Low-iron-loss heat-resistant domain-refined grain oriented silicon steel sheet and laser scribing method therefor

Abstract

The present disclosure relates to a low-iron-loss heat-resistant domain-refined grain oriented silicon steel sheet, the surface of which is provided with at least one scribed area formed by laser scribing; the depth of a melt solidification layer in the scribed area is 8-30 μm; the width of the melt solidification layer in the scribed area is 20-100 μm; and the height Sa of a protrusion on the surface of the scribed area is less than or equal to 3 μm. The present disclosure further relates to a method for performing laser scribing on an oriented silicon steel sheet, comprising: performing laser scribing on the surface of the oriented silicon steel sheet by using laser having an annular spot, so that at least one scribed area is formed on the surface of the oriented silicon steel sheet. The oriented silicon steel sheet of the present disclosure has a low iron loss, a high magnetic induction, and a high lamination factor, and is particularly suitable for manufacturing high-energy-efficiency wound core transformers.

Description

A low iron loss heat-resistant magnetic domain refinement type oriented silicon steel sheet and its laser scoring method Technical Field

[0001] The present disclosure relates to an oriented silicon steel sheet and a manufacturing process thereof, and in particular to a low iron loss heat-resistant magnetic domain refined oriented silicon steel sheet and a laser scoring method thereof. Background Art

[0002] Transformers, essential components of power transmission systems, contribute approximately 40% of their reactive power losses. The transformer's core, made of laminated or wound oriented silicon steel, contributes approximately 20% of its total reactive power losses during operation. These losses in the transformer core are often referred to as iron losses.

[0003] Oriented silicon steel is a ferromagnetic material, named because its internal grain arrangement direction is roughly the same as the rolling direction of the steel plate. Inside the grains, there is a magnetic domain structure caused by the spontaneous magnetization of the ferromagnet. The magnetic moments of the atoms in each magnetic domain spontaneously align in parallel, forming a 180° magnetic domain, which is parallel to the easy magnetization direction of the grain {110} <001> . Adjacent magnetic domains are 180° opposite magnetic domains, and there is a magnetic domain wall consisting of dozens to hundreds of atomic layers between the two. During the magnetization process, the magnetic moments in adjacent magnetic domains move through the magnetic domain walls and are arranged in the same direction, realizing the magnetic conductivity function. The magnetic domain structure is the result of the principle of minimum energy action and is a basic factor affecting the iron loss, magnetic induction and magnetostriction of silicon steel sheets. Since the grain arrangement direction is the direction of easy magnetic conductivity, the higher the grain orientation, the better the magnetic properties of the silicon steel sheet, which is manifested as higher magnetic induction and lower iron loss.

[0004] At present, the magnetic conductivity of silicon steel sheets is expressed as magnetic induction, which is generally represented by B8, that is, the magnetic flux density of the silicon steel sheet under an excitation magnetic field of 800A / m, in T; iron loss is generally expressed in P 17 / 50 Characterizes the ineffective electrical energy consumed by the magnetization of silicon steel sheets when the magnetic flux density in the strip reaches 1.7 T under an AC excitation field of 50 Hz, in W / kg.

[0005] Research has found that steel losses in oriented silicon steel sheets consist of three components: hysteresis loss, eddy current loss, and anomalous eddy current loss. Hysteresis loss is energy loss caused by the hysteresis phenomenon during magnetization, where inclusions, crystal defects, and internal stress in the material hinder the movement of magnetic domain walls, resulting in a lag behind the change in magnetic field intensity. Eddy current loss is energy loss caused by eddy currents caused by the local electromotive force induced by changes in magnetic flux during magnetization, and is related to the conductivity and thickness of the silicon steel sheet. Anomalous eddy current loss is energy loss caused by the different magnetic domain structures during magnetization of the silicon steel sheet, and is primarily affected by the width of the magnetic domain.

[0006] In current technologies, the development direction of silicon steel technology is to continuously reduce the iron loss of silicon steel materials. There are three main technical directions currently available: 1. Metallurgical methods: Using metallurgical methods to control the secondary recrystallization structure, improve grain orientation, and moderately reduce grain size to refine magnetic domains and reduce iron loss; 2. Tension control: Applying a high-tension coating to the surface of the silicon steel sheet, the tension effect of the coating refines the magnetic domains and reduces iron loss; 3. Surface scoring: Applying linear stress or strain to the surface of the silicon steel sheet using lasers or electron beams to refine the magnetic domains and reduce iron loss.

[0007] Among them, the refinement of magnetic domains by scoring has become the main technical improvement point of oriented silicon steel. Among them, the refinement of magnetic domains can effectively reduce the abnormal eddy current loss of oriented silicon steel. Currently, the technology of implementing scoring on the surface of oriented silicon steel to refine magnetic domains and reduce steel loss of oriented silicon steel can be divided into two categories according to the effect of scoring:

[0008] (1) Not resistant to stress relief annealing: Linear thermal stress areas are formed on the surface at a certain distance by means of laser, plasma beam, or electron beam. The stress produces a 90° magnetic domain perpendicular to the rolling direction in the vicinity, thereby reducing the width of the 180° main magnetic domain and reducing iron loss. Since linear thermal stress will disappear due to stress relief annealing, this type of product is generally used to manufacture laminated core transformers that do not require stress relief annealing, and is currently widely used in energy-saving transformers for power transmission networks;

[0009] (2) Stress relief annealing resistant notching: Grooves are formed using mechanical toothed rollers, chemical etching, laser melting, and other methods. Free magnetic poles are generated on both sides of the grooves, increasing surface energy and redistributing energy within the crystal, reducing the magnetic domain width and thus reducing iron loss. Since the strain zone does not change after stress relief annealing, this type of product can be used to manufacture wound core transformers that require stress relief annealing.

[0010] As a more energy-efficient transformer, the market share of wound-core transformers has rapidly expanded in recent years. Wound-core transformers fully utilize the superior rolled-core magnetic properties of oriented silicon steel, offering advantages over laminated core transformers in terms of loss, noise, and material utilization, making them particularly suitable for the manufacture of small and medium-sized energy-saving transformers. However, because the winding of the steel sheets during the manufacturing process generates internal stress, which degrades performance, the core must undergo stress relief annealing. Stress relief annealing typically involves maintaining the core at a temperature above 800°C for at least 2 hours in a protective atmosphere to optimize the magnetic properties of the silicon steel sheets. Targeted silicon steel sheets that have been previously refined by using lasers or electron beams to generate linear stress zones lose this effect after stress relief annealing, eliminating the stress and making them unsuitable for use in wound-core transformers.

[0011] To ensure that the effects of domain refinement persist after stress relief annealing, a stress relief annealing-resistant domain refinement technique has been developed. This technique uses chemical etching, mechanical pressure, and lasers to create grooves of defined shapes on the surface of silicon steel sheets. The presence of free magnetic poles in the grooves and the resulting increase in surface energy redistribute material energy, reducing magnetic domain width and iron loss. Because the grooves remain unchanged during stress relief annealing, grain-oriented silicon steel sheets produced using this technique can be used in the manufacture of wound iron-core transformers. This technique, collectively referred to as heat-resistant notching, is a process known as heat-resistant notching.

[0012] Currently, the production of heat-resistant notched grained silicon steel using lasers has been achieved in the field. However, problems such as melting or spattering and low production efficiency remain difficulties in achieving laser heat-resistant notching.

[0013] A Chinese patent application, publication number CN102941413A, published on February 27, 2013, and titled "A Method for Reducing Iron Losses by Multiple Laser Grooving of Grain-Oriented Silicon Steel," uses repeated low-power laser grooving to overcome the problem of spatter. However, repeated grooving is inefficient and difficult to achieve reproducible positioning within micro-areas, making it difficult to implement on an industrial production line.

[0014] Summary of the Invention

[0015] One of the objectives of this disclosure is to provide a heat-resistant, magnetic domain-refined, low-iron-loss grained silicon steel sheet. The sheet features a sized, molten, solidified layer (a layer formed by melting and solidifying the molten, solidified areas). This layer generates tension in localized micro-regions, thereby enhancing the magnetic domain refinement and resulting in low iron loss in the finished grained silicon steel. This grained silicon steel sheet is particularly suitable for manufacturing energy-saving wound-core transformers.

[0016] Therefore, the present disclosure provides a grain-oriented silicon steel sheet having at least one scored area formed by laser scoring on its surface; the depth of the melt-solidified layer in the scored area is 8-30 μm, for example, 15-25 μm; the width of the melt-solidified layer in the scored area is 20-100 μm, for example, 51-92 μm; the height S of the surface protrusion in the scored area is 100 μm, for example, ... a ≤3.0μm.

[0017] The inventors have discovered that by making the depth of the molten solidified layer formed by laser scoring between 8-30 μm and the width between 20-100 μm, the iron loss, magnetic induction and lamination coefficient of the oriented silicon steel sheet can be improved. When the depth of the molten solidified layer is less than 8 μm, it is difficult to achieve the effect of refining the magnetic domain and reducing the iron loss, resulting in high iron loss of the finished oriented silicon steel; when the depth of the molten solidified layer is greater than 30 μm, the magnetic induction B8 of the oriented silicon steel is low, and it is impossible to manufacture a high-efficiency wound core transformer. When the width of the molten solidified layer is less than 20 μm, the required focused spot size is very small, which is extremely difficult to achieve in industrial production; when the width of the solidified layer is greater than 100 μm, the heat-affected zone formed by laser scoring is very large, and thermal stress warping will occur during the production process, leading to defocusing, and the magnetic induction and lamination coefficient of the steel plate will also be significantly reduced. Therefore, the depth of the melt-solidified layer in the scored area of ​​the grain-oriented silicon steel sheet disclosed herein needs to be controlled between 8 and 30 μm, and the width of the melt-solidified layer in the scored area needs to be controlled between 20 and 100 μm.

[0018] The inventors further studied the characteristics of the molten solidified layer formed by laser scoring and its correlation with the performance characteristics of grain-oriented silicon steel. The results showed that when the density of the molten solidified layer formed by laser scoring is lower than that of the steel plate substrate, inappropriate process conditions may form small holes in the molten solidified layer, which will cause a certain bulge to form in the scoring area. When the height S of the bulge is a When the height is higher than 3.0 μm, the lamination coefficient of the silicon steel sheet is significantly reduced, which cannot meet the processing requirements of the wound core. a Need to be controlled below 3.0μm.

[0019] In a preferred embodiment, the line roughness R of the central position of the scoring area of ​​the oriented silicon steel sheet disclosed in the present invention is a ≤3.0μm. When the line roughness exceeds 3.0μm, the lamination factor of the silicon steel sheet may be reduced.

[0020] In a preferred embodiment, the surface of the oriented silicon steel sheet of the present disclosure has an insulating coating, and the thickness of the insulating coating at the center of the notched area is t c ≥0.2μm(t c The upper limit of t is not critical and may be, for example, 1.0 μm), and t c The thickness of the insulating coating in the non-scored area is n The sum satisfies the following relationship: 0.8μm≤t c +t n When the thickness of the insulating coating is within the above range, the insulation requirements of the oriented silicon steel sheet during use can be more advantageously met.

[0021] When the thickness of the insulating coating at the center of the notch area isc Less than 0.2μm and t c The thickness of the insulating coating in the non-scored area is n When the sum is less than 0.8 μm, the insulation between the sheets of oriented silicon steel is poor, and the core made of the oriented silicon steel sheet has the risk of breakdown. c is 0.2μm or more, but t c The thickness of the insulating coating in the non-scored area is n When the sum exceeds 3.5μm, the lamination coefficient of oriented silicon steel will be reduced.

[0022] In a preferred embodiment, the surface of the grain-oriented silicon steel sheet disclosed herein has at least two laser-scored regions, with the spacing between the scored regions in the rolling direction being 4-20 mm. When the spacing between the scored regions in the rolling direction is within the aforementioned range, the scoring effect of magnetic domain refinement can be more effectively achieved.

[0023] In a preferred embodiment, when the thickness of the oriented silicon steel sheet is ≤0.23 mm, the iron loss P 17 / 50 ≤0.740W / kg, its magnetic induction B8≥1.880T.

[0024] In a preferred embodiment, the lamination factor of the oriented silicon steel sheet disclosed herein is ≥95.0%.

[0025] In addition, given that the previous method of refining the magnetic domains by scoring the molten solidified layer to reduce the iron loss of oriented silicon steel sheets has problems such as the difficulty in controlling the depth of the molten pool and the occurrence of spatter, one of the purposes of the present disclosure is to provide a method for laser scoring oriented silicon steel sheets, which can form a stable molten pool during the scoring process without generating spatter.

[0026] Therefore, the present disclosure provides a method for laser scoring of an oriented silicon steel sheet, comprising: using a laser having an annular spot to perform laser scoring on the surface of the oriented silicon steel sheet, so that at least one scoring area is formed on the surface of the oriented silicon steel sheet, wherein the annular spot of the laser includes a central beam and an outer ring beam surrounding the central beam, the depth of the molten solidified layer in the scoring area is 8-30 μm, for example, 15-25 μm, the width of the molten solidified layer in the scoring area is 20-100 μm, for example, 51-92 μm, and the height S of the surface protrusion of the scoring area is 100-200 μm. a ≤3.0μm.

[0027] Oriented silicon steel can refine the magnetic domains and reduce iron loss by scoring. Due to the presence of magnetic domain structure inside the grains of oriented silicon steel, in the absence of external field conditions, the internal magnetic domains of oriented silicon steel are mainly 180° magnetic domains arranged in reverse parallel, and the width of a single magnetic domain can usually reach tens of microns or even millimeters. There is a transition layer of dozens to hundreds of atomic layers between adjacent magnetic domains, which is called a magnetic domain wall. During the magnetization process, the magnetic moment rotates under the drive of the external field, and the migration of the magnetic domain wall causes adjacent magnetic domains to swallow each other, thereby realizing the magnetic conductivity function. At the same time, the difference in magnetic domain structure in different regions during the migration of the magnetic domain wall causes micro-eddy currents to be generated in the micro-region, thereby generating eddy current losses. This part of the loss is called anomalous eddy current loss P in oriented silicon steel. a . It can be seen that P a It is directly related to the inherent magnetic domain structure of oriented silicon steel, and further, it is directly related to the magnetic domain width. Therefore, reducing the magnetic domain width can reduce P a .

[0028] The other two parts of the loss composition of oriented silicon steel: hysteresis loss Ph and eddy current loss P e , due to the progress of metallurgy and physics, have been reduced to a lower level. Abnormal eddy current loss P a It accounts for a large proportion of the overall loss of oriented silicon steel, especially thin-gauge oriented silicon steel with a thickness of less than 0.23mm. a Therefore, by refining the magnetic domains of oriented silicon steel through scoring, that is, reducing the width of the magnetic domains, the abnormal eddy current loss can be effectively reduced, thereby reducing the overall iron loss of oriented silicon steel.

[0029] The laser scoring method disclosed herein is different from the single-mode or multi-mode lasers used in the prior art, which use an annular focused spot. The single-mode or multi-mode lasers used in the prior art concentrate their energy in a central local area. During the scoring process, in order to make the grooves or the molten solidified layer reach the depth required for magnetic domain refinement, the laser energy must reach a certain penetration depth. This requires increasing the input laser energy, but this will cause a large temperature gradient to form in the thickness direction of the steel plate. The surface temperature is much higher than the melting or even evaporation temperature, thus forming a crater-shaped defect near the scoring. At the same time, a large amount of plasma and metal evaporation droplets are generated during the process. After scanning, the temperature drops, and the plasma and metal droplets re-solidify on the surface near the scoring to form spatter, which reduces the lamination coefficient of the steel plate. Moreover, after the oriented silicon steel plate is made into an iron core, the spatter may fall off due to the magnetostrictive vibration of the steel plate, posing a risk of core breakdown.

[0030] In order to overcome the problems of low energy penetration depth and residual spatter on the surface in the laser scoring method of the prior art, the present invention adopts a ring-shaped spot laser scoring method, wherein the central beam scoring forms a molten pool of a certain depth, and the outer ring beam (outer ring beam) constrains the stability of the molten pool morphology and spatter, thereby avoiding the formation of craters and spatter. The molten solidification layer in the resulting scoring area is controllable, and low iron loss heat-resistant magnetic domain refined oriented silicon steel can be manufactured.

[0031] In a preferred embodiment, in the laser scoring method of the present disclosure, the power density of the laser is 16 kW / mm 2 -80kW / mm 2 In a preferred embodiment, in the laser scoring method disclosed herein, the power density of the laser is 38 kW / mm 2 -80kW / mm 2 In a preferred embodiment, in the laser scoring method of the present disclosure, the scanning speed of the laser is 60 m / s-100 m / s.

[0032] In the laser marking method disclosed herein, the power density of the laser can be controlled to be 16kW / mm 2 and 80kW / mm 2 When the laser power density is lower than the lower limit of 16kW / mm 2 When the laser power density is higher than the upper limit of 80kW / mm, the depth of the molten solidified layer formed by the scratch may not reach 8μm, the magnetic domain refinement effect is insufficient, and the iron loss of the finished product is high. 2 When the magnetic induction is significantly reduced, the scratches may cause the magnetic induction to drop significantly, and the requirements of high-efficiency transformers cannot be met.

[0033] In a preferred embodiment, in the laser scoring method of the present disclosure, the energy ratio between the central beam and the outer ring beam of the annular spot of the laser is 1:1 to 9:1.

[0034] In the scoring method disclosed herein, the ratio of the central beam energy to the outer annular beam energy can be controlled to be between 1:1 and 9:1, that is, the central beam energy accounts for between 50% and 90% of the total energy. When the ratio is lower than 1:1, the annular beam cannot form a stable confinement effect on the molten pool, and spatter residue will be generated in the scoring area. When the ratio is higher than 9:1, the annular beam energy is too high. To achieve sufficient magnetic domain refinement, the energy of the central and annular beams must be increased simultaneously. As a result, the outer annular beam itself will also form a certain amount of melted or even evaporated material, which will also form spatter residue.

[0035] In a preferred embodiment, in the laser scoring method disclosed herein, the diameter a of the annular spot of the laser in the rolling direction is 20-100 μm.

[0036] In a preferred embodiment, in the laser scoring method of the present disclosure, the diameter b of the annular spot of the laser in the laser scoring scanning direction is 1-10 mm.

[0037] Compared with the prior art, the oriented silicon steel sheet and the laser scoring method disclosed in the present invention have the following beneficial effects:

[0038] The oriented silicon steel sheets disclosed herein have a sized, notched, melt-solidified layer that generates tension in localized micro-regions, thereby achieving enhanced magnetic domain refinement and reducing iron loss in the finished oriented silicon steel. The oriented silicon steel sheets disclosed herein are particularly suitable for manufacturing energy-saving wound-core transformers.

[0039] The disclosed laser scoring method uses a circular focused laser spot to create the score, scanning the steel sheet surface in a single pass, effectively achieving the required melt-solidified layer depth to reduce iron loss without generating spatter. Silicon steel sheets produced using this method exhibit low iron loss, high magnetic induction, and a high lamination factor, making them particularly suitable for manufacturing high-efficiency wound-core transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 schematically shows the energy distribution of an annular focused spot.

[0041] FIG2 schematically shows a plurality of scored areas (a plurality of linear scored areas) on the surface of a grain-oriented silicon steel sheet according to one embodiment of the present disclosure.

[0042] FIG3 schematically shows the notched area and S on the surface of the oriented silicon steel sheet according to one embodiment of the present disclosure. a 、R a Measurement area.

[0043] FIG4 schematically shows a melt-solidified layer and an insulating coating in a scored area on the surface of a grain-oriented silicon steel sheet according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0044] The oriented silicon steel sheet and the laser scoring method thereof disclosed herein will be further explained and illustrated below in conjunction with the accompanying drawings and specific embodiments. However, such explanation and illustration do not constitute an undue limitation to the technical solution disclosed herein.

[0045] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0046] In this article, the melt-solidified layer refers to a layer formed by forming a groove on the surface of the silicon steel sheet and then allowing the grooved parts to melt and solidify.

[0047] In this paper, the line roughness R a It is the arithmetic mean roughness, and its measurement method is carried out according to ISO 25178. The measuring equipment is a laser confocal microscope.

[0048] In this paper, the stacking factor of oriented silicon steel sheets is determined using GB / T 19289-2003 “Measurement method for density, resistivity and stacking factor of electrical steel sheets (strips)”.

[0049] In this paper, the height of the protrusion S a , Line roughness R a The thickness of the insulating coating in the scoring area is the average value of the measurement in the area with a length of 100 μm in the direction of laser scoring scanning. The thickness of the insulating coating in the non-scoring area is the average value of the measurement in the area with a length of 100 μm in the non-scoring area. 2 The average value of measurements at any location.

[0050] In this article, magnetic induction (B8) refers to the magnetic flux density of the silicon steel sheet under an excitation magnetic field of 800A / m, in T.

[0051] In this paper, the iron loss (P 17 / 50 ) refers to the ineffective electrical energy consumed by the magnetization of silicon steel sheets when the magnetic flux density reaches 1.7T under a 50Hz AC excitation field, with the unit being W / kg.

[0052] In this paper, magnetic induction (B8) and iron loss (P 17 / 50 ) was determined using the Epstein method.

[0053] It should be noted that the laser scoring disclosed herein can be performed before decarburization annealing, after decarburization annealing, before final hot stretching and leveling annealing, or before and after final hot stretching and leveling annealing during the production process of grain-oriented silicon steel.

[0054] The laser source used in the method of the present invention is not particularly limited. For example, a continuous laser with a wavelength of 1066 nm commonly used in the art can be used, or a pulsed laser can be used.

[0055] The technical solution of the present disclosure will be further described below with reference to specific embodiments and its beneficial effects will be illustrated.

[0056] Examples 1-6 and Comparative Example 1

[0057] The oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 were prepared by the following steps:

[0058] (1) After undergoing ironmaking, steelmaking, continuous casting, and hot rolling, the steel sheet undergoes a single cold rolling process to a final thickness of 0.22 mm. The chemical composition of the oriented silicon steel sheet is as follows: C: 0.07%, Si: 3.25%, Mn: 0.2%, S: 0.025%, P: 0.05%, Als: 0.05%, Cu: 0.05%, N: 0.008%, with the remainder being Fe and unavoidable impurities. It should be noted that the chemical composition of the oriented silicon steel sheet described above is for illustrative purposes only; other composition ratios may also be used.

[0059] (2) After a decarburization annealing process at 850°C to form a surface oxide layer, an MgO separator is coated on the surface and a steel coil is made.

[0060] (3) After the steel coil is made, it is kept under high temperature annealing conditions of 1200℃ for 20 hours.

[0061] (4) Clean the unreacted residual MgO on the surface and dry it.

[0062] (5) A circular spot laser is used to scan the steel plate surface along its transverse direction to perform laser marking (the specific laser marking process parameters are listed in Table 1).

[0063] In Examples 1-6, a continuous single-mode laser with a wavelength of 1066 nm was modulated through an optical fiber to form a ring laser beam. This was then transmitted to a laser head and passed through a focusing lens and a scanning mirror to form an annular spot on the surface of the steel plate. The laser output power and the energy ratio between the central beam and the outer ring beam were adjusted. Each scored area was scanned horizontally across the steel plate. The spacing between adjacent scored areas in the rolling direction was 5 mm. Figure 1 schematically illustrates the energy distribution of the annular focused spot.

[0064] Different from Examples 1-6, Comparative Example 1 uses a conventional single-mode high-power continuous laser for scoring, and does not use an optical fiber to modulate the annular light spot.

[0065] (6) Finally, an insulating coating is applied to the steel sheet surface, followed by final annealing, so that the coating thickness at the center of the notched area is t c The coating thickness in the non-scratched area is 0.5 μm. n 1.0μm.

[0066] FIG2 schematically shows a plurality of scored areas (a plurality of linear scored areas) on the surface of a grain-oriented silicon steel sheet according to one embodiment of the present disclosure.

[0067] As shown in FIG2 , a circular spot laser is used to scan the surface of the oriented silicon steel sheet 1 in the transverse direction to perform laser scoring, thereby obtaining a plurality of scoring lines (i.e., scoring areas) 2 arranged in sequence along the rolling direction, and each scoring area 2 has a rolling spacing in the rolling direction.

[0068] FIG3 schematically shows a notched area 2 and S on the surface of a grained silicon steel sheet according to an embodiment of the present disclosure. a 、R a Measurement area (100 μm in length).

[0069] Fig. 4 schematically shows a melt-solidified layer 21 and an insulating coating 3 in a scored region on the surface of a grain-oriented silicon steel sheet according to an embodiment of the present disclosure. "P" in Fig. 4 indicates the center of the scored region.

[0070] Next, the magnetic permeability (B8) and iron loss (P 17 / 50 Specifically, the Epstein method is used to test the magnetic flux density of oriented silicon steel under an excitation magnetic field of 800A / m to obtain the B8 value, whose unit parameter is T; the Epstein method is used to test the ineffective electric energy consumed by magnetization when the magnetic flux density of oriented silicon steel under an AC excitation magnetic field of 50Hz reaches 1.7T to obtain P 17 / 50 The unit parameter is W / kg.

[0071] Next, after scoring, the stacking coefficients of the grain-oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 were tested. Specifically, the stacking coefficients of the finished steel sheets of Examples 1-6 and Comparative Example 1 after scoring were measured using the method described in GB / T 19289-2003, "Measurement of Density, Resistivity, and Stacking Coefficient of Electrical Steel Sheet (Strip)." The test results for the grain-oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 after scoring are shown in Table 1.

[0072] It can be seen from Table 1 above that the iron loss P of the oriented silicon steel sheets (thickness 0.22 mm) of Examples 1-6 is 17 / 50 All are below 0.74W / kg, the magnetic induction B8 is greater than 1.89T, and the stacking coefficient is greater than 95%, achieving excellent performance of low iron loss, high magnetic induction and high stacking coefficient.

[0073] In contrast, the protrusion height and line roughness of the melt-solidified zone in the notched area of ​​Comparative Example 1 are significantly higher than those of Examples 1-6, and its iron loss is higher and the lamination coefficient is low.

[0074] Examples 7-12 and Comparative Example 2

[0075] The oriented silicon steel sheets of Examples 7-12 and Comparative Example 2 were prepared by the following steps:

[0076] (1) After undergoing ironmaking, steelmaking, continuous casting, and hot rolling, the steel sheet undergoes a single cold rolling process to a final thickness of 0.19 mm. The chemical composition of the oriented silicon steel sheet is as follows: C: 0.06%, Si: 3.45%, Mn: 0.1%, S: 0.025%, P: 0.05%, Als: 0.027%, Cu: 0.2%, N: 0.008%, with the remainder being Fe and unavoidable impurities. It should be noted that the chemical composition of the oriented silicon steel sheet described above is for illustrative purposes only; other composition ratios may also be used.

[0077] (2) After alkaline washing and degreasing to remove residual rolling oil on the surface, a circular spot laser is used to scan the steel plate surface along its transverse direction to implement laser scoring (the specific laser scoring process parameters are listed in Table 2).

[0078] In Examples 7-12, a continuous single-mode laser with a wavelength of 1066 nm was modulated through an optical fiber to form a ring laser beam. This was then transmitted to a laser head and passed through a focusing lens and a scanning mirror to form a ring-shaped spot on the surface of the steel plate. The laser output power and the energy ratio between the central beam and the outer ring beam were adjusted. Each scored area was scanned horizontally along the steel plate. The spacing between adjacent scored areas in the rolling direction was 6 mm.

[0079] (3) After a decarburization annealing process at 850°C to form a surface oxide layer, an MgO separator is coated on the surface and a steel coil is made.

[0080] (4) After the steel coil is made, it is kept under high temperature annealing conditions of 1200°C for 20 hours.

[0081] (5) Clean the unreacted residual MgO on the surface and dry it, then apply an insulating coating on the surface of the steel plate, and then perform final annealing to make the coating thickness t c The coating thickness in the non-score area is 0.3 μm. n 1.0μm.

[0082] Then, after notching, the magnetic conductivity (B8) and iron loss (P 17 / 50 Specifically, the Epstein method is used to test the magnetic flux density of oriented silicon steel under an excitation magnetic field of 800A / m to obtain the B8 value, whose unit parameter is T; the Epstein method is used to test the ineffective electric energy consumed by magnetization when the magnetic flux density of oriented silicon steel under an AC excitation magnetic field of 50Hz reaches 1.7T to obtain P 17 / 50 The unit parameter is W / kg.

[0083] Next, after scoring, the stacking coefficients of the grain-oriented silicon steel sheets of Examples 7-12 and Comparative Example 2 were tested. Specifically, the stacking coefficients of the finished steel sheets of Examples 7-12 and Comparative Example 2 after scoring were measured using the method described in GB / T 19289-2003, "Measurement of density, resistivity, and stacking coefficient of electrical steel sheets (strip)." The test results for the grain-oriented silicon steel sheets of Examples 7-12 and Comparative Example 2 after scoring are shown in Table 2.

[0084] It can be seen from Table 2 above that the iron loss P of the oriented silicon steel sheets (thickness 0.19 mm) of Examples 7-12 is 17 / 50 All are below 0.704W / kg, the magnetic induction B8 is greater than 1.89T, and the stacking coefficient is greater than 95%, achieving excellent performance of low iron loss and high stacking coefficient.

[0085] In contrast, the protrusion height and line roughness of the notched area of ​​Comparative Example 2 were significantly higher, and the lamination coefficient of the finished product was significantly reduced.

[0086] Examples 13-16 and Comparative Examples 3-5

[0087] The oriented silicon steel sheets of Examples 13-16 and Comparative Examples 3-5 were prepared by the following steps:

[0088] (1) After undergoing ironmaking, steelmaking, continuous casting, and hot rolling, the steel sheet undergoes a single cold rolling process to a final thickness of 0.225 mm. The chemical composition of the oriented silicon steel sheet is as follows: C: 0.045%, Si: 3.25%, Mn: 0.2%, S: 0.015%, Als: 0.025%, Cu: 0.07%, N: 0.008%, with the remainder being Fe and unavoidable impurities. It should be noted that the chemical composition of the oriented silicon steel sheet described above is for illustrative purposes only; other composition ratios may also be used.

[0089] (2) After a decarburization annealing process at 860°C to form a surface oxide layer, an MgO isolation agent is coated on the surface.

[0090] (3) After the steel coil is made, it is kept under high temperature annealing conditions of 1200℃ for 20 hours.

[0091] (4) Clean the unreacted residual MgO on the surface and dry it.

[0092] (5) A circular spot laser is used to scan the steel plate surface along its transverse direction to implement laser scoring (the specific laser scoring process parameters are listed in Table 3).

[0093] In Examples 13-16 and Comparative Examples 3-5, a continuous single-mode laser with a wavelength of 1066 nm is modulated through an optical fiber to form a ring laser, which is transmitted to a laser head. After passing through a focusing mirror and a scanning mirror, a ring light spot is formed on the surface of the steel plate. The laser output power and the energy ratio of the central beam and the outer ring beam are adjusted, and scanning is performed horizontally along the steel plate to form each scoring area. The spacing between adjacent scoring areas in the rolling direction is 5 mm.

[0094] (6) Finally, an insulating coating is applied to the surface of the steel sheet, followed by final annealing. The specific parameters of the applied insulating coating are listed in Table 4.

[0095] Table 3.

[0096] Then, after the scoring was completed, the magnetic conductivity (B8) and iron loss (P 17 / 50 Specifically, the Epstein method is used to test the magnetic flux density of oriented silicon steel under an excitation magnetic field of 800A / m to obtain the B8 value, whose unit parameter is T; the Epstein method is used to test the ineffective electric energy consumed by magnetization when the magnetic flux density of oriented silicon steel under an AC excitation magnetic field of 50Hz reaches 1.7T to obtain P 17 / 50 The unit parameter is W / kg.

[0097] Next, after scoring, the stacking coefficients of the grain-oriented silicon steel sheets of Examples 13-16 and Comparative Examples 3-5 were tested. Specifically, the stacking coefficients of the finished steel sheets of Examples 13-16 and Comparative Examples 3-5 after scoring were measured using the method described in GB / T 19289-2003, "Determination of density, resistivity, and stacking coefficient of electrical steel sheets (strip)."

[0098] In addition, insulation properties were evaluated for Examples 13-16 and Comparative Examples 3-5, each coated with an insulating coating. The evaluation method followed the "GB / T 2522-2007 Test Method for Surface Insulation Resistance and Coating Adhesion of Electrical Steel Sheet (Strip)", using the average interlayer resistance of the double-sided coating as the basis. Samples with an average interlayer resistance of ≤30 Ω·m were considered to have poor insulation and were marked as "×", posing a risk of breakdown during service in transformer cores made from them. Samples with an average interlayer resistance greater than 30 Ω·m were considered to have good insulation and were marked as "○", indicating they were suitable for manufacturing energy-saving transformer cores.

[0099] The above test results are listed in Table 4.

[0100] Table 4.

[0101] As can be seen from Table 4, Examples 13-16 have good insulation performance. In contrast, Comparative Examples 3 and 4 have poor insulation performance, posing safety risks during transformer service. The finished product of Comparative Example 5 has a low lamination coefficient.

[0102] All publications, patent applications, patents, and other references mentioned in this disclosure are incorporated by reference in their entirety.

[0103] Although the present disclosure has been illustrated and described with reference to certain preferred embodiments thereof, it should be understood by those skilled in the art that the above description is provided to further illustrate the present disclosure in conjunction with specific embodiments thereof, and that the present disclosure is not limited to these descriptions. Those skilled in the art may make various changes in form and detail, including simple deductions or substitutions, without departing from the spirit and scope of the present disclosure.

Claims

1. A oriented silicon steel sheet having at least one scoring region formed by laser scoring on its surface, wherein: The depth of the melted solidified layer in the scored area is 8-30 μm, the width of the melted solidified layer in the scored area is 20-100 μm, and the height S of the surface protrusion in the scored area is a ≤3.0μm.

2. The oriented silicon steel sheet according to claim 1, wherein: The line roughness R at the center of the notch area a ≤3.0μm.

3. The oriented silicon steel sheet according to claim 1 or 2, wherein: The surface of the oriented silicon steel sheet has an insulating coating, and the thickness of the insulating coating at the central position of the notched area is t c ≥0.2μm, and t c The thickness of the insulating coating in the non-scored area is n The sum satisfies the following relationship: 0.8μm≤t c +t n ≤3.5μm.

4. The oriented silicon steel sheet according to any one of claims 1 to 3, wherein: The surface of the oriented silicon steel sheet has at least two scoring areas formed by laser scoring, and the spacing between the scoring areas in the rolling direction is 4-20 mm.

5. The oriented silicon steel sheet according to any one of claims 1 to 4, wherein: The lamination factor of the oriented silicon steel sheet is ≥95.0%.

6. The oriented silicon steel sheet according to any one of claims 1 to 5, wherein: When the thickness of the oriented silicon steel sheet is greater than 0.23 mm, the iron loss P of the oriented silicon steel sheet is 17 / 50 ≤0.740W / kg, magnetic induction B8≥1.880T.

7. A method for laser scoring an oriented silicon steel sheet, comprising: A laser having an annular spot is used to perform laser scoring on the surface of the oriented silicon steel sheet, so that at least one scoring area is formed on the surface of the oriented silicon steel sheet, wherein the annular spot of the laser includes a central beam and an outer ring beam surrounding the central beam, the depth of the molten solidified layer in the scoring area is 8-30 μm, the width of the molten solidified layer in the scoring area is 20-100 μm, and the height S of the surface protrusion in the scoring area is 100-200 μm. a ≤3.0μm; Preferably, the line roughness R at the center of the notched area is a ≤3.0μm; Preferably, the surface of the oriented silicon steel sheet has an insulating coating, and the thickness of the insulating coating at the central position of the notched area is t c ≥0.2μm, and t c The thickness of the insulating coating in the non-scored area is n The sum satisfies the following relationship: 0.8μm≤t c +t n ≤3.5μm; Preferably, the surface of the oriented silicon steel sheet has at least two scoring areas formed by laser scoring, and the spacing between the scoring areas in the rolling direction is 4-20 mm; Preferably, the lamination factor of the oriented silicon steel sheet is ≥95.0%.

8. The method of claim 7, wherein: The power density of the laser is 16 kW / mm 2 -80kW / mm 2 ; and / or the scanning speed of the laser is 60m / s-100m / s.

9. The method according to claim 7 or 8, wherein: The energy ratio between the central light beam and the outer ring light beam of the annular spot of the laser is 1:1 to 9:

1.

10. The method according to any one of claims 7 to 9, wherein: The diameter a of the annular spot of the laser in the rolling direction is 20-100 μm.

11. The method according to any one of claims 7 to 10, wherein: The diameter b of the annular spot of the laser in the laser scoring scanning direction is 1-10 mm.

Images