Production method of high-grade non-oriented silicon steel hot-rolled sheet

Abstract

The present invention discloses a production method of non-oriented electrical steel hot-rolled sheet. The production method includes: preparing a continuous casting slab through steelmaking and continuous casting; annealing the obtained continuous casting slab, with the annealing temperature being 600 - 700 °C and the annealing duration being 10 - 30 hours; heating the annealed continuous casting slab, with the soaking temperature being 1050 - 1250 °C and the soaking duration being 180 - 220 min; first rolling the heated continuous casting slab into an intermediate slab with a thickness of 40 - 45 mm through rough rolling, and then performing finish rolling and coiling to obtain a hot-rolled sheet; wherein, the rough rolling finishing temperature is 950 - 1000 °C, the finish rolling finishing temperature is 820 - 880 °C, and the coiling temperature is 600 - 680 °C. The present invention can avoid the abnormal growth of ferrite columnar crystals caused by internal stress in the continuous casting slab and eliminate the defect of serrated edge cracks in the hot-rolled sheet.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel material preparation, and relates to a production method of non-oriented silicon steel hot-rolled sheet, in particular to a production method of high-grade non-oriented silicon steel hot-rolled sheet. Background Art

[0002] High-grade non-oriented silicon steel is a key material for manufacturing the iron cores of various high-efficiency motors and large generator sets. Its iron loss is closely related to the operating efficiency of the motor. Specifically, the lower the iron loss of the non-oriented silicon steel, the corresponding operating efficiency of the motor.

[0003] The most effective way to reduce iron loss is to increase the Si / Al alloy content. However, with the increase of Si / Al content, in the production of non-oriented silicon steel, the production difficulty of hot rolling and cold rolling will also increase significantly.

[0004] Therefore, in the existing production process of high-grade non-oriented silicon steel, serrated edge cracking is one of the more common defects of hot-rolled sheets. Furthermore, this serrated edge cracking of hot-rolled sheets is extremely likely to cause serious edge cracking and strip breakage during cold rolling, severely restricting the continuous and stable production of high-grade non-oriented silicon steel.

[0005] In order to overcome the edge cracking defect of hot-rolled sheets, a patent application with the publication number CN117862234A controls the intermediate slab thickness, adjusts the hot rolling temperature, fully descales, and adjusts the hot rolling target reduction rate and other comprehensive control processes to reduce the microcracks at the edges of non-oriented silicon steel. Although this method can reduce the edge cracking defect macroscopically, it does not study the cause of edge cracking of hot-rolled sheets and cannot fundamentally solve the edge cracking problem of high-grade non-oriented silicon steel hot-rolled sheets.

[0006] Other known technologies for solving the edge cracking problem of hot-rolled sheets also generally focus on aspects such as heating temperature and hot rolling load distribution, and still have problems such as large hot rolling difficulty, reduced stability, low finished product conversion rate, and resource waste. Summary of the Invention

[0007] To solve the edge cracking problem of hot-rolled sheets, the purpose of the present invention is to provide a production method of non-oriented silicon steel hot-rolled sheet.

[0008] To achieve the above-mentioned invention purpose, an embodiment of the present invention provides a production method of non-oriented silicon steel hot-rolled sheet. The production method includes the following steps:

[0009] Prepare a continuous casting billet through steelmaking and continuous casting;

[0010] Anneal the obtained continuous casting billet at an annealing temperature of 600-700°C for an annealing duration of 10-30 hours;

[0011] Heat the annealed continuous casting billet, with the soaking temperature being 1050 - 1250 °C and the soaking duration being 180 - 220 min;

[0012] First, roll the heated continuous casting billet through rough rolling to produce an intermediate billet with a thickness of 40 - 45 mm, then perform finish rolling and coiling to obtain a hot-rolled sheet; among them, the rough rolling finishing temperature is 950 - 1000 °C, the finish rolling finishing temperature is 820 - 880 °C, and the coiling temperature is 600 - 680 °C.

[0013] Preferably, the step "anneal the obtained continuous casting billet, with the annealing temperature being 600 - 700 °C and the annealing duration being 10 - 30 hours" includes:

[0014] Detect the bulging amount of the wide surface of the obtained continuous casting billet;

[0015] When the bulging amount does not reach 10 mm, the annealing temperature is 600 - 650 °C and the annealing duration is 10 - 15 hours;

[0016] When the bulging amount is 10 - 15 mm, the annealing temperature is 600 - 650 °C and the annealing duration is 15 - 20 hours;

[0017] When the bulging amount exceeds 15 mm, the annealing temperature is 650 - 700 °C and the annealing duration is 20 - 30 hours.

[0018] Preferably, in the step "first, roll the heated continuous casting billet through rough rolling to produce an intermediate billet with a thickness of 40 - 45 mm, then perform finish rolling and coiling to obtain a hot-rolled sheet":

[0019] The reduction ratio of each pass in rough rolling is controlled at 32 - 38%, and the reduction ratio of each pass in finish rolling is controlled at 30 - 38%.

[0020] Preferably, in the step "first, roll the heated continuous casting billet through rough rolling to produce an intermediate billet with a thickness of 40 - 45 mm, then perform finish rolling and coiling to obtain a hot-rolled sheet":

[0021] The thickness of the obtained hot-rolled sheet is 2.0 - 2.4 mm.

[0022] Preferably, in the step "first, roll the heated continuous casting billet through rough rolling to produce an intermediate billet with a thickness of 40 - 45 mm, then perform finish rolling and coiling to obtain a hot-rolled sheet":

[0023] In each pass of rough rolling, vertical rolls are used for wide surface rolling, and the rolling force of the vertical rolls decreases pass by pass, and the rolling force of the vertical rolls in each pass is controlled within the range of F 1n ~F 2n where F 1n = 2000 + h n × 70 - 500 kN, F 2n= 2000 + h n × 70 + 500 kN, where n in the formula represents the pass number, and h n is the preset thickness of the billet at the exit of the nth pass, with the unit of mm.

[0024] Preferably, the step of "preparing a continuous casting billet through steelmaking and continuous casting" includes:

[0025] During continuous casting, the superheat of the tundish molten steel is 10 - 15 °C.

[0026] Preferably, the step of "preparing a continuous casting billet through steelmaking and continuous casting" includes:

[0027] During continuous casting, the casting speed v, the target thickness t of the slab, and the target width w satisfy 0.21 ≤ v × t × w ≤ 0.22, where the unit of v is m / min, the unit of t is m, and the unit of w is m.

[0028] Preferably, the step of "preparing a continuous casting billet through steelmaking and continuous casting" includes:

[0029] During continuous casting, the cooling rate V of the mold is controlled to satisfy V = 8.5 - 0.5[Si] - 0.3[Al] - 0.2[Mn] ± 0.5 with the mass fractions of Si, Al, and Mn in the molten steel, where the unit of V is °C / s.

[0030] Preferably, the step of "preparing a continuous casting billet through steelmaking and continuous casting" includes:

[0031] During continuous casting, the wide face of the billet is constrained by vertical rolls in the secondary cooling zone.

[0032] Preferably, in the step of "preparing a continuous casting billet through steelmaking and continuous casting", the chemical composition of the continuous casting billet includes, by mass percentage: Si 2.5 - 3.5%, Al 0.5 - 1.5%, Mn 0.2 - 0.8%, and the rest is iron and inevitable impurities.

[0033] Preferably, for the chemical composition of the continuous casting billet, the impurity elements satisfy, by mass percentage: C ≤ 0.0025%, S ≤ 0.0015%, P: 0.03 - 0.05%, Nb ≤ 0.002%, V ≤ 0.002%, Ti ≤ 0.002%, N ≤ 0.002%.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: Compared with the conventional hot-rolled sheet production process of steelmaking, continuous casting, heating, hot rolling, and coiling, before heating the continuous casting billet, the present invention first anneals the continuous casting billet. Through experimental verification, after this annealing treatment, even if high-temperature heating is carried out in the subsequent heating process, the occurrence of serrated edge cracking defects in the obtained hot-rolled sheet can be greatly eliminated. From the perspective of microscopic principles, the annealing treatment can eliminate the internal stress at the edge of the continuous casting billet, thereby avoiding the abnormal growth of ferrite columnar crystals caused by this internal stress during the heating process, and ultimately eliminating the serrated edge cracking defects of the hot-rolled sheet caused by the abnormally grown columnar crystals. In this way, this production method also avoids a series of derivative problems such as reducing the heating temperature, increasing the difficulty of hot rolling, and waste caused by trimming. Specific Embodiments

[0035] The technical solution of the present invention will be further introduced below in conjunction with specific embodiments.

[0036] The present invention provides a production method for steel plates, which is particularly suitable for the production of non-oriented silicon steel hot-rolled sheets. That is, the non-oriented silicon steel hot-rolled sheets can be prepared by adopting this production method, and the serrated edge cracking defects of the non-oriented silicon steel hot-rolled sheets can be solved.

[0037] Specifically, the production method includes the following steps:

[0038] Prepare a continuous casting billet through steelmaking and continuous casting;

[0039] Anneal the obtained continuous casting billet, with the annealing temperature being 600 - 700 °C and the annealing duration being 10 - 30 hours;

[0040] Heat the annealed continuous casting billet, with the soaking temperature being 1050 - 1250 °C and the soaking duration being 180 - 220 min;

[0041] First pass the heated continuous casting billet through rough rolling to form an intermediate billet with a thickness of 40 - 45 mm, and then carry out finish rolling and coiling to obtain a hot-rolled sheet; wherein, the rough rolling finishing rolling temperature is 950 - 1000 °C, the finish rolling finishing rolling temperature is 820 - 880 °C, and the coiling temperature is 600 - 680 °C.

[0042] Through research by the inventors on the causes of serrated edge cracks in hot-rolled sheets, it was found that due to the abnormal growth of ferrite columnar crystals at the edges of continuous casting billets during the heating process, uneven plastic deformation occurs at the edges of the rolled pieces during the hot-rolling process. This uneven plastic deformation directly leads to serrated edge cracks. Compared with the conventional hot-rolled sheet production process of steelmaking, continuous casting, heating, hot-rolling, and coiling, in the present invention, before heating the continuous casting billet, the continuous casting billet is annealed first. Through experimental verification, after this annealing treatment, even during high-temperature heating in subsequent heating processes, the occurrence of serrated edge crack defects in the obtained hot-rolled sheets can be greatly eliminated. From a microscopic principle analysis, the annealing treatment can eliminate the internal stress at the edges of the continuous casting billet, thereby avoiding the abnormal growth of ferrite columnar crystals caused by this internal stress during the heating process, and ultimately eliminating the defects of serrated edge cracks in the hot-rolled sheets caused by the abnormally grown columnar crystals. In this way, this production method also avoids a series of derivative problems such as reducing the heating temperature, increasing the difficulty of hot-rolling, and waste caused by trimming the edges.

[0043] Further, in the annealing process, that is, in the step "anneal the obtained continuous casting billet, the annealing temperature is 600 - 700 °C, and the annealing duration is 10 - 30 hours", it may specifically include:

[0044] Detect the bulging amount of the wide surface of the obtained continuous casting billet;

[0045] When the bulging amount does not reach 10 mm, the annealing temperature is 600 - 650 °C, and the annealing duration is 10 - 15 hours;

[0046] When the bulging amount is 10 - 15 mm, the annealing temperature is 600 - 650 °C, and the annealing duration is 15 - 20 hours;

[0047] When the bulging amount exceeds 15 mm, the annealing temperature is 650 - 700 °C, and the annealing duration is 20 - 30 hours.

[0048] Under the basic concept of annealing the continuous casting billet in the present invention, further optimizing the annealing temperature and annealing duration according to the bulging amount can improve the edge quality of the hot-rolled sheet to a greater extent and better solve the problem of serrated edge crack defects in the hot-rolled sheet.

[0049] Specifically, through research, it was found that when there is bulging deformation on the wide surface of the continuous casting billet, this bulging deformation will cause greater internal stress at the edges of the continuous casting billet, and this internal stress will cause the abnormal growth of ferrite columnar crystals during the heating process, thereby leading to serrated edge cracks in the hot-rolled sheet. In the further improvement scheme of the present invention, corresponding the bulging amount to specific annealing temperature and annealing duration can maximize the elimination of the internal stress of the bulging deformation through the annealing process to improve the edge quality of the hot-rolled sheet.

[0050] Here, the "wide face", "bulging", and "bulging amount" are all professional terms in the field; among them, the "wide face" refers to: two faces in the width direction that are perpendicular to both the head-tail direction and the thickness direction of the continuous casting billet; "bulging" refers to: during the solidification process of the billet, under the action of the hydrostatic pressure of the molten steel, the phenomenon that the solidified shell bulges outwards into a convex surface; "bulging amount" refers to: the difference between the thickness at the center of the wide face and the thickness at the edge.

[0051] Of course, under the inventive concept of this application, it is also possible to directly control the annealing temperature and annealing duration without detecting the bulging amount, and it is also possible to solve the defect problem of serrated edge cracking of the hot-rolled plate. Just by detecting the bulging amount and adjusting the annealing temperature and duration accordingly, the edge quality of the hot-rolled plate can be further optimized.

[0052] Furthermore, in a basic embodiment of the present invention, processes such as steelmaking, continuous casting, heating, hot rolling, and coiling can be implemented in a conventional and known manner; as some preferred methods, some preferred embodiments of the continuous casting process and the hot rolling process will be introduced next to cooperate with the annealing process to further improve the edge quality of the hot-rolled plate and overcome the defect of serrated edge cracking.

[0053] Specifically, in a preferred method, during continuous casting, the superheat of the tundish molten steel is 10 - 15 °C. In this way, by controlling the superheat of the tundish molten steel within 10 - 15 °C, the initial solidified shell thickness of the continuous casting billet (i.e., the shell thickness of the continuous casting billet when it leaves the mold) can be increased, thereby reducing the bulging amount of the wide face of the continuous casting billet to a certain extent, and further eliminating the serrated edge cracking defect of the hot-rolled plate caused by internal stress.

[0054] During continuous casting, it is also possible to control the casting speed v, the target thickness t of the slab, and the target width w to satisfy 0.21 ≤ v × t × w ≤ 0.22, where the unit of v is m / min, the unit of t is m, and the unit of w is m. In this way, the initial solidified shell thickness of the continuous casting billet can also be increased, thereby reducing the bulging amount of the wide face of the continuous casting billet to a certain extent, and further eliminating the serrated edge cracking defect of the hot-rolled plate caused by internal stress.

[0055] From another perspective, in another preferred method, during continuous casting, it is possible to control the cooling rate V of the mold to satisfy V = 8.5 - 0.5[Si] - 0.3[Al] - 0.2[Mn] ± 0.5 with the mass fraction [Si] of Si, the mass fraction [Al] of Al, and the mass fraction [Mn] of Mn in the molten steel, where the unit of V is °C / s.

[0056] For example, the mass fraction [Si] of Si means that when the mass percentage of Si in the molten steel is 2.5%, [Si] is 2.5. In addition, the mass fractions of Si, Al, or Mn in the "molten steel" here can be obtained by detection from the molten steel at the end of steelmaking (alternatively, it can also be the molten steel poured during continuous casting).

[0057] In this way, by correlating the cooling rate V with the chemical composition of the molten steel (i.e., the chemical composition of the continuous casting billet), not only can the initial solidification shell thickness of the continuous casting billet be increased to reduce the bulging amount of the wide face of the continuous casting billet, thereby reducing the serrated edge crack defect of the hot-rolled sheet, but also the preparation of non-oriented electrical steel hot-rolled sheets with various composition changes can be addressed, ensuring the quality stability of non-oriented electrical steel hot-rolled sheets with various compositions and improving the versatility of this production method.

[0058] In addition, during continuous casting, the wide face of the billet can also be constrained by vertical rolls in the secondary cooling zone. In this way, through the constraint of the billet by the vertical rolls, the bulging deformation of the wide face of the billet can be further reduced by vertical roll rolling, thereby macroscopically avoiding the deterioration of the edge quality caused by bulging deformation during hot rolling and reducing the generation rate of serrated edge cracks.

[0059] Vertical rolls are arranged on both sides of the secondary cooling zone to respectively constrain the two wide faces of the billet to reduce the bulging amount of each wide face; preferably, the distance between the vertical rolls on both sides can be set to 1 to 1.01 times the target width w of the slab, or alternatively, the pressure of the vertical rolls is controlled within the range of 500 to 800 kN.

[0060] In a preferred mode, during the hot rolling process, the reduction ratio of each pass in rough rolling is controlled at 32 - 38%, and the reduction ratio of each pass in finish rolling is controlled at 30 - 38%.

[0061] In this application, the thickness of the obtained hot-rolled sheet is 2.0 - 2.4 mm.

[0062] In addition, during the hot rolling process, rough rolling and finish rolling each have multiple passes; in each pass of rough rolling, vertical rolls are used for wide face rolling, and the rolling force of the vertical rolls decreases pass by pass, and the rolling force of the vertical rolls in each pass is controlled within the range of F 1n ~F 2n wherein, F 1n = 2000 + h n × 70 - 500 kN, F 2n = 2000 + h n × 70 + 500 kN, where n represents the pass number, and h n is the preset thickness of the exit billet in the nth pass, with the unit of mm. In this way, the occurrence of serrated edge cracks at the edge can be further macroscopically avoided, preventing edge flanging during hot rolling and ensuring the edge quality of the hot-rolled sheet.

[0063] In addition, the obtained hot-rolled sheet can be cooled by conventional methods such as water cooling and air cooling, and can also be made into non-oriented electrical steel products by known existing technologies subsequently. For example, through processes such as pickling, cold rolling, and finish annealing, non-oriented electrical steel products are obtained. However, these subsequent processes have nothing to do with the serrated edge cracking defect of the hot-rolled sheet, that is, they have nothing to do with the purpose of the present invention, so they will not be elaborated in this application.

[0064] Furthermore, as mentioned above, the production method of the present invention can be used for non-oriented electrical steel, that is, the chemical composition of the hot-rolled sheet, or rather the chemical composition of the continuous casting billet, can be implemented as non-oriented electrical steel, and specifically, the chemical composition of non-oriented electrical steel known in the art can be adopted.

[0065] The production method of the present invention is particularly conducive to the production of hot-rolled sheets of high-grade non-oriented electrical steel. Specifically speaking, high-grade non-oriented electrical steel generally requires a higher Si / Al alloy content, which makes the serrated edge cracking defect of its hot-rolled sheet more serious. Therefore, the production method of the present invention can greatly improve the edge quality of hot-rolled sheets of high-grade non-oriented electrical steel, which is more meaningful for high-grade non-oriented electrical steel.

[0066] Specifically, in one embodiment, the chemical composition of the continuous casting billet includes, by mass percentage: Si 2.5 - 3.5%, Al 0.5 - 1.5%, Mn 0.2 - 0.8%, and the rest is iron and inevitable impurities.

[0067] Here, the impurity elements satisfy, by mass percentage: C ≤ 0.0025%, S ≤ 0.0015%, P ≤ 0.05%, Nb ≤ 0.002%, V ≤ 0.002%, Ti ≤ 0.002%, Cr ≤ 0.03%, Ni ≤ 0.03%, Cu ≤ 0.03%, N ≤ 0.002%.

[0068] Next, the functions and mechanisms of each element in the above chemical composition will be introduced.

[0069] C: In non-oriented electrical steel, C is generally considered a harmful element. When the C content increases, it will lead to fine grains of the finished product, high iron loss, poor magnetic properties, and cause magnetic aging problems. Therefore, it is usually better to control the C content as low as possible. In this embodiment, the C content is controlled below 0.0025%.

[0070] Si: It is an effective additive element to increase the resistivity of electromagnetic steel sheets and reduce iron loss, and can also effectively improve the strength of the steel strip. In this embodiment, the Si content (by mass percentage) is controlled at 2.5 - 3.5% to effectively reduce iron loss and meet the requirements of high-grade non-oriented electrical steel.

[0071] Al: It is also an effective additive element to increase the resistivity of electromagnetic steel sheets and reduce iron loss. However, if its content is too high, it will reduce the magnetic induction intensity, significantly increase the brittleness of the steel sheets, and increase the processing difficulty such as cold rolling. When its content is low, it will lead to too low resistivity and the fine precipitation of nitrides such as AlN, resulting in poor grain growth and inability to meet the requirements of low iron loss. Therefore, in the present invention, the content of Als (i.e., acid-soluble aluminum) is controlled to be 0.5 - 1.5%.

[0072] Mn: It can increase the resistivity of the material and reduce iron loss. Mn easily reacts with S to form MnS. Appropriate addition of Mn can inhibit the hot brittleness caused by S. In the present embodiment, Mn is added and the content of Mn (by mass percentage) is controlled to be 0.2 - 0.8%.

[0073] P: It can effectively improve iron loss. The increase of its content can effectively increase the strength of the steel strip and improve the punching property. However, for high-grade non-oriented silicon steel, exceeding 0.05% will significantly deteriorate the cold formability of the steel. In the present embodiment, in order to further increase the yield strength of the finished non-oriented silicon steel and meet the actual use requirements of high-speed motors, more preferably, the content of P is controlled to be 0.03 - 0.05%.

[0074] S: It is a harmful element and an important component of inclusions in steel. Especially when the steel billet is heated before hot rolling, a large amount of the precipitate MnS in the steel will dissolve, and then precipitate dispersively during the hot working process, which will hinder the grain growth during the annealing process of the finished product and reduce the magnetic properties of the finished product. Therefore, the increase of its content will lead to the reduction of magnetic induction intensity and the increase of iron loss. In the present embodiment, in order to avoid the precipitation of fine MnS during hot rolling, the content of S (by mass percentage) is controlled to be ≤0.0015%.

[0075] N: It is also an important component of inclusions in steel. AlN formed in the steel billet will dissolve in large amounts during the hot rolling heating process, and then precipitate dispersively during the hot working process, which will hinder the grain growth during the annealing process of the finished product and reduce the magnetic properties of the finished product. Therefore, its content is controlled to be N ≤0.002%.

[0076] Nb, V, Ti: Nb, V, and Ti, as carbide and nitride forming elements, are also the main impurity elements. Carbides and nitrides in non-oriented silicon steel will form fine precipitates that will hinder the grain growth of the finished product during the annealing process, deteriorate the magnetic properties of non-oriented silicon steel, resulting in an increase in iron loss and a decrease in magnetic induction intensity. Therefore, their contents are all controlled to not exceed 0.0020%.

[0077] As described above, before heating the continuous casting billet, the continuous casting billet is annealed first. In this way, even if high-temperature heating is carried out in the subsequent heating process, the situation of sawtooth edge cracking defects in the obtained hot-rolled sheet can be greatly eliminated. From the microscopic principle analysis, the annealing treatment can eliminate the internal stress at the edge of the continuous casting billet, thereby avoiding the abnormal growth of ferrite columnar crystals caused by this internal stress during the heating process, and finally eliminating the sawtooth edge cracking defects of the hot-rolled sheet caused by the abnormally grown columnar crystals. In this way, this production method also avoids a series of derivative problems such as reducing the heating temperature, increasing the difficulty of hot rolling, and waste caused by trimming.

[0078] As described above in detail about the inventive concept of the present invention, several embodiments under the inventive concept are provided below to show the beneficial effects of the present invention.

[0079] The specific implementation processes of these embodiments are as follows:

[0080] The first step: Prepare 10 continuous casting billets numbered 1# to 10# through steelmaking and continuous casting. The chemical compositions of each continuous casting billet are shown in Table 1;

[0081] [Table 1]

[0082]

[0083] Among them, the continuous casting billets numbered 1# to 3# are cast with the same heat of molten steel and have the same chemical composition; the continuous casting billets numbered 4# to 6# are cast with the same heat of molten steel and have the same chemical composition; the continuous casting billets numbered 7# to 10# are cast with the same heat of molten steel and have the same chemical composition;

[0084] Moreover, for the embodiments numbered 1# to 10#, during the continuous casting process, the superheat, casting speed v, target thickness t of the slab, and target width w are shown in Table 2 respectively;

[0085] [Table 2]

[0086]

[0087] The second step: Anneal 9 continuous casting billets numbered 1# to 9# respectively. The bulging amount, annealing temperature, and annealing duration of the wide surface of each continuous casting billet are shown in Table 3. At the same time, the 10# continuous casting billet is not annealed, which is indicated by "-" in Table 3;

[0088] [Table 3]

[0089]

[0090] Among them, the annealing temperature of the continuous casting billet No. 9 was 400-450°C and the annealing time was 3 hours during annealing; the annealing temperature and / or annealing time of the continuous casting billets No. 5 and 7 were controlled without reference to the bulging amount, while the bulging amount was further referenced during annealing of the continuous casting billets No. 1-4, 6, and 8 to optimize the control of the annealing temperature and annealing time;

[0091] Step 3: heating the annealed continuous casting billet, the soaking temperature and soaking time are shown in Table 4;

[0092] Step 4: The heated continuous casting slab is firstly rough-rolled into an intermediate slab, and then fine-rolled and coiled to obtain a hot-rolled plate; wherein the rough-rolling final rolling temperature, the fine-rolling final rolling temperature, the coiling temperature, and the thickness of the hot-rolled plate are shown in Table 4;

[0093] In addition, when the continuous casting billets No. 5#, 9# and 10# were hot rolled, they were not rolled on the wide surface by vertical rollers; when the continuous casting billets No. 1#~4#, 6#~8# were hot rolled, they were rolled on the wide surface by vertical rollers;

[0094] [Table 4]

[0095]

[0096] Finally, the edge quality of 10 hot-rolled plates numbered 1# to 10# was tested, and it was found that:

[0097] ① The hot-rolled plates No. 9# and No. 10# have different degrees of serrated edge crack defects. Relatively speaking, the 10# hot-rolled plate is the most serious, with serrated edge cracks throughout the coil, and the depth of the edge cracks is more than 10mm;

[0098] ② The edge quality of hot-rolled plates No. 1#~8# is significantly improved compared with No. 9# and 10#; among them, the edges of hot-rolled plates No. 1#, 2#, 4# and 8# are the best without any edge crack defects; the edges of hot-rolled plates No. 3# and 6# are better without obvious edge crack defects; the hot-rolled coils No. 5# and 7# have sporadic edge crack defects at the head and tail.

[0099] It can be seen that the production method of the present invention can effectively solve the edge crack problem of hot-rolled plates of high-grade non-oriented silicon steel, reduce steel piling caused by edge cracks in the hot rolling process of high-grade non-oriented silicon steel, and effectively improve the yield rate of high-grade non-oriented silicon steel in the cold rolling process.

Claims

1. A production method of a non-oriented silicon steel hot-rolled sheet, characterized in that, The production method includes the following steps: Prepare a continuous casting billet with a target thickness t of 0.21 m, 0.22 m or 0.23 m through steelmaking and continuous casting; during continuous casting, the casting speed v, the target thickness t of the slab and the target width w satisfy 0.21 ≤ v×t×w ≤ 0.22, where the unit of v is m / min, the unit of t is m, and the unit of w is m; Anneal the obtained continuous casting billet, with an annealing temperature of 600 - 700 °C and an annealing duration of 10 - 30 hours; Heat the annealed continuous casting billet, with a soaking temperature of 1050 - 1250 °C and a soaking duration of 180 - 220 min; First pass the heated continuous casting billet through rough rolling to make an intermediate billet with a thickness of 40 - 45 mm, then carry out finish rolling and coiling to obtain a hot-rolled sheet; among them, the rough rolling finishing temperature is 950 - 1000 °C, the finish rolling finishing temperature is 820 - 880 °C, and the coiling temperature is 600 - 680 °C.

2. The production method of the non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that, The step "anneal the obtained continuous casting billet, with an annealing temperature of 600 - 700 °C and an annealing duration of 10 - 30 hours" includes: Detect the bulging amount of the wide surface of the obtained continuous casting billet; When the bulging amount does not reach 10 mm, the annealing temperature is 600 - 650 °C and the annealing duration is 10 - 15 hours; When the bulging amount is 10 - 15 mm, the annealing temperature is 600 - 650 °C and the annealing duration is 15 - 20 hours; When the bulging amount exceeds 15 mm, the annealing temperature is 650 - 700 °C and the annealing duration is 20 - 30 hours.

3. The production method of the non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that, In the step "first pass the heated continuous casting billet through rough rolling to make an intermediate billet with a thickness of 40 - 45 mm, then carry out finish rolling and coiling to obtain a hot-rolled sheet": The reduction rate of each pass in rough rolling is controlled at 32 - 38%, and the reduction rate of each pass in finish rolling is controlled at 30 - 38%.

4. The production method of the non-oriented electrical steel hot-rolled sheet according to claim 1, characterized in that, In the step "first pass the heated continuous casting billet through rough rolling to make an intermediate billet with a thickness of 40 - 45 mm, then carry out finish rolling and coiling to obtain a hot-rolled sheet": The thickness of the obtained hot-rolled sheet is 2.0 - 2.4 mm.

5. The production method of the non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that, In the step "first pass the heated continuous casting billet through rough rolling to make an intermediate billet with a thickness of 40 - 45 mm, then carry out finish rolling and coiling to obtain a hot-rolled sheet": In each pass of rough rolling, vertical rolls are used for wide face rolling. The rolling force of the vertical rolls decreases pass by pass, and the rolling force of the vertical rolls in each pass is controlled within F 1n ~F 2n where F 1n = 2000 + h n × 70 - 500 kN, F 2n = 2000 + h n × 70 + 500 kN. In the formula, n represents the pass sequence number, and h n is the preset thickness of the billet at the outlet of the nth pass, with the unit of mm.

6. The production method of the non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that The step "prepare a continuous casting billet through steelmaking and continuous casting" includes: During continuous casting, the superheat of the tundish molten steel is 10 - 15 °C.

7. The production method of the non-oriented electrical steel hot-rolled sheet according to claim 1, characterized in that, The step "prepare a continuous casting billet through steelmaking and continuous casting" includes: During continuous casting, control the cooling rate V of the mold to satisfy V = 8.5 - 0.5[Si] - 0.3[Al] - 0.2[Mn] ± 0.5 with the mass fraction [Si] of Si, the mass fraction [Al] of Al, and the mass fraction [Mn] of Mn in the molten steel, where the unit of V is °C / s.

8. The production method of the non-oriented electrical steel hot-rolled sheet according to claim 1, characterized in that, The step "prepare a continuous casting billet through steelmaking and continuous casting" includes: During continuous casting, in the secondary cooling zone, restrain the wide surface of the billet through vertical rolls.

9. The production method of the non-oriented electrical steel hot-rolled sheet according to claim 1, characterized in that In the step "prepare a continuous casting billet through steelmaking and continuous casting", the chemical composition of the continuous casting billet includes, by mass percentage: Si 2.5 - 3.5%, Al 0.5 - 1.5%, Mn 0.2 - 0.8%, and the rest is iron and inevitable impurities.

10. The production method of the non-oriented electrical steel hot-rolled sheet according to claim 9, characterized in that, The chemical composition of the continuous casting billet, with impurity elements in mass percentage, satisfies: C ≤ 0.0025%, S ≤ 0.0015%, P: 0.03 - 0.05%, Nb ≤ 0.002%, V ≤ 0.002%, Ti ≤ 0.002%, N ≤ 0.002%.

Images