Preparation method of oriented silicon steel hot-rolled coil and oriented silicon steel hot-rolled coil

Abstract

The invention provides a preparation method of an oriented silicon steel hot-rolled coil and the oriented silicon steel hot-rolled coil. The preparation method comprises the following steps: smelting and refining molten iron in a converter to obtain refined molten steel; the refined molten steel is injected into a tundish and enters a crystallizer through a water gap of the tundish to be poured, and a steel casting blank is obtained; preparing an oriented silicon steel hot-rolled coil: carrying out hot rolling on the steel casting blank to obtain the oriented silicon steel hot-rolled coil; in the continuous casting procedure, the thickness of a steel casting blank ranges from 200 mm to 240 mm, and the width of the steel casting blank ranges from 1000 mm to 1400 mm; the pouring speed is 0.7 m / min to 1.0 m / min; and the argon flow of the water gap is 1.5 NL / min to 3 NL / min. According to the preparation method of the oriented silicon steel hot-rolled coil, continuous casting process parameters are optimized, the proper size of a steel casting blank, the pouring speed matched with the steel casting blank and the argon flow of a water gap are selected, bubbles can fully float and overflow, the bubble defect of the oriented silicon steel casting blank is reduced, the problems of skin, slag inclusion and the like of the formed hot-rolled coil are solved, and the quality of the oriented silicon steel hot-rolled coil is improved. The rejection rate is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of oriented silicon steel hot-rolled coils, and specifically relates to a preparation method of oriented silicon steel hot-rolled coils and oriented silicon steel hot-rolled coils. Background Art

[0002] Grain-oriented silicon steel has excellent magnetic properties and is mainly used in power systems to achieve efficient electromagnetic conversion. Grain-oriented silicon steel is mainly used to manufacture transformer cores. Through its excellent soft magnetic characteristics and magnetization properties, it provides high magnetic flux for transformers, thereby achieving efficient electric-magnetic-electric conversion functions.

[0003] The oriented silicon steel is mainly processed through a series of processes such as hot metal desulfurization, converter blowing, RH refining, and continuous casting. The continuous casting is passed through a crystallizer to obtain an oriented silicon steel ingot, which is then heated and rolled to obtain an oriented silicon steel hot-rolled coil. The hot-rolled coil is processed through pickling (normalization), cold rolling, annealing, coating, stretching and flattening to obtain an oriented silicon steel finished product.

[0004] Due to the high silicon content of oriented silicon steel, the manufacturing process is relatively complex. The hot-rolled coil steel formed by it is prone to defects such as peeling / slag inclusion on the surface, which causes the product grade to decline or even be scrapped, seriously affecting product quality. Summary of the invention

[0005] The present application provides a method for preparing a hot-rolled silicon steel coil and a hot-rolled silicon steel coil, aiming to improve the peeling and slag inclusion problems of the hot-rolled silicon steel coil and reduce the scrap rate of the hot-rolled silicon steel coil. The method of the present application is simple to operate, easy to control, highly repeatable, and suitable for large-scale production.

[0006] The first aspect of the present application provides a method for preparing a oriented silicon steel hot-rolled coil, comprising:

[0007] Smelt and refine the molten iron in a converter to obtain refined molten steel;

[0008] Continuous casting process: the refined molten steel is poured into the tundish, and then enters the crystallizer through the water inlet of the tundish for casting to obtain steel ingots;

[0009] Preparation of oriented silicon steel hot-rolled coil: hot-rolling the steel ingot to obtain oriented silicon steel hot-rolled coil;

[0010] In the continuous casting process, the thickness of the steel ingot is 200 mm to 240 mm, and the width is 1000 mm to 1400 mm; the pouring speed is 0.7 m / min to 1.0 m / min; and the argon flow rate of the water inlet is 1.5 NL / min to 3 NL / min.

[0011] In a feasible implementation manner of the first aspect of the present application, in the continuous casting process, the steel ingot includes the following composition in mass percentage: 0.03%≤C≤0.07%, 3.0%≤Si≤3.60%, 0.05%≤Mn≤0.30%, P≤0.03%, S≤0.011%, 0.015%≤Als≤0.032%, 0.005%≤N≤0.0110%, Cu≤0.6%, and the rest are iron and trace elements.

[0012] In a feasible implementation manner of the first aspect of the present application, in the step of the continuous casting process, the argon flow rate of the stopper rod of the tundish is controlled to be 1NL / min to 2NL / min.

[0013] In a feasible implementation manner of the first aspect of the present application, in the continuous casting process, the superheat degree of the molten steel in the tundish is 30°C to 45°C.

[0014] In a feasible implementation manner of the first aspect of the present application, in the continuous casting process, the insertion depth of the water nozzle of the tundish is 105 mm to 120 mm.

[0015] In a feasible implementation manner of the first aspect of the present application, in the continuous casting process, the liquidus temperature of the molten steel is 1495°C to 1500°C; the temperature of the poured molten steel is 1510°C to 1540°C.

[0016] In a feasible implementation manner of the first aspect of the present application, in the steps of the continuous casting process, the physical and chemical properties of the protective slag used in the crystallizer include: viscosity 0.12Pa*S~0.16Pa*S at 1300℃, melting temperature 950℃~1030℃, and basicity of 0.65~0.7; the protective slag includes the composition of mass percentage: 30%≤SiO2≤35%, 1%≤MgO≤5%, 22%≤CaO≤32%, 1%≤Al2O3≤4%, 0.3%≤Li2O≤1.2%, and the rest are iron and trace elements.

[0017] In a feasible implementation manner of the first aspect of the present application, in the continuous casting process, the molten steel is strongly cooled in the crystallizer, and the water flow rate on the wide side of the crystallizer is 4100L / mim~5500L / mim; the water flow rate on the narrow side of the crystallizer is 550L / mim~610L / mim.

[0018] In a feasible implementation manner of the first aspect of the present application, in the step of preparing the oriented silicon steel hot-rolled coil, the steel ingot is heated in a heating furnace and rolled, the furnace entry temperature of the steel ingot is ≥300°C, the rolling includes 5 rough rolling passes and 7 finish rolling passes, and the total reduction rate of the rough rolling is 80-86%.

[0019] A second aspect of the present application provides a hot-rolled oriented silicon steel coil, which is prepared by the method for preparing a hot-rolled oriented silicon steel coil provided by the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The steel ingot shown in Example 5;

[0021] Figure 2 The steel ingot shown in Example 8;

[0022] Figure 3 The steel ingot shown in Example 2;

[0023] Figure 4 This is a steel coil having a peeling defect on the surface of the bubble defect ingot shown in Comparative Example 1 after rolling. DETAILED DESCRIPTION

[0024] In order to make the invention purpose, technical scheme and beneficial technical effect of the present application clearer, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present application, not for limiting the present application.

[0025] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0026] In the description herein, when a composition is described as containing, comprising or including specific components, or when a process is described as containing, comprising or including specific process steps, it is expected that the composition of the present application also consists essentially of or consists of the components, and the process of the present application also consists essentially of or consists of the process steps.

[0027] The use of the terms "including," "comprising," "containing," and "having" should generally be interpreted as open ended and non-limiting unless expressly stated otherwise.

[0028] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number itself, and the “multiple” in “one or more” means more than two.

[0029] The above-mentioned summary of the invention of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each example, enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0030] In order to improve the quality of oriented silicon steel hot-rolled coils, the inventors analyzed that part of the reason may be that in the continuous casting billet production process, bubble defects are prone to occur due to the characteristics of the process equipment and steel type. When bubble defects appear in the casting billet, after hot rolling, defects such as peeling / slag inclusion will be formed on the surface of the strip, causing the product to be downgraded or even scrapped, seriously affecting the product quality.

[0031] In the continuous casting process of oriented silicon steel, the blown argon bubbles are captured by the solidifying slab shell, which can form bubble defects with a diameter of 0.5mm to 3mm on the ingot. After rolling, linear defects with a width of 2mm to 16mm and a length of up to 400mm will be formed. When the protective slag is wrapped in the bubble, the defect is more serious and will cause a large number of products to be scrapped.

[0032] In view of this, the inventor has proposed a method for preparing a hot-rolled silicon steel coil and a hot-rolled silicon steel coil in this application after a lot of experimental research and demonstration. By optimizing the parameters in the continuous casting process, the bubble defects of the oriented silicon steel are reduced, thereby improving the peeling and slag inclusion problems of the hot-rolled silicon steel coil, improving the qualified rate of the hot-rolled silicon steel coil, and reducing the scrap rate. In addition, the method of the application is simple to operate, easy to control, highly repeatable, and suitable for large-scale production.

[0033] The first aspect of the present application provides a method for preparing a oriented silicon steel hot-rolled coil, comprising:

[0034] Smelt and refine the molten iron in a converter to obtain refined molten steel;

[0035] Continuous casting process: the refined molten steel is poured into the tundish, and then enters the crystallizer through the water inlet of the tundish for casting to obtain steel ingots;

[0036] Preparation of oriented silicon steel hot-rolled coil: hot-rolling the steel ingot to obtain oriented silicon steel hot-rolled coil;

[0037] In the continuous casting process, the thickness of the steel ingot is 200 mm to 240 mm, and the width is 1000 mm to 1400 mm; the pouring speed is 0.7 m / min to 1.0 m / min; and the argon flow rate of the water inlet is 1.5 NL / min to 3 NL / min.

[0038] The preparation method of the oriented silicon steel hot-rolled coil of the present application optimizes the continuous casting process parameters, including selecting the appropriate size of the steel ingot, such as a thickness of 200mm-240mm and a width of 1000mm-1400mm, a corresponding casting speed of 0.7m / min-1.0m / min and a nozzle argon flow rate of 1.5NL / min-3NL / min, reducing the argon flow rate, reducing the number of bubbles, reducing their depth in the molten steel in the crystallizer, and increasing the bubble floating rate, so that the bubbles can fully float and overflow, especially the bubbles near the solidified ingot shell are easily adhered to the ingot shell, which can prevent the argon bubbles from being captured by the solidified ingot shell, and reduce the bubble defects under the oriented silicon steel ingot, thereby improving the problems of skin peeling, slag inclusion and the like of the oriented silicon steel hot-rolled coil formed therefrom, and improving the qualified rate or quality of the oriented silicon steel hot-rolled coil.

[0039] In the preparation method of oriented silicon steel hot-rolled coil of the present application, the method for improving the bubble defect of oriented silicon steel ingot has the following advantages: 1) the process operation is simple and does not require complicated auxiliary equipment; 2) the process parameters are easy to control and there will be no problems such as stopper rod rising; 3) the scrap problem caused by the bubble defect of oriented silicon steel ingot can be effectively improved.

[0040] In some embodiments, in the continuous casting process, the steel ingot includes the following composition in mass percentage: 0.03%≤C≤0.07%, 3.0%≤Si≤3.60%, 0.05%≤Mn≤0.30%, P≤0.03%, S≤0.011%, 0.015%≤Als≤0.032%, 0.005%≤N≤0.0110%, Cu≤0.6%, and the rest are iron and trace elements.

[0041] The high silicon content in oriented silicon steel hot-rolled coils will increase the viscosity and surface tension of the molten steel, making it more difficult for bubbles to escape from the molten steel. At the same time, the grains of oriented silicon steel have a specific orientation, which may make it easier for bubbles to be "trapped" in the molten steel, thereby increasing the difficulty of removing bubbles.

[0042] In some embodiments, during the continuous casting process, the argon flow rate of the stopper rod in the tundish is controlled to be 1 NL / min to 2 NL / min.

[0043] In some embodiments, during the continuous casting process, the superheat degree of the molten steel in the tundish is 30°C to 45°C.

[0044] In some embodiments of the present application, it is found that further controlling the flow rate of argon gas in the stopper rod of the tundish and increasing the superheat of the molten steel in the tundish are also beneficial to the bubbles in the oriented silicon steel to fully float up and overflow, thereby reducing bubble defects in the ingot.

[0045] In some embodiments, during the continuous casting process, the insertion depth of the nozzle of the tundish is 105 mm to 120 mm.

[0046] In some embodiments of the present application, the insertion depth of the tundish nozzle is further controlled within an appropriate range to reduce the insertion depth, which can shorten the distance for bubbles to float up, reduce the probability of being captured, and further control bubble defects.

[0047] In some embodiments, in the continuous casting process, the liquidus temperature of the molten steel is 1495°C to 1500°C; and the temperature of the poured molten steel is 1530°C to 1545°C.

[0048] In some embodiments of the present application, the liquidus temperature of the molten steel and the pouring temperature are reasonably selected, which can be better matched with the composition, size, pouring speed and gas flow rate of the oriented silicon steel of the present application, and jointly reduce the bubble defects of the steel ingot, thereby reducing the scrap rate of the steel coil. If the liquidus temperature of the molten steel is high, it may lead to an increase in bubble defects.

[0049] In some embodiments, in the continuous casting process, the physical and chemical properties of the protective slag used in the crystallizer include: viscosity of 0.12Pa*S~0.16Pa*S at 1300℃, melting temperature of 950℃~1030℃, and basicity of 0.65~0.7; the protective slag includes the composition of mass percentage: 30%≤SiO2≤35%, 1%≤MgO≤5%, 22%≤CaO≤32%, 1%≤Al2O3≤4%, 0.3%≤Li2O≤1.2%, and the rest are iron and trace elements.

[0050] In some embodiments of the present application, there is an interfacial tension between the protective slag and the molten steel. If the interfacial tension is too high, it may cause bubbles between the molten steel to be difficult to overflow during the solidification process, resulting in bubble defects, and the thermal insulation performance of the protective slag and the reasonable selection of the molten steel temperature will also affect the precipitation of bubbles. The present application can further define the physical and chemical properties and composition of the protective slag so that during the production process of the oriented silicon steel slab of the present application, the protective slag and the molten steel have appropriate interfacial tension and thermal insulation performance, and can better absorb the floating slag inclusions in the molten steel, further reducing the bubble defects in the ingot.

[0051] In some embodiments, during the continuous casting process, the molten steel is strongly cooled in the crystallizer, and the water flow rate on the wide side of the crystallizer is 4100L / mim to 5500L / mim; the water flow rate on the narrow side of the crystallizer is 550L / mim to 610L / mim.

[0052] In some embodiments of the present application, it is also found that a suitable cooling process in the crystallizer can further reduce bubble defects. If the water flow rate of the crystallizer is insufficient, the crystallization speed may be too slow, the cooling may be insufficient, and the ingot may be overheated or poorly crystallized. At the same time, the molten steel may be locally overheated, increasing the probability of bubble generation. If the flow rate is too large, excessive crystallization may occur, increasing the defect of cracks in the ingot.

[0053] In some embodiments, in the step of preparing the oriented silicon steel hot-rolled coil, the steel ingot is heated in a heating furnace and rolled, the furnace entry temperature of the steel ingot is ≥300°C, the rolling includes 5 rough rolling passes and 7 finish rolling passes, and the total reduction rate of the rough rolling is 80-86%.

[0054] During the heating and rolling process of steel ingots, a reasonable rolling process is also conducive to reducing the scrap rate of steel coils.

[0055] A second aspect of the present application provides a hot-rolled oriented silicon steel coil, which is prepared by the method for preparing a hot-rolled oriented silicon steel coil provided by the first aspect of the present application.

[0056] Example

[0057] The following examples more specifically describe the disclosure of the present application, which are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0058] Example 1

[0059] A method for preparing a hot-rolled oriented silicon steel coil, comprising:

[0060] Smelt and refine the molten iron in a converter to obtain refined molten steel;

[0061] Continuous casting process: the refined molten steel is poured into the tundish, and then enters the crystallizer through the water inlet of the tundish for casting to obtain steel ingots;

[0062] Preparation of oriented silicon steel hot-rolled coil: hot-rolling the steel ingot to obtain oriented silicon steel hot-rolled coil;

[0063] In the continuous casting process: the thickness of the steel billet is 230mm and the width is 1320mm; the pouring speed is 1.0m / min; the argon flow rate of the nozzle is 3NL / min. The argon flow rate of the stopper rod of the tundish is controlled to be 2NL / min, and a slight positive pressure must be ensured to avoid gas inhalation. The superheat of the molten steel in the tundish is 35℃. The insertion depth of the nozzle of the tundish is 110mm.

[0064] The steel ingot includes the following composition in percentage by mass: C: 0.035%, Si: 3.22%, Mn: 0.022%, P: 0.014%, S: 0.010%, Als: 0.0160%, N: 0.093%, Cu: 0.051%, and the rest are iron and trace elements.

[0065] The liquidus temperature of the molten steel is 1495°C; the temperature of the poured molten steel is 1533°C.

[0066] The physical and chemical properties of the protective slag used in the crystallizer include: viscosity 0.12 Pa*S at 1300°C, melting temperature 980°C, and basicity 0.67; the protective slag includes the composition of mass percentage: SiO2: 33%, MgO: 2%, CaO: 25%, Al2O3: 3.6%, Li2O: 0.6%, and the rest are iron and trace elements.

[0067] The molten steel is strongly cooled in the crystallizer, with a water flow rate of 4400L / mim on the wide side of the crystallizer and 560L / mim on the narrow side of the crystallizer.

[0068] In the steps of preparing the oriented silicon steel hot-rolled coil, the steel ingot is heated in a heating furnace and rolled. The furnace temperature of the steel ingot is ≥300°C. The rolling includes 5 rough rolling passes and 7 finish rolling passes. The total reduction rate of the rough rolling is 82%.

[0069] Example 2

[0070] A method for preparing a hot-rolled oriented silicon steel coil, comprising:

[0071] Smelt and refine the molten iron in a converter to obtain refined molten steel;

[0072] Continuous casting process: the refined molten steel is poured into the tundish, and then enters the crystallizer through the water inlet of the tundish for casting to obtain steel ingots;

[0073] Preparation of oriented silicon steel hot-rolled coil: hot-rolling the steel ingot to obtain oriented silicon steel hot-rolled coil;

[0074] In the continuous casting process: the thickness of the steel billet is 230mm and the width is 1080mm; the pouring speed is 0.8m / min; the argon flow rate of the nozzle is 2NL / min. The argon flow rate of the stopper rod of the tundish is controlled to be 2NL / min, and a slight positive pressure must be ensured to avoid gas inhalation. The superheat of the molten steel in the tundish is 45℃. The insertion depth of the nozzle of the tundish is 105mm.

[0075] The steel ingot includes the following composition in percentage by mass: C: 0.039%, Si: 3.14%, Mn: 0.017%, P: 0.011%, S: 0.011%, Als: 0.0193%, N: 0.083%, Cu: 0.050%, and the rest are iron and trace elements.

[0076] The liquidus temperature of the molten steel is 1495°C; the temperature of the poured molten steel is 1536°C.

[0077] The physical and chemical properties of the protective slag used in the crystallizer include: viscosity 0.15 Pa*S at 1300°C, melting temperature 1030°C, and basicity 0.65; the protective slag includes the composition of mass percentage: SiO2: 34%, MgO: 3.4%, CaO: 28%, Al2O3: 2.2%, Li2O: 0.4%, and the rest are iron and trace elements.

[0078] The molten steel is strongly cooled in the crystallizer, with a water flow rate of 4900L / mim on the wide side of the crystallizer and 560L / mim on the narrow side of the crystallizer.

[0079] In the steps of preparing the oriented silicon steel hot-rolled coil, the steel ingot is heated in a heating furnace and rolled, and the furnace temperature of the steel ingot is ≥300°C; the rolling includes 5 rough rolling passes and 7 finish rolling passes, and the total reduction rate of the rough rolling is 82%.

[0080] Example 3

[0081] A method for preparing a hot-rolled oriented silicon steel coil, comprising:

[0082] Smelt and refine the molten iron in a converter to obtain refined molten steel;

[0083] Continuous casting process: the refined molten steel is poured into the tundish, and then enters the crystallizer through the water inlet of the tundish for casting to obtain steel ingots;

[0084] Preparation of oriented silicon steel hot-rolled coil: hot-rolling the steel ingot to obtain oriented silicon steel hot-rolled coil;

[0085] In the continuous casting process: the thickness of the steel billet is 230mm and the width is 1256mm; the pouring speed is 1.0m / min; the argon flow rate of the nozzle is 2.5NL / min. The argon flow rate of the stopper rod of the tundish is controlled to be 1.5NL / min, and a slight positive pressure must be ensured to avoid gas inhalation. The superheat of the molten steel in the tundish is 40℃. The insertion depth of the nozzle of the tundish is 120mm.

[0086] The steel ingot includes the following composition in percentage by mass: C: 0.058%, Si: 3.21%, Mn: 0.012%, P: 0.026%, S: 0.007%, Als: 0.0260%, N: 0.073%, Cu: 0.001%, and the rest are iron and trace elements.

[0087] The liquidus temperature of molten steel is 1500℃; the temperature of poured molten steel is 1542℃.

[0088] The physical and chemical properties of the protective slag used in the crystallizer include: viscosity 0.16 Pa*S at 1300°C, melting temperature 990°C, and basicity 0.67; the protective slag includes the composition of mass percentage: SiO2: 32%, MgO: 4%, CaO: 25%, Al2O3: 3%, Li2O: 0.7%, and the rest are iron and trace elements.

[0089] The molten steel is strongly cooled in the crystallizer, with a water flow rate of 4700L / mim on the wide side of the crystallizer and 590L / mim on the narrow side of the crystallizer.

[0090] In the steps of preparing the oriented silicon steel hot-rolled coil, the steel ingot is heated in a heating furnace and rolled, and the furnace temperature of the steel ingot is ≥300°C; the rolling includes 5 rough rolling passes and 7 finish rolling passes, and the total reduction rate of the rough rolling is 85%.

[0091] Example 4

[0092] Compared with Example 1, Example 4 mainly differs in that the argon flow rate of the stopper rod in the tundish is larger, which is 2.5NL / min; and the superheat of the molten steel in the tundish is lower, which is 20°C.

[0093] Example 5

[0094] The main difference between Example 5 and Example 1 is that the insertion depth of the water inlet of the tundish is deeper, which is 140 mm.

[0095] Example 6

[0096] Compared with Example 1, Example 6 mainly differs in that the liquidus temperature of the molten steel and the pouring temperature of the molten steel are controlled differently, which are 1513°C and 1527°C respectively.

[0097] Example 7

[0098] Compared with Example 1, Example 7 is different mainly in that the protective slag used in the crystallizer is different. The physical and chemical properties of the protective slag of Example 7 include: viscosity of 0.18 Pa*S at 1300°C, melting temperature of 1063°C, and basicity of 0.77; the protective slag includes the following mass percentage compositions: iO2: 34%, MgO: 4%, CaO: 29%, Al2O3: 3.7%, Li2O: 0.2%, and the rest are iron and trace elements.

[0099] Example 8

[0100] Compared with Example 1, Example 8 is different mainly in that the cooling process in the crystallizer is different. The cooling process of the crystallizer in Example 8 is: weak cooling is used for molten steel in the crystallizer, the water flow rate on the wide surface of the crystallizer is 3900L / mim, and the water flow rate on the narrow surface of the crystallizer is 530L / mim.

[0101] Comparative Example 1

[0102] The difference between Comparative Example 1 and Example 1 is that the casting speed is faster, which is 1.25 m / min; and the argon gas flow rate at the water inlet is larger, which is 4 NL / min.

[0103] Test Section

[0104] Bubble test of steel ingot: visual observation and measurement. The evaluation criteria are: Level 0, no bubbles observed; Level 1, a small number of visible bubble defects with a diameter of 0.5 mm; Level 2, a large number of bubble defects with a diameter of 0.6-1.5 mm; Level 3, a large number of bubble defects larger than 1.5 mm.

[0105] Number of peeling coils and slag inclusion coils: 1,000 oriented silicon steel hot-rolled coils were randomly selected and the number of peeling coils and slag inclusion coils found were counted.

[0106] Scrap rate: Scrap rate = (number of peeling rolls + number of slag inclusion rolls) / 1000.

[0107] The above test results are shown in Table 1 below.

[0108] Table 1:

[0109]

[0110]

[0111] From the data in the table, it can be seen that the oriented silicon steel hot-rolled coil obtained by the preparation method of the oriented silicon steel hot-rolled coil of the present application has less peeling and slag inclusion, a very low scrap rate, and almost no bubble defects in the steel ingot, indicating that the method of the present application can improve the bubble defects of the steel ingot, thereby improving the problems of peeling and slag inclusion in the oriented silicon steel hot-rolled coil, and reducing the scrap rate of the oriented silicon steel hot-rolled coil. In addition, the method of the present application is simple to operate, easy to control, highly repeatable, and suitable for large-scale production.

[0112] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a hot-rolled oriented silicon steel coil, characterized in that: include: Smelt and refine the molten iron in a converter to obtain refined molten steel; Continuous casting process: injecting the refined molten steel into a tundish, and entering a crystallizer through a water inlet of the tundish, and casting to obtain a steel ingot; Preparation of oriented silicon steel hot-rolled coil: hot-rolling the steel ingot to obtain the oriented silicon steel hot-rolled coil; In the continuous casting process, the thickness of the steel ingot is 200 mm to 240 mm, and the width is 1000 mm to 1400 mm; the pouring speed is 0.7 m / min to 1.0 m / min; and the argon flow rate of the water inlet is 1.5 NL / min to 3 NL / min.

2. The method for preparing a oriented silicon steel hot-rolled coil according to claim 1, characterized in that: In the continuous casting process, the steel ingot includes the following composition in percentage by mass: 0.03%≤C≤0.07%, 3.0%≤Si≤3.60%, 0.05%≤Mn≤0.30%, P≤0.03%, S≤0.011%, 0.015%≤Als≤0.032%, 0.005%≤N≤0.0110%, Cu≤0.6%, and the rest are iron and trace elements.

3. The method for preparing a oriented silicon steel hot-rolled coil according to claim 1, characterized in that: In the steps of the continuous casting process, the argon flow rate of the stopper rod in the tundish is controlled to be 1NL / min to 2NL / min.

4. The method for preparing a oriented silicon steel hot-rolled coil according to claim 1, characterized in that: In the continuous casting process, the superheat degree of the molten steel in the tundish is 30°C to 45°C.

5. The method for preparing a oriented silicon steel hot-rolled coil according to claim 1, characterized in that: In the continuous casting process, the insertion depth of the water nozzle of the tundish is 105 mm to 120 mm.

6. The method for preparing a oriented silicon steel hot-rolled coil according to claim 1, characterized in that: In the continuous casting process, the liquidus temperature of the molten steel is 1495°C to 1500°C; the temperature of the poured molten steel is 1510°C to 1545°C.

7. The method for preparing a oriented silicon steel hot-rolled coil according to claim 1, characterized in that: In the steps of the continuous casting process, the physical and chemical properties of the protective slag used in the crystallizer include: viscosity of 0.12Pa*S~0.16Pa*S at 1300℃, melting temperature of 950℃~1030℃, and basicity of 0.65~0.7; the protective slag includes the following mass percentage composition: 30%≤SiO2≤35%, 1%≤MgO≤5%, 22%≤CaO≤32%, 1%≤Al2O3≤4%, 0.3%≤Li2O≤1.2%, and the rest are iron and trace elements.

8. The method for preparing a oriented silicon steel hot-rolled coil according to claim 1, characterized in that: In the steps of the continuous casting process, the molten steel is strongly cooled in the crystallizer, and the water flow rate on the wide surface of the crystallizer is 4100L / mim to 5500L / mim; the water flow rate on the narrow surface of the crystallizer is 550L / mim to 610L / mim.

9. The method for preparing a grain-oriented silicon steel hot-rolled coil according to claim 1, characterized in that: In the step of preparing the oriented silicon steel hot-rolled coil, the steel ingot is heated in a heating furnace and rolled, the furnace entry temperature of the steel ingot is ≥300°C, the rolling includes 5 rough rolling passes and 7 finish rolling passes, and the total reduction rate of the rough rolling is 80-86%.

10. A hot-rolled oriented silicon steel coil, characterized in that: The oriented silicon steel hot-rolled coil is prepared by the method for preparing the oriented silicon steel hot-rolled coil according to any one of claims 1 to 9.

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