AREA)
- Metal Rolling (AREA)
Abstract
The invention discloses a rolling method of a hot rolled pattern steel plate with an extremely thin specification of 1.5mm in the field of hot continuous rolling steel production, which comprises the following steps: adopting common carbon steel and controlling the thickness and length of a steel casting blank; heating by adopting a hot feeding and hot charging mode; rough rolling and finish rolling are carried out; carrying out laminar cooling on the finish-rolled steel strip; and finally, coiling. The invention adopts the slab with proper length, is favorable for reducing the temperature difference between the middle slab and the head and the tail of the steel coil, adopts the hot feeding and hot loading mode for heating, can improve the temperature of the core of the slab, is easy to roll stably, further reduces the temperature drop of a finish rolling inlet by rough rolling 4 times, and can improve the yield of the ultra-thin hot continuous rolling pattern plate by reasonably controlling the rolling speed, the convexity of the slab, the loop quantity, the bending force, the roll shifting quantity and other processes in the finish rolling process, so that the obtained pattern plate with the thickness of 1.5mm has the advantages of good rolling stability, good pattern shape, excellent comprehensive performance and the like.
Description
Technical Field
The invention relates to the field of hot continuous rolling steel production, in particular to a rolling method of a hot rolled pattern steel plate with an extremely thin specification of 1.5 mm.
Background
At present, the conventional thickness of the checkered plate for the automobile is 2.0-6.0 mm, and with the gradual development of the automobile industry towards the light weight and low cost, the demand for hot rolled steel with extremely thin specification is gradually increased. The thickness reduction of the steel plate can reduce the dead weight of the vehicle and the carbon emission, and can replace a cold-rolled plate, thereby further reducing the carbon emission and saving the production cost.
Some methods for producing hot rolled steel of extremely thin gauge are disclosed in the prior art, such as:
CN113996665a discloses a production process for rolling a pattern plate with extreme thin specification by using a thin slab, which comprises slab heating, rough rolling, finish rolling, laminar cooling and coiling, wherein in the slab heating, the thickness of the slab is selected to be 90-105 mm, the slab is centrally charged, and the cantilever quantity at two ends of the slab is controlled to be less than or equal to 700mm; the whole time of the furnace is controlled to be 70-140 min; controlling the temperature of the primary heating furnace to be 750-900 ℃; the secondary heating temperature is controlled at 1050-1130 ℃, and the primary heating and secondary heating total heating time is controlled at 35-70 min; and controlling the temperature of the three-adding soaking furnace section in combination with the furnace time. Compared with the prior art, the invention can stably produce the pattern plates with the extreme thin specification in batches by using the thin plate blanks.
CN112522566a discloses the selective addition of microalloy elements such as B to steel; in the smelting process, the alkalinity of slag, the type of inclusion in steel, the melting point, the free oxygen content in molten steel and the acid-soluble aluminum Als content are controlled; then casting a strip steel with the thickness of 1.5-3mm by twin-roll strip continuous casting, directly entering a lower closed chamber with non-oxidizing atmosphere after the strip steel is discharged from a crystallization roller, and entering an online rolling mill for hot rolling under the closed condition; the rolled strip steel is cooled by adopting an air atomization cooling mode, the thickness of oxide skin on the surface of the strip steel can be effectively reduced by adopting the air atomization cooling mode, the temperature uniformity of the strip steel is improved, and the surface quality of the strip steel is improved. The finally produced steel coil can be directly used as a hot rolled pattern plate/belt, and can also be used as a finishing pattern plate/belt after trimming and leveling.
CN104550256a discloses a TMCP thin gauge automobile structural steel sheet shape control method: heating the steel billet to 1100-1200 ℃, and controlling the temperature difference of the upper layer, the middle layer and the lower layer of the steel billet to be 0-30 ℃; the rolling process parameters are set unchanged, and rolling is carried out by adopting a rolling schedule set by a secondary model; ACC cooling is carried out on the steel plate after finish rolling, the speed of an ACC roller way is set to be 1.0-1.25 m/s, and the final cooling temperature is controlled to be 400-500 ℃; and (3) carrying out online straightening after cooling the steel plate, adopting a secondary model to automatically straighten, and controlling the redness returning temperature of the steel plate to be 500-550 ℃ after straightening.
CN113522967B discloses a control method for short-process rolling 550 MPa-level wide and thin-specification automobile structural steel plate, which solves the technical problems of low finishing efficiency, low comprehensive yield and the like caused by poor plate shape of 550 MPa-level wide and thin-specification steel plate through slab thickness and wedge control, finish rolling strip steel load distribution control, finish rolling strip steel convexity and flatness control.
CN113522988B discloses a control method for the DQ process thin specification super car structural steel plate shape, comprising: rolling, cooling, leveling and transverse cutting. The invention emphasizes a micro-medium wave compensation strategy during rolling, and adopts a sectional cooling mode after the steel coil is rolled, so that the problem of poor plate shape caused by overlarge cooling speed after the steel coil is rolled is mainly solved. The steel coil is immediately flattened within 48 hours after rolling, so that excessive work hardening of the steel plate is avoided, and the flattening effect is ensured. The unevenness of the steel plate produced by the method is between 5 and 8mm/m, and the most preferable can reach 2mm/m.
Although some production processes for producing the pattern steel plate for the automobile exist in the prior art, many requirements on casting blank components are high, the thickness of the steel plate is mostly the thickness of the traditional steel plate, namely 2.0-6.0 mm, for the pattern steel plate with extremely thin specification, such as 1.5mm, the production difficulty is extremely high by adopting the existing rolling process, the uniformity of the thickness of the steel plate and the flatness of the plate shape are not easy to achieve, meanwhile, the integrity of pattern shape is ensured, the production efficiency is lower, and the yield of the steel plate is lower.
Disclosure of Invention
In order to overcome the defects of high production difficulty, low production efficiency, low yield and the like of the existing hot rolled pattern steel plate with extremely thin specification, the invention aims to solve the technical problems that: a rolling method of a hot rolled pattern steel plate with extremely thin specification of 1.5mm, which adopts conventional carbon steel and a conventional hot rolling unit to improve the production efficiency and the yield, is provided.
The technical scheme adopted for solving the technical problems is as follows:
a rolling method of a hot rolled patterned steel plate with an extremely thin specification of 1.5mm is characterized by comprising the following steps:
the steel casting blank for rolling is common carbon steel, and the rolling process comprises the following steps:
step one, controlling the thickness of a steel casting blank to be 200-250 mm, and controlling the length of the casting blank to be 8.5-9.5 m;
step two, loading the steel casting blank into a slab heating furnace in a hot feeding and hot loading mode, wherein the discharging temperature of the slab is 1220-1280 ℃;
step three, rough rolling is carried out on the steel casting blank, two sets of rolling mills are adopted, the first set of rolling mill carries out 1-pass rolling, the second set of rolling mill carries out 3-pass rolling, the inlet temperature of rough rolling is 1160-1200 ℃, the outlet temperature of rough rolling is 1120-1160 ℃, and the outlet speed of rough rolling is 2-5 m/s;
step four, performing finish rolling on the intermediate billet obtained in the step three, wherein the finish rolling inlet temperature is 1060-1120 ℃, the finish rolling outlet temperature is 860-900 ℃, the finish rolling outlet speed is 9.0-10.5 m/s, and the thickness of the steel plate after finish rolling is controlled to be 1.5mm; the number of cooling water opening groups among the frames in the finish rolling process is not more than 1 group, and the number of lubrication rolling opening groups is not less than 3 groups; the finishing mill group comprises 7 groups of finishing rolls, namely F1 to F7 respectively, F7 is a pattern roll, 6 groups of loopers are L1 to L6 respectively, and the finishing rolls and the loopers are controlled according to the following requirements:
convexity of finishing roll: f1: 5-10 mu m, F2: 3-5 μm, F3: 2-3 mu m, F4: 1-2 mu m, F5-F7: 1 μm;
finishing roll gap: f1: 10-15 mm, F2: 5-8 mm, F3: 3-5 mm, F4: 2-3 mm, F5-F7: 1-2 mm;
finishing roll speed: f1: 1.0-1.2 m/s, F2: 1.8-2.3 m/s, F3: 3.0-4.0 m/s, F4:5.0 to 6.0m/s, F5: 7.0-8.0 m/s, F6: 8.5-9.5 m/s, F7:9.0 to 10.5m/s;
loop roll tension: l1: 450-550N/mm 2 ，L2：550～650N/mm 2 ，L3：650～800N/mm 2 ，L4：700～900N/mm 2 ，L5：800～1000N/mm 2 ，L6：900～1200N/mm 2 ；
Roller bending force of finish rolling roller: f1: 100-260N/mm 2 ，F2：100～200N/mm 2 ，F3～F4：100～220N/mm 2 ，F5：100～180N/mm 2 ，F6：120～180N/mm 2 ，F7：40～50N/mm 2 ；
Roll shifting amount of finishing roll: f1: 70-150 mm, F2: 20-60 mm, F3: 20-70 mm, F4: 10-60 mm, F5: -80 to-20 mm, F6: -70 to-15 mm, F7:0mm;
and fifthly, performing laminar cooling on the finish rolled steel plate, wherein the cooling flow ratio of the lower header to the upper header is 1.2-1.4, performing sparse cooling on a laminar cooling model, and coiling after the steel belt is cooled to 600-700 ℃.
Further, in the third step, the thickness of the intermediate billet after rough rolling is controlled to be 30-35 mm.
Further, a heat preservation cover and a hot rolling box are arranged on a conveying roller way between the third step and the fourth step, and intermediate blanks sequentially pass through the heat preservation cover and the hot rolling box and then enter a finishing mill group.
The beneficial effects of the invention are as follows: the invention adopts the slab with proper length, is favorable for reducing the temperature difference between the middle slab and the head and the tail of the steel coil, adopts the hot feeding and hot loading mode for heating, can improve the temperature of the core of the slab, is easy to roll stably, further reduces the temperature drop of a finish rolling inlet by rough rolling for 4 times, and can improve the yield of the hot continuous rolling pattern steel plate with extremely thin specification by reasonably controlling the rolling speed, the plate convexity, the looper, the roll bending force, the roll channeling amount and other processes in the finish rolling process, and the obtained hot continuous rolling pattern steel plate with the thickness of 1.5mm has the advantages of good rolling stability, good pattern shape, excellent comprehensive performance and the like, avoids the defects of the tail part of the steel belt, the wave shape, the waste rolling, the pattern missing and the like in the process of preparing the steel belt in the prior art, and can improve the yield of the hot continuous rolling pattern steel plate with extremely thin specification by more than 95 percent.
Detailed Description
The invention is further illustrated below with reference to examples.
The invention discloses a rolling method of a hot rolled pattern steel plate with an extremely thin specification of 1.5mm, which is characterized by comprising the following steps:
the steel casting blank for rolling is common carbon steel, and the rolling process comprises the following steps:
step one, controlling the thickness of a steel casting blank to be 200-250 mm, and controlling the length of the casting blank to be 8.5-9.5 m;
step two, loading the steel casting blank into a slab heating furnace in a hot feeding and hot loading mode, wherein the discharging temperature of the slab is 1220-1280 ℃;
step three, rough rolling is carried out on the steel casting blank, two sets of rolling mills are adopted, the first set of rolling mill carries out 1-pass rolling, the second set of rolling mill carries out 3-pass rolling, the inlet temperature of rough rolling is 1160-1200 ℃, the outlet temperature of rough rolling is 1120-1160 ℃, and the outlet speed of rough rolling is 2-5 m/s;
step four, performing finish rolling on the intermediate billet obtained in the step three, wherein the finish rolling inlet temperature is 1060-1120 ℃, the finish rolling outlet temperature is 860-900 ℃, the finish rolling outlet speed is 9.5-10.5 m/s, and the thickness of the steel plate after finish rolling is controlled to be 1.5mm; the number of cooling water opening groups among the frames in the finish rolling process is not more than 1 group, and the number of lubrication rolling opening groups is not less than 3 groups; the finishing mill group comprises 7 groups of finishing rolls, namely F1 to F7 respectively, F7 is a pattern roll, 6 groups of loopers are L1 to L6 respectively, and the finishing rolls and the loopers are controlled according to the following requirements:
convexity of finishing roll: f1: 5-10 mu m, F2: 3-5 μm, F3: 2-3 mu m, F4: 1-2 mu m, F5-F7: 1 μm;
finishing roll gap: f1: 10-15 mm, F2: 5-8 mm, F3: 3-5 mm, F4: 2-3 mm, F5-F7: 1-2 mm;
finishing roll speed: f1: 1.0-1.2 m/s, F2: 1.8-2.3 m/s, F3: 3.0-4.0 m/s, F4:5.0 to 6.0m/s, F5: 7.0-8.0 m/s, F6: 8.5-9.5 m/s, F7:9.0 to 10.5m/s;
loop roll tension: l1: 450-550N/mm 2 ，L2：550～650N/mm 2 ，L3：650～800N/mm 2 ，L4：700～900N/mm 2 ，L5：800～1000N/mm 2 ，L6：900～1200N/mm 2 ；
Roller bending force of finish rolling roller: f1: 100-260N/mm 2 ，F2：100～200N/mm 2 ，F3～F4：100～220N/mm 2 ，F5：100～180N/mm 2 ，F6：120～180N/mm 2 ，F7：40～50N/mm 2 ；
Roll shifting amount of finishing roll: f1: 70-150 mm, F2: 20-60 mm, F3: 20-70 mm, F4: 10-60 mm, F5: -80 to-20 mm, F6: -70 to-15 mm, F7:0mm;
and fifthly, performing laminar cooling on the finish rolled steel plate, wherein the cooling flow ratio of the lower header to the upper header is 1.2-1.4, performing sparse cooling on a laminar cooling model, and coiling after the steel belt is cooled to 600-700 ℃.
In the third step, the thickness of the rough rolled intermediate billet is preferably controlled within 30 to 35mm in order to improve the finish rolling efficiency and the steel strip forming quality.
In order to avoid the intermediate billet from being cooled too fast in the process from the roughing mill group to the finishing mill group and reduce the finishing mill inlet temperature, a heat preservation cover and a hot rolling box can be arranged on a conveying roller way between the third step and the fourth step, and the intermediate billet sequentially enters the finishing mill group after passing through the heat preservation cover and the hot rolling box. The heat preservation cover and the hot rolling box can lead the temperature of the intermediate billet to be uniform and stable, simultaneously are beneficial to reducing burning loss and the generation of secondary oxide scales and improve the surface quality of steel.
The reason for the limitation of the production process will be described below with reference to the requirement of the present invention for the control of the patterned steel sheet formation.
First, in terms of heating schedule. Because the slab heating furnace adopts the nozzle for heating, the main heat transfer mode is heat radiation, and the heat is transferred to the core by the slab surface, the core temperature is lower when the slab is cold-packed, the heating speed is slower, the condition of the core temperature being lower easily occurs when the heating system is improper, the deformation can not be fully transferred to the slab core in the follow-up rough rolling, the rolling load is improved, the rolling difficulty is increased, and the core structure is coarse easily caused. When hot feeding and hot charging are adopted, namely, the billet is directly insulated and conveyed to a heating furnace for heating in a high-temperature state, as the slab is naturally cooled in the air after being taken off from continuous casting, the temperature of the core is higher than that of the surface, and the core is higher after being heated by the slab, so that the rolling is easy to stabilize. Thus, the present invention requires: the billet obtained after continuous casting is fed into a plate blank heating furnace by adopting hot feeding, and the tapping temperature of the heating furnace is controlled at a higher level of 1220-1280 ℃.
Second, in terms of rough rolling process. The conventional rough rolling adopts a 3+3 mode, namely rough rolling R1 and R2 are respectively rolled for 3 times, the invention adopts a 1+3 mode, two rolling passes are reduced, the temperature reduction is reduced from the surface, the austenite recrystallization zone rolling is considered when the design of temperature and deformation system is one, the austenite structure refinement is realized through recrystallization, the strong plasticity of the material is improved, therefore, the rough rolling temperature is controlled at a higher level, the rolling deformation is controlled at a higher level, namely the thickness of an intermediate blank is controlled at a lower level; secondly, taking the control of the rough rolling plate shape into consideration, adopting a higher rough rolling temperature to reduce the rolling load. The present invention therefore requires: the rough rolling process is 1+3, the inlet temperature is 1160-1200 ℃, the rough rolling outlet temperature is 1120-1160 ℃, the rough rolling outlet speed is 2-5 m/s, and the thickness of the rough rolled intermediate blank is 30-35 mm.
Thirdly, a heat preservation cover and a hot rolling box are arranged on a roller way between the rough rolling unit and the finish rolling unit, so that the finish rolling temperature is improved, the rolling load is reduced, and on the other hand, the high-temperature intermediate billet is coiled to remove surface iron scales, so that the head and tail temperatures of the steel plate are uniform, and the stable rolling of the thin-specification steel plate is realized.
Fourth, in the finish rolling process. Firstly, the main function of finish rolling is to provide a large number of nucleation points for subsequent phase transformation through large compression ratio rolling, promote the subsequent phase transformation to form fine and uniform tissues, and improve the toughness of the material through fine grain strengthening. The invention adopts higher finish rolling temperature, namely the finish rolling inlet temperature is 1060-1120 ℃, the finish rolling outlet temperature is 860-900 ℃, and mainly aims to ensure that the finish rolling earlier stage (F1-F4) is still in an austenite recrystallization zone for rolling, uniform and fine equiaxed crystals are formed through recrystallization, the finish rolling later stage (F5-F7) is in an austenite non-recrystallization zone for rolling, and sufficient nucleation work and a large number of nucleation points are provided for subsequent phase transformation through flattening of an austenite structure. In addition, the invention adopts a higher finish rolling outlet speed of 9.0-10.5 m/s, and mainly aims to ensure that the finish rolling of the steel plate is completed quickly, reduce the head-tail temperature difference caused by the natural temperature drop of the steel plate and further reduce the head-tail performance difference of the steel plate.
Secondly, the finish rolling process is set in consideration of the problem of controlling the shape of the thin gauge steel sheet. The steel plate disclosed by the invention is thinner, the finish rolling compression ratio is large, and the plate shape is difficult to control. Thus, the present invention requires: firstly, the number of cooling water opening groups among the frames is required to be not more than 1 group so as to reduce the temperature drop in the finish rolling process of the steel plate; secondly, the number of the required lubrication rolling starting groups is not less than 3, and the friction force on the surface of the steel plate is relieved through oil-water lubrication, so that the finish rolling load is relieved; thirdly, the rolling speed, the plate convexity, the loop amount, the roll bending force, the roll shifting amount and other processes are reasonably controlled by finish rolling, the rolling force of F7 is properly increased, the roll shifting amount of F7 is reduced, the control of pattern height and the control of plate shape are facilitated, and the obtained hot continuous rolled steel strip has the characteristics of good rolling stability, excellent comprehensive performance and the like.
The convexity of the finishing roll is set at a reasonable value, which is beneficial to improving the whole-course plate shape precision of the strip steel and avoiding the generation of wave defects and the like in the strip steel; the thickness of an intermediate blank and a finished product of the thin-specification strip steel and the temperature drop in the rolling process are comprehensively considered, and reasonable rolling load distribution can be realized on the premise of guaranteeing the finish rolling deformation through the design of a finishing roll gap; the strip steel is easily drawn to a narrow scale due to the fact that the tension of the loop roller is too high, the strip steel with extremely thin specification is easily drawn between two frames due to the fact that the tension of the loop roller is too low, the strip steel is not good in stability between the frames and the shape of the strip steel is changed, and the risk that the strip steel is rolled out due to the fact that the loop is pulled up is also caused; the roll bending force and the roll shifting amount of the finish rolling roll are mainly set to control the convexity, flatness, shape and the like of the strip steel while adapting to the convexity of the intermediate billet after rough rolling, so that the occurrence of wave defects and the like in the strip steel is avoided.
The outlet speed of the finish rolling mainly influences the temperature drop of the strip steel in the finish rolling process, and the temperature drop of the strip steel in the finish rolling process needs to be ensured by a certain rolling speed, so that the requirements of the inlet temperature and the outlet temperature of the finish rolling can be met. The thinner the thickness, the greater the temperature drop; in addition, as for car structural steel and high-strength weathering steel, the addition of alloying elements such as Ti, cr and Cu increases the temperature drop rate of the strip steel, so that further improvement of rolling speed is required.
Fifth, in laminar cooling. First, in order to avoid formation of coarse ferrite or cementite structure, a high laminar cooling rate of 10-30 ℃ per second is required to refine grains and improve the strength and plasticity of the material. Secondly, the coiling temperature is controlled according to 600-700 ℃, and properly increasing the coiling temperature is beneficial to increasing the elongation of the thin steel plate. Thirdly, because the cooling water of the lower header is influenced by gravity, the upward spraying speed to the surface of the steel plate is lower, and therefore, in order to ensure that the cooling speed of the upper surface and the lower surface is close, the flow rate of the cooling water of the lower header is appropriately higher than that of the upper header, and the flow ratio of the lower header to the upper header is controlled to be 1.2-1.4 by combining industrial production experience. Fourth, because the steel plate changes phase during laminar cooling, internal stress is easy to generate during phase change, and the internal stress is increased when the cooling rate is higher, the cooling rate of the steel plate is properly reduced on the premise of meeting the performance requirement of the steel plate, namely a sparser cooling boiled water mode is adopted, and 1 group of headers are closed every 2 groups of headers are opened.
The following describes the invention in more detail with reference to examples, which are not intended to limit the invention thereto.
Example 1
And a conventional carbon structural steel billet is adopted, and the length of the slab is 8.5m. The steel plate with the thickness of 1.5mm is prepared through the technological processes of heating, rough rolling, hot rolling box, finish rolling, laminar cooling and coiling. The specific process is as follows: the billet is hot-fed into a slab heating furnace, and the tapping temperature is 1258 ℃. The inlet temperature of rough rolling is 1191 ℃, the outlet temperature of rough rolling is 1150 ℃, the outlet speed of rough rolling is 3.3m/s, and the thickness of the intermediate billet obtained after rough rolling is 30mm. The middle part is transported by a roller way after rough rolling, is sequentially subjected to heat preservation by a heat preservation cover, and is sent to a finishing mill group after being coiled by a hot coil box. The finish rolling inlet temperature is 1083 ℃, the finish rolling outlet temperature is 872 ℃, the finish rolling outlet speed is 9.5m/s, cooling water among 1 group of racks is started, and 3 groups of lubrication rolling are started. The finish rolled steel plate is subjected to laminar cooling, wherein a laminar cooling model is formed by opening 2 groups of pipes and 1 group of pipes, the water flow ratio of a lower header pipe to an upper header pipe is 1.32, and the coiling temperature is 695 ℃.
The checkered plate of example 1 had a thickness of 1.5mm, a good plate shape and a pattern height of 0.18mm.
Example 2
And a conventional carbon structural steel billet is adopted, and the length of the slab is 9.5m. The steel plate with the thickness of 1.5mm is prepared through the technological processes of heating, rough rolling, hot rolling box, finish rolling, laminar cooling and coiling. The specific process is as follows: the billet is fed into a plate blank heating furnace by adopting hot feeding, and the tapping temperature is 1278 ℃. The inlet temperature of rough rolling is 1199 ℃, the outlet temperature of rough rolling is 1165 ℃, the outlet speed of rough rolling is 4.0m/s, and the thickness of the intermediate billet obtained after rough rolling is 35mm. The middle part is transported by a roller way after rough rolling, is sequentially subjected to heat preservation by a heat preservation cover, and is sent to a finishing mill group after being coiled by a hot coil box. The finish rolling inlet temperature is 1103 ℃, the finish rolling outlet temperature is 895 ℃, the finish rolling outlet speed is 10.5m/s, cooling water between racks is not started, lubrication rolling is started for 5 groups, laminar cooling is carried out on the finish rolled steel plate, a laminar cooling model is formed by opening 2 groups of pipes and 1 group of pipes, the water flow ratio of a lower header pipe to an upper header pipe is 1.25, and the coiling temperature is 605 ℃.
The checkered plate of example 2 had a thickness of 1.5mm, a good plate shape and a pattern height of 0.19mm.
Example 3
And a conventional carbon structural steel billet is adopted, and the length of the slab is 9.0m. The steel plate with the thickness of 1.5mm is prepared through the technological processes of heating, rough rolling, hot rolling box, finish rolling, laminar cooling and coiling. The specific process is as follows: the billet is fed into a slab heating furnace by adopting hot feeding, and the tapping temperature is 1267 ℃. The inlet temperature of rough rolling is 1196 ℃, the outlet temperature of rough rolling is 1169 ℃, the outlet speed of rough rolling is 3.2m/s, and the thickness of the intermediate billet obtained after rough rolling is 32mm. The middle part is transported by a roller way after rough rolling, is sequentially subjected to heat preservation by a heat preservation cover, and is sent to a finishing mill group after being coiled by a hot coil box. The inlet temperature of finish rolling is 1109 ℃, the outlet temperature of finish rolling is 898 ℃, the outlet speed of finish rolling is 10.0m/s, cooling water between racks is not started, lubrication rolling is started for 5 groups, laminar cooling is carried out on the finish rolled steel plate, a laminar cooling model is formed by opening 2 groups of pipes for 1 group, the water flow ratio of a lower header pipe to an upper header pipe is 1.33, and the coiling temperature is 650 ℃.
The checkered plate of example 3 had a thickness of 1.5mm, a good plate shape and a pattern height of 0.18mm.
Comparative example 1
And a conventional carbon structural steel billet is adopted, and the length of the slab is 11.0m. The steel plate with the thickness of 1.5mm is prepared through the technological processes of heating, rough rolling, hot rolling box, finish rolling, laminar cooling and coiling. The specific process is as follows: the billet is cold-packed into a slab heating furnace, and the tapping temperature is 1220 ℃. The inlet temperature of rough rolling is 1166 ℃, the outlet temperature of rough rolling is 1135 ℃, the outlet speed of rough rolling is 3.0m/s, and the thickness of an intermediate billet obtained after rough rolling is 35mm. And after rough rolling, the intermediate is transmitted through a roller way and is sent to a finishing mill group. The finish rolling adopts a conventional rolling process, the finish rolling inlet temperature is 1075 ℃, the finish rolling outlet temperature is 863 ℃, the finish rolling outlet speed is 9.0m/s, cooling water between frames is not started, 5 groups of lubrication rolling are started, the finished steel plate is subjected to laminar cooling, and the coiling temperature is 650 ℃.
The checkered plate of comparative example 1 had a thickness of 1.5mm, a poor plate shape and a pattern height of 0.14mm.
Therefore, the production process can solve the problems of difficult rolling and material forming performance of the ultra-thin pattern steel plate by using the common carbon steel and the conventional hot continuous rolling machine set, obtain the pattern steel plate with the thickness of 1.5mm with the composite requirement, provide a new thought for preparing the ultra-thin pattern plate, and have good operability and popularization.
Claims (3)
1. A rolling method of a hot rolled patterned steel plate with an extremely thin specification of 1.5mm is characterized by comprising the following steps:
the steel casting blank for rolling is common carbon steel, and the rolling process comprises the following steps:
step one, controlling the thickness of a steel casting blank to be 200-250 mm, and controlling the length of the casting blank to be 8.5-9.5 m;
step two, loading the steel casting blank into a slab heating furnace in a hot feeding and hot loading mode, wherein the discharging temperature of the slab is 1220-1280 ℃;
step three, rough rolling is carried out on the steel casting blank, two sets of rolling mills are adopted, the first set of rolling mill carries out 1-pass rolling, the second set of rolling mill carries out 3-pass rolling, the inlet temperature of rough rolling is 1160-1200 ℃, the outlet temperature of rough rolling is 1120-1160 ℃, and the outlet speed of rough rolling is 2-5 m/s;
step four, performing finish rolling on the intermediate billet obtained in the step three, wherein the finish rolling inlet temperature is 1060-1120 ℃, the finish rolling outlet temperature is 860-900 ℃, the finish rolling outlet speed is 9.0-10.5 m/s, and the thickness of the steel plate after finish rolling is controlled to be 1.5mm; the number of cooling water opening groups among the frames in the finish rolling process is not more than 1 group, and the number of lubrication rolling opening groups is not less than 3 groups; the finishing mill group comprises 7 groups of finishing rolls, namely F1 to F7 respectively, F7 is a pattern roll, 6 groups of loopers are L1 to L6 respectively, and the finishing rolls and the loopers are controlled according to the following requirements:
convexity of finishing roll: f1: 5-10 mu m, F2: 3-5 μm, F3: 2-3 mu m, F4: 1-2 mu m, F5-F7: 1 μm;
finishing roll gap: f1: 10-15 mm, F2: 5-8 mm, F3: 3-5 mm, F4: 2-3 mm, F5-F7: 1-2 mm;
finishing roll speed: f1: 1.0-1.2 m/s, F2: 1.8-2.3 m/s, F3: 3.0-4.0 m/s, F4:5.0 to 6.0m/s, F5: 7.0-8.0 m/s, F6: 8.5-9.5 m/s, F7:9.0 to 10.5m/s;
loop roll tension: l1: 450-550N/mm 2 ，L2：550～650N/mm 2 ，L3：650～800N/mm 2 ，L4：700～900N/mm 2 ，L5：800～1000N/mm 2 ，L6：900～1200N/mm 2 ；
Roller bending force of finish rolling roller: f1: 100-260N/mm 2 ，F2：100～200N/mm 2 ，F3～F4：100～220N/mm 2 ，F5：100～180N/mm 2 ，F6：120～180N/mm 2 ，F7：40～50N/mm 2 ；
Roll shifting amount of finishing roll: f1: 70-150 mm, F2: 20-60 mm, F3: 20-70 mm, F4: 10-60 mm, F5: -80 to-20 mm, F6: -70 to-15 mm, F7:0mm;
and fifthly, performing laminar cooling on the finish rolled steel plate, wherein the cooling flow ratio of the lower header to the upper header is 1.2-1.4, performing sparse cooling on a laminar cooling model, and coiling after the steel belt is cooled to 600-700 ℃.
2. A method for rolling a hot rolled pattern steel sheet of extremely thin gauge of 1.5mm as claimed in claim 1, characterized by: in the third step, the thickness of the rough rolled intermediate billet is controlled to be 30-35 mm.
3. A method for rolling a hot rolled pattern steel sheet of extremely thin gauge of 1.5mm as claimed in claim 1, characterized by: and (3) arranging a heat-insulating cover and a hot rolling box on a conveying roller way between the third step and the fourth step, and enabling the intermediate blank to enter a finishing mill group after passing through the heat-insulating cover and the hot rolling box in sequence.
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