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; the obtained continuous casting billet is annealed, the annealing temperature ranges from 600 DEG C to 700 DEG C, and the annealing time ranges from 10 hours to 30 hours; the annealed continuous casting billet is heated, the soaking temperature ranges from 1050 DEG C to 1250 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. Abnormal growth of ferrite columnar crystals caused by internal stress in the continuous casting billet can be avoided, and the defect of sawtooth-shaped edge cracks of the hot-rolled plate is overcome.

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 purpose, an embodiment of the present invention provides a method for producing a non-oriented silicon steel hot-rolled plate. The production method comprises the following steps: Through steelmaking and continuous casting, continuous casting billets are prepared; The obtained continuous casting billet is annealed at a temperature of 600-700°C for 10-30 hours; The annealed continuous casting billet is heated, the soaking temperature is 1050~1250℃, and the soaking time is 180~220min; The heated continuous casting slab is firstly rough-rolled into an intermediate slab 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.

[0009] Preferably, the step of "annealing the obtained continuous casting billet at a temperature of 600-700° C. for 10-30 hours" comprises: The bulging amount of the wide surface of the obtained continuous casting billet is detected; When the bulge does not reach 10mm, the annealing temperature is 600~650℃ and the annealing time is 10~15 hours; When the bulge is 10-15 mm, the annealing temperature is 600-650°C and the annealing time is 15-20 hours; When the bulge exceeds 15mm, the annealing temperature is 650~700℃ and the annealing time is 20~30 hours.

[0010] 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”: The reduction rate of each rough rolling pass is controlled at 32~38%, and the reduction rate of each finish rolling pass is controlled at 30~38%.

[0011] 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”: The thickness of the obtained hot-rolled plate is 2.0~2.4mm.

[0012] 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”: 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 ×70-500 kN, F 2n =2000+h n ×70+500 kN, where n represents the pass number, h n The preset thickness of the export billet for the nth pass, in mm.

[0013] Preferably, the step of "preparing a continuous casting billet by steelmaking and continuous casting" comprises: During the continuous casting process, the superheat of the molten steel in the tundish is 10~15℃.

[0014] Preferably, the step of "preparing a continuous casting billet by steelmaking and continuous casting" comprises: During the continuous casting process, the drawing speed v, the target slab thickness t and the target width w 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.

[0015] Preferably, 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.

[0016] Preferably, 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.

[0017] Preferably, 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.

[0018] Preferably, the chemical composition of the continuous casting billet, the impurity elements in terms of 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%.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: compared with the conventional hot-rolled plate production process of steelmaking, continuous casting, heating, hot rolling and coiling, the present invention first anneals the continuous casting billet before heating it. It has been verified by 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, the annealing treatment can eliminate the internal stress of 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 finally eliminating the serrated edge crack defects of the hot-rolled plate caused by the abnormally grown columnar crystals. 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

[0020] The technical solution of the present invention is further introduced below in conjunction with specific implementation methods.

[0021] 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.

[0022] Specifically, the production method comprises the following steps: Through steelmaking and continuous casting, continuous casting billets are prepared; The obtained continuous casting billet is annealed at a temperature of 600-700°C for 10-30 hours; The annealed continuous casting billet is heated, the soaking temperature is 1050~1250℃, and the soaking time is 180~220min; The heated continuous casting slab is firstly rough-rolled into an intermediate slab 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.

[0023] The inventors studied the causes of the serrated edge cracks of hot-rolled plates and found that the ferrite columnar crystals at the edges of the continuous casting billets would grow abnormally during the heating process, which would cause uneven plastic deformation of the edges of the rolled pieces during the hot rolling process. Such unevenness and plastic deformation directly led to the serrated edge cracks. Compared with the conventional hot-rolled plate production process of steelmaking, continuous casting, heating, hot rolling and coiling, the present invention anneals the continuous casting billets before heating them. It has been verified by 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 plates can be greatly eliminated. From the perspective of microscopic principles, the annealing treatment can eliminate the internal stress at the edges of the continuous casting billets, thereby avoiding the abnormal growth of ferrite columnar crystals in the heating process caused by the internal stress, and finally eliminating the serrated edge crack defects of the hot-rolled plates caused by the abnormally grown columnar crystals. 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 trimming.

[0024] Furthermore, the annealing process, i.e., the step of "annealing the obtained continuous casting billet at a temperature of 600-700° C. for 10-30 hours", may specifically include: The bulging amount of the wide surface of the obtained continuous casting billet is detected; When the bulge does not reach 10mm, the annealing temperature is 600~650℃ and the annealing time is 10~15 hours; When the bulge is 10-15 mm, the annealing temperature is 600-650°C and the annealing time is 15-20 hours; When the bulge exceeds 15mm, the annealing temperature is 650~700℃ and the annealing time is 20~30 hours.

[0025] Under the basic concept of annealing the continuous casting ingot of the present invention, the annealing temperature and annealing time are further optimized according to the bulging amount, 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.

[0026] Specifically, it has been found through research that when bulging deformation exists on the wide surface of the continuous casting billet, this bulging deformation will cause the edge of the continuous casting billet to have a large internal stress, and this internal stress will cause the abnormal growth of ferrite columnar crystals in the heating process, and then cause the jagged edge cracks of the hot-rolled plate. In a further improvement scheme of the present invention, the bulging amount is corresponding to a specific annealing temperature and annealing time, which can eliminate the internal stress of the bulging deformation to the greatest extent through the annealing process, so as to improve the edge quality of the hot-rolled plate.

[0027] 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.

[0028] Of course, under the inventive concept of this application, the annealing temperature and annealing time can be directly controlled without detecting the bulging amount, which can also solve the problem of jagged edge cracks of hot-rolled plates. The edge quality of hot-rolled plates can be further optimized by detecting the bulging amount and adjusting the annealing temperature and time in a targeted manner.

[0029] Furthermore, in a basic embodiment of the present invention, processes such as steelmaking, continuous casting, heating, hot rolling, and coiling can be implemented in conventionally known ways; and as some preferred methods, some preferred implementation methods of the continuous casting process and the hot rolling process will be introduced below to cooperate with the annealing process to further improve the edge quality of the hot-rolled plate and overcome the defects of jagged edge cracks.

[0030] Specifically, in a preferred embodiment, during the continuous casting process, the superheat of the molten steel in the tundish is 10-15° C. Thus, by controlling the superheat of the molten steel in the tundish to 10-15° C., the initial solidification shell thickness of the continuous casting billet (i.e., the shell thickness of the continuous casting billet when it leaves the crystallizer) can be increased, thereby reducing the bulging amount of the wide surface of the continuous casting billet to a certain extent, thereby reducing the jagged edge crack defects of the hot rolled plate caused by internal stress.

[0031] During the continuous casting process, the drawing speed v, the target slab thickness t and the target width w can also be controlled to meet 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 solidification crust thickness of the continuous casting slab can be increased, thereby reducing the bulging amount of the wide surface of the continuous casting slab to a certain extent, and then reducing the jagged edge crack defects of the hot rolled plate caused by internal stress.

[0032] 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.

[0033] 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).

[0034] In this way, by correlating the cooling rate V with the chemical composition of the molten steel (i.e., 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.

[0035] 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.

[0036] Vertical rollers are arranged on both sides of the secondary cooling zone to constrain the two wide sides of the blank 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 1~1.01 times the target width w of the slab, or the pressure of the vertical rollers is controlled in the range of 500~800kN.

[0037] In a preferred embodiment, in the hot rolling process, the reduction ratio of each pass of rough rolling is controlled at 32-38%, and the reduction ratio of each pass of finish rolling is controlled at 30-38%.

[0038] In the present application, the thickness of the obtained hot-rolled plate is 2.0-2.4 mm.

[0039] In addition, in the hot rolling process, rough rolling and finish rolling have multiple passes respectively; in each pass of rough rolling, vertical rolls are used for wide surface rolling, and the rolling force of the vertical rolls is reduced pass by 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 ×70-500 kN, F 2n =2000+h n ×70+500 kN, where n represents the pass number, h n Preset the thickness of the exit billet for the nth pass in mm. In this way, it is possible to further avoid the occurrence of jagged edge cracks on the edge from a macroscopic perspective, prevent edge flanging during hot rolling, and ensure the edge quality of the hot-rolled plate.

[0040] In addition, 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Here, the impurity elements satisfy the following conditions in terms of 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%, and N≤0.002%.

[0045] The following is an introduction to the functions and mechanisms of each element in the above chemical composition.

[0046] 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%.

[0047] 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.

[0048] Al: It is also an effective additive element for improving the resistivity of electromagnetic steel sheets and reducing iron loss. Too high a content of Al will reduce the magnetic induction intensity, greatly increase the brittleness of the steel sheet, and increase the difficulty of processing such as cold rolling. When the content of Al is low, the resistivity is too low, and nitrides such as AlN are finely precipitated, which makes the grain growth worse and cannot 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%.

[0049] 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%.

[0050] 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%.

[0051] 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 hot rolling, the S content (in terms of mass percentage) is controlled to be ≤0.0015%.

[0052] N: It is also an important component of inclusions in steel. The 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%.

[0053] 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%.

[0054] In summary, the present invention anneals the continuous casting billet before heating it. In this way, even if high-temperature heating is performed in the subsequent heating process, the serrated edge crack defect 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 finally eliminating the serrated edge crack defect of the hot-rolled plate caused by the abnormally grown columnar crystals. 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.

[0055] 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.

[0056] The specific implementation process of these embodiments is as follows: Step 1: Through steelmaking and continuous casting, 10 continuous casting billets numbered 1# to 10# are prepared. The chemical composition of each continuous casting billet is shown in Table 1; [Table 1]

[0057] Among them, the continuous casting billets No. 1#~3# are casted by the same furnace of molten steel and have the same chemical composition; the continuous casting billets No. 4#~6# are casted by the same furnace of molten steel and have the same chemical composition; the continuous casting billets No. 7#~10# are cast by the same furnace of molten steel and have the same chemical composition; Moreover, for the embodiments No. 1# to No. 10#, during the continuous casting process, the superheat, the casting speed v, the target slab thickness t and the target width w are respectively as shown in Table 2; [Table 2]

[0058] Step 2: annealing was performed on the nine continuous casting billets numbered 1# to 9#, and the bulging amount, annealing temperature and annealing time of the wide surface of each continuous casting billet are shown in Table 3. Meanwhile, the 10# continuous casting billet was not annealed, which is indicated by "-" in Table 3; [Table 3]

[0059] 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; Step 3: heating the annealed continuous casting billet, the soaking temperature and soaking time are shown in Table 4; 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; 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; [Table 4]

[0060] Finally, the edge quality of 10 hot-rolled plates numbered 1# to 10# was tested, and it was found that: 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; 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.

[0061] 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 method for producing a non-oriented silicon steel hot-rolled plate, characterized in that: The production method comprises the following steps: Through steelmaking and continuous casting, continuous casting billets are prepared; The obtained continuous casting billet is annealed at a temperature of 600-700°C for 10-30 hours; The annealed continuous casting billet is heated, the soaking temperature is 1050~1250℃, and the soaking time is 180~220min; The heated continuous casting slab is firstly rough-rolled into an intermediate slab 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 "annealing the obtained continuous casting billet at a temperature of 600-700° C. for 10-30 hours" includes: The bulging amount of the wide surface of the obtained continuous casting billet is detected; When the bulge does not reach 10mm, the annealing temperature is 600~650℃ and the annealing time is 10~15 hours; When the bulge is 10-15 mm, the annealing temperature is 600-650°C and the annealing time is 15-20 hours; When the bulge exceeds 15mm, the annealing temperature is 650~700℃ and the annealing time is 20~30 hours.

3. 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 rough rolling pass is controlled at 32~38%, and the reduction rate of each finish rolling pass is controlled at 30~38%.

4. 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 2.0~2.4mm.

5. 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 ×70-500 kN, 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.

6. 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 superheat of the molten steel in the tundish is 10~15℃.

7. 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 drawing speed v, the target slab thickness t and the target width w 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.

8. 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.

9. 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.

10. The method for producing a 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.

11. The method for producing a non-oriented silicon steel hot-rolled sheet according to claim 10, 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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