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

Abstract

The invention discloses a production method of a non-oriented silicon steel hot rolled plate. The production method comprises the following steps: preparing a continuous casting billet through steelmaking and continuous casting; in the continuous casting process, the superheat degree of tundish molten steel is 10-15 DEG C, the pulling speed v, the target thickness t of a slab and the target width w meet the condition that v * t * w is larger than or equal to 0.21 and smaller than or equal to 0.22, the unit of v is m / min, the unit of t is m, and the unit of w is m; the continuous casting billet is heated, the soaking temperature ranges from 1050 DEG C to 1100 DEG C, and the soaking time ranges from 180 min to 220 min; the heated continuous casting billet is roughly rolled into an intermediate billet with the thickness of 40-45 mm, finish rolling and coiling are conducted, and a hot rolled plate is obtained; wherein the finish rolling temperature of rough rolling is 950-1000 DEG C, the finish rolling temperature of finish rolling is 820-880 DEG C, and the coiling temperature is 600-680 DEG C. The method can solve the problem of sawtooth-shaped edge crack defects of the hot rolled plate.

Description

Technical Field

[0001] The invention belongs to the technical field of steel material preparation, and relates to a production method of a non-oriented silicon steel hot-rolled plate, in particular to a production method of a high-grade non-oriented silicon steel hot-rolled plate. 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-scale generator sets. Its iron loss is closely related to the operating efficiency of the motor. Specifically, the lower the iron loss of non-oriented silicon steel, the higher the operating efficiency of the corresponding motor.

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

[0004] Therefore, in the existing production process of high-grade non-oriented silicon steel, serrated edge cracks are one of the more common defects of hot-rolled plates. Furthermore, such serrated edge cracks of hot-rolled plates are very likely to cause serious edge cracks and strip breakage during cold rolling, which seriously restricts the continuous and stable production of high-grade non-oriented silicon steel.

[0005] In order to overcome the edge crack defect of hot-rolled plates, a patent application with technical reference publication number CN117862234A reduces the edge microcracks of non-oriented silicon steel by controlling the thickness of the intermediate slab, adjusting the hot rolling temperature, sufficient descaling, and adjusting the hot rolling target reduction rate. Although this method can reduce the edge crack defect from a macroscopic perspective, it does not study the cause of the edge crack of the hot-rolled plate, and cannot fundamentally solve the edge crack problem of hot-rolled plates of high-grade non-oriented silicon steel.

[0006] Other known technologies for solving the edge crack problem of hot-rolled plates also generally focus on heating temperature, hot rolling load distribution and other aspects, and still have problems such as great difficulty in hot rolling, reduced stability, low conversion rate of finished products and waste of resources. Summary of the invention

[0007] In order to solve the edge crack problem of hot-rolled plates, the present invention aims to provide a production method of non-oriented silicon steel hot-rolled plates.

[0008] To achieve the above-mentioned object of the invention, an embodiment of the present invention provides a method for producing a non-oriented silicon steel hot-rolled plate, characterized in that the production method comprises the following steps:

[0009] The continuous casting slab is prepared by steelmaking and continuous casting; during the continuous casting process, the superheat of the molten steel in the tundish is 10-15° C., and the drawing speed v, the target slab thickness t and the target slab 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;

[0010] The continuous casting billet is heated, the soaking temperature is 1050-1100°C, and the soaking time is 180-220 minutes;

[0011] The heated continuous casting billet is firstly rough-rolled into an intermediate billet with a thickness of 40-45 mm, and then fine-rolled and coiled to obtain a hot-rolled plate; wherein, the rough rolling final rolling temperature is 950-1000°C, the fine rolling final rolling temperature is 820-880°C, and the coiling temperature is 600-680°C.

[0012] Preferably, the step of "preparing a continuous casting billet by steelmaking and continuous casting" comprises:

[0013] During the continuous casting process, the cooling rate V of the crystallizer and the mass fraction of Si [Si], Al [Al], and Mn [Mn] in the molten steel are controlled to satisfy V = 8.5-0.5[Si]-0.3[Al]-0.2[Mn]±0.5, where the unit of V is ℃ / s.

[0014] Preferably, the step of "preparing a continuous casting billet by steelmaking and continuous casting" comprises:

[0015] During the continuous casting process, the wide surface of the billet is constrained by vertical rollers in the secondary cooling zone.

[0016] Preferably, before the step of "heating the continuous casting billet at a soaking temperature of 1050 to 1100° C. for a soaking time of 180 to 220 min":

[0017] The bulging amount of the wide surface of the obtained continuous casting billet is detected;

[0018] When the bulging amount reaches more than 10 mm, the obtained continuous casting billet is annealed at a temperature of 600 to 700° C. for 10 to 30 hours.

[0019] Preferably, when the bulging amount is 10 to 15 mm, the annealing temperature is 600 to 650° C., and the annealing time is 10 to 20 hours;

[0020] When the bulging amount exceeds 15 mm, the annealing temperature is 650-700°C and the annealing time is 20-30 hours.

[0021] Preferably, in the step of “rough rolling the heated continuous casting billet into an intermediate billet with a thickness of 40 to 45 mm, and then performing finish rolling and coiling to obtain a hot-rolled plate”:

[0022] The reduction rate of each pass of rough rolling is controlled at 32-38%, and the reduction rate of each pass of finish rolling is controlled at 30-38%.

[0023] Preferably, in the step of “rough rolling the heated continuous casting billet into an intermediate billet with a thickness of 40 to 45 mm, and then performing finish rolling and coiling to obtain a hot-rolled plate”:

[0024] The thickness of the obtained hot-rolled plate is 2.0 to 2.4 mm.

[0025] Preferably, in the step of “rough rolling the heated continuous casting billet into an intermediate billet with a thickness of 40 to 45 mm, and then performing finish rolling and coiling to obtain a hot-rolled plate”:

[0026] In each pass of rough rolling, vertical rolls are used for wide surface rolling. The rolling force of the vertical rolls decreases with each pass, and the rolling force of the vertical rolls in each pass is controlled at F 1n ~F 2n In the range, F 1n =2000+h n ×70-500kN, F 2n =2000+h n ×70+500kN, where n represents the pass number, h n The preset thickness of the export billet for the nth pass, in mm.

[0027] Preferably, in the step of "preparing a continuous casting billet by steelmaking and continuous casting", the chemical composition of the continuous casting billet comprises, by mass percentage: Si 2.5-3.5%, Al 0.5-1.5%, Mn 0.2-0.8%, and the rest being iron and unavoidable impurities.

[0028] Preferably, the chemical composition of the continuous casting billet, the impurity elements in mass percentage satisfy: C≤0.0025%, S≤0.0015%, P: 0.03-0.05%, Nb≤0.002%, V≤0.002%, Ti≤0.002%, N≤0.002%.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: through the continuous casting technology in the production method of the present invention, specifically through superheat control and pulling speed v control, the initial solidification shell thickness of the continuous casting billet (that is, the shell thickness of the continuous casting billet when it leaves the crystallizer) can be increased, and the bulging amount of the wide surface of the continuous casting billet can be reduced accordingly, thereby avoiding the abnormal growth of ferrite columnar crystals induced by the internal stress of the bulging, and then reducing the jagged edge crack defects of the hot-rolled plate. In this way, the production method also avoids a series of derivative problems such as lowering the heating temperature, increasing the difficulty of hot rolling, and waste caused by cutting edges. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further introduced below in conjunction with specific implementation methods.

[0031] The present invention provides a method for producing a steel plate, which is particularly suitable for the production of non-oriented silicon steel hot-rolled plates. That is, the production method can be used to prepare non-oriented silicon steel hot-rolled plates and solve the jagged edge crack defects of non-oriented silicon steel hot-rolled plates.

[0032] Specifically, the production method comprises the following steps:

[0033] The continuous casting slab is prepared by steelmaking and continuous casting; during the continuous casting process, the superheat of the molten steel in the tundish is 10-15° C., and the drawing speed v, the target slab thickness t and the target slab 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;

[0034] The continuous casting billet is heated, the soaking temperature is 1050-1100°C, and the soaking time is 180-220 minutes;

[0035] The heated continuous casting billet is firstly rough-rolled into an intermediate billet with a thickness of 40-45 mm, and then fine-rolled and coiled to obtain a hot-rolled plate; wherein, the rough rolling final rolling temperature is 950-1000°C, the fine rolling final rolling temperature is 820-880°C, and the coiling temperature is 600-680°C.

[0036] The inventors studied the causes of the serrated edge cracks of the hot-rolled plates and found that the degree of the edge cracks of the hot-rolled plates is positively correlated with the degree of the bulging deformation of the continuous casting billet. That is, the greater the bulging amount of the wide surface of the continuous casting billet, the more serious the serrated edge cracks of the hot-rolled plates. After further study and analysis of the microstructure, it was found that the internal stress of the bulging deformation of the continuous casting billet will induce the abnormal growth of the ferrite columnar crystals at the edge of the continuous casting billet during the heating process, thereby causing uneven plastic deformation of the edge of the rolled piece during the hot rolling process. This unevenness and plastic deformation directly lead to the serrated edge cracks.

[0037] On the basis of the above-mentioned macro and micro research, the inventors have verified through experiments that through the continuous casting technology in the production method of the present invention, specifically through the control of superheat and pulling speed v, the initial solidification shell thickness of the continuous casting billet (that is, the shell thickness of the continuous casting billet when it leaves the crystallizer) can be increased, and the bulging amount of the wide surface of the continuous casting billet can be reduced accordingly, thereby avoiding the abnormal growth of ferrite columnar crystals induced by the internal stress of the bulging, and then reducing the jagged edge crack defects of the hot-rolled plate. In this way, the production method also avoids a series of derivative problems such as lowering the heating temperature, increasing the difficulty of hot rolling, and waste caused by cutting edges.

[0038] From another perspective, in another preferred embodiment, during the continuous casting process, the cooling rate V of the crystallizer and the mass fraction of Si [Si], the mass fraction of Al [Al], and the mass fraction of Mn [Mn] in the molten steel can be controlled to satisfy V = 8.5-0.5[Si]-0.3[Al]-0.2[Mn]±0.5, where the unit of V is ℃ / s.

[0039] For example, the mass fraction of Si [Si] means that if the mass percentage of Si in molten steel is 2.5%, then [Si] is 2.5. In addition, the mass fraction of Si, Al or Mn in "molten steel" here can be obtained by testing the molten steel at the end of steelmaking (or the molten steel poured during continuous casting).

[0040] In this way, by correlating the cooling rate V with the chemical composition of the molten steel (that is, the chemical composition of the continuously cast ingot), not only can the initial solidification shell thickness of the continuously cast ingot be increased to reduce the bulging amount of the wide surface of the continuously cast ingot, thereby eliminating the jagged edge crack defects of the hot-rolled plate, but it can also cope with the preparation of non-oriented silicon steel hot-rolled plates with various composition changes, ensure the quality stability of non-oriented silicon steel hot-rolled plates with various compositions, and improve the versatility of the production method.

[0041] In addition, during the continuous casting process, the wide side of the billet can be constrained by the vertical rollers in the secondary cooling zone. In this way, the billet can be constrained by the vertical rollers, and the bulging deformation of the wide side of the billet can be further reduced by vertical roller rolling, thereby avoiding the deterioration of the edge quality caused by the bulging deformation during the hot rolling process from a macroscopic perspective and reducing the occurrence rate of serrated edge cracks.

[0042] Vertical rollers are arranged on both sides of the secondary cooling zone to constrain the two wide sides of the billet respectively to reduce the bulging amount of each wide side; and preferably, the spacing between the vertical rollers on both sides can be set to 1 to 1.01 times the target width w of the slab, or the rolling force of the vertical rollers is controlled within the range of 500 to 800 kN.

[0043] Furthermore, when the continuous casting billet is heated, the soaking temperature is preferably 1050° C., 1060° C., 1070° C., 1080° C. or 1090° C. Next, some preferred implementations of the hot rolling process will be introduced to further improve the edge quality of the hot rolled plate and overcome the defect of serrated edge cracks.

[0044] In a preferred embodiment, in the hot rolling process, the reduction ratio of each pass of rough rolling is controlled to be 32-38%, and the reduction ratio of each pass of finish rolling is controlled to be 30-38%.

[0045] In the present application, the thickness of the obtained hot-rolled sheet is 2.0 to 2.4 mm.

[0046] In addition, in the hot rolling process, rough rolling and finish rolling each have a plurality of passes.

[0047] In each pass of rough rolling, vertical rolls are used for wide surface rolling. The rolling force of the vertical rolls decreases with each pass, and the rolling force of the vertical rolls in each pass is controlled at F 1n ~F 2n In the range, F 1n =2000+h n ×70-500kN, F 2n =2000+h n ×70+500kN, where n represents the pass number, h n The preset thickness of the export billet for the nth pass, in mm.

[0048] In this way, the occurrence of jagged edge cracks on the edge can be further avoided from a macroscopic perspective, the edge flange can be prevented during hot rolling, and the edge quality of the hot-rolled plate can be ensured.

[0049] Furthermore, in a preferred embodiment, the production method further comprises:

[0050] Before the heating process, the bulging amount of the wide surface of the continuous casting billet is detected;

[0051] When the bulging amount reaches more than 10 mm, the obtained continuous casting billet is annealed at a temperature of 600 to 700° C. for 10 to 30 hours.

[0052] That is, when the bulge of the wide surface of the continuous casting billet reaches 10 mm or more, annealing is performed first and then heating is performed, while when the bulge does not reach 10 mm, annealing is not performed but heating is performed directly.

[0053] Thus, when the amount of bulging is large, a preferred implementation method is to anneal the continuous casting billet before heating it. It has been verified through experiments that after the annealing treatment, even if high-temperature heating is performed in the subsequent heating process, the serrated edge crack defects of the obtained hot-rolled plate can be greatly eliminated. From the perspective of microscopic principles, annealing can eliminate the internal stress at the edge of the continuous casting billet, thereby avoiding the abnormal growth of ferrite columnar crystals in the heating process caused by the internal stress, and ultimately eliminating the serrated edge crack defects of the hot-rolled plate caused by the abnormally grown columnar crystals.

[0054] Specifically, when the bulging amount is 10-15 mm, the annealing temperature is 600-650° C., and the annealing time is 10-20 hours; when the bulging amount exceeds 15 mm, the annealing temperature is 650-700° C., and the annealing time is 20-30 hours.

[0055] In this way, the annealing temperature and annealing time can be further optimized according to the amount of bulging, which can improve the edge quality of the hot-rolled plate to a greater extent and better solve the defect problem of jagged edge cracks of the hot-rolled plate.

[0056] Here, the "wide surface", "bulging" and "bulging amount" are all professional terms in this field; among them, "wide surface" refers to: two surfaces in the width direction that are perpendicular to the head and tail directions and the thickness direction of the continuous casting billet; "bulging" refers to: during the solidification process of the billet, under the action of the static pressure of the molten steel, the solidified shell bulges outward into a convex surface; "bulging amount" refers to: the difference between the thickness in the center of the wide surface and the thickness at the edge.

[0057] In addition, in the present application, the obtained hot-rolled plate can be cooled by conventional methods such as water cooling and air cooling, and can subsequently be prepared into a non-oriented silicon steel product by existing known technologies, for example, through pickling, cold rolling, product annealing and other processes, to obtain a non-oriented silicon steel product, but these subsequent processes are irrelevant to the jagged edge crack defects of the hot-rolled plate, that is, they are irrelevant to the purpose of the present invention, and will not be described in detail in this application.

[0058] Furthermore, as mentioned above, the production method of the present invention can be used for non-oriented silicon steel, that is, the chemical composition of the hot-rolled plate, or the chemical composition of the continuous casting billet can be implemented as non-oriented silicon steel, specifically, the chemical composition of non-oriented silicon steel known in the art can be adopted.

[0059] The production method of the present invention is particularly beneficial to the production of high-grade non-oriented silicon steel hot-rolled plates. Specifically, high-grade non-oriented silicon steel generally requires a higher Si / Al alloy content, which makes its hot-rolled plates have more serious serrated edge crack defects. Therefore, the production method of the present invention can greatly improve the edge quality of high-grade non-oriented silicon steel hot-rolled plates, which is more meaningful for high-grade non-oriented silicon steel.

[0060] 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 unavoidable impurities.

[0061] Here, the impurity elements satisfy, in terms of mass percentage, the following conditions: 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%, and N≤0.002%.

[0062] The following is an introduction to the functions and mechanisms of each element in the above chemical composition.

[0063] C: In non-oriented silicon steel, C is generally considered to be a harmful element. An increase in C content will result in fine grains, high iron loss, poor magnetic properties, and magnetic aging problems in the finished product. Therefore, the C content is usually controlled as low as possible. In this embodiment, the C content is controlled to be below 0.0025%.

[0064] Si: It is an effective additive element for increasing the resistivity of electromagnetic steel sheets and reducing iron loss. It can also effectively increase the strength of steel strips. In this embodiment, the Si content (in mass percentage) is controlled at 2.5-3.5% to effectively reduce iron loss and meet the requirements of high-grade non-oriented silicon steel.

[0065] Al: It is also an effective additive element for improving the resistivity of electromagnetic steel sheets and reducing iron loss. If its content is too high, the magnetic induction intensity will be reduced, and the brittleness of the steel sheet will be greatly increased, increasing the difficulty of processing such as cold rolling. If its content is low, the resistivity will be too low, and nitrides such as AlN will be finely precipitated, which will deteriorate the grain growth and fail to meet the requirements of low iron loss. Therefore, in the present invention, the content of Als (also known as acid-soluble aluminum) is controlled to be 0.5-1.5%.

[0066] Mn: can improve the resistivity of the material and reduce the iron loss. Mn easily reacts with S to form MnS. Adding a proper amount of Mn can suppress the hot brittleness caused by S. In this embodiment, Mn is added and the Mn content (in mass percentage) is controlled to be 0.2-0.8%.

[0067] P: can effectively improve iron loss, and increasing its content can effectively increase the strength of the steel strip and enhance the punching performance. However, for high-grade non-oriented silicon, exceeding 0.05% will significantly deteriorate the cold ductility of the steel. In this embodiment, in order to further improve the yield strength of the non-oriented silicon steel product and meet the actual use requirements of high-speed motors, it is more preferred that the P content is controlled at 0.03-0.05%.

[0068] S: is a harmful element and an important component of inclusions in steel. In particular, when the steel billet is heated before hot rolling, a large amount of precipitate MnS in the steel will be dissolved, and then dispersed and precipitated during the hot working process, which will hinder the growth of grains during the annealing process of the finished product and reduce the magnetic properties of the finished product. Therefore, an increase in its content will lead to a decrease in magnetic induction intensity and an increase in iron loss. In this embodiment, in order to avoid the precipitation of fine MnS during the hot rolling process, the S content (in terms of mass percentage) is controlled to be ≤0.0015%.

[0069] N: It is also an important component of inclusions in steel. AlN formed in the billet will be dissolved in large quantities during the hot rolling heating process, and then dispersed and precipitated during the hot working process, which will hinder the growth of grains during the annealing process of the finished product and reduce the magnetic properties of the finished product. Therefore, its content is controlled to N≤0.002%.

[0070] Nb, V, Ti: Nb, V, and Ti are carbide and nitride forming elements and are also the main impurity elements. Carbides and nitrides in non-oriented silicon steel will form fine precipitates, which will hinder the growth of finished grains during annealing, deteriorate the magnetic properties of non-oriented silicon steel, and lead to increased iron loss and reduced magnetic induction intensity. Therefore, their contents are controlled to not exceed 0.0020%.

[0071] In summary, through the continuous casting technology in the production method of the present invention, specifically through the control of superheat and pulling speed v, the initial solidification shell thickness of the continuous casting billet (that is, the shell thickness of the continuous casting billet when it leaves the crystallizer) can be increased, and the bulging amount of the wide surface of the continuous casting billet can be reduced accordingly, thereby avoiding the abnormal growth of ferrite columnar crystals induced by the internal stress of the bulging, and then eliminating the jagged edge crack defects of the hot-rolled plate. In this way, the production method also avoids a series of derivative problems such as lowering the heating temperature, increasing the difficulty of hot rolling, and waste caused by cutting edges.

[0072] The inventive concept of the present invention has been described in detail above. Several embodiments of the inventive concept are provided below to illustrate the beneficial effects of the present invention.

[0073] The specific implementation process of these embodiments is as follows:

[0074] Step 1: Through steelmaking and continuous casting, 7 continuous casting billets numbered A to G are prepared according to the superheat, drawing speed v, target slab thickness t and target width w in Table 1;

[0075] Among them, in the embodiments numbered A, B, D and F, during the continuous casting process, the superheat of the molten steel in the tundish is 10-15°C, and the pulling speed v, the target slab thickness t and the target width w are controlled to satisfy 0.21≤v×t×w≤0.22, wherein the unit of v is m / min, the unit of t is m, and the unit of w is m; while in the embodiments numbered E and G, during the continuous casting process, the superheat of the molten steel in the tundish is relatively high; in the embodiments numbered C and G, during the continuous casting process, the pulling speed v, the target slab thickness t and the target width w are controlled not to satisfy 0.21≤v×t×w≤0.22, as shown in Table 1;

[0076] [Table 1]

[0077] serial number Superheat, ℃ Pulling speed v, m / min Target slab thickness t, m Target slab width w, m A 10 0.8 0.22 1.2 B 12 0.83 0.22 1.2 C 15 0.85 0.22 1.25 D 12 0.9 0.22 1.1 E 20 0.8 0.21 1.25 F 12 0.85 0.21 1.2 G 30 1.1 0.22 1.2

[0078] The chemical compositions of the continuous casting billets numbered A to G are shown in Table 2;

[0079] [Table 2]

[0080] serial number C Si Mn Al P S N Ti Nb V A 0.0022 2.65 0.25 0.55 0.035 0.0011 0.0013 0.0011 0.0012 0.0012 B 0.0022 2.65 0.25 0.55 0.035 0.0011 0.0013 0.0011 0.0012 0.0012 C 0.0022 2.65 0.25 0.55 0.035 0.0011 0.0013 0.0011 0.0012 0.0012 D 0.0020 3.00 0.50 1.5 0.032 0.0009 0.0011 0.0012 0.0013 0.001 E 0.0020 3.00 0.50 1.5 0.032 0.0009 0.0011 0.0012 0.0013 0.001 F 0.0020 3.50 0.8 1.0 0.043 0.0005 0.001 0.0009 0.001 0.0013 G 0.0020 3.50 0.8 1.0 0.043 0.0005 0.001 0.0009 0.001 0.0013

[0081] Step 2: Detect the bulging amount of the wide surface of the 7 continuous casting billets numbered A to G;

[0082] Then, the continuous casting billets numbered D and G are all directly heated in the heating furnace regardless of the bulge amount; the continuous casting billets numbered A and F are directly heated in the heating furnace due to their small bulge amount, and the continuous casting billets numbered B, C, D and E are annealed according to the bulge amount, and then enter the heating furnace for heating after annealing;

[0083] When the continuous casting billets numbered A to G are heated in the heating furnace, the soaking temperature is controlled at 1050 to 1100° C., and the soaking time is controlled at 180 to 220 minutes;

[0084] The bulging amount, annealing temperature and annealing time of the wide surface of each continuous casting billet are shown in Table 3; "-" in Table 3 means that no corresponding treatment (such as no annealing) is performed; [Table 3]

[0085]

[0086] Step 3: 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;

[0087] Furthermore, the continuous casting billets numbered C, D, and G were not subjected to wide surface rolling by vertical rollers during hot rolling; the continuous casting billets numbered A, B, E, and F were subjected to wide surface rolling by vertical rollers during hot rolling;

[0088] [Table 4]

[0089]

[0090] Finally, the edge quality inspection of the seven hot-rolled plates numbered A to G revealed that:

[0091] ① The hot-rolled plate of Example G has serrated edge cracks throughout the coil, the depth of the edge cracks is more than 10 mm, and the edge defects are the most serious among the 7 examples;

[0092] ②The hot-rolled plates with numbers A, B and F have the best edges without any edge crack defects;

[0093] ③The edges of the hot-rolled plates No. C and E are good, without obvious edge crack defects;

[0094] ④ The hot-rolled plate numbered D has sporadic edge crack defects at the head and tail.

[0095] It can be seen that the production method of the present invention effectively solves the edge crack problem of hot-rolled plates of high-grade non-oriented silicon steel, reduces steel piling caused by edge cracks during the hot rolling process of high-grade non-oriented silicon steel, and effectively improves the yield rate of high-grade non-oriented silicon steel during the cold rolling process.

Claims

1. A method for producing a non-oriented silicon steel hot-rolled plate, characterized in that: The production method comprises the following steps: The continuous casting slab is prepared by steelmaking and continuous casting; during the continuous casting process, the superheat of the molten steel in the tundish is 10-15° C., and the drawing speed v, the target slab thickness t and the target slab 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; The continuous casting billet is heated, the soaking temperature is 1050-1100°C, and the soaking time is 180-220 minutes; The heated continuous casting billet is firstly rough-rolled into an intermediate billet with a thickness of 40-45 mm, and then fine-rolled and coiled to obtain a hot-rolled plate; wherein, the rough rolling final rolling temperature is 950-1000°C, the fine rolling final rolling temperature is 820-880°C, and the coiling temperature is 600-680°C.

2. The method for producing non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that: The step of "preparing a continuous casting billet by steelmaking and continuous casting" comprises: During the continuous casting process, the cooling rate V of the crystallizer and the mass fraction of Si [Si], Al [Al], and Mn [Mn] in the molten steel are controlled to satisfy V = 8.5-0.5[Si]-0.3[Al]-0.2[Mn]±0.5, where the unit of V is ℃ / s.

3. The method for producing non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that: The step of "preparing a continuous casting billet by steelmaking and continuous casting" comprises: During the continuous casting process, the wide surface of the billet is constrained by vertical rollers in the secondary cooling zone.

4. The method for producing non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that: Before the step "heating the continuous casting billet, the soaking temperature is 1050-1100°C, and the soaking time is 180-220min": The bulging amount of the wide surface of the obtained continuous casting billet is detected; When the bulging amount reaches more than 10 mm, the obtained continuous casting billet is annealed at a temperature of 600 to 700° C. for 10 to 30 hours.

5. The method for producing non-oriented silicon steel hot-rolled sheet according to claim 4, characterized in that: When the bulge is 10-15 mm, the annealing temperature is 600-650°C and the annealing time is 10-20 hours; When the bulging amount exceeds 15 mm, the annealing temperature is 650-700°C and the annealing time is 20-30 hours.

6. The method for producing non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that: In the step "rough rolling the heated continuous casting slab into an intermediate slab with a thickness of 40 to 45 mm, and then finishing rolling and coiling to obtain a hot-rolled plate": The reduction rate of each pass of rough rolling is controlled at 32-38%, and the reduction rate of each pass of finish rolling is controlled at 30-38%.

7. The method for producing non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that: In the step "rough rolling the heated continuous casting slab into an intermediate slab with a thickness of 40 to 45 mm, and then finishing rolling and coiling to obtain a hot-rolled plate": The thickness of the obtained hot-rolled plate is 2.0 to 2.4 mm.

8. The method for producing non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that: In the step "rough rolling the heated continuous casting slab into an intermediate slab with a thickness of 40 to 45 mm, and then finishing rolling and coiling to obtain a hot-rolled plate": In each pass of rough rolling, vertical rolls are used for wide surface rolling. The rolling force of the vertical rolls decreases with each pass, and the rolling force of the vertical rolls in each pass is controlled at F 1n ~F 2n In the range, F 1n =2000+h n ×70-500kN, F 2n =2000+h n ×70+500kN, where n represents the pass number, h n The preset thickness of the export billet for the nth pass, in mm.

9. The method for producing non-oriented silicon steel hot-rolled sheet according to claim 1, characterized in that: In the step of "preparing a continuous casting billet by 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 unavoidable impurities.

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

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