CN111394656A - A kind of hot-rolled coil and production method of hot-rolled coil - Google Patents

Abstract

The invention belongs to the technical field of metallurgy, in particular to a hot-rolled coil and a production method thereof; the chemical components of the material by weight percentage are as follows: c: 0.12-0.20%; mn: 0.25 to 0.31 percent; si: 0.23-0.3%; s: 0.045%; p: 0.045%; ca: 0.010-0.030%; n is less than or equal to 0.09 percent; and Als: 0.050-0.080%; and the ratio of Ca/Als is 0.15-0.3; cryolite powder: 0.3-0.50%; the balance being Fe; the method comprises the following steps: s1: a refining process; s2: a continuous casting process; s3: a hot rolling step; s4: a coiling step; the Ca/Als ratio is controlled to be 0.15-0.30, so that the phenomenon that a molten steel solution expands a rod during casting can be prevented, further, casting powder in a crystallizer is mixed into the molten steel solution, the phenomenon that produced hot-rolled coils are clamped, and further, the production quality problem of the hot-rolled coils is easy to occur.

Description

A kind of hot-rolled coil and production method of hot-rolled coil

technical field

The invention belongs to the technical field of metallurgy, in particular to a hot-rolled coil plate and a production method of the hot-rolled coil plate.

Background technique

Hot-rolled coils are made of slabs, which are mainly continuous casting billets. After heating, they are made into strips by rough rolling mills and finishing mills. The hot strips from the last rolling mill of finishing rolling are cooled by laminar flow. At a fixed temperature, the coil is rolled into a steel strip coil, and the cooled steel strip coil is leveled, straightened, cross-cut or longitudinally cut, inspected, weighed, and packaged by different finishing lines according to the different needs of users. And signs and other processing to become steel plate, flat roll and slit steel strip products.

The Chinese patent discloses a hot-rolled coil and a production method for the hot-rolled coil. The patent application number is 2018109706831; wherein, the hot-rolled coil, in terms of mass percentage, has the following chemical components: C 0.16-0.20%, Si0. 10～0.50%, Mn 1.20～1.50%, P≤0.030%, S≤0.030%, Nb 0.007～0.070%, Als0.020～0.050, Ca 0.0010～0.0030%, N≤0.009, the balance is Fe and other raw materials residual elements. Through the technical scheme of the present invention, the preparation process and method of a thick-gauge hot-rolled coil plate with a C-Mn-Nb low alloy and low cost are adopted.

Although the above-mentioned use of adding trace alloying elements, taking advantage of the 2250mm hot rolling production line, and using the controlled rolling and controlled cooling process, further achieves the matching of strength and plasticity through the fine grain strengthening mechanism, and improves the comprehensive mechanical properties of the material; but the existing hot rolled coils During the raw material ratio of the plate, if the raw materials put in are too large or the ratio is uneven, it will cause the phenomenon of slag inclusion defects in the production of the hot-rolled coil, which will lead to the reduction of the quality of the hot-rolled coil; At the same time, it is difficult to control the phenomenon of slag inclusion in the molten steel solution in the embryo shell when the hot-rolled coil plate is formed into the embryo shell by the existing production method of the hot-rolled coil.

SUMMARY OF THE INVENTION

In order to make up for the deficiencies of the prior art, the present invention proposes a hot-rolled coil and a production method for the hot-rolled coil. If the raw materials are too large or the ratio is uneven, it will cause the phenomenon of slag inclusion defects in the production of hot-rolled coils, which in turn leads to the phenomenon that the quality of hot-rolled coils is reduced; at the same time, the existing production methods of hot-rolled coils It is also difficult to control the phenomenon of slag inclusion in the molten steel solution in the embryo shell when the hot-rolled coil is formed into the shell.

The technical scheme adopted in the technical problem solved by the present invention is: a kind of hot-rolled coil of the present invention, its chemical composition, in weight percentage, is:

C: 0.12-0.20%; Mn: 0.25-0.31%; Si: 0.23-0.3%; S: 0.045%; P: 0.045%; Ca: 0.010-0.030%; N≤0.09%; Als: 0.050-0.080%; And the ratio of Ca/Als is 0.15-0.30; cryolite powder: 0.3-0.50%; the balance is Fe;

The added cryolite powder can eliminate the slag inclusion of ductile iron castings caused by magnesium sulfide and magnesium oxide, or add a part of it at the bottom of the bag and then add it on the surface of the molten steel solution;

Controlling the ratio of Ca/Als to 0.15 to 0.30 can prevent the steel solution from rising during the pouring process. If the steel solution expands during pouring, it will easily lead to large fluctuations in the molten steel entering the mold, and further As a result, the mold slag in the mold is mixed into the molten steel solution, resulting in the phenomenon of slag inclusion in the produced hot-rolled coil, which is prone to production quality problems of the hot-rolled coil.

The production method of a hot-rolled coil according to the present invention is suitable for the production of the above-mentioned hot-rolled coil; the method comprises the following steps:

S1: Refining process: LF furnace controls the process of slagging, deoxidation, desulfurization and removal of inclusions, adding ferromanganese, ferrosilicon and ferroniobium alloy to fine-tune the composition of molten steel according to the composition of molten steel, and the content of silicon is 0.5% higher than that of manganese; then RH vacuum refining device is used to refine molten steel; the content of silicon is controlled to be 0.5% higher than the content of manganese, in order to form slag with low melting point and easy to float in the steel metal solution, which is convenient for the mold slag in the mold. absorb;

S2: Continuous casting process: run the molten steel refined in step S1 into the ladle, and the molten steel solution in the ladle enters the intermediate tank through the drainage pipe. The injection pipe is injected into a group of water-cooled copper molds, and the molten steel gradually solidifies along the periphery of the mold into a billet shell. And through water spray cooling in the secondary cooling area to make the casting billet completely solidified; before pouring, it is necessary to blow argon and exhaust air to the intermediate tank, which can prevent the secondary oxidation phenomenon of molten steel entering the intermediate tank;

S3: Hot rolling process: Use a 1580 roughing mill as a four-high reversing rolling mill with vertical rolls in step S2, and roll 5 to 7 passes to reduce the billet to 25 to 50 mm; then the hot coil box is used for intermediate billets. For heat preservation, the rolling line adopts seven-point descaling, high-pressure water descaling ability is strong, and the working pressure is greater than or equal to 20MPa; then the rolled sheet with the scale removed is subjected to finishing rolling through the finishing mill;

S4: Coiling process: 1580 coiling equipment is used to coil the rolled sheet cooled in step S3;

Wherein, the crystallizer is composed of each composite wall plate and an inner wall copper plate and an outer wall steel cooling water tank connected by studs; a cooling groove is milled on the outer side of the inner wall copper plate; one side of the cooling water wash is provided There is a water inlet pipe, and the other side wall is provided with a water outlet pipe; the bottom end of the injection pipe extends into the copper plate of the inner wall, and a plurality of liquid guide holes are opened on the outer circumferential wall of the bottom end of the injection pipe; The liquid guiding nozzles are installed obliquely downward in the liquid guiding holes, and the plurality of liquid guiding nozzles are located below the liquid level of the molten steel solution; the bottom end of the injection pipe is provided with a diverting arc block, and the diverting arc block It is located at the nozzle position of the liquid guide nozzle; there is a mold slag layer above the molten steel solution on the inner wall of the inner wall copper plate; when working, when the molten steel solution enters the intermediate tank, it will enter the bottom end of the injection pipe, and the injection The diverter arc block set on the inner wall of the bottom end of the flow pipe will divert the molten steel solution into a plurality of downwardly inclined liquid guide nozzles, and then flow into the molten steel solution in the inner wall copper plate through the diverter nozzle. With the cooperation of two inclined liquid guide nozzles, the split arc block can evenly distribute the molten steel solution into the liquid guide nozzle, and then the liquid guide nozzle can evenly introduce the molten steel solution into the steel plate that is solidifying and forming the embryo shell inside the mold. , so that the molten steel solution can flow stably in the molten steel process, effectively preventing the molten steel solution from forming a columnar fluid impact due to the immersed injection pipe set in the existing mold, and the bottom end of the injection pipe is open. into the molten steel flow field of the mold, which will cause the molten steel flow field to roll upwards, which will easily cause the mold slag set on the upper surface of the molten steel flow field to cause confusion or downward precipitation in the state of molten steel rolling, which not only leads to production failure. The phenomenon of inclusion of mold slag in the hot-rolled coil will lead to the phenomenon that the mold slag layer forms a protective film on the upper surface of the molten steel flow field and ruptures, thereby affecting the protective effect of the mold slag layer on the molten steel flow field.

Preferably, the inclined angle formed by the liquid guiding nozzle and the molten steel surface above the liquid guiding nozzle is 21°-25°; the cross section of the liquid guiding nozzle is set to a square hole structure, and the liquid guiding nozzle of the square structure is The expansion angle of the nozzles is 12°~16°; the height of the top of the liquid guide nozzles from the bottom end face of the mold powder is 90~105mm; if the downward inclination angle of the liquid guide nozzles is too large, it will cause the liquid guide nozzles The sprayed molten steel solution is easy to impact on the shell being formed, which will cause the hot-rolled coil to be dented or have holes inside, thereby affecting the production quality of the hot-rolled coil; if the angle of the liquid guide nozzle is too small, It will cause the molten steel solution ejected from the liquid guide nozzle to impact above, causing the phenomenon of tumbling above the molten steel flow field. And because the fluidity of the molten steel solution in the mold is poor, the impact force of the molten steel solution in the molten steel flow field can be reduced, and the tumbling phenomenon of the molten steel flow field can be reduced.

Preferably, a limit slot is formed at the upper end of the inner wall copper plate, and a metal filter screen plate is slidably inserted into the limit slot; the metal filter screen plate is located in the mold slag layer; the mold slag layer includes a powder slag layer, a sintered layer and melting layer; the metal filter screen plate is located in the middle of the sintered layer; the set metal filter screen plate can make the mold slag form a stable protective film layer on the upper surface of the molten steel flow field, to prevent the mold slag from being loose, In turn, the formation time of the protective layer is poor, and the protective layer is unstable, which in turn affects the effect of the mold slag layer on the thermal insulation of the molten steel flow field. The non-metallic impurities on the steel slag interface can effectively prevent the slag inclusions floating in the molten steel solution from being involved in the solidification shell, thereby causing defects on the surface or lower skin of the hot-rolled coil; and the content of silicon is controlled to be higher than that of manganese. 0.5%, in order to form slag with low melting point and easy to float in the steel metal solution, so that the layered mold slag layer can better absorb.

Preferably, a plurality of slag guide pipes are arranged in the horizontal direction of the metal filter screen plate, and a plurality of nozzle holes are opened on the slag guide pipes; the ends of the plurality of lead pipes are connected through a communication pipe, and the communication pipe is connected to the outside world. The mold slag introduction pipe is connected; the mold slag of the mold slag layer can be injected into the slag guide pipe through the connecting pipe, and then evenly dispersed into the mold slag layer through the nozzle holes, and the dosage of the mold slag is controlled to be frequent, less and The principle of uniformity can reduce the phenomenon of slag adjustment bars; at the same time, it can prevent too much mold slag from being put in. Due to the influence of the metal filter, the mold slag cannot be completely melted on the upper surface of the molten steel flow field, which in turn causes the mold slag layer to become The phenomenon of precipitation, which in turn affects the solidification and crusting of the molten steel solution by the crystallizer.

Preferably, the mold powder of the mold powder layer is made of the following raw materials by weight: SiO ₂ : 45-60%; CaO: 30-50%; Al ₂ O ₃ : 5-15%; FeO : ≤1%; carbonaceous material: 2～5%;

Among them, SiO ₂ is easy to absorb TiO ₂ which is difficult to tolerate scum; CaO is easy to absorb Al ₂ O ₃ and Cr ₂ O ₃ ; FeO: ≤1% can reduce the oxidation of slag; carbonaceous material: 2-5% can be controlled It can prevent the phenomenon of rod expansion in the molten steel solution during pouring. If the phenomenon of rod expansion occurs during pouring, the mold slag in the mold will be mixed into the molten steel solution, resulting in the phenomenon of slag inclusion in the hot-rolled coil produced. In turn, production quality problems of hot-rolled coils are prone to occur.

The beneficial effects of the present invention are as follows:

1. The present invention can eliminate the slag inclusion of ductile iron castings caused by magnesium sulfide and magnesium oxide by adding cryolite powder; control the Ca/Als ratio to be 0.08 to 0.12, and the liquid can flow stably in the molten steel process, thereby preventing the molten steel flow field. The phenomenon of upward tumbling is generated, which effectively reduces the phenomenon of inclusion of mold slag in the produced hot-rolled coil. The content of silicon is controlled to be 0.5% higher than the content of manganese, in order to form slag with a low melting point and easy to float in the steel metal solution, thereby facilitating the absorption of the slag by the mold slag in the mold.

2. In the present invention, through the cooperation of setting a split arc block and a plurality of inclined liquid guide nozzles, the split arc block can evenly divide the molten steel solution into the liquid guide nozzle, and then the liquid guide nozzle can uniformly introduce the molten steel solution into the crystal. In the steel plate that is solidifying to form the embryo shell inside the device, the melting speed of molten molten slag is made.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is the production method flow chart of the hot-rolled coil of the present invention;

Fig. 2 is the perspective view of the crystallizer of the present invention;

Fig. 3 is the sectional view of the crystallizer of the present invention;

In the figure: crystallizer 1, inner wall copper plate 2, cooling tank 3, cooling water tank 4, water inlet pipe 5, injection pipe 6, liquid guide hole 7, liquid guide nozzle 8, shunt arc block 9, metal filter screen plate 10, guide Slag pipe 11 , nozzle hole 111 , communication pipe 12 .

Detailed ways

A hot-rolled coil and a method for producing a hot-rolled coil according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 3 .

Example 1:

The hot-rolled coil according to the embodiment of the present invention, in terms of mass percentage, its chemical composition is C: 0.16%; Mn: 0.27%; Si: 0.28%; S: 0.045%; P: 0.045%; Ca: 0.015% ; N: 0.09%; Als: 0.058%; cryolite powder: 0.3%; the rest is Fe; the hot-rolled coil is produced by the method for producing a hot-rolled coil of the present invention.

Embodiment 2:

The hot-rolled coil according to the embodiment of the present invention, in terms of mass percentage, its chemical composition is C: 0.16%; Mn: 0.27%; Si: 0.28%; S: 0.045%; P: 0.045%; Ca: 0.020% ; N: 0.09%; Als: 0.067%; cryolite powder: 0.38%; the rest is Fe; the hot-rolled coil is produced by the production method of the hot-rolled coil of the present invention.

Embodiment three:

The hot-rolled coil according to the embodiment of the present invention, in terms of mass percentage, its chemical composition is C: 0.16%; Mn: 0.27%; Si: 0.28%; S: 0.045%; P: 0.045%; Ca: 0.025% ; N: 0.09%; Als: 0.074%; cryolite powder: 0.44%; the rest is Fe; the hot-rolled coil is produced by the method for producing a hot-rolled coil of the present invention.

Embodiment 4:

The hot-rolled coil according to the embodiment of the present invention, in terms of mass percentage, its chemical composition is C: 0.16%; Mn: 0.27%; Si: 0.28%; S: 0.045%; P: 0.045%; Ca: 0.030% ; N: 0.09%; Als: 0.080%; cryolite powder: 0.50%; the rest is Fe; the hot-rolled coil is produced by the method for producing a hot-rolled coil of the present invention.

As shown in Figures 1 to 3, a method for producing a hot-rolled coil according to the present invention is suitable for the production of the above-mentioned hot-rolled coil; the method comprises the following steps:

S1: Refining process: LF furnace controls the process of slagging, deoxidation, desulfurization and removal of inclusions, adding ferromanganese, ferrosilicon and ferroniobium alloy to fine-tune the composition of molten steel according to the composition of molten steel, and the content of silicon is 0.5% higher than that of manganese; then RH vacuum refining device is used to refine molten steel; the content of silicon is controlled to be 0.5% higher than the content of manganese, in order to form slag with low melting point and easy to float in the steel metal solution, and then it is convenient for the mold 1 in the mold 1. to absorb;

S2: Continuous casting process: run the molten steel refined in step S1 into the ladle, and the molten steel solution in the ladle enters the intermediate tank through the drainage pipe. The injection pipe 6 is injected into a group of water-cooled copper molds 1, and the molten steel gradually solidifies along the periphery of the mold 1 into a billet shell. Pull out, and spray water in the secondary cooling zone to completely solidify the casting billet; before pouring, it is necessary to blow argon and exhaust air to the intermediate tank, which can prevent the secondary oxidation phenomenon of molten steel entering the intermediate tank;

S3: Hot rolling process: Use a 1580 roughing mill as a four-high reversing rolling mill with vertical rolls in step S2, and roll 5 to 7 passes to reduce the billet to 25 to 50 mm; then the hot coil box is used for intermediate billets. For heat preservation, the rolling line adopts seven-point descaling, high-pressure water descaling ability is strong, and the working pressure is greater than or equal to 20MPa; then the rolled sheet with the scale removed is subjected to finishing rolling through the finishing mill;

S4: Coiling process: use 1580 coiling equipment to coil the rolled sheet cooled in step S3;

Wherein, the crystallizer 1 is composed of each composite wall plate and an inner wall copper plate 2 and an outer wall steel cooling water tank 4 connected by studs; the outer side of the inner wall copper plate 2 is milled with a cooling groove 3; the cooling One side of the washing is provided with a water inlet pipe 5, and the other side wall is provided with a water outlet pipe; the bottom end of the injection pipe 6 extends into the inner wall copper plate 2, and the outer circumferential wall of the bottom end of the injection pipe 6 is provided with A plurality of liquid guide holes 7; a plurality of liquid guide holes 7 are installed with liquid guide nozzles 8 inclined downward, and the plurality of liquid guide nozzles 8 are located below the liquid level of the molten steel solution; the injection pipe 6 A shunt arc block 9 is arranged inside the bottom end of the inner wall, and the shunt arc block 9 is located at the nozzle position of the liquid guide nozzle 8; the upper part of the molten steel solution on the inner wall of the inner wall copper plate 2 is provided with a mold slag layer; when working, when the molten steel solution After entering the intermediate tank, it will enter the bottom end of the injection pipe 6, and the diverter arc block 9 arranged on the inner wall of the bottom end of the injection pipe 6 will divert the molten steel solution into a plurality of downwardly inclined liquid guide nozzles 8, and then The molten steel solution flows into the inner wall copper plate 2 through the liquid guide nozzles 8, and then the distribution arc block 9 can evenly divide the molten steel solution into the guide nozzles 8 through the cooperation of the distribution arc block 9 and the plurality of inclined liquid guide nozzles 8. Inside the liquid nozzle 8, and then the liquid guide nozzle 8 can evenly introduce the molten steel solution into the steel plate that is solidifying to form the shell inside the mold 1, so that the molten steel solution can flow stably in the molten steel process, effectively preventing the existing mold The immersed injection pipe 6 is set in 1, and the bottom end of the injection pipe 6 is in an open state, which in turn causes the molten steel to form a columnar fluid impacting the molten steel flow field of the mold 1, which in turn causes the molten steel flow field to generate upwards. The phenomenon of tumbling can easily lead to the phenomenon that the mold slag set on the upper surface of the molten steel flow field is chaotic or precipitated downward when the molten steel is tumbling. A protective film is formed on the upper surface of the molten steel flow field to cause fracture, which in turn affects the protective effect of the mold slag layer on the molten steel flow field.

As an embodiment of the present invention, the inclined angle formed by the liquid guide nozzle 8 and the molten steel surface above the liquid guide nozzle 8 is 21°-25°; the cross section of the liquid guide nozzle 8 is set as a square hole structure, and the expansion angle of the liquid guiding nozzle 8 of the square structure is 12°～16°; the height of the top of the plurality of the liquid guiding nozzle 8 from the bottom end face of the mold powder is 90～105mm; if the downward slope of the liquid guiding nozzle 8 When the included angle is too large, the molten steel solution sprayed from the liquid guide nozzle 8 will easily impact the shell being formed, which will cause the hot-rolled coil to be dented or have holes inside, which will affect the production of the hot-rolled coil. quality; if the angle of inclination of the liquid guide nozzle 8 is too small, the molten steel solution sprayed from the liquid guide nozzle 8 will impact to the top, causing the phenomenon of tumbling above the molten steel flow field; 8. The area of the molten steel solution flowing out of the liquid guide nozzle 8 can be increased, and because the fluidity of the molten steel solution in the mold 1 is poor, the impact force of the molten steel solution in the molten steel flow field can be reduced, and the molten steel can be reduced. The tumbling phenomenon of the flow field.

As an embodiment of the present invention, the upper end of the inner wall copper plate 2 is provided with a limit slot, and a metal filter screen plate 10 is slidably inserted into the limit slot; the metal filter screen plate 10 is located in the mold slag layer; the The mold slag layer includes a powder slag layer, a sintered layer and a molten layer; the metal filter screen plate 10 is located in the middle of the sintered layer; the metal filter screen plate 10 is arranged so that the mold powder can form a stable surface on the upper surface of the molten steel flow field. The protective film layer prevents the relatively loose mold slag, which leads to the poor formation time of the protective layer and the instability of the protective layer, which in turn affects the thermal insulation effect of the mold slag layer on the molten steel flow field; In the layer, the molten layer can absorb and dissolve the non-metallic impurities floating on the steel slag interface, and effectively prevent the slag inclusions floating in the molten steel solution from being involved in the solidification shell, thereby causing defects on the surface or lower skin of the hot-rolled coil. And the content of silicon is controlled to be 0.5% higher than the content of manganese, in order to form a low melting point and easy to float slag in the steel metal solution, so that the layered mold slag layer can better absorb.

As an embodiment of the present invention, the metal filter screen plate 10 is provided with a plurality of slag guide pipes 11 in the horizontal direction, and the slag guide pipes 11 are provided with a plurality of nozzle holes 111; Through the communication pipe 12, the communication pipe 12 is communicated with the external mold flux introduction pipe; the mold flux of the mold flux layer can be injected into the slag guide pipe 11 through the communication pipe 12, and then evenly dispersed into the protection flux through the nozzle holes 111. In the slag layer, and control the amount of mold slag in the principle of frequent, small and even, which can reduce the phenomenon of slag adjustment bars; at the same time, it can prevent too much mold slag from being put in. Due to the influence of the metal filter, the mold slag will be in the molten steel. The upper surface of the flow field is not completely melted, which in turn leads to the phenomenon that the mold slag layer is deposited downward, which in turn affects the solidification and encrustation of the molten steel solution by the crystallizer 1 .

As an embodiment of the present invention, the mold powder of the mold powder layer is made of the following raw materials by weight percentage: SiO ₂ : 45-60%; CaO: 30-50%; Al ₂ O ₃ : 5～15%; FeO: ≤1%; Carbonaceous material: 2～5%;

Among them, SiO ₂ is easy to absorb TiO ₂ which is difficult to tolerate scum; CaO is easy to absorb Al ₂ O ₃ and Cr ₂ O ₃ ; FeO: ≤1% can reduce the oxidation of slag; carbonaceous material: 2-5% can be controlled The melting rate of the slag.

The specific workflow is as follows:

During operation, when the molten steel solution enters the intermediate tank, it will enter the bottom end of the injection pipe 6, and the diverter arc block 9 arranged on the inner wall of the bottom end of the injection pipe 6 will divert the molten steel solution to a plurality of inclined downward guides. into the liquid nozzle 8, and then flow into the molten steel solution in the inner wall copper plate 2 through the liquid guide nozzle 8, and then through the cooperation of the distribution arc block 9 and the plurality of inclined liquid guide nozzles 8, the distribution arc block 9 can be evenly distributed. The molten steel solution is divided into the liquid guiding nozzle 8, and then the liquid guiding nozzle 8 can evenly introduce the molten steel solution into the steel plate that is solidifying and forming the shell in the mold 1. out, and spray cooling through the secondary cooling zone to completely solidify the slab.

In the description of the present invention, it is to be understood that the terms "center", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate The orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation or be constructed in a specific orientation. and operation, and therefore should not be construed as limiting the protection scope of the present invention.

Although the present invention is described through specific embodiments, those skilled in the art should understand that various changes and equivalent substitutions can be made to the present invention without departing from the scope of the present invention. In addition, various modifications may be made to adapt a particular situation or material to the invention without departing from the scope of the invention. Therefore, the inventions are not to be limited to the specific embodiments disclosed, but are to include all embodiments falling within the scope of the claims of this invention.

Claims (6)

1. a hot-rolled coil is characterized in that: its chemical composition is in weight percent: C: 0.12～0.20%; Mn: 0.25～0.31%; Si: 0.23～0.3%; S: 0.045%; P: 0.045%; Ca0.0010～0.0030%; N≤0.009%; Als: 0.020～0.050%; And the ratio of Ca/Als is 0.15-0.3; cryolite powder: 0.3-0.50%; the balance is Fe. 2. A method for producing a hot-rolled coil, characterized in that: the method is suitable for the production of the hot-rolled coil described in claim 1; the method comprises the steps: S1: Refining process: LF furnace controls the process of slag making, deoxidation, desulfurization and removal of inclusions, adding ferromanganese, ferrosilicon, and ferroniobium alloy to fine-tune the composition of molten steel according to the composition of molten steel, and the content of silicon is 0.5% higher than that of manganese; then Use RH vacuum refining device to refine molten steel; S2: Continuous casting process: run the molten steel refined in step S1 into the ladle, and the molten steel solution in the ladle enters the intermediate tank through the drainage pipe. The injection pipe (6) is injected into a group of water-cooled copper molds (1), the molten steel gradually solidifies along the periphery of the mold (1) into a billet shell, and when the molten steel level rises to a certain height, the billet shell solidifies to a certain thickness The billet is pulled out by the post-stretching leveler, and the billet is completely solidified by water spray cooling in the secondary cooling zone; S3: Hot rolling process: Use a 1580 roughing mill as a four-high reversing rolling mill with vertical rolls in step S2, and roll 5 to 7 passes to reduce the billet to 25 to 50 mm; then the hot coil box is used for intermediate billets. For heat preservation, the rolling line adopts seven-point descaling, high-pressure water descaling ability is strong, and the working pressure is greater than or equal to 20MPa; then the rolled sheet with the scale removed is subjected to finishing rolling through the finishing mill; S4: Coiling process: use 1580 coiling equipment to coil the rolled sheet cooled in step S3; Wherein, the crystallizer (1) is composed of each composite wall plate and an inner wall copper plate (2) and an outer wall steel cooling water tank (4) connected by studs; the outer side surface of the inner wall copper plate (2) is milled. There is a cooling tank (3); one side of the cooling water wash is provided with a water inlet pipe (5), and the other side wall is provided with a water outlet pipe; the bottom end of the injection pipe (6) extends into the inner wall copper plate (2) ), and a plurality of liquid guide holes (7) are opened on the outer circumferential wall of the bottom end of the injection pipe (6); a liquid guide nozzle (8) is installed incline downward in the plurality of said liquid guide holes (7), And the plurality of liquid guide nozzles (8) are all located below the liquid level of the molten steel solution; the bottom end of the injection pipe (6) is provided with a diverter arc block (9), and the diverter arc block (9) is located in the diverter arc block (9). The nozzle position of the liquid nozzle (8); a mold slag layer is provided above the molten steel solution on the inner wall of the inner wall copper plate (2). 3. The method for producing a hot-rolled coil according to claim 2, characterized in that: the inclined angle formed by the liquid guide nozzle (8) and the molten steel surface above the liquid guide nozzle (8) is 21° to 25°; the cross section of the liquid guide nozzle (8) is set to a square hole structure, and the expansion angle of the liquid guide nozzle (8) of the square structure is 12° to 16°; a plurality of the liquid guide nozzles ( 8) The height of the top from the bottom end face of the mold powder is 90-105mm. 4. The method for producing a hot-rolled coil according to claim 3, characterized in that: a limit groove is provided at the upper end of the inner wall copper plate (2), and a metal filter screen plate ( 10); the metal filter screen plate (10) is located in the mold slag layer; the mold powder layer includes a powder slag layer, a sintered layer and a melting layer; the metal filter screen plate (10) is located in the middle of the sintered layer. 5 . The method for producing a hot-rolled coil according to claim 4 , wherein: a plurality of slag guide pipes ( 11 ) are arranged in the horizontal direction of the metal filter screen plate ( 10 ), and the slag guide pipes ( 11 ). The pipe (11) is provided with a plurality of nozzle holes (111); the ends of the plurality of lead pipes are communicated through a communication pipe (12), and the communication pipe (12) is communicated with an external mold flux introduction pipe. 6 . The method for producing a hot-rolled coil according to claim 5 , wherein the mold flux of the mold flux layer is made of the following raw materials by weight percent: SiO ₂ : 45-60 %; CaO: 30-50%; Al ₂ O ₃ : 5-15%; FeO: ≤1%; carbonaceous material: 2-5%.

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