Heat-resistant laser-scribed grain-oriented silicon steel and efficient scribing method therefor

Abstract

Heat-resistant laser-scribed grain-oriented silicon steel and an efficient scribing method therefor. The surface of the grain-oriented silicon steel has a plurality of parallel linear grooves (2), a roughness mean value Ra of a central line at the bottom of each groove (2) is less than or equal to 0.92 μm, and the ratio Rz / d of the maximum height Rz of the central line at the bottom of the groove (2) to the depth d of the groove (2) is less than or equal to 0.45. The scribing method comprises: using a pulsed laser to scan the surface of a grain-oriented silicon steel plate (1) so as to form a plurality of parallel linear grooves (2), wherein a repetition frequency of the pulsed laser falls within 10-400 MHz, and a spot overlap rate during laser scanning is greater than or equal to 96.4%.

Description

Laser heat-resistant notch oriented silicon steel and efficient notch method thereof TECHNICAL FIELD

[0001] The present application relates to an oriented silicon steel and a manufacturing method thereof, in particular to a laser notch oriented silicon steel and a manufacturing method thereof. BACKGROUND

[0002] At present, the heat-resistant notch technology mainly includes chemical corrosion method and mechanical notch method. The chemical corrosion method has poor groove uniformity and process controllability, and pollutes the environment; the mechanical pressure forming strain zone technology has high requirements for the hardness and processing precision of the mechanical device due to the high hardness of the silicon steel material and the small size of the groove.

[0003] In view of the excellent effect of laser in other micro-processing fields and the significant advantage in the efficient production of non-heat-resistant notch oriented silicon steel, the researchers and engineering technicians in the field have long been committed to realizing the production of heat-resistant notch oriented silicon steel by using laser micro-processing. However, due to the fast heat conduction speed of steel materials, the laser inevitably produces melting or even evaporation when forming notch grooves on the surface of the steel plate, and the formed molten or evaporated droplets accumulate on the surface of the steel plate, causing the stacking coefficient of the steel plate to decrease, and also existing the risk of falling off during service, reducing the reliability of the manufactured transformer.

[0004] The Chinese patent document with publication number CN102941413A and publication date of February 27, 2013, entitled "A method for reducing iron loss of oriented silicon steel by multiple laser grooving" discloses a method for reducing iron loss of oriented silicon steel by multiple laser grooving, which uses multiple low-power laser notches to overcome the problem of splash generation, but the repeated notching efficiency is low.

[0005] The Chinese patent document with publication number CN110323044A and publication date of October 11, 2019, entitled "Heat-resistant magnetic domain refinement type oriented silicon steel and manufacturing method thereof" discloses a heat-resistant magnetic domain refinement type oriented silicon steel and a manufacturing method thereof, which uses a laser light splitting method combined with a single pulse laser with very high instantaneous peak power density to overcome the problems of multiple scanning times and laser heat melting, but still has the problems of complex optical path and high maintenance cost. SUMMARY

[0006] One of the purposes of the present application is to provide a laser heat-resistant notch oriented silicon steel, which has the advantages of low iron loss and high stacking coefficient.

[0007] To achieve the above object, the present application provides an oriented silicon steel, which has a plurality of parallel linear grooves on the surface, the mean roughness of the center line of the groove bottom is ≤0.92μm, and the ratio of the maximum height Rz of the center line of the groove bottom to the depth d of the groove is ≤0.45.

[0008] In the present application, the center line of the groove bottom is the connecting line of the center points of the groove bottom in the cross-sectional width direction. The mean roughness of the center line Ra is the average value of the absolute value of the deviation of the center line profile from its arithmetic mean line, the maximum height Rz of the center line is the sum of the maximum peak height and the minimum valley depth of the center line profile, and the depth of the groove is the vertical distance from the center line of the groove bottom to the reference plane determined by the surface of the steel plate not affected by the groove.

[0009] In the present application, the center line roughness of the groove bottom affects the magnetic induction of the finished oriented silicon steel plate and the size of the vibration noise in the alternating magnetic field. When the mean roughness of the center line Ra exceeds 0.92μm, too much residue is attached to the groove bottom, and the magnetic lines form obvious bending when passing through, which on the one hand reduces the magnetic induction of the finished product, and on the other hand increases the electromagnetic oscillation, so that the noise of the finished transformer increases. In the present application, the smaller the Ra is, the better.

[0010] The inventors have also found that the ratio of the maximum height Rz of the center line of the groove bottom to the depth d of the groove also has an important influence on the magnetic induction of the finished oriented silicon steel plate and the size of the vibration noise in the alternating magnetic field, and based on this, the present application controls the range of Rz / d to be not more than 0.45. When the ratio exceeds this value, the magnetic induction of the finished oriented silicon steel plate will decrease, and the noise of the finished transformer in service state will increase.

[0011] Preferably, in the laser heat-resistant notch oriented silicon steel described in the present application, the protrusion height of the groove edge is ≤4μm.

[0012] The protrusion height of the groove edge is the vertical distance from the highest point of the groove edge to the reference plane determined by the surface of the steel plate not affected by the groove.

[0013] The protrusion of the groove edge is generated due to the thermal melting of the base material when excessive laser energy is introduced. The protrusion reduces the stacking factor of the oriented silicon steel plate, and the reduction of the stacking factor increases the gap between the finished core sheets, which not only increases the volume of the core, but also intensifies the vibration between the sheets, resulting in an increase in the overall service noise of the finished transformer. Therefore, in the present application, the protrusion height of the groove edge is ≤4μm, and the lower the protrusion height is, the better.

[0014] In the present application, the parallel linear grooves refer to linear grooves parallel to the transverse direction of the silicon steel, and the spacing between adjacent grooves refers to the spacing between adjacent grooves in the rolling direction of the silicon steel.

[0015] In the present application, the distance between the adjacent notch lines on the surface of the steel plate in the rolling direction is controlled according to the distance of the general laser notch, which is preferably between 2-10 mm, and more preferably between 3-8 mm, which is determined by the effect of the notch refining magnetic domain to reduce iron loss. If the distance exceeds 10 mm, the effect of the notch reducing iron loss is limited; and if the distance is less than 2 mm, the notch will introduce excessive surface energy, which will also reduce the effect of the notch reducing iron loss, and will also result in the decrease of the magnetic permeability B8 of the steel plate. In the laser heat-resistant notch oriented silicon steel described in the present application, the distance between the adjacent grooves can be, for example, 4.5-6.0 mm.

[0016] Preferably, in the laser heat-resistant notch oriented silicon steel described in the present application, the depth of the groove is 10-30 μm. When the depth of the groove is less than the lower limit 10 μm, the effect of the groove refining magnetic domain to reduce iron loss is slightly low, and the iron loss of the finished oriented silicon steel plate is slightly high; and when the depth of the groove is higher than the upper limit 30 μm, the magnetic flux leakage through the groove is slightly large, and the magnetic induction of the finished oriented silicon steel plate is reduced. Therefore, the range of the groove depth is controlled to be between 10-30 μm in the present application.

[0017] Preferably, in the laser heat-resistant notch oriented silicon steel described in the present application, the maximum height Rz of the central line of the bottom of the groove is as low as possible, for example, below 13.3 μm.

[0018] Preferably, in the laser heat-resistant notch oriented silicon steel described in the present application, the width of the groove is 10-45 μm.

[0019] Preferably, in the present application, the oriented silicon steel plate for forming the laser heat-resistant notch oriented silicon steel is formed by smelting, casting, hot rolling, and cold rolling. Then, the oriented silicon steel plate is sequentially subjected to laser notch, decarburization annealing, coating of annealing separator, high-temperature annealing, coating of insulating coating, and final annealing to form the finished oriented silicon steel plate. Of course, in some embodiments of the present application, the laser notch can also be performed after the high-temperature annealing.

[0020] Unless otherwise specified, the laser heat-resistant notch oriented silicon steel or the oriented silicon steel of the present application refers to the finished oriented silicon steel with an insulating coating.

[0021] Preferably, the thickness of the laser heat-resistant notch oriented silicon steel described in the present application is 0.18-0.23 mm.

[0022] Preferably, the iron loss P1 of the laser heat-resistant notch oriented silicon steel described in the present application is 0.5-1.0 W / kg. 17 / 50 The magnetic induction B8 is above 1.89 T at 0.75 W / kg, and more preferably at 0.73 W / kg. Preferably, the stacking factor of the laser heat-resistant notch oriented silicon steel described in the present application is ≥95%.

[0023] Another object of the present application is to provide a method for laser hot-etching orientation silicon steel, which can overcome the problems of low ablation efficiency and complex optical system of short pulse width laser caused by the melting zone and the decrease of stacking factor in the prior art, and can realize efficient manufacturing of laser hot-etching orientation silicon steel plate, and the obtained laser hot-etching orientation silicon steel has the advantages of low iron loss and high stacking factor.

[0024] In order to achieve the above object, the present application provides a method for laser hot-etching orientation silicon steel, which comprises: scanning the surface of the orientation silicon steel plate by using a pulse laser to form a plurality of parallel linear grooves, wherein the repetition frequency of the pulse laser is 10-400 MHz, preferably 50-400 MHz, and more preferably 100-400 MHz, and the spot overlap rate during laser scanning is ≥96.4%, preferably, the short axis a of the spot during scanning is 16-40 μm, the long axis b of the spot is 16-164 μm, and a≤b.

[0025] Preferably, the entire surface of the steel plate has the above-mentioned parallel linear grooves.

[0026] The present application uses an ultrashort pulse laser to efficiently form grooves in a "cold" and "hot" processing cooperative manner. The inventors have found that by significantly increasing the repetition frequency of the pulse laser, the "cold" and "hot" processing cooperative effect can be achieved, greatly improving the efficiency and quality of the grooving. This is because, when the notch is formed only in the "cold" processing mode, the laser irradiation area of the steel plate is always in a low temperature state, the micro surface of the laser receiving area has a low laser absorption rate, the laser energy utilization rate is low, and therefore the ablation grooving efficiency is low. When the high repetition frequency laser of the present application is used to notch the surface of the orientation silicon steel in a high overlap rate manner, the overlapping effect between the front and rear laser pulses can be formed due to the short interval between the pulses, so that the micro surface of the laser receiving area is always in a molten state, which can improve the laser absorption efficiency of the material and reduce the damage threshold of the laser energy. Since the pulse width is very small, the molten micro area is limited to a very shallow surface layer, about tens to hundreds of atomic layers, and before the heat of the molten state diffuses to the inside of the substrate, it is ablated and peeled off by the subsequent pulse laser, thereby achieving the dual goals of high efficiency and high quality processing.

[0027] In the present application, the repetition frequency of the pulse laser is limited to 10 MHz or more. The repetition frequency R F of the pulse refers to the number of pulses output by the laser in 1 s, and the reciprocal of the repetition frequency is the time interval between pulses. The lower the repetition frequency, the weaker the overlapping effect between the front and rear pulses.

[0028] If the repetition frequency of the pulsed laser is lower than 10 MHz, the molten state of the micro region on the surface of the silicon steel cannot be maintained, the laser scanning forms a groove mainly by "cold" processing, and the scoring efficiency is low; the higher the repetition frequency, the stronger the superposition effect between the front and rear pulses, which is beneficial to improve the scoring efficiency and thus the production efficiency, but too high repetition frequency will increase the molten layer depth of the micro region on the surface of the silicon steel receiving laser irradiation, and easily form a raised edge and splashes near the groove. Therefore, the repetition frequency of the pulsed laser is controlled to be 10-400 MHz in the present application.

[0029] The spot overlap rate reflects the strength of the superposition effect of the front and rear laser pulses. When the spot overlap rate is lower than 96.4%, the superposition effect of the laser pulses is weak, which affects the effect of the present application.

[0030] Preferably, in the high-efficiency scoring method of the present application, the laser spot overlap rate during scanning is 96.4%-99.7%.

[0031] When the spot overlap rate is higher than 99.7%, the superposition effect of the laser pulses is too strong, which may reduce the quality of the groove formed by the score.

[0032] Preferably, in the high-efficiency scoring method of the present application, the scanning speed of the laser is ≥10 m / s.

[0033] In the present application, the scanning speed is preferably as large as possible within the above range, and the higher the scanning speed, the higher the production efficiency.

[0034] In this embodiment, the lower limit of the scanning speed is 10 m / s, which takes into account the requirements of efficient production and scanning score quality. If the scanning speed is lower than 10 m / s, the production efficiency is low, the laser spot overlap rate is too high, and the quality of the groove may also decrease to some extent. Considering the production cost and other factors, the scanning speed is usually below 100 m / s in the present application.

[0035] Preferably, the output power of the laser is 100-1000 W.

[0036] Preferably, in the high-efficiency scoring method of the present application, the single pulse width of the pulsed laser is ≤40 ps. The present application does not limit the lower limit of the single pulse width, but it is usually above 0.5 ps, for example, above 0.6 ps.

[0037] In the present application, the single pulse width t p The single pulse width t p is the time maintained by a single pulse when the laser releases outward in the form of pulses. In the present application, the single pulse width t pWhen the laser mark forms a groove, the process is mainly thermal melting and evaporation, the quality of the groove is poor, and splashed material inevitably exists near the groove, which cannot meet the requirements of the finished product oriented silicon steel plate stacking coefficient and safe service. The shorter the single pulse width, the better the quality of the groove formed by the mark, and the higher the mark efficiency.

[0038] Preferably, in the high-efficiency marking method of the present application, the single pulse energy density of the pulsed laser is 0.12-3.25J / cm 2 .

[0039] In the present application, the single pulse instantaneous peak power density is required to be in the range of 0.12J / cm 2 ~3.25J / cm 2 If the value is lower than the lower limit requirement of 0.12J / cm 2 , the energy carried by the laser single pulse is too low, and the efficiency of forming a groove by marking on the surface of silicon steel is very low; if the value is higher than the upper limit of 3.25J / cm 2 , the energy carried by the laser single pulse is too high, which will form evaporation, plasma gasification and other phenomena during marking, and the protrusion of the groove edge will increase, which will affect the quality of the groove.

[0040] The laser heat-resistant marked oriented silicon steel and the high-efficiency marking method thereof have the following advantages and beneficial effects compared with the prior art:

[0041] The high-efficiency marking method of the laser heat-resistant marked oriented silicon steel can overcome the problems of melting zone leading to the decrease of stacking coefficient and the low ablation efficiency and complex optical system of very short pulse width laser in the prior art, and realize the efficient manufacturing of laser heat-resistant marked oriented silicon steel plate.

[0042] The laser heat-resistant marked oriented silicon steel has the advantages of low iron loss and high stacking coefficient.

[0043] In some embodiments, the iron loss P 17 / 50 When the magnetic induction B8 is above 1.89T and the stacking coefficient is ≥95% below 0.75W / kg. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a schematic diagram of the laser heat-resistant marked oriented silicon steel in an embodiment of the present application.

[0045] Figure 2 is a schematic diagram of the pulsed laser used in an embodiment of the present application.

[0046] Figure 3 is a schematic diagram of laser marking on the surface of the steel plate using the high-efficiency marking method of the present application.

[0047] Fig. 4 is a schematic diagram of the central line of the bottom of the groove.

[0048] Fig. 5 is a schematic diagram of the groove depth d, width w and protrusion height h of the laser heat-resistant notch oriented silicon steel in an embodiment of the present application.

[0049] Reference signs: 1 - oriented silicon steel plate, 2 - groove. DETAILED DESCRIPTION

[0050] The laser heat-resistant notch oriented silicon steel and the efficient notch method thereof described in the present application will be further explained and described below in conjunction with the drawings of the specification and specific examples, however, the explanation and description do not constitute undue limitations on the technical solutions of the present application.

[0051] The various properties of the present application are determined as follows:

[0052] The groove depth, width, groove edge protrusion height of the surface of the oriented silicon steel are determined by using a laser confocal microscope, the magnification is kept above 200 times, and the measurement accuracy is kept above ±0.5 μm. The groove spacing is determined using a conventional ruler or meter ruler, and the measurement accuracy is above ±0.2 mm.

[0053] The average roughness R a of the central line of the groove bottom of the surface of the oriented silicon steel z : determined according to ISO4287:1997.

[0054] The iron loss P 17 / 50 of the oriented silicon steel, the magnetic induction B8: determined according to GB / T 3655-2022 "Method for measuring the magnetic properties of electrical steel strip (sheet) with Epstein frame";

[0055] The stacking factor of the oriented silicon steel: determined according to GB / T 19289-2019 "Method for measuring the resistivity, density and stacking factor of electrical steel strip (sheet)".

[0056] Fig. 1 schematically shows a schematic diagram of the laser heat-resistant notch oriented silicon steel in an embodiment of the present application.

[0057] As shown in Fig. 1, the surface of the laser heat-resistant notch oriented silicon steel plate 1 has a plurality of parallel linear grooves 2 formed by laser notching arranged in sequence along the rolling direction thereof, wherein each groove 2 extends in the transverse direction of the oriented silicon steel plate.

[0058] The present application uses a high-repetition-frequency pulsed laser to scan the surface of the oriented silicon steel plate to form the above-mentioned parallel linear grooves.

[0059] As shown in Fig. 2, the present application uses a high-repetition-frequency pulsed laser to scan the surface of the oriented silicon steel plate to form the above-mentioned parallel linear grooves. fThe pulse laser, or laser pulse, has a repetition frequency of 10 MHz or more in the present application. The repetition frequency of the pulse is represented by R F , which is the number of pulses output by the laser in 1 s. The reciprocal of R , i.e. the time interval between pulses, is represented by t p in Figure 2. The single pulse width is represented by t

[0060] Figure 3 schematically shows a laser marking on the surface of a steel sheet in one embodiment of the high-efficiency marking method of the present application.

[0061] As shown in Figure 3, the running direction P of the steel strip is consistent with the rolling direction of the steel sheet, and the laser scanning direction Q is consistent with the direction in which the groove 2 extends. In some embodiments, laser pulses with an elliptical spot can be used for scanning marking, and a and b in the figure represent the short axis and long axis of the elliptical spot, respectively.

[0062] Figure 4 schematically shows the bottom center line L of the groove A.

[0063] Figure 5 schematically shows the groove depth d, width w and protrusion height h of the laser heat-resistant marked oriented silicon steel according to the present application.

[0064] The average roughness Ra of the bottom center line L of the groove 2 prepared by the high-efficiency marking method of the present application is ≤0.92 μm, and the ratio Rz / d of the maximum height Rz of the bottom center line L of the groove to the groove depth d is ≤0.45.

[0065] The following Examples 1-18 and Comparative Examples 1-2 further verify the implementation effect of the present application:

[0066] Examples 1-9 and Comparative Example 1

[0067] The oriented silicon steel of Examples 1-9 and the comparative steel sheet of Comparative Example 1 according to the present application are prepared by the following steps:

[0068] The oriented silicon steel is obtained by iron-making, steel-making, continuous casting, hot rolling process, and then once cold rolling to obtain the oriented silicon steel plate with a final thickness of 0.22 mm. The same steel plate is used for subsequent treatment in Examples 1-9 and Comparative Example 1. After degreasing cleaning, continuous grooves are formed on the surface of the steel plate by rapid scanning with an ultra-short pulse laser. The single pulse width of the laser is controlled to be 40 ps, and the interval of adjacent grooves in the rolling direction is 6 mm. The specific process parameters of the high-efficiency notch step of Examples 1-9 and Comparative Example 1 are listed in Table 1. Then, the strip steel is subjected to decarburization annealing at 850°C to form a surface oxidation layer, and then MgO release agent is coated on the surface. After being wound into a steel coil and annealed at a high temperature of 1200°C for 20 hours, the surface is cleaned of residual unreacted MgO and dried. Finally, the finished oriented silicon steel plate is obtained by coating an insulating coating on the surface of the steel plate and then performing final annealing.

[0069] In the above embodiment, the composition of the oriented silicon steel plate obtained after cold rolling is as follows in terms of mass percentage: C: 0.03%-0.10%, Si: 2.5%-4.0%, Mn: 0.06%-0.20%, P: 0.005%-0.012%, S: 0.005%-0.05%, Als: 0.01%-0.04%, N: 0.005%-0.015%, Cr: 0.01%-0.45%, and the balance being Fe and unavoidable impurities.

[0070] Table 1.

[0071] Then, the groove parameters and magnetic properties of the finished oriented silicon steel plates of Examples 1-9 and the comparative steel of Comparative Example 1 are measured, and the test results are listed in Table 2.

[0072] Table 2.

[0073] As can be seen from Table 2 above, the iron loss P 17 / 50 of the finished oriented silicon steel plates of Examples 1-9 of the present application are all less than 0.75 W / kg, the magnetic induction B8 is all greater than 1.89 T or more, and the stacking factor is all greater than or equal to 95%.

[0074] However, the repetition frequency of Comparative Example 1 is 1 MHz, and the single pulse energy is 16.24 J / cm 2 , and the average roughness Ra and Rz / d of the central line of the groove bottom do not meet the requirements of the present application, thereby resulting in high iron loss and low stacking factor of the finished oriented silicon steel plate.

[0075] Examples 10-18 and Comparative Example 2

[0076] The oriented silicon steel of embodiments 10-18 and the comparative steel of comparative example 2 of the present application were prepared by the following steps:

[0077] The oriented silicon steel was prepared by iron making, steel making, continuous casting, hot rolling process, and then cold rolling to obtain the final thickness of 0.195 mm. The same steel plate was used for the subsequent treatment of embodiments 10-18 and comparative example 2, and then decarburization annealing process at 860℃ was carried out to form a surface oxidation layer, and then MgO release agent was coated on the surface, and then the steel plate was rolled into a coil and annealed at high temperature of 1200℃ for 20 hours, and then the surface was cleaned and dried, and then laser marking was carried out on the surface of the steel plate along the transverse direction of the steel plate, and the ultra-short pulse laser with a single pulse width of 0.6 ps was used, and the distance between adjacent marking lines was 4.5 mm. Table 3 lists the specific process parameters used in the high-efficiency marking step of embodiments 10-18 and comparative example 2 of the present application. Finally, the finished oriented silicon steel plate was prepared by coating an insulating coating on the surface of the steel plate and then carrying out final annealing.

[0078] In the above embodiment, the composition of the oriented silicon steel plate obtained after cold rolling is as follows in terms of mass percentage: C: 0.03% to 0.10%, Si: 2.5% to 4.0%, Mn: 0.06% to 0.20%, P: 0.005% to 0.012%, S: 0.005% to 0.05%, Als: 0.01% to 0.04%, N: 0.005% to 0.015%, Cr: 0.01% to 0.45%, and the balance is Fe and unavoidable impurities.

[0079] Table 3.

[0080] Then, the groove parameters and magnetic properties of the finished oriented silicon steel plates of embodiments 10-18 and the comparative steel plate of comparative example 2 were measured, and the test results are listed in Table 4.

[0081] Table 4.

[0082] As can be seen from the above Table 4, the iron loss P 17 / 50 of embodiments 10-18 of the present application is less than 0.75 W / kg, the magnetic induction B8 is greater than 1.89 T, and the stacking factor is greater than or equal to 95.0%.

[0083] However, the laser parameters of comparative example 2 are not within the scope of the present application, the groove depth is shallow, the protrusion height is large, and the average central line roughness of the groove bottom is also large, so the silicon steel plate prepared has high iron loss and small stacking factor.

[0084] It should be noted that the combination of the technical features in the case is not limited to the combination of the claims in the case or the combination of the embodiments in the case. All the technical features disclosed in the case can be freely combined or combined in any way, unless contradictory.

[0085] It should also be noted that the above-mentioned embodiments are only specific embodiments of the present application. Obviously, the present application is not limited to the above-mentioned embodiments, and similar changes or modifications made in accordance with the disclosure of the present application are directly derived or easily conceived by those skilled in the art, and should all fall within the scope of protection of the present application.

Claims

1. An oriented silicon steel characterized by, The surface of the oriented silicon steel has a plurality of parallel linear grooves, the mean roughness Ra of the central line of the groove bottom is ≤0.92μm, and the ratio Rz / d of the maximum height Rz of the central line of the groove bottom to the depth d of the groove is ≤0.

45.

2. The oriented silicon steel of claim 1, wherein, The protrusion height of the groove edge is ≤4μm.

3. The oriented silicon steel of claim 1, wherein, The depth d of the groove is 10-30μm, and / or the maximum height Rz of the central line of the groove bottom is below 13.3μm.

4. The oriented silicon steel of claim 1, wherein, The width of the groove is 10-45μm.

5. The oriented silicon steel of claim 1, wherein, The oriented silicon steel has a magnetic induction B8 of 1.89 T or more at 0.75 W / kg or less. 17 / 50 The magnetic induction B8 is 1.89 T or more at 0.75 W / kg or less.

6. The oriented silicon steel of claim 1, wherein, The stacking factor of the oriented silicon steel is ≥95%.

7. A method of forming the score of the oriented silicon steel of any one of claims 1-6, characterized by: A pulse laser is used to scan the surface of the oriented silicon steel plate to form a plurality of parallel linear grooves, wherein the repetition frequency of the pulse laser is 10-400MHz, preferably 50-400MHz, more preferably 100-400MHz, and the spot overlap rate during laser scanning is ≥96.4%.

8. The method of scoring according to claim 7 wherein, The spot overlap rate during laser scanning is 96.4%-99.7%, and / or the short axis a of the spot during laser scanning is 16-40μm, the long axis b of the spot is 16-164μm, and a≤b.

9. The method of scoring according to claim 7 wherein, The speed of laser scanning is ≥10m / s, and / or the output power of the laser is 100-1000W.

10. The method of scoring according to claim 7 wherein, The single pulse width of the pulse laser is ≤40ps.

11. The method of scoring according to claim 7 wherein, The single pulse energy density of the pulsed laser is 0.12-3.25 J / cm 2 .

Images