PRODUCTION PLANT FOR CONTINUOUS CASTING AND INFINITE ROLLING FOR STRIP STEEL WITH THICKNESS OF 0.6 TO 4 mm, METHOD FOR PRODUCING STRIP STEEL (OPTIONS) AND METHOD FOR PRODUCING BLANK (OPTIONS)

Abstract

FIELD: steel making.SUBSTANCE: invention relates to the production of strip steel by means of continuous casting and endless rolling using a production plant. The production unit comprises a continuous casting machine, a first cutter, a first scale removal device, a first heating device, a roughing mill, a second cutter, a releasing stacking device, a third cutter, a second heating device, a second scale removal device, a first cooling unit, a finishing stand, a second cooling unit, a fourth cutter and a winding machine, which are arranged in series. The first scale removal device provides water pressure of 13-28 MPa. The second scale removal device provides water pressure of 35-40 MPa. The first refrigeration unit is an ultra-fast cooling device. The second refrigeration unit is a laminar cooling device. Three four-high stands with working roll diameters of 825-735 mm are used as roughing stands of the rolling mill.EFFECT: production of ultra-thin strip steel with a thickness of 0.6 to 4 mm.9 cl, 6 dwg, 5 ex

Description

[0001] Field of technology to which the invention relates

[0002] The present invention relates to the field of hot rolling technology, namely to a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm and methods for producing strip steel and solid blanks thereof.

[0003] Technology Level

[0004] Continuous casting and rolling technology for thin slabs is one of the most important technological advances in the steel industry over the past 30 years, known as the "third technological revolution" in the steel industry. As of January 2021, 72 continuous casting and rolling production lines for thin slabs had been established worldwide, and 20 continuous casting and rolling lines for thin slabs had been established in China. Moreover, ESP production technology has been widely adopted due to its compact layout, low production cost, and high overall economic efficiency; almost all projects built and put into production in China over the past five years are of this type.The typical layout of an ESP plant is as follows: continuous casting → three-stand roughing mill → pendulum cutting → discharge and stacking device / insulation jacket → drum cutting → induction heating furnace → high-pressure water descaling machine → five-stand finishing mill → laminar cooling system → high-speed cut-off cutter → underfloor coiler. However, this layout also has some challenges in actual production:

[0005] 1. The ESP production line is very rigid and has only one flexible buffer zone. Because the continuous casting section is directly connected to the rolling section, the equipment layout is quite dense, and the two operations must be closely coordinated, placing high demands on production management. Furthermore, due to poor flexibility and inflexible production, failure of the rough rolling or pendulum cutting machine before the buffer zone will directly lead to an emergency stop of the upstream operations, causing accidents such as delays in continuous slab casting; long on-site restoration times, extensive setup work, and prolonged production downtime lead to material loss and reduced production efficiency.

[0006] 2. Poor product surface quality. In the existing ESP layout, only scale removal equipment is installed before finish rolling, which only solves the problem of iron scale formation on ordinary carbon steel. However, for high-alloy and special steel grades, the problem of surface scale formation is more serious and requires urgent resolution.

[0007] 3. Relatively high yield strength to tensile strength ratio of products. The existing ESP layout does not ensure a stable process for ferrite package rolling; the manufactured products have a relatively high yield strength to tensile strength ratio (usually >0.75, reaching >0.8), resulting in poor ductility and deep drawing properties; the product range and performance of "hot-cold rolling replacement" technology are limited, affecting market share.

[0008] 4. Inability to achieve stable mass production of ultra-thin strip steel. Relevant production reports show that ESP can achieve stable mass production of strip steel with a minimum thickness of at least 0.8 mm. The production capability of ultra-thin strip steel needs to be improved, but the thickness range of "hot-rolled-cold-rolled" products is limited.

[0009] Essence of the invention

[0010] The technical problem solved by the present invention is to provide a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm, and methods for producing strip steel and solid blanks thereof, which not only improves the flexibility of the production line, thereby improving the adaptability of the organization and management of production, but also integrates the technologies of high-temperature rolling of austenite and low-temperature rolling of ferrite to adjust and improve the yield strength to tensile strength ratio of the products; in addition, it also has the modes of rolling composite products of solid blanks, continuous rolling and endless rolling, and with the increase in production volume, it also makes it possible to stably produce in batches ultra-thin strip steel with a thickness of at least 0.6 mm.

[0011] The first aspect of the present invention provides a continuous casting and endless rolling production plant for hot rolled strip steel with a thickness of 0.6 to 4 mm, which comprises a continuous casting machine, a first slitter, a first scale remover, a first heating device, a rough rolling mill, a second slitter, a release stacking device, a third slitter, a second heating device, a second scale remover, a first cooling unit, a finishing stand, a second cooling unit, a fourth slitter and a winding machine, which are arranged in series,

[0012] the first and second cutting machines are pendulum type cutting machines, the third cutting machine is a drum or crank type cutting machine, the fourth cutting machine is a high-speed cutting machine, the first and second heating devices are electric induction heating furnaces that use a transverse and longitudinal magnetic step heating method with uniform temperature distribution, the heating unit of the first heating device contains 2-7 transverse magnets and 1 longitudinal magnet, and the heating unit of the second heating device contains 8-10 transverse magnets and 1-2 longitudinal magnets, the installation location of the discharging stacking device is provided with a heat-insulating casing with a burner that uses excess industrial gas generated during the preceding operations of iron and steel production before the said continuous casting operation of the workpiece,to implement energy-saving heating of the edge of the rolled workpiece and the function of compensating the average temperature of the reverse temperature field,

[0013] The first descaling device is a medium-pressure water descaling mechanism with a descaling pressure range of 13-28 MPa, the second descaling device is a high-pressure water descaling mechanism with a descaling pressure range of 35-40 MPa, the first descaling device is a multi-functional device with two working modes, when the need for descaling is high, the on-line descaling function is turned on, and when the need for descaling is low, the off-line descaling nozzle anti-clogging function is turned on,

[0014] The first cooling unit is an ultra-rapid cooling device, and the second cooling unit is a laminar cooling device; the first cooling unit has two working modes. When using thermomechanically controlled rolling and controlled cooling in the high-temperature rolling of austenite and low-temperature rolling of ferrite on-line, the cooling of the ultra-rapid cooling device is turned on; when using controlled rolling of the recrystallization type and controlled cooling in the high-temperature rolling of austenite, the ultra-rapid cooling device is turned on in an off-line mode to prevent clogging of the nozzles;

[0015] The continuous casting machine is a straight-line continuous casting machine equipped with 11-15 fan-shaped segments, the roughing stand group of the rolling mill is composed of three four-high stands with the function of controlling the convexity of the movable rolls, the diameter of the working rolls is 825-735mm, the stroke of the movable rolls is ±100mm to ensure that the intermediate blanks are less than 6mm thick, and the convexity of the incoming materials for finish rolling, and the winding machine is a quickly switchable winding machine with two working modes and two winding drums.

[0016] In a second aspect of the present invention, there is provided a method for producing strip steel with a thickness of 0.6 to 4 mm by continuous casting and endless rolling using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to claim 1, characterized in that it includes the following steps performed sequentially:

[0017] After the molten metal is solidified into a billet through continuous casting, it is descaled with medium-pressure water to remove the iron oxide scale on the surface of the billet, then it is heated for the first time and temperature equalized before entering the rough rolling to complete the first rolling deformation and roll the billet into an intermediate billet; after heat insulation, the billet enters the second preheating and temperature equalization, and then high-pressure hydrotreating to complete the second step of iron oxide descaling; after that, it is directly entered into the ultra-rapid pre-cooling device to reduce the temperature of the intermediate billet, the second rolling deformation is completed after entering the finish rolling to roll the intermediate billet into strip steel that meets the requirements of the finished products;then the strip steel undergoes heat treatment using the laminar cooling method, and the fourth cutter completes cutting the strip steel into rolls, after which the strip steel goes to the winding stage and is wound into a steel roll.

[0018] In a third aspect of the present invention, there is provided a method for producing strip steel by continuous rolling using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to claim 1, characterized in that it includes the following steps performed sequentially:

[0019] After the molten metal is solidified into a billet through continuous casting, it is descaled with medium pressure water to remove the iron oxide scale on the surface of the billet, then it is heated for the first time and temperature equalized before entering the rough rolling to complete the first rolling deformation and rolling of the billet into an intermediate billet, then the intermediate billet enters the second slitter where it is cut into the rolling length, after heat insulation, if the speed of the intermediate billet exceeds the speed of the second slitter, it enters the third slitter to complete the longitudinal cutting of the intermediate billet, then it enters the second heating and temperature equalization, and then high pressure hydrocleaning to complete the second step of iron oxide descaling,After that, it directly enters the ultra-rapid pre-cooling device to reduce the temperature of the intermediate blank to a suitable temperature range, the second rolling deformation is completed after entering the finish rolling to roll the intermediate blank into strip steel that meets the requirements of the finished products; then the strip steel undergoes heat treatment by laminar cooling, and the fourth slitter completes cutting the strip steel into coils, after that, the strip steel enters the winding stage and is wound into a steel coil.

[0020] In a fourth aspect of the present invention, there is provided a method for producing a solid blank of strip steel using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to claim 1, characterized in that it includes the following steps performed sequentially:

[0021] After the molten metal is solidified into a billet through continuous casting, it enters the first slitter, which cuts the continuously cast billet into solid blanks of fixed length, after descaling with medium pressure water to remove iron oxide scale on the surface of the billet, it enters the first heating and temperature equalization, and then rough rolling to complete the first rolling deformation and rolling of the billet into an intermediate billet, after heat insulation, the billet enters the third slitter to complete the cutting of the head and tail of the intermediate billet, and then the second heating and temperature equalization, then it enters the high pressure hydrocleaning to complete the second step of iron oxide scale removal,After that, it directly enters the ultra-rapid pre-cooling device to reduce the temperature of the intermediate blank to a suitable temperature range, the second rolling deformation is completed after entering the finishing rolling to roll the intermediate blank into strip steel that meets the requirements of the finished products; then the strip steel undergoes heat treatment by laminar cooling method, and finally, the strip steel enters the winding stage and is wound into a steel coil.

[0022] In a fifth aspect of the present invention, there is provided a method for producing a solid blank of strip steel using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to claim 1, characterized in that it includes the following steps performed sequentially:

[0023] After the molten metal is solidified into a billet through continuous casting, it is descaled with medium pressure water to remove the iron oxide scale on the surface of the billet, then it enters the first heating and temperature equalization, after rough rolling to complete the first rolling deformation and rolling of the billet into an intermediate billet, it enters the second cutting machine to complete the cutting of the intermediate billet, and finally enters the discharging stacking device to remove the finished products from the production line.

[0024] In a sixth aspect of the present invention, there is provided a method for producing a solid blank of strip steel using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to claim 1, characterized in that high-temperature rolling of austenite or low-temperature rolling of ferrite is carried out, wherein the high-temperature rolling of austenite is carried out by controlled rolling and controlled cooling of a recrystallization type or a thermomechanically controlled rolling and controlled cooling process;

[0025] When using controlled rolling and controlled cooling of the recrystallization type, the continuous casting output temperature range is 1020-1050°C, the rough rolling input temperature range is 1050-1180°C, and the finish rolling input temperature range is 1020-1100°C;

[0026] When using thermomechanically controlled rolling and controlled cooling process, the continuous casting output temperature range is 1020-1050°C, the rough rolling input temperature range is 1050-1180°C, and the finish rolling input temperature range is 980-1050°C;

[0027] When using the low temperature ferrite rolling process, the continuous casting output temperature range is 1020-1050°C, the rough rolling input temperature range is 1000-1050°C, and the finish rolling input temperature range is 800-900°C.

[0028] In one preferred embodiment, when using controlled rolling and controlled cooling of the recrystallization type, the range of the input temperature of the rough rolling of carbon steel is 1050-1080°C, and the range of the input temperature of the finish rolling is 1020-1050°C; the range of the input temperature of the rough rolling of alloy steel is 1080-1180°C, and the range of the input temperature of the finish rolling is 1050-1100°C.

[0029] In another preferred embodiment, when using a thermomechanically controlled rolling and controlled cooling process, the range of the rough rolling input temperature of carbon steel is 1050-1080°C, and the range of the finish rolling input temperature is 980-1000°C; the range of the rough rolling input temperature of alloy steel is 1080-1180°C, and the range of the finish rolling input temperature is 1000-1050°C.

[0030] In another preferred embodiment, when using low-temperature rolling of ferrite, the range of the input temperature of finish rolling is 840-860°C.

[0031] The implementation of a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm and methods for producing strip steel and solid blanks thereof, provided by the present invention, has the following beneficial effects:

[0032] (1) A multifunctional continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm disclosed in the present invention includes a first slitter installed at the outlet of a continuous casting section, this first slitter serves as a backup and is flexibly allocated depending on the production situation: the first slitter participates in production only when production requires rolling a solid billet, and is in a standby mode at other times.For example, rolling special steel grades requires a narrow rolling deformation temperature range, high deformation efficiency, and high rolling speed; the use of solid billet rolling allows for the separation of steel rolling from continuous casting, enabling high-speed rolling and achieving an ideal product structure; for example, when switching to endless rolling, the initial and final blanks of a continuous casting ladle can be experimentally produced using solid billet rolling, further increasing the yield.Additionally, a temporary buffer zone can be created for subsequent operations in case of emergencies; for example, if a rough rolling mill or pendulum cutting machine fails, the first cutting equipment can be activated before the discharge stacker. This avoids emergencies such as sudden stoppages of upstream processes and continuous casting stagnation, reduces downtime, increases productivity, and reduces the number of defective slabs per ton of steel.

[0033] (2) The multifunctional continuous casting and endless rolling production plant for hot-rolled strip steel disclosed in the present invention is provided with a medium-pressure water descaling mechanism and a high-pressure water descaling mechanism downstream of the first cutting device and the second heating device, respectively, the descaling pressure ranges are 13-28 MPa and 35-40 MPa, respectively; unlike the ESP production line, which is only provided with a high-pressure water descaling mechanism upstream of the finishing stand, the multi-point descaling configuration of the present invention can effectively remove iron oxide scale and improve the surface quality of the strip steel.Iron oxide scale on the surface of continuously cast workpieces is a spindle-shaped primary scale with large cavities inside, which is relatively easy to remove. Using a medium-pressure water descaling machine with a pressure of 13-28 MPa not only effectively removes the scale but also, thanks to the lower water pressure, avoids excessive reduction in the workpiece temperature, which facilitates rough rolling and saves energy. Iron oxide scale on the surface of workpieces before finish rolling is a ribbon-shaped secondary scale that is difficult to remove, so a high-pressure water descaling machine with a pressure of 35-40 MPa is used.In addition, the first scale removal device provided by the present invention is a multifunctional device with two operating modes, in which the scale removal function is activated in the operating mode for special grade steel and alloy steel with high scale removal requirements on-line, and the function of preventing nozzle clogging from scale in an autonomous mode is activated in the operating mode for ordinary carbon steel with low scale removal requirements.

[0034] (3) The multifunctional continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm disclosed in the present invention uses induction heating with a block with 2 to 4 transverse magnets + 1 longitudinal magnet, which is located after the first scale removal mechanism.Generally, the temperature drop rate of air cooling after continuous casting is about 2°C / m, and the temperature drop of pressurized water dephosphorization in the first dephosphorization is about 15-20°C; according to this patent, the distance from continuous casting to rough rolling takes into account a total temperature drop of 40-50°C in the first descaling, unlike the ESP heating arrangement without a heating device and the QSP without a tunnel furnace, the present invention takes into account the high temperature requirements of rough rolling of special grade steel and fully considers the aspect of energy saving, for additional heating before the rough stand, an induction heating unit with 2-4 transverse magnets + 1 longitudinal magnet is provided, which heats the continuous casting billet to a predetermined rough rolling temperature range before rolling.Before additional heating, the continuous casting blank is in a state of reverse temperature field with a high core temperature and a low surface temperature. The placement of an induction heating block with 2-4 transverse magnets and 1 longitudinal magnet also helps solve the problem of temperature unevenness in the continuous casting blank, which contributes to improved product performance.In addition, the heat-insulating casing on the discharge stacking device used in the present invention is equipped with an insulating cover with a burner, and excess coal gas, natural gas and other combustible gases used in previous processes of iron and steel production are used as the gas for the burner; the purpose is to use excess production gas for uniform heating of the edges and all intermediate blanks, reducing cracks on the edges, improving overall mechanical properties and reducing energy losses during subsequent electric induction heating.

[0035] (4) The multifunctional continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm disclosed in the present invention uses an induction heating unit with 8 to 10 transverse magnets + 1 to 2 longitudinal magnets, high-pressure water descaling and an ultra-rapid cooling device, which are arranged between the third cutting unit and the finishing stand; first, the intermediate workpiece after rough rolling is rapidly heated to a high temperature above 1,100°C to improve the descaling effect by the high-pressure water descaling mechanism, and then the strip steel is pre-cooled to an appropriate temperature range by the ultra-rapid cooling device.The ultra-rapid cooling device used in the present invention has two operating modes: when using the high-temperature austenite rolling technology with thermomechanically controlled rolling and cooling or the low-temperature ferrite rolling technology, the ultra-rapid cooling device operates in the on-line cooling mode. When using the high-temperature austenite rolling technology with controlled rolling and controlled recrystallization-type cooling, the ultra-rapid cooling device operates in the offline mode to prevent nozzle clogging.

[0036] (5) The multifunctional continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm disclosed in the present invention uses a winding device with a fast changeover capability, which is located after the high-speed chopping shear, which can achieve stable winding of strip steel with a thickness of 0.6 to 4 mm; this winding device has a single-drive double-drum structure, since it is located close to the pressure roller at the outlet of the high-speed chopping shear, and the dual-mode drum can change the position of 180 degrees, this can realize smooth switching between the front and rear rolls at the outlet of the high-speed chopping shear, ensuring stable bundle winding of strip steel with a thickness of 0.6 to 4 mm.

[0037] (6) The multifunctional continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm disclosed in the present invention uses three four-high stands with a large roll diameter, high rigidity and a strip convexity control function as the roughing stand of the rolling mill, the maximum reduction pressure is 40,000-43,000 kN, the diameter of the working rolls is 825-735 mm, the stroke of the movable rolls is ±100 mm, which ensures the production of intermediate blanks with a thickness of less than 6 mm and good convexity of the incoming materials for finish rolling.

[0038] Description of the attached graphic materials

[0039] The present invention is described in more detail below with the help of the accompanying drawings and embodiments, where:

[0040] Fig. 1 shows a layout diagram of a multifunctional continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm, provided by the present invention;

[0041] Fig. 2 shows a flow chart of the production mode of endless rolling of strip steel with a thickness of 0.6 to 4 mm in the present embodiment;

[0042] Fig. 3 shows a flow chart of the continuous rolling production mode of strip steel in the present embodiment;

[0043] Fig. 4 is a diagram showing a production mode for rolling a solid strip steel blank in the present embodiment;

[0044] Fig. 5 is a diagram of a mode for producing medium and thick plates in the present embodiment;

[0045] Fig. 6 is a diagram of a continuous casting production mode of a blank in the present embodiment;

[0046] where: 1. continuous casting machine; 2. first slitter; 3. first scale remover; 4. first heating device; 5. roughing mill; 6. second slitter; 7. discharge stacking device; 8. third slitter; 9. second heating device; 10. second scale remover; 11. first cooling unit; 12. finishing stand; 13. second cooling unit; 14. fourth slitter; 15. quickly changeover winding machine; 16. heat-insulating jacket with burner.

[0047] Specific embodiments

[0048] In order to more clearly illustrate the technical features, objectives and effects of the present invention, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] As shown in Fig. 1, a multifunctional continuous casting and endless rolling production plant for ultra-thin strip steel includes a continuous casting machine 1, a first slitter 2, a first scale remover 3, a first heating device 4, a roughing mill 5, a second slitter 6, a discharge stacking device 7, a third slitter 8, a second heating device 9, a second scale remover 10, a first cooling unit 11, a finishing stand 12, a second cooling unit 13, a fourth slitter 14 and a winding machine 15, which are arranged in series.

[0050] In the present invention, it is preferable that the above-mentioned first 2 and second cutters 6 are pendulum type cutters, the third cutter 8 is an emergency cutter, preferably a drum rotary cutter, the fourth cutter 14 is a high-speed chopping cutter; it is preferable that the first scale removing device 3 is a medium-pressure water scale removing mechanism with a scale removal pressure range of 13-28 MPa, the second scale removing device 10 is a high-pressure water scale removing mechanism with a scale removal pressure range of 35-40 MPa; it is preferable that the first refrigeration unit 11 is an ultra-rapid cooling device, and the second refrigeration unit 13 is a laminar cooling device;the first heating device 4 and the second heating device 9 are induction heating furnaces, wherein the number of heating elements of the first heating device 4 is 2-8 blocks, preferably 2-4 transverse magnets + 1 longitudinal magnet, the second heating device 9 has 10-12 heating elements; the releasing stacking device 9 is provided with a heat-insulating casing with a burner 16; the continuous casting machine 1 is a straight-line continuous casting machine equipped with 13 fan-shaped segments, the winding machine 15 is a quickly switchable winding machine; the roughing mill 5 and the finishing stand 12 are a four-high stand, the roughing mill 5 has three columns, and the finishing stand 12 has five columns.

[0051] Implementation option 1:

[0052] Figure 2 is a flow chart of the production mode of endless rolling of ultra-thin strip steel described in the present invention, which can be used for the fully continuous production of ultra-thin strip steel with a finished product thickness of less than 4 mm and a minimum thickness of 0.6 mm. This method includes the following steps performed sequentially: continuous casting, descaling, heating, rough rolling, heat insulation, heating, descaling, pre-cooling, finish rolling, laminar cooling, cutting and winding. Specific implementation steps are as follows:

[0053] First, the continuous casting machine 1 casts the continuous casting billet (continuous casting) - the continuous casting billet passes through the medium pressure water descaling device 3 to remove the primary iron scale on the surface (descaling) - the continuous casting billet passes through the induction heating furnace 4 with 2-4 transverse magnets + 1 longitudinal magnet for supplementary heating (heating) - after rolling on the roughing mill 5 with a large reduction, an intermediate billet is obtained (rough rolling) - the intermediate billet sequentially passes through the heat-insulating jacket 16 with supplementary heating function and the induction heating furnace 9 with 8-10 transverse magnets + 1-2 longitudinal magnets for rapid supplementary heating (heat insulation,heating) - secondary iron scale is removed by a high-pressure water scale remover 10 (scale removal) - cooling to a predetermined final temperature by an ultra-rapid cooling device 11 (pre-cooling) - after entering the finishing stand 12, hot-rolled finished strip steel is obtained (finish rolling) - after cooling in a laminar cooling system 13 (laminar cooling) and high-speed chopping 14 (cutting), the strip steel is wound into a roll by a winding machine 15 (winding).,

[0054] The above embodiment uses three roughing mills to roll a continuous casting blank with a thickness of 70-130 mm into an intermediate blank with a thickness of 6-20 mm. Five finishing stands are used to roll the intermediate blank with a thickness of 6-20 mm into ultra-thin finished strip steel with a minimum thickness of 0.6 mm. In the above process, the pendulum cutting machine 2, pendulum cutting machine 6, discharge stacker 7, and emergency cutting machine 8 are not involved; before the high-speed cutting machine 14, the strip steel is a continuous solid piece, so this production mode is called the endless rolling method of ultra-thin strip steel.

[0055] Implementation option 2:

[0056] Fig. 3 is a flow chart of the semi-continuous rolling process of ultra-thin strip steel described in the present invention, which can be used to produce strip steel with a thickness of 2-10 mm. This method includes the following steps, performed sequentially: continuous casting, descaling, heating, rough rolling, cutting, heat insulation, heating, descaling, pre-cooling, finish rolling, laminar cooling, cutting and winding. Specific implementation steps are as follows:

[0057] First, the continuous casting machine 1 casts the continuous casting billet (continuous casting) - the continuous casting billet passes through the medium pressure water descaling device 3 to remove the primary iron scale on the surface (descaling) - the continuous casting billet passes through the induction heating furnace 4 with 2-4 transverse magnets + 1 longitudinal magnet for additional heating (heating) - after rolling by the roughing mill 5 with a large reduction, an intermediate billet is obtained (rough rolling) - the intermediate billet is first subjected to pendulum cutting 6 according to the size of one or more steel coils (cutting), if the speed of the intermediate billet exceeds the range of pendulum cutting 6,then the intermediate blank is subjected to emergency cutting 8 according to the size of one or more steel coils - then the cut intermediate blank sequentially passes through the heat-insulating casing 16 with the function of additional heating and the induction heating furnace 9 with 8-10 transverse magnets + 1-2 longitudinal magnets for rapid additional heating (heat insulation, heating) - the secondary iron scale is removed by the high-pressure water scale remover 10 (scale removal) - cooling to a predetermined final temperature by the ultra-rapid cooling device 11 (pre-cooling) - after entering the finishing stand 12, hot-rolled finished strip steel is obtained (finish rolling) - after cooling in the laminar cooling system 13 (laminar cooling) and high-speed chopping 14 (cutting), the strip steel is wound into a roll by the winding machine 15 (winding).,

[0058] In the above process, the pendulum cutting device 2, the discharge stacking device 7, and the emergency cutting device 8 (depending on the speed of the intermediate billet) are not involved; although the continuous casting billet and the intermediate billet are separated, the intermediate billet and the hot-rolled strip steel are continuous, so this strip steel production method is called the semi-continuous rolling method of ultra-thin strip steel.

[0059] Implementation option 3:

[0060] Figure 4 is a flow chart of the production mode of rolling a solid blank of strip steel described in the present invention, which can be used for the production of strip steel with a thickness of 4-12.7 mm. This method includes the following steps performed sequentially: continuous casting, cutting, descaling, heating, rough rolling, heat insulation, heating, descaling, pre-cooling, finish rolling, laminar cooling, cutting and winding. Specific implementation steps are as follows:

[0061] First, the continuous casting machine 1 casts the continuous casting billet (continuous casting) - the continuous casting billet is subjected to pendulum cutting 2, where it is cut into solid billets according to the size of one or more steel coils (cutting) - the continuous casting solid billets pass through a medium pressure water descaling device 3 to remove the primary iron scale on the surface (descaling) - passes through an induction heating furnace 4 with 2-4 transverse magnets + 1 longitudinal magnet for additional heating (heating) - after rolling on a roughing mill 5 with a large reduction, an intermediate billet is obtained (rough rolling) - the intermediate billet sequentially passes through a heat-insulating jacket 16 with additional heating function and an induction heating furnace 9 with 8-10 transverse magnets + 1-2 longitudinal magnets for fast additional heating (thermal insulation,heating) - secondary iron scale is removed by a high-pressure water scale remover 10 (scale removal) - cooling to a predetermined finish rolling temperature by an ultra-rapid cooling device 11 (pre-cooling) - after entering the finishing stand 12, hot-rolled finished strip steel is obtained (finish rolling) - after cooling in the laminar cooling system 13 (laminar cooling), the strip steel is wound into a roll by a winding machine 15 (winding).,

[0062] In the above process, the pendulum cutting machine 6, the discharge stacking device 7 and the emergency cutting machine 8 are not involved; the continuous casting blank is supplied to the hot rolling line as a solid block, so this production mode is called the strip steel solid blank rolling mode.

[0063] In the above-mentioned ultra-thin strip steel endless rolling process, ultra-thin strip steel semi-continuous rolling process, and strip steel solid blank rolling process, any of the high-temperature austenite rolling and low-temperature ferrite rolling technologies can be adopted. The high-temperature austenite rolling technology is divided into the recrystallization-type controlled rolling and controlled cooling technology and the thermomechanical rolling and cooling technology. The specific production process is as follows:

[0064] A. Using the high-temperature austenite rolling technology of controlled rolling and controlled cooling of the recrystallization type, the continuously casting workpiece is heated to 1050-1180°C in an induction heating furnace 4 with a group of 2-4 transverse magnets + 1 longitudinal magnet, and it is preferable that the temperature range of ordinary carbon steel is 1050-1080°C, and the temperature range of alloy steel is 1080-1180°C. The intermediate workpiece is heated to a temperature of 1100-1200°C in an induction heating furnace 9 with a group of 8-10 transverse magnets + 1-2 longitudinal magnets, after removing scale with high-pressure water, the range of the input temperature of finish rolling is 1020-1100°C, while it is preferable that the temperature range of ordinary carbon steel is 1020-1050°C, and the temperature range of alloy steel is 1050-1100°C.

[0065] In the above process, the roughing and finishing rolling temperatures are in the high-temperature zone above the dynamic recrystallization temperature line. Dynamic recrystallization refining of austenite will occur throughout the rolling process. Because ordinary carbon steel contains fewer alloying elements, controlling the rolling temperature in the lower recrystallization temperature range avoids abnormal coarsening of austenite grains and improves the grain size of the strip steel. Because alloy steel contains more alloying elements and austenite grains are not prone to abnormal coarsening, controlling the rolling temperature in the higher recrystallization temperature range reduces the rolling pressure and saves energy consumption. Therefore, the above rolling technology is called controlled rolling and controlled cooling recrystallization type technology.

[0066] B. Using the high-temperature austenite rolling technology with thermomechanically controlled rolling and cooling, the continuous casting workpiece is heated to 1050-1180°C in an induction heating furnace 4 with a group of 2-4 transverse magnets + 1 longitudinal magnet, and it is preferable that the temperature range of ordinary carbon steel is 1050-1080°C, and the temperature range of alloy steel is 1080-1180°C. The intermediate workpiece is heated to a temperature of 1100-1200°C in an induction heating furnace 9 with a group of 8-10 transverse magnets + 1-2 longitudinal magnets, and after removing scale with high-pressure water, it is pre-cooled to 980-1020°C in an ultra-rapid cooling device, while it is preferable that the temperature range of ordinary carbon steel is 980-1000°C, and the temperature range of alloy steel is 1000-1020°C.

[0067] In the above process, the rough rolling temperature is above the dynamic recrystallization temperature line, and the finish rolling temperature is near the dynamic recrystallization temperature line. Therefore, dynamic recrystallization refining will occur in the rough rolling deformation zone, subdynamic recrystallization and static recrystallization refining will occur in the air cooling zone between the stands, and a small amount of dynamic recrystallization refining will occur in the finish rolling deformation zone. The deformation will accumulate in the austenite structure, forming work-hardened austenite. During subsequent cooling, the crystals will be refined due to subdynamic recrystallization, static recrystallization, and deformation-induced phase transformation. Therefore, the above rolling technology is called thermomechanically controlled rolling and cooling technology.

[0068] When using the low-temperature ferrite rolling technology, the continuous casting blank is heated to 1000-1050°C in an induction heating furnace 4 with a group of 2-4 transverse magnets + 1 longitudinal magnet, the intermediate blank is heated to a temperature of 1100-1200°C in an induction heating furnace 9 with a group of 8-10 transverse magnets + 1-2 longitudinal magnets, and after descaling with high-pressure water, the intermediate blank is pre-cooled to 800-900°C in an ultra-rapid cooling device, preferably the temperature is 840-860°C.

[0069] In the above process, the rough rolling temperature is in the low temperature range above the dynamic recrystallization temperature line. Due to the deformation caused by large reduction during rough rolling, the deformation should be above the recrystallization temperature line to reduce the deformation force, protect the equipment, and save energy consumption. However, when rolling ferrite, the rough rolling temperature should not be too high. A lower deformation temperature can reduce the deformation energy consumption for recovery and recrystallization, and also increase the ferrite nucleation coefficient in the subsequent finish rolling. The input temperature range of finish rolling is 800-900°C, preferably 840-860°C. This temperature range represents the two-phase region where ferrite is just beginning to nucleate, and the deformation resistance is minimal.

[0070] When using the high-temperature austenite rolling technology with controlled rolling and controlled cooling of the recrystallization type, the ultra-rapid cooling device is not used. When using the high-temperature austenite rolling technology with thermomechanically controlled rolling and cooling and the low-temperature ferrite rolling technology, the ultra-rapid cooling device is activated to precisely control the temperature by adjusting the amount of water.

[0071] Implementation option 4:

[0072] Fig. 5 is a flow chart of the medium thickness sheet production mode described in the present invention, which can be used for custom production and in case of finishing stand failure of medium thickness sheets with a finished product thickness of 6-20 mm, and mainly includes the following steps: continuous casting, heating, descaling, rough rolling, cutting and product release from a conveyor.

[0073] When the medium thickness sheet needs to be produced, the continuous casting machine 1 first casts the continuous casting billet (continuous casting) - the continuous casting billet passes through the medium pressure water descaling device 3 to remove the primary iron scale on the surface (descale) - the continuous casting billet passes through the induction heating furnace 4 with 2-4 transverse magnets + 1 longitudinal magnet for additional heating (heating) - after rolling on the roughing mill 5 with a large reduction, an intermediate billet is obtained (rough rolling) - the intermediate billet is subjected to pendulum cutting 6 according to the set length of the medium thickness sheet (cutting) - and finally, the discharging stacking device 7 discharges the finished medium thickness sheets from the production line (discharge of products from the conveyor).

[0074] When the finishing stand fails, the finishing mill frame rises to form a roll gap, continuous casting continues, pendulum cutting 6 and emergency cutting 8 operate simultaneously. The emergency cutting 8 breaks the rolled blank between pendulum cutting 6 and emergency cutting 8, and the scrap is then stored in the scrap storage area. Meanwhile, the intermediate blank before pendulum cutting 6 is subjected to pendulum cutting 6 according to the specified length of the medium-thickness sheet. Finally, the discharge stacker 7 releases the finished medium-thickness sheets from the production line. After the accident has been rectified, the strip steel will be re-threaded and rolled in accordance with the above-described production mode.

[0075] Implementation option 5:

[0076] Fig. 6 shows a flow chart of the continuous casting blank production mode described in the present invention, which can be used for custom production and in case of failure of the roughing mill of continuous casting blanks with a thickness of 70-130 mm, and mainly includes the following steps: continuous casting, cutting and releasing products from a conveyor.

[0077] When it is necessary to produce continuous casting blanks, firstly, the continuous casting machine 1 casts the continuous casting blank (continuous casting) - the continuous casting blank is subjected to pendulum cutting 2 according to the set length of the continuous casting blank (cutting) - and finally, the discharging stacking device 7 discharges the finished continuous casting blanks from the production line (discharging products from the conveyor).

[0078] When the roughing mill fails, the roughing mill frame rises to form a roll gap, continuous casting continues, pendulum cutting 2 and emergency cutting 8 operate simultaneously. Emergency cutting 8 breaks the rolled blank between pendulum cutting 2 and emergency cutting 8, and the scrap is then stored in the scrap storage area. At the same time, the continuously casted blank is subjected to pendulum cutting 2 according to the specified length, and finally, the discharge stacker 7 releases the finished continuously casted blanks from the production line. After the accident is resolved, the strip steel will be re-threaded and rolled in accordance with the above-described production mode.

[0079] The embodiments of the present invention are described above together with the accompanying drawings, however, the present invention is not limited to the above-mentioned specific embodiments; the above-mentioned specific embodiments are merely illustrative and do not limit the present invention; using the present invention, those skilled in the art can also create a variety of forms without departing from the principles and claims of the present invention, which fall within the protection scope of the present invention.

Claims

1. A continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm, characterized in that it comprises a continuous casting machine, a first slitter, a first scale remover, a first heating device, a rough rolling mill, a second slitter, a release stacking device, a third slitter, a second heating device, a second scale remover, a first cooling unit, a finishing stand, a second cooling unit, a fourth slitter and a winding machine, which are arranged in series, the first and second cutters are pendulum-type cutters, the third cutter is a drum or crank cutter, the fourth cutter is a high-speed cutter, the first and second heating devices are electric induction heating furnaces that use a method of transverse and longitudinal magnetic step heating with a uniform temperature distribution, the heating unit of the first heating device contains 2-7 transverse magnets and 1 longitudinal magnet, and the heating unit of the second heating device contains 8-10 transverse magnets and 1-2 longitudinal magnets, the installation location of the releasing stacking device is equipped with a heat-insulating casing with a burner that uses excess industrial gas generated during previous operations of iron and steel production before the said operation of continuous casting of the workpiece,to implement energy-saving heating of the edge of the rolled workpiece and the function of compensating the average temperature of the reverse temperature field, The first descaling device is a medium-pressure water descaling mechanism with a descaling pressure range of 13-28 MPa, the second descaling device is a high-pressure water descaling mechanism with a descaling pressure range of 35-40 MPa, the first descaling device is a multifunctional device with two working modes, when the need for descaling is high, the on-line descaling function is turned on, and when the need for descaling is low, the offline nozzle clogging protection function is turned on, the first refrigeration unit is an ultra-rapid cooling device, and the second refrigeration unit is a laminar cooling device; the first refrigeration unit has two operating modes, when using thermomechanically controlled rolling and controlled cooling in the high-temperature rolling process of austenite and low-temperature rolling of ferrite on the line, the cooling of the ultra-rapid cooling device is turned on; when using controlled rolling of the recrystallization type and a controlled cooling process in the high-temperature rolling process of austenite, the ultra-rapid cooling device is turned on in an autonomous mode to prevent clogging of the nozzles; The continuous casting machine is a straight-line continuous casting machine equipped with 11-15 fan-shaped segments, the roughing stand group of the rolling mill consists of three four-high stands with the function of controlling the convexity of the movable rolls, while the diameter of the working rolls is 825-735 mm, the stroke of the movable rolls is ±100 mm to ensure the production of intermediate blanks with a thickness of less than 6 mm, and the convexity of the incoming materials for finish rolling, and the winding machine is a quickly switchable winding machine with two working modes and two winding drums.

2. A method for producing strip steel with a thickness of 0.6 to 4 mm by continuous casting and endless rolling using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to paragraph 1, characterized in that it includes the following steps performed sequentially: After the molten metal is solidified into a billet by continuous casting, it is descaled by medium-pressure water to remove the iron oxide scale on the surface of the billet, then it is heated for the first time and temperature equalized before entering the rough rolling to complete the first rolling deformation and roll the billet into an intermediate billet; after heat insulation, the billet is sent to the second preheating and temperature equalization, and then to high-pressure hydrocleaning to complete the second step of removing iron oxide scale; after that, it is directly entered into the ultra-rapid pre-cooling device to reduce the temperature of the intermediate billet, the second rolling deformation is completed after entering the finish rolling to roll the intermediate billet into strip steel meeting the requirements of finished products;then the strip steel undergoes heat treatment using the laminar cooling method, and the fourth cutter completes cutting the strip steel into rolls, after which the strip steel goes to the winding stage and is wound into a steel roll.

3. A method for producing strip steel by continuous rolling using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to paragraph 1, characterized in that it includes the following steps performed sequentially: After the molten metal is solidified into a billet by continuous casting, it is descaled with medium-pressure water to remove the iron oxide scale on the surface of the billet, then it is heated for the first time and temperature equalized before entering the rough rolling to complete the first rolling deformation and rolling of the billet into an intermediate billet, then the intermediate billet enters the second slitter where it is cut into the rolling length, after heat insulation, if the speed of the intermediate billet exceeds the speed of the second slitter, it enters the third slitter to complete the longitudinal cutting of the intermediate billet, then it enters the second heating and temperature equalization, and then high-pressure hydrocleaning to complete the second step of removing iron oxide scale,After that, it directly enters the ultra-rapid pre-cooling device to reduce the temperature of the intermediate blank to a suitable temperature range, the second rolling deformation is completed after entering the finish rolling to roll the intermediate blank into strip steel that meets the requirements of the finished products; then the strip steel undergoes heat treatment by laminar cooling, and the fourth slitter completes cutting the strip steel into coils, after that, the strip steel enters the winding stage and is wound into a steel coil.

4. A method for producing a solid blank from strip steel using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to paragraph 1, characterized in that it includes the following stages, performed sequentially: After the molten metal is solidified into a billet by continuous casting, it enters the first slitter, which cuts the continuously cast billet into solid billets of fixed length, after being descaled by medium pressure water to remove iron oxide scale on the surface of the billet, it enters the first heating and temperature equalization, and then the rough rolling to complete the first rolling deformation and roll the billet into an intermediate billet, after heat insulation, the billet enters the third slitter to complete the cutting of the head and tail of the intermediate billet, and then the second heating and temperature equalization, then it enters the high-pressure hydrocleaning to complete the second step of iron oxide scale removal, after which it directly enters the ultra-rapid pre-cooling device to reduce the temperature of the intermediate billet to a suitable temperature range,The second rolling deformation is completed after entering the finishing rolling mill to roll the intermediate blank into strip steel that meets the requirements of the finished product; then the strip steel undergoes heat treatment using the laminar cooling method, and finally, the strip steel enters the winding stage and is wound into a steel coil.

5. A method for producing a solid blank from strip steel using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to paragraph 1, characterized in that it includes the following stages, performed sequentially: After the molten metal is solidified into a blank by continuous casting, it is descaled by medium pressure water to remove the iron oxide scale on the surface of the blank, then it enters the first heating and temperature equalization, after rough rolling to complete the first rolling deformation and rolling of the blank into an intermediate blank, it enters the second cutting machine to complete the cutting of the intermediate blank, and finally enters the discharging stacking device to remove the finished products from the production line.

6. A method for producing a solid blank from strip steel using a continuous casting and endless rolling production plant for hot-rolled strip steel with a thickness of 0.6 to 4 mm according to paragraph 1, characterized in that high-temperature rolling of austenite or low-temperature rolling of ferrite is carried out, wherein the high-temperature rolling of austenite is carried out by controlled rolling and controlled cooling of the recrystallization type or a thermomechanically controlled rolling and controlled cooling process; When using controlled rolling and controlled cooling of the recrystallization type, the output temperature range of continuous casting is 1020-1050°C, the input temperature range of rough rolling is 1050-1180°C, and the input temperature range of finish rolling is 1020-1100°C; When using the thermomechanically controlled rolling and controlled cooling process, the continuous casting output temperature range is 1020-1050°C, the rough rolling input temperature range is 1050-1180°C, and the finish rolling input temperature range is 980-1050°C; When using the low-temperature ferrite rolling process, the continuous casting output temperature range is 1020-1050°C, the rough rolling input temperature range is 1000-1050°C, and the finish rolling input temperature range is 800-900°C.

7. The method according to claim 6, characterized in that when using controlled rolling and controlled cooling of the recrystallization type, the range of the input temperature of rough rolling of carbon steel is 1050-1080°C, and the range of the input temperature of finish rolling is 1020-1050°C; the range of the input temperature of rough rolling of alloy steel is 1080-1180°C, and the range of the input temperature of finish rolling is 1050-1100°C.

8. The method according to claim 6, characterized in that when using a thermomechanically controlled rolling process and controlled cooling, the range of the input temperature of rough rolling of carbon steel is 1050-1080°C, and the range of the input temperature of finish rolling is 980-1000°C; the range of the input temperature of rough rolling of alloy steel is 1080-1180°C, and the range of the input temperature of finish rolling is 1000-1050°C.

9. The method according to paragraph 6, characterized in that when using low-temperature rolling of ferrite, the range of the input temperature of the finish rolling is 840-860°C.

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