Low iron loss heat-resistant magnetic domain refinement type grain-oriented silicon steel sheet and laser scribing method thereof

Abstract

This disclosure relates to a low iron loss heat-resistant magnetic domain refinement type grain-oriented silicon steel sheet having at least one scribed region formed on its surface by laser scribing, wherein the depth of the molten solidification layer of the scribed region is 8 to 30 μm, the width of the molten solidification layer of the scribed region is 20 to 100 μm, and the height S of the surface protrusion of the scribed region. a This disclosure relates to a grain-oriented silicon steel sheet having a thickness of ≤3 μm. The disclosure further relates to a method for laser scribing a grain-oriented silicon steel sheet, comprising the step of performing laser scribing on the surface of the grain-oriented silicon steel sheet using a laser having an annular spot to form at least one scribed region on the surface of the grain-oriented silicon steel sheet. The grain-oriented silicon steel sheet of this disclosure has low iron loss, high magnetic flux density, and high space factor, and is particularly applicable to the manufacture of high-efficiency wound core transformers.

Description

[Technical Field]

[0001] This disclosure relates to grain-oriented silicon steel sheets and their manufacturing processes, and more particularly to low iron loss heat-resistant magnetic domain refinement grain-oriented silicon steel sheets and a laser scribing method thereof. [Background technology]

[0002] Transformers are fundamental components in power transmission systems, and their reactive losses account for approximately 40% of the total losses in such systems. In such transformers, the core, which is made by laminating or winding grain-oriented silicon steel, accounts for approximately 20% of the total losses in its operating state due to reactive losses. Losses caused by such transformer cores are commonly abbreviated as iron losses.

[0003] Grain-oriented silicon steel is an iron magnetic material, and its name comes from the fact that the orientation of its internal crystal grains is almost the same as the rolling direction of the steel sheet. Within the crystal grains, there is a magnetic domain structure created by the spontaneous magnetization of the iron magnetic material, and within each magnetic domain, the magnetic moments of each atom spontaneously align in parallel, forming 180° magnetic domains, which are in the direction in which the crystal grains are easily magnetized {110}. <001> It is parallel to the direction. Adjacent magnetic domains are 180° domains in opposite directions, and between them is a domain wall consisting of layers of tens to hundreds of atoms. During the magnetization process, the magnetic moments within adjacent domains become aligned in the same direction through the movement of the domain wall, realizing permeability. The magnetic domain structure is the result of the minimum energy action mechanism and is a fundamental element that affects the iron loss, magnetic flux density, and magnetostrictive oscillations of silicon steel sheets. Since the alignment direction of the crystal grains is the direction that facilitates magnetization, it is shown that the higher the orientation of the crystal grains, the better the magnetic performance of the silicon steel sheet, and the higher the magnetic flux density, the lower the iron loss.

[0004] Currently, the permeability of silicon steel sheets manifests as magnetic induction and is generally expressed by the magnetic flux density (unit: T) B8 of the silicon steel sheet under an excitation magnetic field of 800 A / m. Iron loss is generally expressed as the reactive power (unit: W / kg) P consumed by the silicon steel sheet due to magnetization when the magnetic flux density in the steel strip reaches 1.7 T under an AC excitation magnetic field of 50 Hz.17 / 50 This is shown.

[0005] According to research, the iron loss in grain-oriented silicon steel consists of three parts: hysteresis loss, eddy current loss, and anomalous eddy current loss. Of these, hysteresis loss is the energy loss caused by the hysteresis phenomenon, in which inclusions, crystal defects, and internal stresses in the material hinder the movement of magnetic domain walls during the magnetization process, causing the magnetic induction strength to lag behind the change in magnetic field strength. Eddy current loss is the energy loss caused by the induction of local electromotive forces by changes in magnetic flux during the magnetization process, resulting in eddy currents, and is related to the electrical conductivity and thickness of the silicon steel sheet. Anomalous eddy current loss is the energy loss caused by differences in the magnetic domain structure when the silicon steel sheet is magnetized, and is mainly influenced by the magnetic domain width.

[0006] In current conventional technology, continuously reducing iron loss in silicon steel materials is the direction of development for silicon steel technology. Currently, there are three main technological trends that are feasible: 1. A metallurgical method that controls the secondary recrystallization structure by metallurgical methods to increase the orientation of crystal grains and reduce the size of crystal grains to refine the magnetic domains and reduce iron loss; 2. A tension control method that applies a high-tensile coating to the surface of the silicon steel sheet and reduces iron loss by refining the magnetic domains through the tension effect of the coating; and 3. A surface scribe method that reduces iron loss by refining the magnetic domains by applying linear stress or strain to the surface of the silicon steel sheet using means such as lasers or electron beams.

[0007] Among these, achieving magnetic domain refinement through scribing is a major technological improvement in grain-oriented silicon steel. By refining the magnetic domains, the anomalous eddy current loss in grain-oriented silicon steel can be effectively reduced. Currently, techniques for refining magnetic domains by scribing the surface of grain-oriented silicon steel, thereby reducing iron loss in grain-oriented silicon steel, can be broadly classified into two types based on the effect of scribing:

[0008] (1) Scribe without stress relief annealing resistance: Linear thermal stress regions are formed on the surface at predetermined intervals by means of laser, plasma beam, or electron beam. The stress generates 90° magnetic domains perpendicular to the rolling direction in the surrounding region, thereby reducing the width of the 180° main magnetic domain and reducing iron loss. Since the linear thermal stress disappears by stress relief annealing, this type of product is generally used in the manufacture of laminated core transformers that do not require stress relief annealing, and is currently widely applied in energy-saving transformers for power grids;

[0009] (2) Scribe resistant to stress relief annealing: Grooves are formed using means such as mechanical toothed rolls, chemical corrosion, or laser melting. Free poles and increased surface energy are created on both sides of the grooves, and energy is redistributed within the crystal, resulting in a smaller domain width and thus reduced iron loss. Since the strain region does not change after stress relief annealing, this type of product can be used in the manufacture of wound core transformers where stress relief annealing is required.

[0010] Wound core transformers have seen a rapid increase in market share in recent years due to their superior energy efficiency. Wound core transformers fully utilize the superior magnetic performance of grain-oriented silicon steel in the rolling direction, 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, during the manufacturing process, internal stress is generated in the steel sheet due to winding, leading to performance degradation; therefore, the core must undergo stress relief annealing. The stress relief annealing process typically involves heating the silicon steel sheet at over 800°C for 2 hours or more in a protective atmosphere to optimize its magnetic performance. Conventional grain-oriented silicon steel sheets, which have had linear stress regions created and magnetic domains refined using lasers or electron beams, cannot be used in the manufacture of wound core transformers because the effect of magnetic domain refinement disappears after stress relief annealing along with the disappearance of stress.

[0011] In order to maintain the magnetic domain refinement effect even after stress relief annealing, a stress relief annealing-resistant magnetic domain refinement technology has been developed, which forms grooves with a predetermined shape on the surface of a silicon steel sheet by means of chemical erosion, mechanical pressure and laser. Due to the presence of free magnetic poles in the grooves and the increase in surface energy, the energy of the material is redistributed, the magnetic domain width is reduced, and iron loss is reduced. Since the grooves do not change during the stress relief annealing process, the grain-oriented silicon steel sheet produced by this technology can be applied to the manufacture of wound-core transformers, and this technology is collectively referred to as heat-resistant scribing technology.

[0012] Currently, the production of heat-resistant scribed grain-oriented silicon steel using lasers has been realized in the art. However, problems such as molten substances, sputtered substances and low production efficiency have still been difficulties in realizing laser-based heat-resistant scribing.

[0013] In the Chinese patent application with publication number CN102941413A, publication date of February 27, 2013, and titled "Iron Loss Reduction Method by Multiple Laser Grooving of Grain-Oriented Silicon Steel", the problem of spatter generation is overcome by using a method of repeatedly performing low-power laser scribing multiple times. However, repeated scribing has low efficiency, and the difficulty of repeated positioning in micro-areas is high, making it difficult to realize mass production on industrial production lines. Summary of the Invention Problem to be Solved by the Invention

[0014] One of the objects of the present disclosure is to provide a low iron loss, heat-resistant magnetic domain refined grain-oriented silicon steel sheet having a scribed molten solidified layer (a layer formed by melting and solidifying a scribed portion) of a predetermined size formed on a surface thereof. This molten solidified layer can produce a certain tensile effect in local micro-areas, thereby enhancing the magnetic domain refinement effect and reducing the iron loss of the product grain-oriented silicon steel. This grain-oriented silicon steel sheet is particularly applicable to the manufacture of energy-saving wound-core transformers. Means for Solving the Problem

[0015] Therefore, the present disclosure relates to a grain-oriented silicon steel sheet having at least one scribed region formed on its surface by laser scribing, wherein the depth of the molten and solidified layer of the scribed region is 8 to 30 μm (e.g., 15 to 25 μm), the width of the molten and solidified layer of the scribed region is 20 to 100 μm (e.g., 51 to 92 μm), and the height S of the surface protrusion of the scribed region. a The present invention provides a grain-oriented silicon steel sheet with a thickness of ≤3.0 μm.

[0016] The inventors have found that by setting the depth of the molten solidification layer formed by laser scribing to between 8 and 30 μm and its width to between 20 and 100 μm, it is possible to simultaneously improve iron loss, magnetic flux density, and packing factor of grain-oriented silicon steel sheets. If the depth of the molten solidification layer is less than 8 μm, it is difficult to achieve the effect of reducing iron loss by refining the magnetic domains, leading to high iron loss in the grain-oriented silicon steel product; if the depth of the molten solidification layer exceeds 30 μm, the magnetic flux density B8 of the grain-oriented silicon steel becomes low, making it impossible to manufacture high-energy-efficiency wound core transformers; if the width of the molten solidification layer is less than 20 μm, the required focusing spot size becomes very small, making it extremely difficult to realize in industrial production; and if the width of the solidification layer exceeds 100 μm, the heat-affected zone formed by laser scribing becomes very large, causing warping due to thermal stress during the production process and leading to focus misalignment, as well as significantly reducing the magnetic flux density and packing factor of the steel sheet. Therefore, it is necessary to control the depth of the molten and solidified layer in the scribed region of the orientation silicon steel sheet of this disclosure to be between 8 and 30 μm, and to control the width of the molten and solidified layer in the scribed region to be between 20 and 100 μm.

[0017] The inventors further investigated the properties of the molten and solidified layer formed by laser scribing and its relationship to the usage characteristics of grain-oriented silicon steel. They found that when the density of the molten and solidified layer formed by laser scribing is lower than that of the steel base material, micropores may be formed in the molten and solidified layer due to unfavorable process conditions, resulting in the formation of certain protrusions in the scribed region. The height S of these protrusions aexceeds 3.0 μm, the space factor of the silicon steel sheet is significantly reduced, and cannot meet the requirements of the wound core processing process. Therefore, the height S of the surface protrusions of the grain-oriented silicon steel sheet of the present disclosure a needs to be controlled to 3.0 μm or less.

[0018] In one preferred embodiment, the line roughness R at the central position of the scribed region of the grain-oriented silicon steel sheet of the present disclosure a ≤ 3.0 μm. If this line roughness exceeds 3.0 μm, it may cause a reduction in the space factor of the silicon steel sheet.

[0019] In one preferred embodiment, the surface of the grain-oriented silicon steel sheet of the present disclosure has an insulating coating, and the thickness t of the insulating coating at the central position of the scribed region c ≥ 0.2 μm (the upper limit of t c is not definitive, and may be, for example, 1.0 μm), and the sum of t c and the thickness t of the insulating coating in the non-scribed region n satisfies the relational expression 0.8 μm ≤ t c + t n ≤ 3.5 μm. When the thickness of the insulating coating is within the above range, the insulation requirements during the use of the grain-oriented silicon steel sheet can be more advantageously satisfied.

[0020] When the thickness t of the insulating coating at the central position of the scribed region c is less than 0.2 μm, and the sum of t c and the thickness t of the insulating coating in the non-scribed region n is 0.8 μ m less than 0.8 μm, the insulation between grain-oriented silicon steel sheets is poor, and there is a risk of dielectric breakdown in the iron core manufactured from the grain-oriented silicon steel sheets. When the thickness t of the insulating coating at the central position of the scribed region c is 0.2 μm or more, but the sum of t c and the thickness t of the insulating coating in the non-scribed region n exceeds 3.5 μm, the space factor of the grain-oriented silicon steel will decrease to some extent.

[0021] In one preferred embodiment, the surface of the grain-oriented silicon steel sheet of the present disclosure has at least two scribed regions formed by laser scribing, wherein the spacing between each scribed region in the rolling direction is 4 to 20 mm. When the spacing between each scribed region in the rolling direction is within the above range, the magnetic domain refinement effect by scribing can be more advantageously achieved.

[0022] In one preferred embodiment, the grain-oriented silicon steel sheet of the present disclosure has a thickness of ≤0.23 mm, and its iron loss P 17 / 50 The power is ≤0.740 W / kg, and the magnetic flux density B8 ≥ 1.880 T.

[0023] In one preferred embodiment, the space factor of the grain-oriented silicon steel sheet of the present disclosure is ≥ 95.0%.

[0024] Furthermore, in light of the problems that existed in conventional methods for reducing iron loss in grain-oriented silicon steel sheets by refining magnetic domains using molten solidification layer scribing means, such as the difficulty in controlling the depth of the resulting molten pool and the occurrence of sputter defects, one of the objectives of this disclosure is to provide a method for laser scribing grain-oriented silicon steel sheets that does not generate sputter material during the scribing process and can form a stable molten pool.

[0025] Accordingly, the present disclosure provides a method for laser scribing a grain-oriented silicon steel sheet, comprising the step of performing laser scribing on the surface of the grain-oriented silicon steel sheet using a laser having an annular spot to form at least one scribed region on the surface of the grain-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 of the scribed region is 8 to 30 μm (e.g., 15 to 25 μm), the width of the molten solidified layer of the scribed region is 20 to 100 μm (e.g., 51 to 92 μm), and the height S of the surface protrusion of the scribed region. a This provides a method for a size of ≤3.0 μm.

[0026] Grain-oriented silicon steel can have its magnetic domains refined by scribing, thereby reducing iron loss. Because a magnetic domain structure exists within the crystal grains of grain-oriented silicon steel, under conditions without an external magnetic field, the magnetic domains within grain-oriented silicon steel are mainly antiparallel-aligned 180° domains, and the width of a single domain can typically reach tens of micrometers to several millimeters. Between adjacent magnetic domains, there is a transition layer called a domain wall, consisting of layers of tens to hundreds of atoms. During the magnetization process, under the drive of an external magnetic field, the magnetic moment rotates, and the movement of the domain walls causes adjacent domains to merge, thereby achieving magnetic permeability. Furthermore, differences in the magnetic domain structure of different regions during the domain wall movement process generate minute eddy currents in minute regions, resulting in eddy current loss. This loss is known as anomalous eddy current loss P in grain-oriented silicon steel. a It is called P. a It can be seen that this is directly related to the intrinsic magnetic domain structure of oriented silicon steel, and furthermore, directly related to the magnetic domain width. Therefore, by reducing the magnetic domain width, P a It can be reduced.

[0027] The other two components of the loss structure in grain-oriented silicon steel are hysteresis loss Ph and eddy current loss P. e Due to advances in metallurgy and physics, these have both decreased to low levels. Abnormal eddy current loss P a P accounts for a large proportion of the total loss in grain-oriented silicon steel, and especially in thin grain-oriented silicon steel with a thickness of 0.23 mm or less, a The proportion accounted for by over 40% Therefore, by refining the magnetic domains of grain-oriented silicon steel (i.e., reducing the magnetic domain width) using scribing means, abnormal eddy current losses can be effectively reduced, thereby reducing the overall iron loss of grain-oriented silicon steel.

[0028] Unlike the single-mode or multi-mode lasers used in the prior art, the laser scribing method of this disclosure employs an annular focused spot. In the single-mode or multi-mode lasers used in the prior art, the energy is concentrated in a central local region, and in the scribing process, in order to make the groove or molten solidified layer reach the depth required for magnetic domain refinement, the input laser energy must be increased so that the laser energy reaches a predetermined penetration depth. However, this creates a large temperature gradient in the thickness direction of the steel sheet, and the surface temperature far exceeds the melting temperature or evaporation temperature, resulting in the formation of volcanic vent-like defects near the scribe. In addition, a large amount of plasma and metal evaporation droplets are generated during the process, and when the temperature drops after scanning, the plasma and metal droplets resolidify on the surface near the scribe, forming sputtered material, which reduces the packing density of the steel sheet. Furthermore, after manufacturing the iron core from a grain-oriented silicon steel sheet, there is a risk that the sputtered material may fall off due to magnetostrictive vibration of the steel sheet, creating a risk of dielectric breakdown in the iron core.

[0029] To overcome the problems of low energy penetration depth and surface sputtering in conventional laser scribing methods, this disclosure employs a laser scribing method using an annular spot, in which the central beam forms a molten pool to a predetermined depth, and the outer annular beam (outer ring beam) provides stability constraints on the shape of the molten pool and the sputtering, thereby avoiding the formation of craters and sputtering, and allowing control of the molten solidification layer in the formed scribed region, enabling the production of low iron loss heat-resistant grain-oriented silicon steel with refined magnetic domains.

[0030] In one preferred embodiment, the laser scribe method of the present disclosure has a laser power density of 16 kW / mm². 2 ~80kW / mm 2 In one preferred embodiment, the laser scribe method of the present disclosure has a laser power density of 38 kW / mm². 2 ~80kW / mm 2In one preferred embodiment, the laser scribe method of the present disclosure has a laser scanning speed of 60 m / s to 100 m / s.

[0031] In the laser scribe method disclosed herein, the laser power density is set to 16 kW / mm². 2 and 80kW / mm 2 It can be controlled during the following timeframe. The laser power density is at its lower limit of 16 kW / mm². 2 If the value is less than 8 μm, the depth of the molten and solidified layer formed by scribing may not reach 8 μm, resulting in insufficient magnetic domain refinement and high iron loss in the product; the laser power density is less than the upper limit of 80 kW / mm². 2 If it exceeds this value, scribing may cause a significant decrease in magnetic flux density, failing to meet the requirements for a high-efficiency transformer.

[0032] In one preferred embodiment, in the laser scribe method of the present disclosure, the energy ratio of the central beam to the outer ring beam of the laser annular spot is 1:1 to 9:1.

[0033] In the scribe method of this disclosure, the ratio of the energy of the central beam to the energy of the outer annular beam can be controlled between 1:1 and 9:1. That is, the energy of the central beam is set to between 50% and 90% of the total energy. If the ratio of the energy of the central beam to the energy of the outer annular beam is less than 1:1, the annular beam cannot form a stable constraint effect on the molten pool, and sputtered material remains in the region near the scribe during the scribe process; if the ratio of the energy of the central beam to the energy of the outer annular beam exceeds 9:1, the energy of the annular beam is too high, and in order to achieve a sufficient magnetic domain refinement effect, it is necessary to increase the energy of both the central beam and the annular beam simultaneously, so the outer annular beam itself also forms a certain amount of molten or evaporated material, and sputtered material remains in a similar manner.

[0034] In one preferred embodiment, in the laser scribe method of the present disclosure, the diameter a of the annular spot of the laser in the rolling direction is 20 to 100 μm.

[0035] In one preferred embodiment, in the laser scribing method of the present disclosure, the diameter b of the annular spot of the laser in the laser scribing scanning direction is 1 to 10 mm. [Effects of the Invention]

[0036] The orientation silicon steel sheet and the laser scribing method thereof disclosed herein have the following beneficial effects compared to the prior art: The grain-oriented silicon steel sheet of this disclosure has a scribe molten solidification layer of a predetermined size, and this molten solidification layer can generate a certain tension effect in local micro-regions, thereby achieving a better magnetic domain refinement effect and reducing iron loss in the grain-oriented silicon steel product. The grain-oriented silicon steel sheet of this disclosure is particularly applicable to the manufacture of energy-saving wound core transformers.

[0037] The laser scribing method of this disclosure uses a laser with an annular focused spot to scribe and shape the surface of a steel sheet in a single scan, efficiently reaching the molten and solidified layer depth necessary for reducing iron loss, without generating sputter. The silicon steel sheet produced by the method of this disclosure has low iron loss, high magnetic flux density, and high space factor, and is particularly applicable to the manufacture of high-efficiency wound core transformers. [Brief explanation of the drawing]

[0038] [Figure 1] This diagram schematically shows the energy distribution of annular focused spots. [Figure 2] This figure schematically shows multiple scribe regions (multiple linear scribes) on the surface of a grain-oriented silicon steel sheet according to one embodiment of the present disclosure. [Figure 3] This figure schematically shows the scribe region and the Sa and Ra measurement region on the surface of a grain-oriented silicon steel sheet according to one embodiment of the present disclosure. [Figure 4] This figure schematically shows the molten and solidified layer and insulating coating in a scribed region on the surface of a grain-oriented silicon steel sheet according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0039] The orientation silicon steel sheet and the laser scribing method thereof of this disclosure will be further interpreted and described below based on the description of the drawings and specific embodiments. However, this interpretation and description will not limit the technical invention of this disclosure.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art in the field to which this disclosure belongs.

[0041] In this specification, the term "molten solidified layer" refers to a layer formed by forming scribes on the surface of a silicon steel sheet, and then melting and solidifying the scribed areas.

[0042] In this specification, line roughness R a This represents the arithmetic mean roughness, and its measurement method is carried out in accordance with ISO 25178, using a laser confocal microscope as the measuring instrument.

[0043] In this specification, the packing factor of grain-oriented silicon steel sheets is measured using GB / T 19289-2003 "Method for measuring density, resistivity, and packing factor of electrical steel sheets (strips)".

[0044] In this specification, the height S of the protrusion a Line roughness R a The thickness of the insulating coating in the scribe region is, in all cases, within a region with a length of 100 μm in the laser scribe scanning direction. This is the average measurement value. The thickness of the insulating coating in the non-scribed region is calculated based on an area of ​​100 μm² within the non-scribed region. 2 This is the average value of measurements taken at any given position.

[0045] In this specification, magnetic flux density (B8) refers to the magnetic flux density of a silicon steel sheet under an excitation magnetic field of 800 A / m, with the unit T.

[0046] In this specification, iron loss (P 17 / 50 ) is the reactive power consumed by a silicon steel sheet due to magnetization when the magnetic flux density reaches 1.7T under a 50Hz AC excitation field, and its unit is W / kg.

[0047] In this specification, magnetic flux density (B8) and iron loss (P 17 / 50 ) is measured using the Epstein method.

[0048] Furthermore, the laser scribing described herein can be performed in the manufacturing process of grain-oriented silicon steel before decarburization annealing, after decarburization annealing, before final hot extension planarization annealing, or before and after final hot extension planarization annealing.

[0049] The laser source used in the method of this disclosure is not particularly limited, and may be a continuous laser with a wavelength of 1066 nm, which is commonly used in the art, or a pulsed laser.

[0050] The following describes the technical proposal of this disclosure in more detail based on specific examples, and explains its beneficial effects.

[0051] Examples 1-6 and Comparative Example 1 The grain-oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 were obtained by the following process: (1) The sheet was rolled to a final thickness of 0.22 mm through ironmaking, steelmaking, continuous casting, and hot rolling processes, followed by a single cold rolling. The chemical composition of the grain-oriented silicon steel sheet was 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. Note that the above chemical composition of the grain-oriented silicon steel sheet is merely an example, and other component compositions may be used. (2) After forming a surface oxide layer through a decarburization annealing process at 850°C, an MgO separating agent was applied to the surface, and then steel coils were manufactured. (3) After manufacturing the steel coils, they were held at a high temperature of 1200°C for 20 hours. (4) Unreacted residual MgO on the surface was washed off and dried. (5) Laser scribing was performed by scanning the surface of the steel plate along its transverse direction using an annular spot laser (the specific laser scribing process parameters are shown in Table 1).

[0052] In Examples 1 to 6, a continuous single-mode laser with a wavelength of 1066 nm was modulated in an optical fiber to form an annular laser, which was then transmitted to a laser head. After passing through a focusing lens and a scanning lens, an annular spot was generated on the surface of the steel plate. The laser power density and the energy ratio between the central beam and the outer ring beam were adjusted, and scanning was performed laterally along the steel plate to form each scribe region. The spacing between adjacent scribe regions in the rolling direction was set to 5 mm in all cases. Figure 1 schematically shows the energy distribution of the annular focused spot.

[0053] Unlike Examples 1-6, Comparative Example 1 used a conventional single-mode high-power continuous laser for scribing, rather than an optical fiber-modulated annular spot.

[0054] (6) Finally, the thickness t of the coating at the central position of the scribe region. c The thickness of the coating in the non-scribed region is t, where t is 0.5 μm. n An insulating coating was applied to the surface of the steel plate to achieve a thickness of 1.0 μm, and then finish annealing was performed.

[0055] Figure 2 schematically shows multiple scribe regions (multiple linear scribes) on the surface of a grain-oriented silicon steel sheet according to one embodiment of the present disclosure.

[0056] As shown in Figure 2, in order to perform laser scribing, a laser with an annular spot was scanned along the transverse direction on the surface of the grain-oriented silicon steel sheet 1 to obtain a plurality of scribe lines (i.e., scribe regions) 2 that are sequentially arranged along the rolling direction. Each scribe region 2 has a spacing in the rolling direction.

[0057] Figure 3 shows a single scribed region 2 and S on the surface of a grain-oriented silicon steel sheet according to one embodiment of the present disclosure. a , R a The measurement area (a region with a length of 100 μm) is schematically shown.

[0058] Figure 4 schematically shows the molten and solidified layer 21 and insulating coating 3 of the scribed region on the surface of a grain-oriented silicon steel sheet according to one embodiment of the present disclosure. In Figure 4, "P" indicates the central position of the scribed region.

[0059] Next, the magnetic permeability (B8) and iron loss (P) of the grain-oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 were examined. 17 / 50 The following tests were conducted. Specifically, the magnetic flux density of grain-oriented silicon steel under an excitation magnetic field of 800 A / m was measured using the Epstein method, and the B8 value (unit: T) was obtained. The reactive power consumed by the magnetization of grain-oriented silicon steel when the magnetic flux density reached 1.7 T under an AC excitation magnetic field of 50 Hz was measured using the Epstein method, and P 17 / 50 The value (in units: W / kg) was obtained.

[0060] Next, after scribing was completed, the packing density of the grain-oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 was measured. Specifically, the packing density of the product steel sheets of Examples 1-6 and Comparative Example 1 after scribing was measured using the method described in GB / T 19289-2003 "Method for measuring density, resistivity, and packing density of electrical steel sheets (strips)". The measurement results of the grain-oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 after scribing are shown in Table 1.

[0061] [Table 1]

[0062] As can be seen from Table 1 above, the grain-oriented silicon steel sheets (thickness 0.22 mm) of Examples 1 to 6 have iron loss P 17 / 50 All of these values ​​are 0.74 W / kg or less, the magnetic flux density B8 is over 1.89 T in all cases, and the packing factor is over 95% in all cases, achieving excellent performance with low iron loss, high magnetic flux density, and high packing factor.

[0063] In contrast, Comparative Example 1 shows that the height and line roughness of the convex portion of the molten and solidified region of the scribe region are In all cases, the values ​​were significantly higher than in Examples 1-6, with high iron loss and low fill factor.

[0064] Examples 7-12 and Comparative Example 2 The grain-oriented silicon steel sheets of Examples 7-12 and Comparative Example 2 were obtained by the following process: (1) The sheet was rolled to a final thickness of 0.19 mm through ironmaking, steelmaking, continuous casting, and hot rolling processes, followed by a single cold rolling. The chemical composition of the grain-oriented silicon steel sheet was 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. Note that the above chemical composition of the grain-oriented silicon steel sheet is merely an example, and other component compositions may be used. (2) After removing residual rolling oil from the surface by alkaline cleaning and degreasing, laser scribing was performed on the surface of the steel plate by scanning it along its transverse direction with an annular spot laser (the specific process parameters for laser scribing are shown in Table 2).

[0065] In Examples 7-12, a continuous single-mode laser with a wavelength of 1066 nm was modulated in an optical fiber to form an annular laser, which was then transmitted to a laser head. After passing through a focusing lens and a scanning lens, an annular spot was generated on the surface of the steel plate. The laser power density and the energy ratio between the central beam and the outer ring beam were adjusted, and scanning was performed laterally along the steel plate to form each scribe region. The spacing between adjacent scribe regions in the rolling direction was set to 6 mm in all cases.

[0066] (3) After forming a surface oxide layer through a decarburization annealing process at 850°C, an MgO separating agent was applied to the surface, and then steel coils were manufactured. (4) After manufacturing the steel coils, they were held at a high temperature of 1200°C for 20 hours. (5) Wash away any unreacted residual MgO from the surface, dry it, and then measure the coating thickness t at the center of the scribed area. c The coating thickness in the non-scribed region is 0.3 μm. n An insulating coating was applied to the surface of the steel plate to achieve a thickness of 1.0 μm, and then finish annealing was performed.

[0067] Next, after scribing, the magnetic permeability (B8) and iron loss (P) of the grain-oriented silicon steel sheets of Examples 7-12 and Comparative Example 2 were examined. 17 / 50 The following tests were conducted. Specifically, the magnetic flux density of grain-oriented silicon steel under an excitation magnetic field of 800 A / m was measured using the Epstein method, and the B8 value (unit: T) was obtained. The reactive power consumed by the magnetization of grain-oriented silicon steel when the magnetic flux density reached 1.7 T under an AC excitation magnetic field of 50 Hz was measured using the Epstein method, and P 17 / 50 The value (in units: W / kg) was obtained.

[0068] Next, after scribing was completed, the packing density of the grain-oriented silicon steel sheets of Examples 7-12 and Comparative Example 2 was measured. Specifically, the packing density of the product steel sheets of Examples 7-12 and Comparative Example 2 after scribing was measured using the method described in GB / T 19289-2003 "Method for Measuring Density, Resistivity, and Packing Density of Electromagnetic Steel Sheets (Strips)". The measurement results of the grain-oriented silicon steel sheets of Examples 7-12 and Comparative Example 2 after scribing are shown in Table 2.

[0069] [Table 2]

[0070] As can be seen from Table 2 above, the grain-oriented silicon steel sheets (thickness 0.19 mm) of Examples 7-12 have iron loss P 17 / 50 All of these exhibited values ​​of 0.704 W / kg or less, magnetic flux density B8 exceeding 1.89 T in all cases, and packing factor exceeding 95% in all cases, achieving excellent performance with low iron loss and high packing factor.

[0071] In contrast, Comparative Example 2 shows significantly higher height and roughness of the convex portion in the scribed area, resulting in a significantly reduced product fill factor.

[0072] Examples 13-16 and Comparative Examples 3-5 The grain-oriented silicon steel sheets of Examples 13-16 and Comparative Examples 3-5 were obtained by the following process: (1) The sheet was rolled to a final thickness of 0.225 mm through ironmaking, steelmaking, continuous casting, and hot rolling processes, followed by a single cold rolling. The chemical composition of the grain-oriented silicon steel sheet was 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. Note that the above chemical composition of the grain-oriented silicon steel sheet is merely an example, and other component compositions may be used. (2) After forming a surface oxide layer through a decarburization annealing process at 860°C, an MgO separating agent was applied to the surface. (3) After manufacturing the steel coils, they were held at a high temperature of 1200°C for 20 hours. (4) Unreacted residual MgO on the surface was washed off and dried. (5) Laser scribing was performed on the surface of the steel plate by scanning it along its transverse direction using an annular spot laser (the specific laser scribing process parameters are shown in Table 3).

[0073] In Examples 13-16 and Comparative Examples 3-5, a continuous single-mode laser with a wavelength of 1066 nm was modulated in an optical fiber to form an annular laser, which was transmitted to a laser head, and then passed through a focusing lens and a scanning lens to generate an annular spot on the surface of the steel plate. The laser power density and the energy ratio between the central beam and the outer ring beam were adjusted, and scanning was performed laterally along the steel plate to form each scribe region, with the spacing between adjacent scribe regions in the rolling direction being 5 mm in all cases. (6) Finally, an insulating coating was applied to the surface of the steel plate, followed by finish annealing. The specific parameters of the applied insulating coating are shown in Table 4.

[0074] [Table 3]

[0075] Next, after the scribing is complete, the magnetic permeability (B8) and iron loss (P) of the oriented silicon steel sheets of Examples 13-16 and Comparative Examples 3-5 are further evaluated. 17 / 50 The following tests were conducted. Specifically, the magnetic flux density of grain-oriented silicon steel under an excitation magnetic field of 800 A / m was measured using the Epstein method, and the B8 value (unit: T) was obtained. The reactive power consumed by the magnetization of grain-oriented silicon steel when the magnetic flux density reached 1.7 T under an AC excitation magnetic field of 50 Hz was measured using the Epstein method, and P 17 / 50 The value (in units: W / kg) was obtained.

[0076] Next, after the scribing was completed, the packing density of the grain-oriented silicon steel sheets of Examples 13-16 and Comparative Examples 3-5 was measured. Specifically, the packing density of the product steel sheets of Examples 13-16 and Comparative Examples 3-5 after scribing was measured using the method described in GB / T 19289-2003 "Method for Measuring Density, Resistivity and Packing Density of Electromagnetic Steel Sheets (Strips)".

[0077] Furthermore, insulation performance evaluations were performed on Examples 13-16 and Comparative Examples 3-5, which were coated with insulating coatings. The evaluation method referred to "GB / T 2522-2007 Surface Insulation Resistance and Coating Adhesion Test Method for Electrical Steel Sheets (Strips)," and the average value of the interlayer resistance of the double-sided coatings was used as the standard. Steel sheet samples with an average interlayer resistance of ≤30Ω·m were determined to have poor insulation performance and were recorded as "×," indicating that there was a risk of dielectric breakdown during use when manufacturing transformer cores. Steel sheet samples with an average interlayer resistance of >30Ω·m were determined to have good insulation performance and were recorded as "○," indicating that they could meet the manufacturing requirements for energy-saving transformer cores.

[0078] The detection results are summarized in Table 4.

[0079] [Table 4]

[0080] As can be seen from Table 4, the insulation performance of Examples 13 to 16 was good. In contrast, the insulation performance of Comparative Examples 3 and 4 was inferior, and there was a safety risk during the operation of the transformers. The fill factor of the product in Comparative Example 5 was low.

[0081] All publications, patent applications, patents, and other references referenced herein are incorporated herein by reference in their entirety.

[0082] While the Disclosure has been illustrated and described based on some preferred embodiments, it will be apparent to those skilled in the art that the above provides further detail about the Disclosure based on specific embodiments, and that the specific embodiments of the Disclosure are not limited to those described. Those skilled in the art can make various modifications, including some simple inferences or substitutions, formally or in minor details, without departing from the spirit and scope of the Disclosure.

Claims

1. A grain-oriented silicon steel sheet having at least one scribed region formed on its surface by laser scribing, wherein the depth of the molten and solidified layer of the scribed region is 8 to 30 μm, the width of the molten and solidified layer of the scribed region is 20 to 100 μm, and the height S of the surface protrusion of the scribed region. ａ A grain-oriented silicon steel sheet characterized by having a thickness of ≤3.0 μm.

2. Line roughness R at the central position of the scribe region ａ The grain-oriented silicon steel sheet according to claim 1, wherein the thickness is ≤ 3.0 μm.

3. The surface of the grain-oriented silicon steel sheet has an insulating coating, and the thickness t of the insulating coating at the central position of the scribe region. ｃ ≥ 0.2 μm and t ｃ and the thickness t of the insulating coating in the non-scribed region ｎ The sum of the following is given by the following relationship: 0.8μm≦t ｃ +t ｎ ≦3.5μm A grain-oriented silicon steel sheet according to claim 1 or 2, satisfying the requirements.

4. The grain-oriented silicon steel sheet according to any one of claims 1 to 3, wherein the grain-oriented silicon steel sheet has at least two scribed regions formed on its surface by laser scribing, and the spacing between each scribed region in the rolling direction is 4 to 20 mm.

5. The grain-oriented silicon steel sheet according to any one of claims 1 to 4, wherein the packing ratio of the grain-oriented silicon steel sheet is ≥ 95.0%.

6. When the thickness of the grain-oriented silicon steel sheet is 0.23 mm or more, the iron loss P of the grain-oriented silicon steel sheet １７／５０ ≦ 0.740 W / kg, magnetic flux density B ８ ≧ 1.880 T, the grain-oriented silicon steel sheet according to any one of claims 1 to 5.

7. A method comprising the step of performing laser scribing on the surface of a grain-oriented silicon steel sheet using a laser having an annular spot to form at least one scribed region on the surface of the grain-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 and solidified layer of the scribed region is 8 to 30 μm, the width of the molten and solidified layer of the scribed region is 20 to 100 μm, and the height S of the surface protrusion of the scribed region. ａ ≤ 3.0 μm; Preferably, the line roughness R at the central position of the scribe region. ａ ≤ 3.0 μm; Preferably, the surface of the grain-oriented silicon steel sheet has an insulating coating, and the thickness t of the insulating coating at the central position of the scribe region is ｃ ≥ 0.2 μm and t ｃ and the thickness t of the insulating coating in the non-scribed region ｎ The sum of these is 0.8 μm ≤ t ｃ +t ｎ The relationship ≤ 3.5 μm is satisfied; Preferably, the surface of the grain-oriented silicon steel sheet has at least two scribed regions formed by laser scribing, with a spacing of 4 to 20 mm between each scribed region in the rolling direction; Preferably, a method for performing laser scribing on a grain-oriented silicon steel sheet, characterized in that the packing ratio of the grain-oriented silicon steel sheet is ≥ 95.0%.

8. The output density of the laser is 16 kW / mm². ２ ~80kW / mm ２ and / or, The method according to claim 7, wherein the scanning speed of the laser is 60 m / s to 100 m / s.

9. The method according to claim 7 or 8, wherein the energy ratio of the central beam to the outer ring 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 to 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 scribe scanning direction is 1 to 10 mm.

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