Production method for improving edge quality of high-magnetic-induction oriented silicon steel

Abstract

The invention 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 part of a hot-rolled steel plate to obtain an extruded steel plate; the extrusion positions are the upper surface and the lower surface which are 0-15mm away from the width edge of the steel plate; and 2, normalizing annealing, cold rolling, decarburization annealing, nitriding treatment, high-temperature annealing and stretching flattening annealing are conducted on the extruded steel plate, and then the high-magnetic-induction oriented silicon steel can be obtained. The production method is low in cost and high in efficiency, and the edge quality of the high-magnetic-induction oriented silicon steel finished product steel plate can be effectively improved through the production method.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon steel edge production and manufacturing, and specifically relates to a production method for improving the edge quality of high magnetic induction oriented silicon steel. Background Art

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

[0003] During the high temperature annealing process, this silicon steel coil needs to be kept warm for a long time at a high temperature of about 1200℃, and the total processing time exceeds 150 hours. Since the weight of the steel coil is usually between 15 and 25 tons, during high temperature annealing, due to the influence of high temperature creep and thermal expansion and contraction, the steel coil part close to the bottom plate of the high temperature annealing furnace is prone to defects such as edge cracks and poor plate shape.

[0004] These defects are mainly manifested as cracks along the length of the edge of the steel coil, forming obvious cracks. The main reason for these defects is that the bottom of the silicon steel coil undergoes high-temperature creep under the influence of the support force of the furnace bottom plate and its own gravity, resulting in obvious wrinkles on the edge; at the same time, during the heating process, the steel coil expands outward; and during the cooling stage, the steel coil shrinks inward. This process causes the bottom of the steel coil to rub violently with the furnace bottom plate, especially the outer ring of the steel coil, which has the largest displacement and suffers the most serious friction damage. If the levelness or flatness of the furnace table or furnace bottom plate is not good, the support force of the furnace bottom plate is unevenly distributed, and the friction force on the local part of the steel coil increases sharply, it may cause edge cracks in the silicon steel coil.

[0005] Edge cracks in high magnetic induction oriented silicon steel can lead to a series of problems: after high temperature annealing, the edges of the steel coils tend to stick together, resulting in more scrap when unwinding; during stretching and flattening annealing, the cracks on the edges of the steel coils tend to expand, which may cause product breakage and production stoppage; during laser scoring, due to the large amplitude of steel plate beating and uneven plate surface, the scoring is uneven and the scoring effect is poor. Ultimately, these edge cracks and poor plate shape defects must be removed during the shearing and packaging stage, otherwise the product cannot be shipped as a qualified product, which will cause a large loss of yield.

[0006] In order to reduce the occurrence of these defects, the existing technology usually controls related defects by adjusting the high-temperature annealing cooling rate, strengthening the quality maintenance of the high-temperature annealing furnace bottom plate, adjusting the strip tension in the annealing furnace of the stretching and flattening production line, etc. However, these measures have limited effects on the one hand, and on the other hand may lead to a significant increase in production costs, a decrease in production efficiency, and even a negative impact on the magnetic level of the product. Summary of the invention

[0007] In order to overcome the defects of the above-mentioned background technology, the present invention provides a production method for improving the edge quality of high magnetic induction oriented silicon steel; the production method of the present invention is simple, suitable for industrial production, and the production method can effectively improve the edge quality.

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

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

[0010] Step 1: Extruding the edge of the hot-rolled steel plate to obtain an extruded steel plate;

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

[0012] Step 2: The high magnetic induction oriented silicon steel can be obtained by subjecting the extruded steel plate to normalizing annealing, cold rolling, decarburization annealing, nitriding treatment, high temperature annealing and stretching flattening annealing.

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

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

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

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

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

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

[0019] The heating temperature of the first normalization stage is 1000-1120° C., and the holding time is 0.5-3 min. Preferably, the heating temperature of the first normalization stage is 1000-1120° C., and the holding time is 1-3 min.

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

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

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

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

[0024] In some preferred embodiments, the temperature of the decarburization annealing is 800-900° C.; the time of the decarburization annealing is 60-200 s, preferably, the time of the decarburization annealing 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, preferably 10 to 60 seconds.

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

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

[0029] In some preferred embodiments, the first stage of high temperature annealing: the temperature is raised to 550-750°C and kept warm, the heating rate is 5-50°C / h, the holding time is 20-40h, the atmosphere is a mixture of N2 and H2, and the proportion of H2 in the mixture is 20-80%; 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: the temperature is raised to 1150-1250°C and kept warm for 20-40h, the heating rate is 5-20°C / h, the heating atmosphere is a mixture of N2 and H2, and the atmosphere in the insulation stage is pure hydrogen.

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

[0032] In some preferred embodiments, the high magnetic induction oriented 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 the high magnetic induction oriented silicon steel is stretched, flattened, annealed, and laser scored, the fine grains at the edges are sheared off and then packaged to obtain a high magnetic induction oriented silicon steel finished product.

[0034] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention destroys the Gaussian texture at the edge of the hot-rolled steel plate through an extrusion process, which prevents secondary recrystallization of this part during the final high-temperature annealing process, thereby effectively controlling the grain size of the edge, improving the toughness of the edge of the finished steel plate, and further improving the edge quality of the high magnetic induction oriented silicon steel. By adjusting the extrusion reduction rate to control the degree of destruction of the Gaussian texture at the edge of the hot-rolled plate, the grain size of the edge of the finished plate is controlled, and the quality of the edge of the finished plate is improved.

[0037] 2. After normalizing treatment, abnormally grown grains with disordered orientation will appear on the edge of the hot-rolled plate, such as Figure 1 As shown in the figure above; these grains will not undergo secondary recrystallization during the final high temperature annealing process, keeping the grains small, such as Figure 1 As shown in the figure below.

[0038] 3. The production method of the present invention is not only easy to operate, but also realizes 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 rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The above figure 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 DESCRIPTION

[0040] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0041] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0042] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60-120 and 80-110 is listed for a specific parameter, it is understood that the range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present invention, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] If not otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0044] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0045] If not 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), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0046] If there is no special explanation, the "include" and "comprising" mentioned in the present invention represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0047] If not specifically stated, in the present invention, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": 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 embodiments and comparative examples are composed of the following elements in 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 rest are Fe and unavoidable impurities.

[0049] Example 1

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

[0051] Step 2: After normalizing annealing, pickling, cold rolling, decarburization annealing, nitriding treatment, high temperature annealing and stretching and leveling annealing, high magnetic induction oriented silicon steel can be obtained.

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

[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 0.17 mm.

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

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

[0056] In this embodiment, the high temperature annealing process includes a first stage of high temperature annealing with a temperature rise and a second stage of high temperature annealing;

[0057] The first stage of high temperature annealing: heating to 600℃ and keeping the temperature, the heating rate is 25℃ / h, the holding time is 36h, the atmosphere is a mixture of N2 and H2, and the proportion of H2 in the mixture is 60%;

[0058] The second stage of high temperature annealing: the temperature is raised to 1150°C and kept warm for 24 hours, the heating rate is 10°C / h, the heating atmosphere is a mixture of N2 and H2, and the atmosphere during the holding stage is pure hydrogen.

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

[0060] Finally, after stretching, flattening annealing, laser scoring, shearing and removing fine grains at the edge, high magnetic induction oriented silicon steel products are obtained after packaging. The thickness of the high magnetic induction oriented silicon steel products is 0.18mm.

[0061] Figure 1 The above figure shows the steel plate after normalization and pickling in Example 1, and a strip-shaped fine-grained area is formed at its edge; Figure 1 The figure below shows the steel plate obtained after high temperature annealing treatment in Example 1, and the matrix grain morphology after removing the surface coating and the magnesium silicate bottom layer. The edge grains did not undergo secondary recrystallization and the grains were fine.

[0062] Comparative Example 1

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

[0064] This comparative example does not undergo extrusion treatment, and other steps and parameters are the same as those of Example 1.

[0065] Example 2

[0066] The difference between this embodiment and embodiment 1 is that:

[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 plate are extruded within a range of 0 to 10 mm from the width edge of the steel plate, and the extrusion reduction rate is 2%.

[0069] The thickness of the steel plate after cold rolling is 0.19 mm.

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

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

[0072] 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 that:

[0075] This comparative example does not undergo extrusion treatment, and the other steps and parameters are the same as those of Example 2.

[0076] Example 3

[0077] The difference between this embodiment and embodiment 1 is that:

[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 plate are extruded within a range of 0 to 7 mm from the width edge of the steel plate, and the extrusion reduction rate is 2%.

[0080] The thickness of the steel plate after cold rolling is 0.22 mm.

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

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

[0083] 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 that:

[0086] This comparative example does not undergo extrusion treatment, and other steps and parameters are the same as those of Example 3.

[0087] Example 4

[0088] The difference between this embodiment and embodiment 1 is that:

[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 plate are extruded within a range of 0 to 5 mm from the width edge of the steel plate, and the extrusion reduction rate is 4%.

[0091] The thickness of the steel plate after cold rolling is 0.26 mm.

[0092] After decarburization annealing, a nitriding process is required. The nitriding process uses a mixed gas of N2, H2 and NH3, and the nitriding time is 20s.

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

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

[0095] 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 that:

[0098] This comparative example does not undergo extrusion treatment, and the other steps and parameters are the same as those of Example 4.

[0099] Example 5

[0100] The difference between this embodiment and embodiment 1 is that:

[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 plate within a range of 3 mm from the width edge of the steel plate were extruded, and the extrusion reduction rate was 5%.

[0103] The thickness of the steel plate after cold rolling is 0.285 mm.

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

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

[0106] 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:

[0109] This comparative example does not undergo extrusion treatment, and the other steps and parameters are the same as those of Example 5.

[0110] The quality of the finished products of high magnetic induction oriented silicon steel of 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 conditions, count the number and distribution of cracks on the edge of high magnetic induction oriented silicon steel products. Pay attention to the length, width and distribution density of the cracks. Record whether there are cracks and other defects on the surface of the silicon steel sheet.

[0113] (2) Detailed measurement: Use non-contact scanning method or other measuring tools to measure the roughness of high magnetic induction oriented silicon steel products in detail, measure the amplitude (wave height) and wavelength (wave distance) to describe the roughness, and the calculation formula is (amplitude / wavelength) × 100%.

[0114] (3) Evaluation standard: Maximum unevenness < 1.5% is qualified flatness, refer to the national standard GB / T2521.2-2016.

[0115] Table 1

[0116]

[0117]

[0118] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A production method for improving the edge quality of high magnetic induction oriented silicon steel, characterized in that: The following steps are involved: Step 1: Extruding the hot-rolled steel plate to obtain an extruded steel plate; The extrusion position is the upper and lower surfaces within a range of 0 to 15 mm from the width edge of the steel plate; Step 2: The high magnetic induction oriented silicon steel can be obtained by subjecting the extruded steel plate to normalizing annealing, cold rolling, decarburization annealing, nitriding treatment, high temperature annealing, and stretching and flattening annealing.

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

3. The production method for improving the edge quality of high magnetic induction oriented silicon steel according to claim 1, characterized in that: Satisfy at least one of the following conditions ① to ③: ① The thickness of the hot-rolled steel plate is 1.5 to 3.0 mm; ② The extrusion position is the upper and lower surfaces within a range of 0 to 15 mm from the width edge of the steel plate; ③ The reduction rate of the extrusion is 1 to 5%.

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

5. The production method for improving the edge quality of high magnetic induction oriented silicon steel according to claim 1, characterized in that: The cold rolling adopts a one-step cold rolling method; And / or, the thickness of the cold-rolled steel plate is 0.15 to 0.35 mm.

6. The production method for improving the edge quality of high magnetic induction oriented silicon steel according to claim 1, characterized in that: The temperature of the decarburization annealing is 800-900° C., and the time of the decarburization annealing is 60-200 seconds.

7. The production method for improving the edge quality of high magnetic induction oriented silicon steel according to claim 1, characterized in that: The decarburization annealing further includes a nitriding operation; Wherein, the nitriding time is 5 to 60 seconds; the nitriding gas is a mixed gas of N2, H2 and NH3.

8. The production method for improving the edge quality of high magnetic induction oriented silicon steel according to claim 1, characterized in that: The high temperature annealing process includes a first stage of high temperature annealing with a rising temperature and a second stage of high temperature annealing.

9. The production method for improving the edge quality of high magnetic induction oriented silicon steel according to claim 8, characterized in that: The first high temperature annealing: heating to 550-750°C for insulation, heating rate of 5-50°C / h, insulation time of 20-40h, atmosphere of a mixture of N2 and H2, H2 ratio of 20-80% in the mixture; And / or, the second stage of high temperature annealing: heating to 1150-1250°C and keeping warm for 20-40h, heating rate 5-20°C / h, heating atmosphere is a mixture of N2 and H2, the proportion of H2 in the mixture is 20-80%; the atmosphere in the insulation stage is pure hydrogen.

10. The production method for improving the edge quality of high magnetic induction oriented silicon steel according to claim 1, characterized in that: The grain size of the high magnetic induction oriented silicon steel in the range of 0 to 15 mm from the width edge of the steel plate is 50 to 3000 μm.

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