A production method for improving the quality of the edge portion of high-magnetic-induction oriented silicon steel

Abstract

The application discloses a production method for improving the edge quality of high-magnetic-induction oriented silicon steel, and belongs to the technical field of oriented silicon steel production and manufacturing. The production method comprises the following steps: step 1, quantitatively extruding the edge of a hot-rolled steel plate to obtain an extruded steel plate; the extrusion position is the upper and lower surfaces within the range of 0-15 mm from the edge of the steel plate in width; step 2, performing normalizing annealing, cold rolling, decarburization annealing, nitriding treatment, high-temperature annealing, and stretch leveling annealing on the extruded steel plate to obtain the high-magnetic-induction oriented silicon steel. The production method is low in cost and high in efficiency, and can effectively improve the edge quality of the high-magnetic-induction oriented silicon steel finished plate.

Description

Technical Field

[0001] This invention belongs to the field of silicon steel edge manufacturing technology, specifically a production method for improving the quality of edges of high magnetic induction oriented silicon steel. Background Technology

[0002] High magnetic induction oriented silicon steel is a special electrical steel material known for its highly uniform grain orientation, which gives it extremely high magnetic polarization intensity in the rolling direction. Therefore, it is often used to manufacture transformer cores.

[0003] During the high-temperature annealing process, this silicon steel sheet coil needs to be held at a high temperature of approximately 1200°C for an extended period, with a total processing time exceeding 150 hours. Since the weight of the steel coil is typically between 15 and 25 tons, during high-temperature annealing, due to the effects of high-temperature creep and thermal expansion and contraction, the portion of the steel coil near the bottom plate of the high-temperature annealing furnace is prone to defects such as edge cracks and poor sheet shape.

[0004] These defects mainly manifest as cracks along the length of the steel coil's edge, forming obvious fissures. The primary cause of these defects is the high-temperature creep at the bottom of the silicon steel coil under the support of the furnace bottom plate and its own weight, leading to noticeable wrinkles at the edge. Simultaneously, during heating, the coil expands outwards; during cooling, it contracts inwards. This process causes intense friction between the bottom of the coil and the furnace bottom plate, especially on the outer ring where the displacement is greatest and the frictional damage is most severe. If the furnace platform or furnace bottom plate is not level or flat, or the support force of the furnace bottom plate is unevenly distributed, the frictional force on the coil increases sharply in certain areas, potentially leading to edge cracks in the silicon steel coil.

[0005] Edge cracks in high-magnetic-induction grain-oriented silicon steel can lead to a series of problems: after high-temperature annealing, the edges of the steel coil are prone to sticking together, resulting in increased scrap during uncoiling; during stretching and leveling annealing, the edge cracks are prone to propagation, potentially causing strip breakage and production stoppage; during laser marking, the large runout and uneven surface of the steel sheet result in uneven marking and poor marking effect. Ultimately, these edge cracks and poor sheet shape defects must be removed during the shearing and packaging stage; otherwise, the product cannot be shipped as qualified, resulting in significant yield losses.

[0006] To reduce these defects, existing technologies typically control them by adjusting parameters such as the high-temperature annealing cooling rate, strengthening the quality maintenance of the high-temperature annealing furnace bottom plate, and adjusting the strip tension in the annealing furnace of the stretching and leveling production line. However, these measures have limited effectiveness and may lead to a significant increase in production costs, a decrease in production efficiency, and even a negative impact on the magnetic properties of the product. Summary of the Invention

[0007] To overcome the shortcomings of the aforementioned background technology, this invention provides a production method for improving the edge quality of high magnetic induction oriented silicon steel. The production method of this invention is simple, suitable for industrial production, and can effectively improve the edge quality.

[0008] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0009] This invention discloses a production method for improving the edge quality of high magnetic induction oriented silicon steel, comprising the following steps:

[0010] Step 1: Extrude the edges of the hot-rolled steel sheet to obtain an extruded steel sheet;

[0011] The extrusion location is the upper and lower surfaces within a range of 0 to 15 mm from the edge of the steel plate width;

[0012] Step 2: High magnetic orientation silicon steel can be obtained by performing normalizing annealing, cold rolling, decarburizing annealing, nitriding treatment, high temperature annealing and stretching and leveling annealing on the extruded steel sheet.

[0013] In some preferred embodiments, the hot-rolled steel sheet comprises the following elements by mass percentage: C: 0.045%–0.080%, Si: 2.8%–3.4%, Mn: 0.05%–0.30%, Als: 0.0230%–0.0310%, N: 0.006%–0.009%, Sn: ≤0.10%, Cr: ≤0.20%, P: ≤0.050%, S: 0.003%–0.016%.

[0014] In some preferred embodiments, the hot-rolled steel sheet is composed of the following elements by mass percentage: C: 0.045%–0.080%, Si: 2.8%–3.4%, Mn: 0.05%–0.30%, Als: 0.0230%–0.0310%, N: 0.006%–0.009%, Sn: ≤0.10%, Cr: ≤0.20%, P: ≤0.050%, S: 0.003–0.016%, with the remainder being Fe and unavoidable impurities.

[0015] In some preferred embodiments, the thickness of the hot-rolled steel sheet is 1.5 to 3.0 mm.

[0016] In some preferred embodiments, the extrusion is performed on the upper and lower surfaces within a range of 0 to 15 mm from the edge of the steel plate width.

[0017] In some preferred embodiments, the compression rate of the extrusion is 1 to 5%.

[0018] In some preferred embodiments, the normalizing annealing process includes:

[0019] The heating temperature for the first stage of normalization is 1000–1120℃, and the holding time is 0.5–3 min; preferably, the heating temperature for the first stage of normalization is 1000–1120℃, and the holding time is 1–3 min.

[0020] The heating temperature for the second stage of normalization is 870–950℃, and the holding time is 1–3 min; preferably, the heating temperature for the second stage of normalization is 900–950℃, and the holding time is 1–3 min.

[0021] In some preferred embodiments, the cold rolling process further includes a pickling step, which is a conventional operation in the art.

[0022] In some preferred embodiments, the cold rolling method is a single-stage cold rolling process.

[0023] In some preferred embodiments, the thickness of the cold-rolled steel sheet is 0.15–0.35 mm, more preferably 0.17–0.285 mm.

[0024] In some preferred embodiments, the decarburization annealing temperature is 800–900°C; the decarburization annealing time is 60–200 s, and more preferably, the decarburization annealing time is 100–200 s.

[0025] In some preferred embodiments, the decarburization annealing may further include a nitriding operation.

[0026] In some preferred embodiments, the nitriding time is 5 to 60 seconds, more preferably 10 to 60 seconds.

[0027] In some preferred embodiments, the gas used for nitriding is conventional in the art. The nitriding gas is a mixture of N2, H2, and NH3.

[0028] In some preferred embodiments, the high-temperature annealing process includes a first stage of high-temperature annealing heating and a second stage of high-temperature annealing.

[0029] In some preferred embodiments, the first stage of high-temperature annealing involves heating to 550–750°C and holding at that temperature for 20–40 hours at a rate of 5–50°C / h. The atmosphere is a mixture of N2 and H2, with H2 comprising 20–80% of the mixture. More preferably, the heating rate of the first stage of high-temperature annealing is 20–50°C / h.

[0030] In some preferred embodiments, the second stage of high-temperature annealing involves heating to 1150–1250°C and holding for 20–40 hours at a heating rate of 5–20°C / hour. The heating atmosphere is a mixture of N2 and H2, and the holding atmosphere is pure hydrogen.

[0031] In some preferred embodiments, the grain size of the high magnetic induction oriented silicon steel is 50-3000 μm in the range of 0-15 mm from the edge of the steel plate width, and more preferably 300-3000 μm.

[0032] In some preferred embodiments, the high magnetic orientation silicon steel needs to be sheared in the final shearing and packaging process to remove fine grains at the edges.

[0033] In some preferred embodiments, after stretching, flattening, annealing, and laser scoring of the high magnetic induction oriented silicon steel, the fine grains on the edges are removed by shearing before packaging to obtain the finished high magnetic induction oriented silicon steel.

[0034] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. This invention disrupts the Gaussian texture at the edges of hot-rolled steel sheets through an extrusion process. This process prevents secondary recrystallization in this area during the final high-temperature annealing, thereby effectively controlling the grain size at the edges, improving the edge toughness of the finished steel sheet, and further enhancing the edge quality of high-magnetic-induction grain-oriented silicon steel. By adjusting the extrusion reduction rate, the degree of disruption of the Gaussian texture at the edges of the hot-rolled sheet is controlled, thereby controlling the grain size at the edges of the finished sheet and improving the edge quality of the finished sheet.

[0037] 2. After normalizing, the edges of the hot-rolled sheet may exhibit abnormally large, randomly oriented grains, such as... Figure 1 As shown in the image above, these grains do not undergo secondary recrystallization during the final high-temperature annealing process, maintaining a fine grain size, such as... Figure 1 As shown in the image below.

[0038] 3. The production method of the present invention is not only simple to operate, but also achieves precise control of the edge grain size of high magnetic induction oriented silicon steel without significantly increasing additional costs, thereby improving product quality and yield. Attached Figure Description

[0039] Figure 1 The image above shows the steel plate obtained after normalization and pickling treatment in Example 1; Figure 1 The figure below shows the steel plate obtained after high-temperature annealing in Example 1. Detailed Implementation

[0040] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0041] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0042] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is understood that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this invention, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein; "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer greater than or equal to 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0044] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0045] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0047] Unless otherwise specified, the term "or" is inclusive in this invention. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0048] The hot-rolled steel sheets used in the following examples and comparative examples are composed of the following elements by mass percentage: C: 0.065%, Si: 2.72%, Mn: 0.16%, Als: 0.0290%, N: 0.008%, Sn: 0.04%, Cr: 0.13%, P: 0.030%, S: 0.007%; the remainder being Fe and unavoidable impurities.

[0049] Example 1

[0050] Step 1: The thickness of the hot-rolled steel plate in this embodiment is 1.5mm. The upper and lower surfaces of the hot-rolled steel plate are extruded within a range of 0 to 13mm from the edge of the steel plate width, and the extrusion reduction rate is 1%.

[0051] Step 2: High magnetic orientation silicon steel can be obtained by performing normalizing annealing, pickling, cold rolling, decarburizing annealing, nitriding, high temperature annealing and stretching and leveling annealing.

[0052] In this embodiment, the normalizing annealing includes: the heating temperature of the first normalizing stage is 1050℃, and the holding time is 3min; the heating temperature of the second normalizing stage is 900℃, and the holding time is 2min.

[0053] In this embodiment, the cold rolling method is a single cold rolling method, and the thickness of the steel plate after cold rolling is 0.17mm.

[0054] In this embodiment, decarburization annealing is performed at 800°C for 160 seconds.

[0055] In this embodiment, nitriding treatment was performed at 830°C, and the nitriding amount was 227 ppm.

[0056] In this embodiment, the high-temperature annealing process includes a first stage of high-temperature annealing heating and a second stage of high-temperature annealing.

[0057] The first stage of high-temperature annealing: the temperature is raised to 600℃ and held at that temperature. The heating rate is 25℃ / h and the holding time is 36h. The atmosphere is a mixture of N2 and H2, with H2 accounting for 60% of the mixture.

[0058] The second stage of high-temperature annealing: the temperature is raised to 1150℃ and held for 24 hours, with a heating rate of 10℃ / h. The heating atmosphere is a mixture of N2 and H2, and the holding atmosphere is pure hydrogen.

[0059] After high-temperature annealing, the grain size of high magnetic induction oriented silicon steel is 1000-3000μm in the range of 0-14mm from the edge of the steel plate width;

[0060] Finally, after stretching, flattening, annealing, and laser scoring, the fine grains at the edges are removed by shearing before packaging to obtain the high magnetic orientation silicon steel finished product, which has a thickness of 0.18mm.

[0061] Figure 1 The image above shows the steel plate after normalization and pickling in Example 1, with a strip-shaped fine grain region formed at its edge; Figure 1 The figure below shows the matrix grain morphology of the steel plate obtained after high-temperature annealing in Example 1, after removing the surface coating and magnesium silicate underlayer. The edge grains did not undergo secondary recrystallization and the grains are fine.

[0062] Comparative Example 1

[0063] The difference between this comparative example and Example 1 is as follows:

[0064] This comparative example does not involve extrusion processing; all other steps and parameters are the same as in Example 1.

[0065] Example 2

[0066] The difference between this embodiment and Embodiment 1 is as follows:

[0067] The thickness of the hot-rolled steel plate in this embodiment is 1.8 mm.

[0068] The upper and lower surfaces of the hot-rolled steel sheet are extruded within a range of 0 to 10 mm from the edge of the steel sheet width, with an extrusion reduction rate of 2%.

[0069] The thickness of the cold-rolled steel plate is 0.19 mm.

[0070] After high-temperature annealing, the grain size of high magnetic induction oriented silicon steel is 1500-2500μm in the range of 0-9mm from the edge of the steel plate width;

[0071] The thickness of the finished high magnetic induction oriented silicon steel is 0.20mm.

[0072] All other steps and parameters are the same as in Example 1.

[0073] Comparative Example 2

[0074] The difference between this comparative example and Example 2 is as follows:

[0075] This comparative example does not involve extrusion processing; all other steps and parameters are the same as in Example 2.

[0076] Example 3

[0077] The difference between this embodiment and Embodiment 1 is as follows:

[0078] The thickness of the hot-rolled steel plate in this embodiment is 2.2 mm.

[0079] The upper and lower surfaces of the hot-rolled steel sheet are extruded within a range of 0 to 7 mm from the edge of the steel sheet width, with an extrusion reduction rate of 2%.

[0080] The thickness of the cold-rolled steel plate is 0.22 mm.

[0081] After high-temperature annealing, the grain size of high magnetic induction oriented silicon steel is 300-1800μm in the range of 0-7mm from the edge of the steel plate width;

[0082] The thickness of the finished high magnetic induction oriented silicon steel is 0.23mm.

[0083] All other steps and parameters are the same as in Example 1.

[0084] Comparative Example 3

[0085] The difference between this comparative example and Example 3 is as follows:

[0086] This comparative example does not involve extrusion processing; all other steps and parameters are the same as in Example 3.

[0087] Example 4

[0088] The difference between this embodiment and Embodiment 1 is as follows:

[0089] The thickness of the hot-rolled steel plate in this embodiment is 2.4 mm.

[0090] The upper and lower surfaces of the hot-rolled steel sheet are extruded within a range of 0 to 5 mm from the edge of the steel sheet width, with an extrusion reduction rate of 4%.

[0091] The thickness of the cold-rolled steel plate is 0.26 mm.

[0092] After decarburization annealing, a nitriding process is required. Nitriding uses a mixture of N2, H2 and NH3 gases and the nitriding time is 20 seconds.

[0093] After high-temperature annealing, the grain size of high magnetic induction oriented silicon steel is 500-1000μm in the range of 0-4mm from the edge of the steel plate width;

[0094] The thickness of the finished high magnetic induction oriented silicon steel is 0.27mm.

[0095] All other steps and parameters are the same as in Example 1.

[0096] Comparative Example 4

[0097] The difference between this comparative example and Example 4 is as follows:

[0098] This comparative example does not involve extrusion processing; all other steps and parameters are the same as in Example 4.

[0099] Example 5

[0100] The difference between this embodiment and Embodiment 1 is as follows:

[0101] The thickness of the hot-rolled steel plate in this embodiment is 2.8 mm.

[0102] The upper and lower surfaces of the hot-rolled steel sheet within a 3mm range from the edge of the sheet width are extruded, with an extrusion reduction rate of 5%.

[0103] The thickness of the cold-rolled steel plate is 0.285 mm.

[0104] After high-temperature annealing, the grain size of high magnetic induction oriented silicon steel is 800-2000μm in the range of 0-4mm from the edge of the steel plate width;

[0105] The thickness of the finished high magnetic induction oriented silicon steel is 0.30mm.

[0106] All other steps and parameters are the same as in Example 1.

[0107] Comparative Example 5

[0108] The difference between this comparative example and Example 5 is as follows:

[0109] This comparative example does not involve extrusion processing; all other steps and parameters are the same as in Example 5.

[0110] The quality of the high magnetic induction oriented silicon steel products in the above embodiments and comparative examples was statistically analyzed by visual inspection. The results are shown in Table 1.

[0111] The specific process is as follows:

[0112] (1) Visual inspection: Under visual inspection, count the number and distribution of cracks on the edges of the finished high magnetic induction oriented silicon steel. Pay attention to the length, width, and distribution density of the cracks. Record whether there are any defects such as cracks on the surface of the silicon steel sheet.

[0113] (2) Detailed measurement: The unevenness of the high magnetic induction oriented silicon steel finished product is measured in detail using non-contact scanning method or other measuring tools. The unevenness is described by measuring the amplitude (wave height) and wavelength (wave distance). The calculation formula is (amplitude / wavelength) × 100%.

[0114] (3) Evaluation criteria: The maximum unevenness is less than 1.5% and is considered to be qualified flatness. See national standard GB / T2521.2-2016.

[0115] Table 1

[0116]

[0117]

[0118] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this invention. It should be understood that the above descriptions are merely specific embodiments of this invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A production method for improving the edge quality of high magnetic induction oriented silicon steel, characterized in that, Includes the following steps: Step 1: Extrude the hot-rolled steel sheet to obtain an extruded steel sheet; The extrusion location is the upper and lower surfaces within a range of 0~15mm from the edge of the steel plate width; The compression rate of the extrusion is 1-5%; Step 2: After normalizing annealing, cold rolling, decarburizing annealing, nitriding treatment, high-temperature annealing, and stretching and leveling annealing, high magnetic induction oriented silicon steel can be obtained from the extruded steel sheet.

2. The production method for improving the edge quality of high magnetic induction oriented silicon steel as described in claim 1, characterized in that, The hot-rolled steel plate comprises the following elements by mass percentage: C: 0.045%~0.080%, Si: 2.8%~3.4%, Mn: 0.05%~0.30%, Als: 0.0230%~0.0310%, N: 0.006%~0.009%, Sn: ≤0.10%, Cr: ≤0.20%, P: ≤0.050%, S: 0.003~0.016%.

3. The production method for improving the edge quality of high magnetic induction oriented silicon steel as described in claim 1, characterized in that, The thickness of the hot-rolled steel plate is 1.5~3.0mm.

4. The production method for improving the edge quality of high magnetic induction oriented silicon steel as described in claim 1, characterized in that, The normalizing annealing process includes: The heating temperature for the first stage of normalization is 1000~1120℃, and the holding time is 0.5~3min; The heating temperature for the second stage of normalization is 870~950℃, and the holding time is 1~3 minutes.

5. The production method for improving the edge quality of high magnetic induction oriented silicon steel as described in claim 1, characterized in that, The cold rolling process is a single-stage cold rolling method. And / or, the thickness of the cold-rolled steel sheet is 0.15~0.35mm.

6. The production method for improving the edge quality of high magnetic induction oriented silicon steel as described in claim 1, characterized in that, The decarburization annealing temperature is 800~900℃, and the decarburization annealing time is 60~200s.

7. The production method for improving the edge quality of high magnetic induction oriented silicon steel as described in claim 1, characterized in that, The decarburization annealing process also includes a nitriding operation. The nitriding time is 5-60 seconds; the nitriding gas is a mixture of N2, H2 and NH3.

8. The production method for improving the edge quality of high magnetic induction oriented silicon steel as described in claim 1, characterized in that, The high-temperature annealing process includes a first stage of high-temperature annealing heating and a second stage of high-temperature annealing.

9. The production method for improving the edge quality of high magnetic induction oriented silicon steel as described in claim 8, characterized in that, The first stage of high-temperature annealing involves heating to 550~750℃ and holding at that temperature, with a heating rate of 5. 50℃ / h, heat preservation time is 20 For 40 hours, the atmosphere is a mixture of N2 and H2, with H2 accounting for 20-80% of the mixture; And / or, the second stage of high-temperature annealing: heating to 1150~1250℃ and holding for 20~40h, heating rate 5~20℃ / h, heating atmosphere is a mixture of N2 and H2, the proportion of H2 in the mixture is 20~80%; the holding stage atmosphere is pure hydrogen.

10. The production method for improving the edge quality of high magnetic induction oriented silicon steel as described in claim 1, characterized in that, The high magnetic induction oriented silicon steel has a grain size of 50~3000μm in the range of 0~15mm from the edge of the steel plate width.

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