Oriented silicon steel, preparation method thereof and steel product

Abstract

The invention relates to oriented silicon steel, a preparation method thereof and a steel product. The preparation method of the oriented silicon steel comprises the following steps that a casting blank is subjected to hot rolling, and a hot-rolled plate is obtained; the hot-rolled plate is sequentially subjected to acid pickling, first-time cold rolling, decarburization annealing and second-time cold rolling; the initial rolling temperature of the first cold rolling is not less than 50 DEG C; the first cold rolling step comprises at least three passes of rolling on the hot rolled plate, the speed of the first pass of rolling is smaller than or equal to 300 m / min, the speed of each middle pass of rolling is 600 m / min-800 m / min, and the speed of the final pass of rolling is 650 m / min-750 m / min; in the first cold rolling process, the reduction rates of the first-pass rolling and the middle-pass rolling are 31%-45% respectively and independently, and the reduction rate of the final-pass rolling is 20%-30%. According to the method, the first cold rolling, the decarburization annealing and the second cold rolling are coordinated, and the rolling starting temperature and the rolling speed of the first cold rolling are controlled, so that the edge crack and strip breakage occurrence rate is effectively reduced, and the cold rolling yield is increased.

Description

Technical Field

[0001] The present application belongs to the technical field of steel production, and in particular relates to an oriented silicon steel, a preparation method thereof, and a steel product. Background Art

[0002] Grain-oriented silicon steel, primarily used in transformer cores, is an important soft magnetic material. Half of its silicon content is above 3%. This high silicon content makes it brittle, resists deformation during cold rolling, and is prone to edge cracking and strip breakage. Grain-oriented silicon steel can be categorized by its hot-rolling temperature as low-temperature, medium-temperature, or high-temperature oriented silicon steel. The hot-rolling temperature for medium-temperature oriented silicon steel ranges from 1250°C to 1350°C. The higher the hot-rolling temperature, the more susceptible it is to edge cracking and strip breakage during cold rolling. High-temperature oriented silicon steel has been phased out of the market, with low-temperature and medium-temperature oriented silicon steel being the primary production targets. The main finished thickness specifications for oriented silicon steel are 0.18mm, 0.20mm, 0.23mm, 0.27mm, 0.30mm, and 0.35mm; thicknesses of 0.18-0.23mm are considered thin. Reducing the thickness is an effective means to reduce steel loss of oriented silicon steel. However, as the thickness decreases, the cold rolling reduction rate increases and the deformation resistance increases accordingly, which brings great difficulties to cold rolling. During the production process, problems such as strip breakage, roll wrapping, and difficulty in plate shape control are very likely to occur, greatly reducing the yield rate of thin-gauge oriented silicon steel.

[0003] Patent CN113403463A discloses a method for improving the cold rolling processability of oriented silicon steel. The process route applicable to this method is: steelmaking - hot rolling - normalizing pickling - primary cold rolling - decarburization and nitriding - high temperature annealing - coating and stretching and leveling annealing. This method changes the pre-rolling structure by regulating the thickness of the hot rolling intermediate billet, the final rolling temperature and the coiling temperature, the normalizing cooling water volume and the control method, thereby improving the cold rolling yield. Patent CN114769336B discloses a rolling method for suppressing cold-rolled edge cracking of oriented silicon steel. This method preheats the steel coil in a water bath device, cold-rolls the 1.8-2.3mm normalized plate to the finished thickness, uses a low milk supply of 500-600L / min on both sides of the rolling mill for the 1st to 3rd passes, and uses a high milk supply of 1000-2000L / min from the 4th pass to the finished pass to improve the cold rolling efficiency and yield. The above method is mainly applicable to the production of oriented silicon steel by low-temperature heating of slabs and single cold rolling, and the minimum thickness of the finished product is only 0.23 mm. There are no reports on the production of thinner oriented silicon steel by medium-temperature heating and double cold rolling. Summary of the Invention

[0004] In view of this, the present application provides a method for preparing grain-oriented steel, which can reduce the edge crack rate during cold rolling and improve the cold rolling yield rate. Furthermore, a grain-oriented silicon steel and steel products are provided.

[0005] In a first aspect, the present application provides a method for preparing grain-oriented silicon steel, comprising the following steps:

[0006] hot rolling the ingot to obtain a hot-rolled plate;

[0007] The hot-rolled plate is sequentially subjected to pickling, first cold rolling, decarburization annealing and second cold rolling;

[0008] The first cold rolling step includes rolling the hot-rolled plate at least three times, wherein the speed of the first rolling pass is ≤300m / min, the speed of each intermediate rolling pass is 600m / min-800m / min, and the speed of the last rolling pass is 650m / min-750m / min; the starting rolling temperature of the first cold rolling is ≥50°C; during the first cold rolling process, the reduction rates of the first rolling pass and the intermediate rolling pass are independently 31%-45%, and the reduction rate of the last rolling pass is 20%-30%.

[0009] In this preparation method, the hot-rolled sheet undergoes a first cold rolling, decarburization annealing, and a second cold rolling. Controlling the starting rolling temperature to ≥50°C improves the material's plasticity and reduces the risk of brittle fracture. Combined with pass-by speed gradient control and reduction ratio control, the deformation process is optimized in stages, effectively reducing the incidence of edge cracking and strip breakage. Furthermore, the synergistic combination of decarburization annealing and secondary cold rolling further improves the cold rolling yield and surface quality, achieving efficient, low-defect cold rolling production.

[0010] In some embodiments, the first cold rolling is carried out in a twenty-roll reversible cold rolling mill, which includes support rolls, intermediate rolls and working rolls, the roughness of the working rolls is 2.0μm-3.0μm, and the convexity of the intermediate rolls is 0.15mm-0.35mm; preferably, the cold rolling mill is a twenty-roll reversible cold rolling mill.

[0011] In some embodiments, the second cold rolling step includes rolling the steel coil after decarburization annealing treatment for at least three times, wherein the speed of the first rolling pass is ≤300m / min, the speed of each intermediate rolling pass is 600m / min-800m / min, and the speed of the last rolling pass is 650m / min-750m / min.

[0012] In some embodiments, the above preparation method satisfies at least one of the following conditions:

[0013] (1) During the second cold rolling process, the reduction rate of each pass is 20%-35%;

[0014] (2) During each rolling pass of the first cold rolling process, an emulsion is introduced at a flow rate of 2000 L / min-2500 L / min;

[0015] (3) During the second cold rolling process, emulsion is introduced during each rolling pass, and the flow rate of the emulsion is 2000L / min-2500L / min.

[0016] In some embodiments, the hot rolling step includes: heating the ingot to 1280° C.-1350° C., keeping the temperature for 200 min-400 min, and then performing 1-2 rough rolling passes and 6-7 finish rolling passes in sequence.

[0017] In some embodiments, the decarburization annealing temperature is 830° C.-880° C., and the holding time is 4 min-8 min.

[0018] In some embodiments, the casting slab includes the following components by weight:

[0019] C: 0.025%-0.045%, Si: 2.8%-3.5%, Als: 0.013%-0.025%, N: 0.007%-0.012%, Mn: 0.1%-0.3%, Cu: 0.4%-0.6%, S: 0.003%-0.010%, Sn: 0.01%-0.15%, Cr: 0.01%-0.20%, and the rest is Fe and unavoidable impurities.

[0020] A second aspect of the present application provides a grain-oriented silicon steel, which is prepared according to the preparation method provided in the first aspect.

[0021] In some embodiments, the grain-oriented silicon steel has a thickness of 0.18 mm to 0.23 mm.

[0022] A third aspect of the present application provides a steel product, which includes the oriented silicon steel provided in the second aspect. DETAILED DESCRIPTION

[0023] In order to more clearly understand the above-mentioned objectives, features and advantages of the present application, the scheme of the present application will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present application may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present application, rather than all of the embodiments.

[0025] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values ​​and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0027] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0028] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0029] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0030] Unless otherwise specified, this application adopts conventional test methods or test methods recommended by the instrument.

[0031] A method for preparing oriented steel

[0032] In one embodiment of the present application, a method for preparing grain-oriented steel is provided, comprising the following steps:

[0033] hot rolling the ingot to obtain a hot-rolled plate;

[0034] The hot-rolled plate is sequentially subjected to pickling, first cold rolling, decarburization annealing and second cold rolling;

[0035] The first cold rolling step includes rolling the hot-rolled plate at least three times, wherein the speed of the first rolling pass is ≤300m / min, the speed of each intermediate rolling pass is 600m / min-800m / min, and the speed of the last rolling pass is 650m / min-750m / min; the starting rolling temperature of the first cold rolling is ≥50°C; during the first cold rolling process, the reduction rates of the first rolling pass and the intermediate rolling pass are independently 31%-45%, and the reduction rate of the last rolling pass is 20%-30%.

[0036] In this preparation method, the hot-rolled sheet undergoes pickling, a first cold rolling, decarburization annealing, and a second cold rolling. Controlling the start rolling temperature to ≥50°C improves the material's plasticity and reduces the risk of brittle fracture. Combined with pass-by speed gradient control and reduction ratio control, the deformation process is optimized in stages, effectively reducing the incidence of edge cracking and strip breakage. Furthermore, the synergistic combination of decarburization annealing and secondary cold rolling further improves the cold rolling yield and surface quality, achieving efficient, low-defect cold rolling production.

[0037] As an example, the starting rolling temperature of the first cold rolling can be 50°C, 55°C, 60°C, 65°C, 70°C or other temperatures within the above ranges. Further, the starting rolling temperature of the first cold rolling is 50°C-60°C.

[0038] For example, during the first cold rolling process, the first-pass rolling speed can be 300 m / min, 250 m / min, 200 m / min, 150 m / min, or any other value within the aforementioned range. Furthermore, the first-pass rolling speed is 150 m / min-300 m / min. Rolling the first pass at a lower speed can reduce the occurrence of edge cracks and large edge waves on the steel plate.

[0039] As an example, the rolling speed of each intermediate pass can be 600m / min, 620m / min, 650m / min, 680m / min, 700m / min, 750m / min, 780m / min or 800m / min. Furthermore, the rolling speed of each intermediate pass can be any other value within the range formed by the above-mentioned arbitrary two point values ​​as end values. Controlling the rolling speed of each intermediate pass within the above-mentioned range can improve the stability of the rolling state and reduce the rolling time, so that the steel plate of the required thickness can be obtained in a shorter time. Furthermore, the above-mentioned intermediate pass rolling can be one pass rolling or two or more passes rolling.

[0040] As an example, the speed of the final rolling pass can be 650 m / min, 680 m / min, 700 m / min, 720 m / min, 740 m / min, or 750 m / min. Furthermore, during the first cold rolling process, the speed of the final rolling pass can be any other value within the range defined by any two of the aforementioned values. The final rolling pass in the cold rolling process is also the final rolling pass. The final rolling pass within the aforementioned range ensures a stable, controllable shape of the steel plate and smooth rolling.

[0041] As an example, during the first cold rolling process, the reduction ratios of the first and intermediate passes are independently 31%-45%. Wherein, reduction ratio = (thickness before rolling - thickness after rolling) / thickness before rolling × 100%. It is understood that the reduction ratio of the first rolling pass can be 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44% or 45%. Furthermore, it can also be any value within the range formed by any two of the above point values ​​as end values. Similarly, the reduction rate of the intermediate rolling pass can be 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44% or 45%. Furthermore, it can also be any value within the range formed by any two of the above point values ​​as end values.

[0042] Furthermore, during the first cold rolling process, the final rolling reduction can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%. Controlling the rolling reductions of each pass in the first cold rolling process within the aforementioned ranges can forcibly break up coarse grains, promote uniform distribution of inhibitors, and lay the foundation for the formation of a Gaussian texture during subsequent decarburization annealing. This also allows for efficient sheet thinning and reduces processing energy consumption.

[0043] In some embodiments, the first cold rolling step includes rolling the pickled hot-rolled plate through 3-4 passes.

[0044] In some embodiments, during each rolling pass of the first cold rolling process, an emulsion is introduced at a flow rate of 2000 L / min to 2500 L / min. Introducing the emulsion during rolling and controlling the emulsion flow rate can facilitate uniform thermal expansion of the rolls and control stress at the edges of the steel strip.

[0045] In some embodiments, the first cold rolling is performed in a cold rolling mill. The cold rolling mill includes support rolls, intermediate rolls, and work rolls. The work rolls are primarily used to control thickness and surface, while the intermediate rolls are primarily used to control plate shape.

[0046] In some embodiments, the work roll roughness is 2.0 μm to 3.0 μm. The roughness of the work roll affects the friction between the roll and the plate. An appropriate roughness balances rolling force and bite stability, preventing slippage. It also prevents temperature rise defects caused by excessive friction, which can lead to increased brittleness of the plate.

[0047] In some embodiments, the crown of the intermediate roll is 0.15mm-0.35mm. Controlling the crown of the intermediate roll serves two primary purposes: First, crown adjustment optimizes rolling force distribution, reduces localized stress concentration, and prevents edge cracking or strip breakage. Second, it compensates for lateral deformation differences in the sheet during rolling. Too little crown can result in thinning at the edges, while too much can result in excessive thickening in the center. Proper crown design can reduce "edge waves" and "center waves" defects, improving sheet flatness.

[0048] In some practical examples, the cold rolling mill is a twenty-high reversing cold rolling mill.

[0049] In some embodiments, the second cold rolling step includes rolling the steel coil after decarburization annealing treatment for at least three times, wherein the speed of the first rolling pass is ≤300m / min, the speed of each intermediate rolling pass is 600m / min-800m / min, and the speed of the last rolling pass is 650m / min-750m / min.

[0050] For example, during the second cold rolling process, the first-pass rolling speed can be 300 m / min, 250 m / min, 200 m / min, 150 m / min, or any other value within the aforementioned range. Furthermore, the first-pass rolling speed can be between 150 m / min and 300 m / min. Performing the first-pass rolling at a lower speed can further reduce the occurrence of edge cracks and large edge waves on the steel plate.

[0051] As an example, during the second cold rolling process, the rolling speed of each intermediate pass can be 600m / min, 620m / min, 650m / min, 680m / min, 700m / min, 750m / min, 780m / min or 800m / min. Furthermore, the rolling speed of each intermediate pass can be any other value within the range formed by the above-mentioned arbitrary two point values ​​as end values. Controlling the rolling speed of each intermediate pass within the above-mentioned range can improve the rolling state stability, and can also reduce the rolling time, so that the steel plate of the required thickness can be obtained in a shorter time. Furthermore, the above-mentioned intermediate pass rolling can be one pass rolling, or it can be two or more passes rolling.

[0052] As an example, during the second cold rolling process, the speed of the final rolling pass can be 650 m / min, 680 m / min, 700 m / min, 720 m / min, 740 m / min, or 750 m / min. Furthermore, during the second cold rolling process, the speed of the final rolling pass can be any other value within the range formed by the aforementioned two arbitrary point values ​​as end values. The final rolling pass in the cold rolling process is also the finished product rolling pass. The final rolling pass within the aforementioned range can ensure a stable, controllable shape of the steel plate and smooth rolling.

[0053] In some embodiments, during the second cold rolling process, the reduction rate of each rolling pass is 20%-35%. It is understood that the reduction rate of each rolling pass performed during the second cold rolling process can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 32%, 34% or 35%. Furthermore, it can also be any value within the range value formed by any two of the above point values ​​as end values. Controlling the reduction rate of each rolling pass during the second cold rolling process within the above range can protect the integrity of the texture formed after decarburization annealing, avoid brittle fracture, and accurately control the final thickness and surface quality. At the same time, edge cracking and band breakage are further suppressed, thereby improving the yield rate.

[0054] In some embodiments, during each rolling pass of the second cold rolling process, an emulsion is introduced, and the flow rate of the emulsion is 2000 L / min-2500 L / min.

[0055] In some embodiments, the decarburization annealing temperature is 830° C.-880° C. It is understood that the decarburization annealing temperature can be 830° C., 840° C., 850° C., 860° C., 870° C., or 880° C.; further, it can be any value within a range formed by any two of the above-mentioned points as end values.

[0056] In some embodiments, the holding time for decarburization annealing is 4-8 minutes. By reducing the carbon content in the steel, decarburization annealing effectively eliminates cold rolling work hardening, restores the material's plasticity, and completes primary recrystallization, significantly reducing the risk of edge cracking and strip breakage during subsequent cold rolling. It also optimizes the microstructure and texture, improving the magnetic properties of grain-oriented steel. Furthermore, annealing forms a well-defined oxide layer, laying the foundation for the formation of a superior base layer during subsequent high-temperature annealing, ultimately resulting in excellent finished product surface quality.

[0057] In some embodiments, the decarburization annealing process is performed in a mixed gas atmosphere of wet hydrogen and nitrogen.

[0058] In some embodiments, the hot rolling step includes heating the ingot to 1280°C-1350°C, holding the ingot at that temperature for 200-400 minutes, and then sequentially performing 3-5 rough rolling passes and 6-7 finish rolling passes. It is understood that the rough rolling and finish rolling in the hot rolling step are conventional rough rolling and conventional finish rolling steps used in the art.

[0059] In some embodiments, pickling is performed using concentrated hydrochloric acid at a concentration of 150-250 g / L at a temperature of 75-90° C. Pickling the hot-rolled plate before the first cold rolling step can remove impurities such as an oxide layer on the surface of the hot-rolled plate, which is more conducive to the subsequent first cold rolling process.

[0060] Furthermore, in order to improve the pickling efficiency and the pickling effect, the hot-rolled plate may be shot blasted before pickling.

[0061] In some embodiments, the casting slab includes the following components by weight:

[0062] C: 0.025%-0.045%, Si: 2.8%-3.5%, Als: 0.013%-0.025%, N: 0.007%-0.012%, Mn: 0.1%-0.3%, Cu: 0.4%-0.6%, S: 0.003%-0.010%, Sn: 0.01%-0.15%, Cr: 0.01%-0.20%, and the rest is Fe and unavoidable impurities. Furthermore, the ingot includes the following components: C: 0.025%-0.043%, Si: 2.8%-3.4%, Als: 0.013%-0.022%, N: 0.007%-0.011%, Mn: 0.21%-0.29%, Cu: 0.45%-0.6%, S: 0.003%-0.010%, Sn: 0.01%-0.15%, Cr: 0.01%-0.20%, and the rest is Fe and unavoidable impurities. Furthermore, the ingot includes the following components: C: 0.025%-0.038%, Si: 2.8%-3.2%, Als: 0.013%-0.02%, N: 0.007%-0.01%, Mn: 0.21%-0.29%, Cu: 0.5%-0.55%, S: 0.003%-0.010%, Sn: 0.01%-0.15%, Cr: 0.015%-0.20%, and the rest is Fe and unavoidable impurities.

[0063] Grain-oriented silicon steel

[0064] In one embodiment of the present application, a grain-oriented silicon steel is provided. The grain-oriented silicon steel is prepared by the above-mentioned preparation method.

[0065] In some embodiments, the above-mentioned grain-oriented silicon steel is a plate.

[0066] In some embodiments, the grain-oriented silicon steel has a thickness of 0.18 mm to 0.23 mm.

[0067] steel products

[0068] In one embodiment of the present application, a steel product is provided, which includes the above-mentioned oriented silicon steel.

[0069] In some embodiments, the steel product includes, but is not limited to, power transformer core.

[0070] Example

[0071] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, 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 used directly without further processing, and all instruments used in the examples are commercially available.

[0072] Example 1

[0073] (1) Steelmaking: Steel was produced by converter-refining-continuous casting to obtain a casting having the following composition (by weight percentage): C: 0.043%, Si: 3.4%, Als: 0.022%, N: 0.011%, Mn: 0.25%, Cu: 0.58%, S: 0.003%, Sn: 0.025%, Cr: 0.010%, and the remainder being Fe and unavoidable impurities.

[0074] (2) Hot rolling: The ingot was heated to 1330°C and kept at this temperature for 320 min. Then, it was subjected to 5 rough rolling passes and 7 finish rolling passes to obtain a hot-rolled plate with a thickness of 2.3 mm.

[0075] (3) Pickling: The hot-rolled plate was placed in a hydrochloric acid pickling solution at 80°C and a concentration of 200 g / L for pickling.

[0076] (4) First cold rolling: The steel coil after pickling is put on the cold rolling machine in time to reduce the temperature drop, ensuring that the temperature of the steel coil is 52°C when it is put on the cold rolling machine. Cold rolling is carried out in the cold rolling mill. After three passes of rolling, the first cold rolled coil with a thickness of 0.52 mm is obtained. The process parameters controlled during the first cold rolling process are shown in Table 1 below.

[0077] (5) Decarburization annealing: In a wet H2 and N2 atmosphere, at 835°C, keep warm for 6 minutes to obtain the annealed material.

[0078] (6) Second cold rolling: When the temperature of the annealed material is 35°C, the second cold rolling is performed for three passes to obtain a second cold-rolled coil with a thickness of 0.18 mm. The process parameters controlled during the second cold rolling process are shown in Table 1 below.

[0079] Comparative Example 1

[0080] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the starting rolling temperature of the first cold rolling in step (4) of Comparative Example 1 is 10°C; and the rolling conditions of each pass of the first cold rolling and the second cold rolling are different from those of Example 1. The specific rolling conditions are shown in Table 1.

[0081] Comparative Example 2

[0082] The preparation method of Comparative Example 2 is basically the same as that of Example 1. The main difference is that the rolling conditions of each pass of the first cold rolling in Comparative Example 2 are different from those in Example 1. The specific rolling conditions are shown in Table 1.

[0083] Table 1

[0084]

[0085]

[0086] Note: The edge crack incidence rate in the table = the number of coils with edge cracks / the total number of coils rolled in a batch × 100%;

[0087] Cold rolling yield = weight of cold rolled finished product / weight of incoming material × 100%.

[0088] As can be seen from the data in Table 1, Example 1 uses the preparation method of the present application, controlling the start rolling temperature of the first cold rolling, and controlling the rolling rate and reduction ratio of each pass during the first cold rolling process, and then coordinating decarburization annealing and the second cold rolling process; its edge crack incidence rate is 8%, and the cold rolling yield rate is 93.2%. In contrast, in Comparative Example 1, when preparing medium-temperature grain-oriented steel, the first cold rolling process begins when the temperature of the hot-rolled plate after pickling is 10°C, and the rolling is carried out at a constant and relatively high rate during the first cold rolling process, and the reduction ratio of the first rolling pass is too high; its edge crack rate is as high as 29.5%, and the cold rolling yield rate is 84.3%. In Comparative Example 2, when preparing medium-temperature grain-oriented steel, the first cold rolling process has a relatively high rolling rate of 450 m / min in the first cold rolling process, and the rolling rate of the intermediate pass and the finished pass is controlled at 500 m / min. The results show that its edge crack incidence rate is 33%, and the cold rolling yield rate is 82%. It can be seen that the present application reduces the edge crack rate of steel during the cold rolling process and improves the cold rolling yield rate by controlling the starting rolling temperature of the first cold rolling and controlling the rolling rate of each pass during the first cold rolling process within a specific range, and then coordinating decarburization annealing and the second cold rolling treatment. It can also obtain thinner steel plates more quickly and reduce processing time costs.

[0089] Example 2

[0090] (1) Steelmaking: Steel was produced by converter-refining-continuous casting to obtain a casting having the following composition (by weight): C: 0.038%, Si: 3.2%, Als: 0.019%, N: 0.0095%, Mn: 0.29%, Cu: 0.52%, S: 0.003%, Sn: 0.15%, Cr: 0.018%, and the remainder being Fe and unavoidable impurities.

[0091] (2) Hot rolling: The ingot was heated to 1286°C and kept at this temperature for 280 min. Then, it was subjected to 5 rough rolling passes and 7 finish rolling passes to obtain a hot-rolled plate with a thickness of 2.3 mm.

[0092] (3) Pickling: The hot-rolled plate was placed in a hydrochloric acid pickling solution at 85°C and a concentration of 180 g / L for pickling.

[0093] (4) First cold rolling: The steel coil after pickling is put on the cold rolling machine in time to reduce the temperature drop, ensuring that the temperature of the steel coil is 56°C when it is put on the cold rolling machine. Cold rolling is carried out in the cold rolling mill. After three passes of rolling, the first cold rolled coil with a thickness of 0.63 mm is obtained. The process parameters controlled during the first cold rolling process are shown in Table 2 below.

[0094] (5) Decarburization annealing: in wet H2 and N2 atmosphere, at 840℃, keep warm for 6.5min.

[0095] (6) Second cold rolling: When the temperature of the annealed material is 25°C, the second cold rolling is performed for 4 passes to obtain a second cold-rolled coil with a thickness of 0.23 mm. The process parameters controlled during the second cold rolling process are shown in Table 2 below.

[0096] Comparative Example 3

[0097] The preparation method of Comparative Example 3 is basically the same as that of Example 2, except that the starting rolling temperature of the first cold rolling in step (4) of Comparative Example 3 is 30°C; and the rolling conditions of each pass of the first cold rolling and the second cold rolling of Comparative Example 3 are different from those of Example 2. The specific rolling conditions are shown in Table 2.

[0098] Table 2

[0099]

[0100] Example 3

[0101] (1) Steelmaking: Steelmaking is carried out through converter-refining-continuous casting to obtain a casting having the following composition (by weight percentage): C: 0.026%, Si: 2.85%, Als: 0.0135%, N: 0.0090%, Mn: 0.21%, Cu: 0.52%, S: 0.009%, Sn: 0.1%, Cr: 0.195%, and the remainder being Fe and unavoidable impurities.

[0102] (2) Hot rolling: The ingot was heated to 1283°C and kept at this temperature for 210 min. Then, it was subjected to three passes of rough rolling and seven passes of finish rolling to obtain a hot-rolled plate with a thickness of 2.2 mm.

[0103] (3) Pickling: The hot-rolled plate was placed in a concentrated hydrochloric acid pickling solution at 78°C and a concentration of 210 g / L for pickling.

[0104] (4) First cold rolling: When the pickled steel plate is cooled to 55°C, it is cold rolled in a cold rolling mill. After three passes, a first cold rolled coil with a thickness of 0.58 mm is obtained. The process parameters during the first cold rolling process are shown in Table 3 below.

[0105] (5) Decarburization annealing: In a wet H2 and N2 atmosphere, at 836°C, keep warm for 6 minutes to obtain the annealed material.

[0106] (6) Second cold rolling: When the temperature of the annealed material is 20°C, the second cold rolling is performed for 3 passes to obtain a second cold-rolled coil with a thickness of 0.20 mm. The process parameters during the second cold rolling process are shown in Table 3 below.

[0107] Comparative Example 4

[0108] The preparation method of Comparative Example 4 is basically the same as that of Example 3, except that the rolling conditions of the first cold rolling and the second cold rolling are different from those of Example 3. The specific rolling conditions are shown in Table 3.

[0109] Table 3

[0110]

[0111] The above description is only a specific embodiment of the present application. Those skilled in the art will clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the scope of protection of the present application.

Claims

1. A method for preparing oriented silicon steel, characterized in that: The steps include: hot rolling the ingot to obtain a hot-rolled plate; The hot-rolled plate is sequentially subjected to pickling, a first cold rolling, a decarburization annealing, and a second cold rolling; The first cold rolling step includes rolling the pickled hot-rolled plate for at least three passes, wherein the speed of the first rolling pass is ≤300m / min, the speed of each intermediate rolling pass is 600m / min-800m / min, and the speed of the last rolling pass is 650m / min-750m / min; the starting rolling temperature of the first cold rolling is ≥50°C; during the first cold rolling process, the reduction rates of the first rolling pass and the intermediate rolling pass are independently 31%-45%, and the reduction rate of the last rolling pass is 20%-30%.

2. The preparation method according to claim 1, characterized in that The first cold rolling is carried out in a cold rolling mill, which includes support rolls, intermediate rolls and working rolls. The roughness of the working rolls is 2.0 μm-3.0 μm, and the convexity of the intermediate rolls is 0.15 mm-0.35 mm. Preferably, the cold rolling mill is a twenty-roll reversible cold rolling mill.

3. The preparation method according to any one of claims 1 to 2, characterized in that The second cold rolling step includes rolling the steel coil after decarburization annealing for at least three passes, wherein the speed of the first pass is ≤300m / min, the speed of each intermediate pass is 600m / min-800m / min, and the speed of the last pass is 650m / min-750m / min.

4. The preparation method according to claim 3, characterized in that The preparation method satisfies at least one of the following conditions: (1) During the second cold rolling process, the reduction rate of each rolling pass is 20%-35%; (2) During each rolling pass of the first cold rolling process, an emulsion is introduced at a flow rate of 2000 L / min to 2500 L / min; (3) During each rolling pass of the second cold rolling process, an emulsion is introduced, and the flow rate of the emulsion is 2000L / min-2500L / min.

5. The preparation method according to any one of claims 1 to 2 and 4, characterized in that The hot rolling step comprises: heating the ingot to 1280° C.-1350° C., keeping the temperature for 200 min-400 min, and then sequentially performing 3-5 passes of rough rolling and 6-7 passes of finish rolling.

6. The preparation method according to any one of claims 1 to 2 and 4, characterized in that The decarburization annealing temperature is 830° C.-880° C., and the holding time is 4 min-8 min.

7. The preparation method according to any one of claims 1 to 2 and 4, characterized in that The casting blank comprises the following components in terms of mass percentage: C: 0.025%-0.045%, Si: 2.8%-3.5%, Als: 0.013%-0.025%, N: 0.007%-0.012%, Mn: 0.1%-0.3%, Cu: 0.4%-0.6%, S: 0.003%-0.010%, Sn: 0.01%-0.15%, Cr: 0.01%-0.20%, and the rest is Fe and unavoidable impurities.

8. A oriented silicon steel, characterized in that: The oriented silicon steel is prepared according to the preparation method according to any one of claims 1 to 7.

9. The oriented silicon steel according to claim 8, characterized in that: The thickness of the oriented silicon steel is 0.18 mm to 0.23 mm.

10. A steel product, characterized in that: The steel product includes the oriented silicon steel according to any one of claims 8 to 9.

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