CN111589865B - Low-yield-ratio thin strip steel continuous casting and rolling production line and production process - Google Patents

Low-yield-ratio thin strip steel continuous casting and rolling production line and production process Download PDF

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CN111589865B
CN111589865B CN202010454972.3A CN202010454972A CN111589865B CN 111589865 B CN111589865 B CN 111589865B CN 202010454972 A CN202010454972 A CN 202010454972A CN 111589865 B CN111589865 B CN 111589865B
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rolling
strip steel
rough
continuous casting
thin strip
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CN111589865A (en
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韩会全
王万慧
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CISDI Engineering Co Ltd
CISDI Research and Development Co Ltd
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CISDI Engineering Co Ltd
CISDI Research and Development Co Ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B1/00Metal-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
    • B21B1/46Metal-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
    • B21B1/463Metal-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 in a continuous process, i.e. the cast not being cut before rolling
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/06Ferrous alloys, e.g. steel alloys containing aluminium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/12Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/14Ferrous alloys, e.g. steel alloys containing titanium or zirconium

Abstract

The invention belongs to the technical field of steel continuous casting and rolling, and particularly discloses a thin strip steel continuous casting and rolling production line with a low yield ratio and a production process. The production line comprises a continuous casting machine, a high-pressure water rough descaling device, a rough rolling unit, a pendulum shear, a waste billet pushing and stacking device, an accident shear, an induction heating furnace, a high-pressure water fine descaling device, a fine rolling unit, a high-speed flying shear and a coiling unit which are sequentially arranged along the rolling direction. The production process comprises continuous casting and blank forming → high-pressure water rough descaling → rough rolling → induction heating → high-pressure water fine descaling → fine rolling → high-speed flying shear coil splitting → coiling. The invention realizes the production of thin strip steel with high surface quality and low yield ratio by adding rough descaling, reducing the number of induction heating groups, lengthening the distance between the finish rolling middle stand and shortening the distance between the finish rolling last stand and the coiler, and simultaneously, the invention can reduce the construction and operation investment cost of the production line due to the reduction of rolling line equipment and the shortening of the length of the production line.

Description

Low-yield-ratio thin strip steel continuous casting and rolling production line and production process
Technical Field
The invention relates to the technical field of steel continuous casting, in particular to a thin strip steel continuous casting and rolling production line with low yield ratio and a production process.
Background
Continuous casting and rolling have been developed, and representative techniques such as CSP, ISP, FTSR, ESP, MCCR and the like have been developed. In recent years, the endless continuous hot rolling technology represented by ESP of Arvedi of Italy has been industrially well applied, and thin strip steel with the thickness of less than 1.2mm can be stably produced, so that the thickness forbidden zone which cannot be related to the conventional hot continuous rolling is broken through. Compared with conventional hot continuous rolling, the ESP has the following advantages: the threading and the tail flicking of the strip steel are eliminated by the endless rolling, so that the control precision and the stability of the overall length and the performance of the steel coil are greatly improved; the continuous casting and rolling line is tightly connected, and the high continuous casting speed greatly improves the production efficiency from molten steel to steel coils; the compact arrangement and the low energy consumption reduce the production cost of each ton of steel; the thinner thickness can partially replace a cold-rolled coil, and the added value of the product is improved. These advantages all mark a significant advance in hot rolling technology. However, although the ESP product is advantageous, it has a product yield ratio of 0.76 or more due to the absence of conventional hot rolling processes, such as cooling, reheating and recrystallization of the cast slab, and a conventional hot rolling yield ratio of 0.7 or less, resulting in poor formability. Meanwhile, the ESP continuous casting billet is directly provided with iron scales to be subjected to rough rolling, so that the genetic iron scale residue defect on the surface of the final finished product strip steel is caused, and the quality of steel is limited.
The ferrite rolling technology is researched and developed by a Belgian steel research center at the end of the 20 th century 80 years, is effective for solving the problem of high yield ratio of low-carbon steel on a continuous casting and rolling production line, reduces the rolling force during ferrite area rolling, is favorable for reducing energy consumption, is often applied to trial production by CSP and FTSR production lines, and has certain effects, but due to the process arrangement limitation of the CSP and FTSR production lines, the trial production is carried out in a single blank rolling mode, the production control of the whole roll of strip steel is unstable, and the effect of really realizing endless strip steel ferrite rolling cannot be achieved.
Patent CN201810660032.2 discloses a method for applying ferrite rolling to a continuous casting and rolling production line, which controls the start rolling temperature, the finish rolling temperature and the coiling temperature of the finish rolling of hot rolled strip steel by setting the distance between an intermediate rolling unit and a finishing rolling unit and applying an intermediate water cooling device and a cooling device after rolling, so as to achieve the purpose of ferrite rolling. However, it still exists in terms of achieving a true ferritic rolling: 1. cooling between frames and after rolling, which causes large temperature fluctuation; 2. the finishing mill group is difficult to realize full ferrite rolling, otherwise, the finishing temperature is too low, and the coiling temperature is further influenced; 3. if the final rolling and coiling temperatures are ensured, the finish rolling inlet temperature is in an austenite and ferrite two-phase region, so that the mixed crystal phenomenon of a final structure is caused, and the performance is influenced.
Disclosure of Invention
In view of the above disadvantages of the prior art, the present invention provides a continuous casting and rolling production line and a production process for thin strip steel with low yield ratio, wherein the present invention combines ferrite rolling technology and ESP technology to create a new specialized process flow, and is expected to realize low yield ratio and high surface quality of low-carbon thin strip steel under endless rolling production conditions, thereby widening the product application market.
To achieve the above and other related objects, a first aspect of the present invention provides a thin strip steel continuous casting and rolling line with a low yield ratio, the production line comprises a continuous casting machine, a high-pressure water rough descaling device, a rough rolling unit, a pendulum shear, a waste billet pushing and stacking device, an accident shear, an induction heating furnace, a high-pressure water fine descaling device, a fine rolling unit, a high-speed flying shear and a coiling unit which are sequentially arranged along the rolling direction, the rough rolling unit comprises a plurality of rough rolling frames which are sequentially arranged along the rolling direction, the finishing rolling unit comprises a plurality of finishing rolling frames which are sequentially arranged along the rolling direction, the underground recoiling unit comprises a plurality of recoiling machines which are sequentially arranged along the rolling direction, the distance between the central lines of a second finish rolling rack and a third finish rolling rack of the finish rolling unit is 7-9 m, and the distance between the central lines of other adjacent finish rolling racks is 4-5 m.
Further, the distance between the outlet of the continuous casting machine and the center line of the first rough rolling frame of the rough rolling unit in the rolling direction is 6-8 m, and preferably 6.5 m.
Further, the center line distance between the third rough rolling stand of the rough rolling mill group in the rolling direction and the first finish rolling stand of the finish rolling mill group in the rolling direction is not more than 43 m.
Further, a center line distance between a last finishing stand of the finishing mill group in the rolling direction and a first coiler of the underground coiler group in the rolling direction is not more than 40 m.
Further, the continuous casting machine comprises a crystallizer, and the distance between the center line of the crystallizer and the center line of a first frame coiling machine of the underground coiling machine set in the rolling direction is not more than 140 m.
Furthermore, the rough rolling unit comprises three rough rolling frames, the finishing rolling unit comprises five finishing rolling frames, and the underground coiling unit comprises three coiling machines.
Further, the induction heating furnace comprises a plurality of groups of induction heaters, and the number of the induction heaters is not more than 8.
The invention provides a production process for producing a thin strip steel with a low yield ratio by using the thin strip steel continuous casting and rolling production line with a low yield ratio, which comprises the following steps: continuous casting and billet forming → high-pressure water rough descaling → rough rolling → induction heating → high-pressure water fine descaling → fine rolling → high-speed flying shear coil splitting → coiling.
Further, the thin strip is transformed from austenite to ferrite between the second and third finishing stands, so that the thin strip is rolled in the ferrite zone after entering the third finishing stand.
Further, the continuous casting outlet temperature of the thin strip steel is 1030 +/-10 ℃.
Further, the rough rolling outlet temperature of the thin strip steel is 980 +/-10 ℃.
Further, the induction heating inlet temperature of the thin strip steel is 930 +/-10 ℃, and the induction heating outlet temperature of the thin strip steel is 1020 +/-10 ℃.
Furthermore, the outlet temperature of the thin strip steel in the second finish rolling stand is 910 +/-10 ℃, the inlet temperature of the thin strip steel in the third finish rolling stand is 860 +/-10 ℃, and the finishing temperature of the thin strip steel is 780 +/-10 ℃.
Further, the coiling temperature of the thin strip steel is 680 +/-10 ℃.
Further, the continuous casting speed of the continuous casting machine is not lower than 5.5m/min, and the thickness of a casting blank is 90-100 mm.
Further, the thickness of the thin strip steel produced by the production line is 0.8-6 mm, and the yield ratio of the thin strip steel is not more than 0.76.
Further, the thin strip steel comprises the following chemical components in percentage by mass: less than or equal to 0.05 percent of C, less than or equal to 0.5 percent of Mn, less than or equal to 3 percent of Si, less than or equal to 0.015 percent of P, less than or equal to 0.015 percent of S, less than or equal to 0.05 percent of Als, and the balance of Fe and impurities.
In a third aspect, the invention provides a thin steel strip produced using the production process of the second aspect. As mentioned above, the thin strip steel continuous casting and rolling production line with low yield ratio and the production process have the following beneficial effects:
based on the prior ESP technology, the invention combines the ferrite rolling technology, reduces the number of induction heating groups by additionally arranging rough descaling, lengthens the distance between a finish rolling intermediate frame and shortens the distance between a finish rolling final frame and a coiler, and creates process conditions for realizing ferrite rolling by reasonably controlling the finish rolling temperature, low-temperature initial rolling, low-temperature final rolling and high-temperature coiling, thereby realizing the production of thin strip with high surface quality and low yield ratio and expanding the market application range of the thin strip which is 'hot to cold'; in addition, because ferrite rolling is adopted, the finish rolling initial rolling temperature is lower, the number of induction heating sets is reduced, the cold layer after rolling is cancelled, the line rolling equipment is reduced, the length of a production line is shortened, and the construction and operation investment cost of the production line is reduced.
Drawings
Fig. 1 shows a schematic layout of a conventional ESP production line of the related art.
Fig. 2 is a schematic layout of a thin strip steel continuous casting and rolling production line with a low yield ratio in an embodiment of the invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated. The structures, proportions, sizes, and other dimensions shown in the drawings and described in the specification are for understanding and reading the present disclosure, and are not intended to limit the scope of the present disclosure, which is defined in the claims, and are not essential to the art, and any structural modifications, changes in proportions, or adjustments in size, which do not affect the efficacy and attainment of the same are intended to fall within the scope of the present disclosure. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.
Description of reference numerals:
the system comprises a continuous casting machine 1, a steel ladle 101, a crystallizer 102, a high-pressure water rough descaling device 2, a rough rolling mill unit 3, a pendulum shear 4, a waste billet pushing and stacking device 5, an accident shear 6, an induction heating furnace 7, a high-pressure water fine descaling device 8, a finishing rolling mill unit 9, a laminar cooling device 10, a high-speed flying shear 11 and an underground recoiling unit 12.
As shown in fig. 1, the conventional ESP production line includes a continuous caster 1, a roughing mill group 3, a pendulum shear 4, a slab pushing and stacking device 5, an accident shear 6, an induction heating furnace 7, a high-pressure water finishing descaling device 8, a finishing mill group 9, a laminar cooling device 10, a high-speed flying shear 11 and an underground recoiling unit 12, which are sequentially arranged along a rolling direction; the continuous casting machine 1 comprises a ladle 101 and a crystallizer 102, and the roughing mill group 3 comprises three roughing stands, namely a first roughing stand R1, a second roughing stand R2 and a third roughing stand R3; the induction heating furnace 7 is provided with 14 groups of induction heaters; the finishing mill group 9 comprises five finishing mill frames, namely a first finishing mill frame F1, a second finishing mill frame F2, a third finishing mill frame F3, a fourth finishing mill frame F4 and a fifth finishing mill frame F5; the down coiler group 12 includes three coilers, a primary coiler DC1, a secondary coiler DC2, and a tertiary coiler DC 3. The distance between the center line of the crystallizer 102 and the outlet of the continuous caster 1 is about 20m, the distance between the outlet of the continuous caster 1 and the center line of the first rough rolling stand R1 is 4.4m, the distance between the center line of the third rough rolling stand R3 and the center line of the first finish rolling stand F1 is 47.2m, the distance between the center lines of the second finish rolling stand F2 and the third finish rolling stand F3 is 4.5m, the distance between the center lines of the remaining finish rolling stands is 4.5m, and the distance between the center line of the fifth finish rolling stand F5 and the center line of the first coiler DC1 is 69 m; the centerline spacing from the crystallizer 102 to the first coiler DC1 for the entire ESP line is approximately 176 m. As shown in fig. 2, the thin strip steel continuous casting and rolling production line with low yield ratio of the invention comprises a continuous casting machine 1, a high-pressure water rough descaling device 2, a rough rolling unit 3, a pendulum shear 4, a slab pushing and stacking device 5, an accident shear 6, an induction heating furnace 7, a high-pressure water fine descaling device 8, a finishing rolling unit 9, a high-speed flying shear 11 and an underground recoiling unit 12 which are arranged in sequence along the rolling direction; the continuous casting machine 1 comprises a ladle 101 and a crystallizer 102, and the roughing mill group 3 comprises three roughing stands, namely a first roughing stand R1, a second roughing stand R2 and a third roughing stand R3; the induction heating furnace 7 is provided with no more than 8 groups of induction heaters, specifically 6 groups in the embodiment; the finishing mill group 9 comprises five finishing mill frames, namely a first finishing mill frame F1, a second finishing mill frame F2, a third finishing mill frame F3, a fourth finishing mill frame F4 and a fifth finishing mill frame F5; the down coiler group 12 includes three coilers, a primary coiler DC1, a secondary coiler DC2, and a tertiary coiler DC 3. The distance between the center line of the crystallizer 102 and the outlet of the continuous caster 1 is about 20m, the distance between the outlet of the continuous caster 1 and the center line of the first rough rolling stand R1 is 6.5m, the distance between the center line of the third rough rolling stand R3 and the center line of the first finish rolling stand F1 is not more than 43m, specifically 41.2m, the distance between the center lines of the second finish rolling stand F2 and the third finish rolling stand F3 is 7-9 m, specifically 7m, the distance between the center lines of the remaining finish rolling stands is 4-5 m, specifically 4.5m, and the distance between the center line of the fifth finish rolling stand F5 and the center line of the first coiler DC1 is not more than 40m, specifically 29 m; the overall line, centerline spacing from the crystallizer 102 to the first coiler DC1 is no more than about 140m, specifically 140 m.
Compared with a conventional ESP production line, the production line provided by the invention has the advantages that the high-pressure water rough descaling device 2 is added, the distance from the outlet of the continuous casting machine 1 to the center line of the first rough rolling machine frame R1 is changed from 4.4m to 6.5m, the distance between the center lines of the third rough rolling machine frame R3 and the first finish rolling machine frame F1 is reduced from 47m to no more than 43m, the distance between the center lines of the second finish rolling machine frame F2 and the third finish rolling machine frame F3 is increased from 4.5m to 7-9 m, the distance between the center lines of the rest finish rolling machine frames is 4.5-5 m, and the distance between the center lines of the fifth finish rolling machine frame F5 and the first coiler DC1 is reduced from 69m to no more than 40 m; the centerline spacing between the entire main production line secondary crystallizer 102 and the first coiler DC1 is reduced from about 176m to no more than 140 m.
Compared with the conventional ESP production line, the production line of the invention has the main differences that:
1. in the production line, the high-pressure water rough descaling device 2 is additionally arranged between the continuous casting machine 1 and the roughing mill group 3, so that the problem that continuous casting iron scale is pressed in at the roughing stage to cause difficulty in subsequent fine descaling and further cause the defect of residual iron scale on the surface of finished product strip steel can be avoided.
2. The number of induction heaters in the induction heating furnace 7 in the production line of the invention is changed from 14 groups of the conventional ESP production line to 8 groups or less, thereby shortening the distance between the third rough rolling stand R3 and the first finish rolling stand F1, reducing the energy consumption of heating and temperature compensation, and simultaneously meeting the requirements of finish rolling and low-temperature start rolling.
3. In the production line of the invention, the finishing mill group 9 comprises 5 stands, the distance between the central lines of the second finishing mill stand F2 and the third finishing mill stand F3 is larger than the distance between other finishing mill stands along the rolling direction, and the strip steel can reach a ferrite phase transition area through air cooling temperature reduction by enlarging the distance, so that the strip steel is in the ferrite area for rolling at 3 stands at the tail part of the finishing mill group 3.
4. In the production line of the invention, the laminar cooling device 10 is not arranged behind the finishing mill group 3, thereby shortening the distance between central lines between the underground recoiling unit 12 and the fifth finishing mill frame F5, realizing close-range high-temperature coiling and leading the thin strip steel to reach the coiling temperature through air cooling.
The production process flow of the thin strip steel with low yield ratio of the invention is as follows:
the normal endless thin strip steel production process flow is as follows: continuous casting and billet forming → high-pressure water rough descaling → rough rolling → induction heating → high-pressure water fine descaling → fine rolling → high-speed flying shear coil splitting → coiling.
For continuous casting start pouring or waste blank pouring close to the tail sound, the cutting of the waste blank is started similarly to the conventional ESP production line, and the production process flow is as follows: continuous casting and billet forming → high-pressure water rough descaling → rough rolling → pendulum shear → scrap billet pushing and plate stacking. When the accident occurs in the process of finish rolling or after finish rolling, the accident shears are started to separate the rough rolling area from the finish rolling area, so that the waste material treatment is convenient.
The ferrite rolling of low-carbon steel requires low-temperature initial rolling (i.e. ferrite area rolling), low-temperature final rolling (<800 ℃) and high-temperature coiling (>660 ℃). As can be seen from the analysis of fig. 1, it is difficult to realize ferrite rolling in the conventional ESP production line. The method mainly comprises the following points: (1) the rolling and the continuous casting are a hard connection whole, the speed of the strip steel in the subsequent process is limited by the continuous casting speed, and the acceleration and the deceleration cannot be realized. This leads to two difficulties, one is that it is difficult to leave a distance and time for the transformation of the austenitic structure of the strip into ferritic structure in the case of a compact arrangement of the finishing stands. Secondly, if the finish rolling is carried out, the temperature is reduced to a ferrite area, which leads to lower finish rolling temperature and coiling temperature. (2) In the conventional ESP production line, the distance between a finish rolling end rack F5 and the central line of a coiler is too long, even if layer cooling is not adopted, the air cooling is only adopted, the temperature drop time of thin strip steel is too long, high-temperature coiling is difficult to realize, if the coiling reaches 660 ℃, the corresponding finishing temperature reaches more than 880 ℃, and the strip steel cannot be rolled in a ferrite area.
The invention lengthens the distance between the finish rolling second machine frame F2 and the finish rolling third machine frame F3 in the finish rolling unit, and ensures the transformation from austenite to ferrite; meanwhile, the accumulated deformation of three racks F3, F4 and F5 at the tail of the finishing mill group is more than 50% when the three racks are rolled in a ferrite area, so that the recrystallization energy storage is ensured; and the coiling machine is close to the finishing mill group, so that high-temperature coiling is ensured. Therefore, the invention can meet the ferrite rolling requirement from the aspect of process system.
The process flow of the present invention for producing a thin strip with low yield ratio by ferritic endless rolling will be described in detail with reference to the following examples.
The strip steel comprises the following chemical components in percentage by mass: less than or equal to 0.015 percent of C, less than or equal to 0.15 percent of Mn, less than or equal to 0.035 percent of Si, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, less than 0.08 percent of Nb and Ti, less than or equal to 0.05 percent of Als, and the balance of Fe and impurities. Casting the steel strip into a 92mm continuous casting blank through a high-speed continuous casting process, controlling the continuous casting drawing speed to be 5.8m/min, controlling the surface temperature of the continuous casting blank at an outlet of the continuous casting to be 1030 +/-10 ℃, then performing rough descaling to remove iron scales on the surface of the casting blank, wherein the rough rolling temperature is about 1000 +/-10 ℃, the thickness of the steel strip is 9.5-10.5 mm after 3 frames of rough rolling, and the temperature of the steel strip is slightly reduced to 980 +/-10 ℃. Cooling the steel strip to 930 +/-10 ℃ through air cooling, supplementing the temperature to 1020 +/-10 ℃ after 5 groups of induction heating, and performing fine descaling and fine rolling on F1 and F2 to obtain the steel strip with the thickness of 2.8-3 mm and the temperature of 910 +/-10 ℃. Then the steel is cooled to the inlet temperature of 860 +/-10 ℃ of F3 in a 7m long air, enters a ferrite zone for rolling, is rolled into 1mm strip steel after passing through 3 racks, and has the accumulated ferrite zone deformation of 66 percent, the final rolling temperature of 780 +/-10 ℃ and the outlet speed of about 8.4 m/s. And then cooling in 29m of air, and coiling in a first coiler DC1 at a coiling temperature of 680 +/-10 ℃.
After the process, the ferrite subjected to rolling deformation is recrystallized and softened in the coiling process, so that the yield ratio can be effectively reduced.
Table 1 lists the properties of mild steel of the above composition after die casting, on a laboratory mill, after a simulated ferrite rolling process.
TABLE 1
Figure BDA0002508893150000061
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (9)

1. The production line is characterized by comprising a continuous casting machine, a high-pressure water rough descaling device, a rough rolling unit, a pendulum shear, a waste billet pushing and stacking device, an accident shear, an induction heating furnace, a high-pressure water finish descaling device, a finishing rolling unit, a high-speed flying shear and an underground recoiling unit which are sequentially arranged along a rolling direction, wherein the rough rolling unit comprises a plurality of rough rolling frames which are sequentially arranged along the rolling direction, the finishing rolling unit comprises a plurality of finish rolling frames which are sequentially arranged along the rolling direction, the underground recoiling unit comprises a plurality of recoiling machines which are sequentially arranged along the rolling direction, the distance between the central lines of a second finish rolling frame and a third finish rolling frame of the finishing rolling unit is 7-9 m, and the distance between the central lines of other adjacent finish rolling frames is 4-5 m; the induction heating furnace comprises a plurality of groups of induction heaters, and the number of the induction heaters is not more than 8.
2. The production line of claim 1, wherein: the distance between the outlet of the continuous casting machine and the center line of the first rough rolling frame of the rough rolling unit in the rolling direction is 6-8 m;
and/or the distance between the center lines of a third rough rolling frame of the rough rolling unit in the rolling direction and a first finish rolling frame of the finish rolling unit in the rolling direction is not more than 43 m;
and/or the distance between the center line of the last finishing stand of the finishing mill group along the rolling direction and the first coiler of the underground coiler group along the rolling direction is not more than 40 m;
and/or the continuous casting machine comprises a crystallizer, and the distance between the center line of the crystallizer and the center line of a first frame coiling machine of the underground coiling machine set in the rolling direction is not more than 140 m.
3. The production line of claim 2, wherein: the rough rolling unit comprises three rough rolling machine frames, the finish rolling unit comprises five finish rolling machine frames, and the underground recoiling unit comprises three recoiling machines.
4. A process for producing thin low yield ratio strip using the thin low yield ratio strip casting and rolling line of any one of claims 1 to 3, comprising the steps of: continuous casting blank → high-pressure water rough descaling → rough rolling → induction heating → high-pressure water fine descaling → fine rolling → high-speed flying shear coil splitting → coiling; the thin strip steel is converted from austenite to ferrite between the second finish rolling stand and the third finish rolling stand, so that the thin strip steel is in a ferrite region for rolling after entering the third finish rolling stand; the induction heating inlet temperature of the thin strip steel is 930 +/-10 ℃, and the induction heating outlet temperature is 1020 +/-10 ℃; the outlet temperature of the thin strip steel at the second finish rolling stand is 910 +/-10 ℃, the inlet temperature of the thin strip steel at the third finish rolling stand is 860 +/-10 ℃, the finishing temperature of the thin strip steel is 780 +/-10 ℃, and the coiling temperature of the thin strip steel is 680 +/-10 ℃.
5. The production process according to claim 4, characterized in that: the continuous casting outlet temperature of the thin strip steel is 1030 +/-10 ℃;
and/or the rough rolling outlet temperature of the thin strip steel is 980 +/-10 ℃.
6. The production process according to claim 4, characterized in that: the continuous casting speed of the continuous casting machine is not lower than 5.5m/min, and the thickness of a casting blank is 90-100 mm.
7. The production process according to claim 4, characterized in that: the thickness of the thin strip steel produced by the production line is 0.8-6 mm, and the yield ratio of the thin strip steel is not more than 0.76.
8. The production process according to claim 4, characterized in that: the thin strip steel comprises the following chemical components in percentage by mass: less than or equal to 0.05 percent of C, less than or equal to 0.5 percent of Mn, less than or equal to 3 percent of Si, less than or equal to 0.015 percent of P, less than or equal to 0.015 percent of S, less than or equal to 0.05 percent of Als, and the balance of Fe and impurities.
9. Thin steel strip produced by the process according to any one of claims 4 to 8.
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