Heat-resistant magnetic domain refinement type low-iron-loss oriented silicon steel sheet and laser nicking method thereof

Abstract

The invention discloses a heat-resistant magnetic domain refinement type low-iron-loss oriented silicon steel sheet. The surface of the silicon steel sheet is provided with a nick area formed by laser nicking. The depth of the fused solidification layer of the nick area is 8-30 [mu] m; the width of the fused solidification layer in the nick area is 20-100 microns; and the height Sa of the surface bulge of the nick area is less than or equal to 3 microns. The invention further provides a laser nicking method for the heat-resistant magnetic domain refinement type low-iron-loss oriented silicon steel sheet, laser nicking is carried out on the surface of a steel plate by adopting laser with annular light spots, so that nicking is carried out on a micro-area on the surface of the oriented silicon steel plate to form a molten solidification layer, and therefore the magnetic domain is refined, and the heat-resistant magnetic domain refinement type low-iron-loss oriented silicon steel sheet is obtained. And the heat-resistant magnetic domain refined oriented silicon steel with low iron loss and high lamination coefficient is obtained.

Description

Technical Field

[0001] The invention relates to an oriented silicon steel and a manufacturing process thereof, and in particular to an oriented silicon steel plate and a laser scoring method thereof. Background Art

[0002] As a basic component of the power transmission system, the reactive power loss of the transformer accounts for about 40% of the total loss in the power transmission system. In this transformer, the iron core made of oriented silicon steel stacked or wound, the reactive power loss under working condition accounts for about 20% of the total loss. This loss caused by the transformer core is usually referred to as iron loss.

[0003] Oriented silicon steel is a ferromagnetic material, named because the direction of its internal grain arrangement is roughly the same as the rolling direction of the steel plate. Inside the grain, there is a magnetic domain structure caused by the spontaneous magnetization of the ferromagnet. The magnetic moments of the atoms in each magnetic domain are spontaneously arranged in parallel to form 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 to achieve the magnetic conductivity function. The magnetic domain structure is the result of the minimum energy principle and is a basic factor affecting the iron loss, magnetic induction and magnetostriction of silicon steel sheets. Since the grain arrangement direction is the easy magnetic conductivity direction, 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 silicon steel sheets under an excitation magnetic field of 800A / m, in units of T; iron loss is generally expressed by P 17 / 50 It is the ineffective electric energy consumed by the magnetization of silicon steel sheets when the magnetic flux density in the strip reaches 1.7T under an AC excitation field of 50Hz, in W / kg.

[0005] Research has found that the steel loss of oriented silicon steel consists of three parts: hysteresis loss, eddy current loss and abnormal eddy current loss. Among them, hysteresis loss is the energy loss caused by the hysteresis phenomenon that the magnetic induction intensity lags behind the change of magnetic field intensity due to the factors of inclusions, crystal defects and internal stress in the material hindering the movement of magnetic domain walls during the magnetization process; eddy current loss is the energy loss caused by eddy current caused by the local electromotive force induced by the change of magnetic flux during the magnetization process, which is related to the conductivity and thickness of the silicon steel plate; abnormal eddy current loss is the energy loss caused by the different magnetic domain structures when the silicon steel plate is magnetized, which is mainly affected by the width of the magnetic domain.

[0006] In the current existing technology, continuously reducing the iron loss of silicon steel materials is the development direction of silicon steel technology. There are three main technical directions that can be realized at present: 1. Metallurgical method: control the secondary recrystallization structure through metallurgical methods, improve the grain orientation, and moderately reduce the grain size to refine the magnetic domains and reduce iron loss; 2. Tension control: apply a high-tension coating on the surface of the silicon steel plate, and refine the magnetic domains through the tension effect of the coating to reduce iron loss; 3. Surface scoring: apply linear stress or strain on the surface of the silicon steel plate by laser or electron beam to refine the magnetic domains and reduce iron loss.

[0007] Among them, the refinement of magnetic domains by notching 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. At present, the technology of implementing notching 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 notching:

[0008] (1) One type is not resistant to stress relief annealing notches. Linear thermal stress zones are formed on the surface at a certain interval by laser, plasma beam, or electron beam. Stress produces 90° magnetic domains 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. It has been widely used in energy-saving transformers for power transmission networks.

[0009] (2) The other type is resistant to stress relief annealing notches. Its basic technical solution is to form grooves by mechanical gear rollers, chemical corrosion, laser melting, etc. The free magnetic poles and surface energy generated on both sides of the grooves increase, and the energy inside the crystal is redistributed, which reduces the width of the magnetic domain and thus reduces the 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 transformer manufacturing solution with better energy-saving performance, the market for wound core transformers has expanded rapidly in recent years. Wound core transformers make full use of the excellent magnetic properties of oriented silicon steel in the rolling direction. Therefore, compared with laminated core transformers, they have more advantages in terms of loss, noise, and material utilization, and are particularly suitable for the manufacture of small and medium-sized energy-saving transformers. However, due to the internal stress generated by the steel plate due to winding during the manufacturing process, the performance deteriorates, so the core must undergo stress relief annealing. The process of stress relief annealing is usually to keep the temperature at 800°C or above for not less than 2 hours in a protective atmosphere to achieve the best magnetic properties of the silicon steel sheet. The oriented silicon steel sheet that uses laser or electron beam to generate linear stress zones to refine the magnetic domains will disappear after stress relief annealing as the stress disappears, so it cannot be used in the manufacture of wound core transformers.

[0011] In order to maintain the above-mentioned effect of refining magnetic domains after stress relief annealing, people have developed a technology for refining magnetic domains resistant to stress relief annealing, that is, using chemical etching, mechanical pressure, and laser to form grooves with a certain shape on the surface of silicon steel sheets. The presence of free magnetic poles in the grooves and the increase in surface energy redistribute the material energy, reduce the width of the magnetic domains, and reduce iron losses. Since the grooves do not change during the stress relief annealing process, the oriented silicon steel sheets produced using this type of technology can be used in the manufacture of wound core transformers, collectively referred to as heat-resistant notching technology.

[0012] At present, those skilled in the art have realized the production of heat-resistant notched grained silicon steel using laser. However, the problems of melt or spatter and production efficiency are still the difficulties in realizing laser heat-resistant notching.

[0013] In a Chinese patent document with publication number CN102941413A and publication date February 27, 2013, entitled “A method for reducing iron loss by multiple laser grooving of oriented silicon steel”, the problem of spatter generation is overcome by using multiple low-power laser grooving repetitively. However, the efficiency of repeated grooving is low, and repeated positioning in micro-areas is difficult, making it difficult to achieve mass production on an industrial assembly line. Summary of the invention

[0014] One of the purposes of the present invention is to provide a heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet, which can form a stable molten pool without generating splashing materials during the scoring process, and form a scoring molten solidification layer with a certain size, so that the molten solidification forms a certain tension effect in the local micro-region, the magnetic domain refinement effect is better, and the finished oriented silicon steel sheet has low iron loss, which is particularly suitable for the manufacture of energy-saving wound core transformers.

[0015] In order to achieve the above-mentioned object, the present invention provides a heat-resistant magnetic domain refinement type low iron loss oriented silicon steel sheet, the surface of which has a scoring area formed by laser scoring; the depth of the molten solidified layer in the scoring area is between 8-30 μm; the width of the molten solidified layer in the scoring area is 20-100 μm; the height S of the surface protrusion of the scoring area is a ≤3μm.

[0016] The depth of the molten solidified layer formed by the laser scoring of the present invention is between 8-30μm, and the width is between 20-100μm, which is the result of taking into account the improvement of iron loss, magnetic induction degradation, and lamination coefficient. When the depth of the molten solidified layer is less than 8μm, it is difficult to achieve the effect of refining the magnetic domain to reduce iron loss, and the iron loss of the finished oriented silicon steel sheet is high; when the depth of the molten solidified layer is greater than 30μm, the magnetic induction B8 of the finished oriented silicon steel sheet is low, which cannot meet the manufacturing of high-efficiency wound core transformers. When the lower limit of the solidified layer width is lower than 20μm, the required focused spot size is very small, which is extremely difficult to achieve in industrial production; when the upper limit of the solidified layer width is higher than 100μm, the laser scoring forms a large heat-affected zone, and thermal stress warping will occur during the production process, resulting in defocusing, and the magnetic induction and lamination coefficient of the steel plate will also be significantly reduced. Therefore, in the present invention, the depth of the molten solidified layer in the scoring area can be controlled to be between 8-30μm; the width of the molten solidified layer in the scoring area is 20-100μm.

[0017] The inventors further studied the characteristics of the molten solidified layer formed by the annular spot laser scoring and its correlation with the use characteristics of oriented silicon steel. It was found that the density of the molten solidified layer formed by the annular spot laser scoring is lower than that of the steel plate substrate. Inappropriate process conditions may even form small holes in the molten solidified layer, which causes a certain bulge to form in the scoring area. a When it is higher than 3μm, the lamination coefficient of the silicon steel sheet is significantly reduced and cannot meet the requirements of the wound core processing technology.

[0018] Furthermore, in the heat-resistant magnetic domain refinement type low iron loss oriented silicon steel sheet of the present invention, the central position line roughness R of the notched area is a ≤3μm.

[0019] Exceeding this range may also result in a decrease in the stacking factor of the silicon steel sheet.

[0020] Furthermore, in the heat-resistant magnetic domain refinement type low iron loss oriented silicon steel sheet of the present invention, the thickness of the insulating coating at the central position of the notched area is t c ≥0.2μm, and the thickness of the insulating coating in the non-scratched area is t n The sum satisfies:

[0021] 0.8μm≤t c +t n ≤3.5μm.

[0022] In order to meet the insulation requirements of oriented silicon steel sheets during use, the present invention determines the thickness range of the insulating coating at the notch. c Less than 0.2 μm, and its insulation coating thickness t nWhen the sum is below 0.8μm, the insulation between the oriented silicon steel sheets is poor, and there is a risk of breakdown of the iron core. The thickness of the insulating coating at the center of the notch area is t c Above 0.2μm, but with the insulating coating thickness t in the non-scratched area n When the thickness is above 3.5 μm, the lamination factor of the silicon steel sheet will be reduced. Therefore, the thickness of the insulating coating at the center of the notch area in the present invention is t c The thickness of the insulating coating in the non-scored area is n The sum should satisfy: t c ≥0.2μm; 0.8μm≤t c +t n ≤3.5μm.

[0023] The above-mentioned protrusion height S of the present invention a , Line roughness R a The thickness of the insulating coating at the center of the notch is the average value of the measurement within 100μm in the notch scanning direction. The thickness of the insulating coating in the non-notch area is the thickness of any position within 100μm in the non-notch area. 2 The mean value of the measurements within .

[0024] Furthermore, in the heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet described in the present invention, the spacing between each notched area in the rolling direction is 4-20 mm.

[0025] In order to ensure the effect of notching to refine the magnetic domain, the rolling spacing of the notched area can be controlled to be in the range of 4-20 mm in the present invention. When the rolling spacing of the notched area is less than 4 mm, the magnetic induction caused by notching decreases significantly; when the rolling spacing is greater than 20 mm, the magnetic domain refinement effect of reducing iron loss cannot be achieved.

[0026] Furthermore, the heat-resistant magnetic domain refinement type low iron loss oriented silicon steel sheet of the present invention has an iron loss P of 0.23 mm or less for the oriented silicon steel sheet. 17 / 50 ≤0.74W / kg, its magnetic induction B8≥1.88T.

[0027] Furthermore, the lamination factor of the heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet described in the present invention is ≥95%.

[0028] Correspondingly, another object of the present invention is to provide a low iron loss oriented silicon steel sheet and a method for manufacturing the same, in order to address the problem that the depth of the molten pool is difficult to control and there are defects such as spatter in the previous process of reducing the iron loss of oriented silicon steel sheets by refining the magnetic domains by scoring the molten solidified layer. The method uses a circular focused spot laser scoring to scan and form the steel plate surface in one step, and efficiently achieves the molten solidified layer depth required for reducing the iron loss without generating spatter. The silicon steel sheet has low iron loss, high magnetic induction, and high lamination coefficient, and is particularly suitable for the manufacture of high-efficiency wound core transformers.

[0029] In order to achieve the above object, the present invention provides a laser scoring method for the above-mentioned oriented silicon steel sheet with uniform and good iron loss performance, which uses a laser with an annular spot to perform laser scoring on the surface of the steel sheet.

[0030] Oriented silicon steel can reduce iron loss by refining magnetic domains through notching. Due to the existence 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 an 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 abnormal 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. Reducing the magnetic domain width can reduce P a .

[0031] 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, the 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 0.23 mm and below. a The proportion can reach more than 40%. Therefore, by refining the magnetic domain of oriented silicon steel through scoring, that is, reducing the width of the magnetic domain, the abnormal eddy current loss can be effectively reduced, thereby reducing the overall iron loss of oriented silicon steel.

[0032] The laser scoring method described in the present invention is different from the single-mode or multi-mode laser used in the prior art, and uses an annular focused spot. The single-mode or multi-mode laser used in the prior art concentrates its energy in the central local area. During the scoring process, in order to make the groove or the molten solidified layer reach the depth required for magnetic domain refinement, the laser energy must reach a certain penetration depth, which requires increasing the input laser energy. However, this will cause a large temperature gradient to form in the thickness direction of the steel plate, and the surface temperature is much higher than the melting or even evaporation temperature, thereby 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 decreases, and the plasma and metal droplets re-solidify on the surface near the scoring to form splashes, which reduces the lamination coefficient of the steel plate. After the oriented silicon steel plate is made into an iron core, the splashes may fall off due to the magnetostrictive vibration of the steel plate, and the iron core is at risk of breakdown.

[0033] In order to overcome the problems of low energy penetration depth and residual spatter on the surface during laser scoring, the present invention adopts an annular spot laser scoring method. The central light beam forms a molten pool of a certain depth, and the outer annular light 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 scored area is controllable, and heat-resistant magnetic domain refinement, low iron loss oriented silicon steel can be manufactured.

[0034] Furthermore, in the laser scoring method of the present invention, the total power density of the laser is 16 kW / mm 2 -80kW / mm 2 .

[0035] In the laser scoring method of the present invention, the power density of the annular spot laser can be controlled to be 16 kW / mm 2 and 80kW / mm 2 When the power density of the annular spot laser is lower than the lower limit of 16kW / mm 2 When the power density of the annular spot laser is higher than the upper limit of 80kW / mm, the depth of the molten solidification 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 At the same time, the scratches may cause a significant decrease in magnetic induction and cannot meet the requirements for the manufacture of high-efficiency transformers.

[0036] Furthermore, in the laser scoring method described in the present invention, the energy ratio between the central beam and the outer ring beam of the laser with the annular spot is 1-9.

[0037] In the scoring method of the present invention, the ratio of the energy of the central beam to the energy of the outer annular beam can be controlled to be between 1 and 9, that is, the energy of the central beam accounts for between 50% and 90% of the total energy. When the ratio of the energy of the central beam to the energy of the outer annular beam is lower than 1, the annular beam cannot form a stable constraint effect on the molten pool, and spatter residues are generated in the scoring area during the scoring process; when the ratio is higher than 9, the energy of the annular spot is too high. In order to achieve the laser energy that satisfies the magnetic domain refinement effect, the energy of the central beam and the annular beam must be increased simultaneously. Therefore, the outer annular beam itself will also form a certain amount of melted or even evaporated material, and spatter residues will also be formed.

[0038] Furthermore, in the laser scoring method of the present invention, the diameter a of the annular light spot in the rolling direction is 20-100 μm.

[0039] Furthermore, in the laser scoring method of the present invention, the diameter b of the annular light spot in the laser scoring scanning direction is 1-10 mm.

[0040] The heat-resistant magnetic domain-refined low iron loss oriented silicon steel sheet and the laser scoring method thereof described in the present invention have the following beneficial effects compared with the prior art:

[0041] The laser scoring method described in the present invention adopts annular focused spot laser scoring, which is scanned and formed on the surface of the steel plate once, and effectively reaches the depth of the molten solidification layer required to reduce iron loss without generating splashing materials. The silicon steel sheet has low iron loss, high magnetic induction and high lamination coefficient, and is particularly suitable for the manufacture of high-efficiency wound core transformers.

[0042] The oriented silicon steel sheet prepared by the laser scoring method described in the present invention can form a molten solidified layer with a certain size of scoring, and preferably the protrusion height of the scoring area is low, the molten solidification forms a certain tension effect in the local micro-area, the magnetic domain refinement effect is better, the steel loss of the finished oriented silicon steel is low, and it is particularly suitable for the manufacture of energy-saving wound core transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The schematic diagram of the energy distribution of the annular focused light spot of the heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet described in the present invention is schematically shown.

[0044] Figure 2 The score lines on the steel plate surface of the heat-resistant magnetic domain-refined low iron loss oriented silicon steel sheet of the present invention are schematically shown.

[0045] Figure 3 The notched area and S of the heat-resistant magnetic domain refinement type low iron loss oriented silicon steel sheet according to the present invention are schematically shown. a , R a Measurement area.

[0046] Figure 4 The notched molten solidified layer and the surface insulating coating of the heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet of the present invention are schematically shown. DETAILED DESCRIPTION

[0047] The heat-resistant magnetic domain-refined low iron loss oriented silicon steel sheet and its laser scoring method described in the present invention will be further explained and illustrated below in combination with the accompanying drawings and specific embodiments. However, such explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0048] It should be noted that the laser scoring of the present invention can be performed before decarburization annealing, after decarburization annealing, before final hot stretching and leveling annealing, or before or after final hot stretching and leveling annealing during the manufacturing process of oriented silicon steel.

[0049] The present invention has no special limitation on the use of the laser source. For example, a continuous laser with a wavelength of 1066 nm commonly used in the art may be used, or a pulsed laser may be used.

[0050] The following will use specific example data to further describe the technical solution of the present invention and prove its beneficial effects:

[0051] Examples 1-6 and Comparative Example 1

[0052] The oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 were prepared by the following steps:

[0053] (1) After ironmaking, steelmaking, continuous casting, hot rolling, and then cold rolling to a final thickness of 0.22 mm, its composition is C 0.07%, Si 3.25%, Mn 0.2%, S 0.025%, P 0.05%, Als 0.05%, Cu 0.05%, N 0.008%, and the rest is Fe and inevitable impurities; it should be noted that the present invention does not improve the steel composition, so the composition is only an illustrative specific example, and is not intended to limit the present invention. The present invention can also be implemented by using other composition ratios;

[0054] (2) After a decarburization annealing process at 850°C to form a surface oxide layer, a MgO separator is coated on the surface and the steel is rolled into a steel coil;

[0055] (3) After being rolled into a steel coil, it is kept under high temperature annealing conditions of 1200°C for 20 hours;

[0056] (4) cleaning the unreacted residual MgO on the surface and drying;

[0057] (5) Scanning the steel plate surface in the transverse direction with an annular spot laser to perform laser scribing (specific laser scribing process parameters are listed in Table 1);

[0058] In Example 1-6, a continuous single-mode laser with a wavelength of 1066 nm is modulated by an optical fiber to form a ring laser, which is transmitted to a laser head, and after passing through a focusing mirror and a scanning mirror, a ring 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 each scoring area is formed by scanning along the horizontal direction of the steel plate, and the spacing between adjacent scoring areas in the rolling direction is 5 mm. Figure 1 The energy distribution diagram of the annular focused light spot of the heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet of the present invention is schematically shown.

[0059] (6) Finally, after applying the insulating coating on the steel sheet surface, final annealing is performed to maintain the coating thickness t at the center of the notched area. c The coating thickness in the non-scratched area is 0.5 μm. n is 1.0μm.

[0060] Figure 2The figure schematically shows the score lines on the steel plate surface of the heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet of the present invention.

[0061] like Figure 2 As shown, 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.

[0062] Figure 3 A notch area and Sa and Ra measurement areas of the heat-resistant magnetic domain refinement type low iron loss oriented silicon steel sheet of the present invention are schematically shown.

[0063] like Figure 3 As shown, the protrusion height S a , Line roughness R a The thickness of the insulating coating at the center of the notch is the average value of the measurement within 100μm in the notch scanning direction. The thickness of the insulating coating in the non-notch area is the thickness of any position within 100μm in the non-notch area. 2 The mean value of the measurements within .

[0064] Figure 4 The molten solidified layer 21 in the notched area and the surface insulating coating 3 of the heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet according to the present invention are schematically shown. Figure 4 The “P” in the figure indicates the center position of the notched area.

[0065] Different from the above embodiments 1-6, comparative example 1 uses a commonly used single-mode high-power continuous laser and does not use optical fiber to modulate the annular spot.

[0066] For the oriented silicon steel sheets of Examples 1-6 and Comparative Example 1, magnetic conductivity (B8) and iron loss (P 17 / 50 ) test, specifically, the Epstein method is used to test the magnetic flux density of oriented silicon steel under an excitation magnetic field of 800A / m, and the B8 value is obtained, 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, and the P is obtained. 17 / 50 Value, the unit parameter is W / kg.

[0067] Accordingly, after the notching was completed, the stacking coefficients of the oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 were also tested, and the method described in GB / T 19289-2003 "Measurement Method for Density, Resistivity and Stacking Coefficient of Electrical Steel Sheets (Strips)" was specifically adopted to measure the stacking coefficients of the final oriented silicon steel sheets of Examples and Comparative Example after notching. The oriented silicon steel sheets of Examples 1-6 and Comparative Example 1 tested after notching are listed in Table 1.

[0068] Table 1.

[0069]

[0070] It can be seen from Table 1 that, in Examples 1-6 implemented by the present invention, for an oriented silicon steel sheet with a thickness of 0.22 mm, the iron loss P 17 / 50 The magnetic induction B8 is greater than 1.89T, and the lamination coefficient is greater than 95%. This proves that the oriented silicon steel sheet with low iron loss, high magnetic induction and high lamination coefficient can be obtained by adopting the present invention.

[0071] However, in Comparative Example 1, the annular spot laser scoring described in the present invention is not adopted, and the protrusion height and line roughness of the melt solidification zone in the scoring area are significantly higher than those of the present invention, and the lamination coefficient is low.

[0072] Examples 7-12 and Comparative Example 2

[0073] The oriented silicon steel sheets of Examples 7-12 and Comparative Example 2 were prepared by the following steps:

[0074] (1) After ironmaking, steelmaking, continuous casting, hot rolling, and then cold rolling to a final thickness of 0.19 mm, the composition is C 0.06%, Si 3.45%, Mn 0.1%, S 0.025%, P 0.05%, Als 0.027%, Cu 0.2%, N 0.008%, and the rest is Fe and inevitable impurities; it should be noted that the present invention does not improve the steel composition, so the composition is only an illustrative specific example, and is not intended to limit the present invention. The present invention can also be implemented by using other composition ratios;

[0075] (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 in the transverse direction to perform laser scoring (specific laser scoring process parameters are listed in Table 2);

[0076] In Examples 7-12, a continuous single-mode laser with a wavelength of 1066 nm is modulated by an optical fiber to form a ring laser, which is transmitted to a laser head and forms a ring spot on the surface of the steel plate after passing through a focusing mirror and a scanning mirror. The laser output power and the energy ratio of the central beam and the outer ring beam are adjusted, and each scoring area is formed by scanning along the horizontal direction of the steel plate. The spacing between adjacent scoring areas in the rolling direction is 6 mm.

[0077] (3) After a decarburization annealing process at 850°C, a surface oxide layer is formed, and then a MgO separator is coated on the surface, and the steel is rolled into a steel coil;

[0078] (4) After being rolled into a steel coil, it is kept under high temperature annealing conditions of 1200°C for 20 hours;

[0079] (5) After cleaning the unreacted residual MgO on the surface and drying it, an insulating coating is applied to the steel sheet surface and a final annealing is performed, maintaining the coating thickness t at the center of the notched area. c The coating thickness in the non-scratched area is 0.3 μm. n is 1.0μm.

[0080] After notching, the oriented silicon steel sheets of Examples 7-12 and Comparative Example 2 were further tested for magnetic conductivity (B8) and iron loss (P 17 / 50 ) test, specifically, the Epstein method is used to test the magnetic flux density of oriented silicon steel under an excitation magnetic field of 800A / m, and the B8 value is obtained, 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, and the P is obtained. 17 / 50 Value, the unit parameter is W / kg.

[0081] Accordingly, after the notching was completed, the stacking coefficients of the oriented silicon steel sheets of Examples 7-12 and Comparative Examples 9-16 were also tested, and the method described in GB / T 19289-2003 "Measurement Method for Density, Resistivity and Stacking Coefficient of Electrical Steel Sheets (Strips)" was specifically adopted to measure the stacking coefficients of the final oriented silicon steel sheets of the embodiments and comparative examples after notching. The oriented silicon steel sheets of the relevant embodiments 7-12 and comparative example 2 after notching are listed in Table 2.

[0082] Table 2.

[0083]

[0084] It can be seen from Table 1 that in Examples 7 to 12 of the present invention, for oriented silicon steel sheets with a thickness of 0.19 mm, the iron loss P 17 / 50 All of them are less than or equal to 0.704W / kg, their magnetic induction B8 are greater than 1.89T, and their stacking coefficients are greater than or equal to 95%, so that oriented silicon steel sheets with low iron loss and high stacking coefficient performance can be obtained.

[0085] However, in Comparative Example 2, the annular spot laser scoring described in the present invention was not adopted, and the protrusions and line roughness formed by the scoring were significantly higher, and the stacking 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 ironmaking, steelmaking, continuous casting, hot rolling, and then cold rolling to a final thickness of 0.225 mm, its composition is C 0.045%, Si 3.25%, Mn 0.2%, S 0.015%, Als 0.025%, Cu 0.07%, N 0.008%, and the rest is Fe and inevitable impurities; it should be noted that the present invention does not improve the steel composition, so the composition is only an illustrative specific example, and is not intended to limit the present invention. The present invention can also be implemented by using other composition ratios;

[0089] (2) After a decarburization annealing process at 860°C, a surface oxide layer is formed and then a MgO separator is coated on the surface;

[0090] (3) After being rolled into a steel coil, it is kept under high temperature annealing conditions of 1200°C for 20 hours;

[0091] (4) cleaning the unreacted residual MgO on the surface and drying;

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

[0093] In Examples 13-16 and Comparative Examples 3-4, a continuous single-mode laser with a wavelength of 1066nm is modulated through optical fiber to form a ring laser, which is transmitted to the laser head. After passing through a focusing mirror and a scanning mirror, a ring spot is formed on the surface of the steel plate. The laser output power and the energy ratio of the central light beam and the outer ring light beam are adjusted, and each scoring area is formed by scanning along the transverse direction of the steel plate. The spacing between adjacent scoring areas in the rolling direction is 5mm.

[0094] (6) Finally, after the insulating coating is applied on the surface of the steel plate, final annealing is performed. The specific parameters of applying the insulating coating are listed in Table 4.

[0095] Table 3.

[0096]

[0097] The inventors further measured the magnetic conductivity (B8) and iron loss (P 17 / 50 ) test, specifically, the Epstein method is used to test the magnetic flux density of oriented silicon steel under an excitation magnetic field of 800A / m, and the B8 value is obtained, 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, and the P is obtained. 17 / 50 Value, the unit parameter is W / kg.

[0098] Correspondingly, after completing the notching, the stacking coefficients of the oriented silicon steel sheets of Examples 13-16 and Comparative Examples 3-5 were also tested, specifically using the method described in GB / T 19289-2003 "Measurement method for density, resistivity and stacking coefficient of electrical steel sheets (strips)" to measure the stacking coefficients of the final finished plates of the embodiments and comparative examples after notching.

[0099] In addition, the insulation properties of Examples 13-16 and Comparative Examples 3-5 coated with insulating coatings were evaluated, and the method was based on GB / T 2522-2007 Test Method for Surface Insulation Resistance and Coating Adhesion of Electrical Steel Sheets (Strips), and the average interlayer resistance of the double-sided coating was used as the basis. For samples with an average interlayer resistance of ≤30Ω·m, it was determined that the insulation properties were poor and recorded as "×", and the transformer core made of them had a breakdown risk during service; for samples with an average interlayer resistance of >30Ω·m, it was determined that the insulation properties were good and recorded as "○", which could meet the needs of manufacturing energy-saving transformer cores.

[0100] The above test results are listed in Table 4.

[0101] Table 4.

[0102]

[0103]

[0104] It can be seen from Table 4 that the thickness of the insulating coating of Examples 13-16 is within the required range of the preferred embodiment of the present invention, so the insulation effect is good and the lamination factor is high.

[0105] However, the thickness of the insulating coatings in Comparative Examples 3 and 4 does not meet the requirements of the preferred embodiment of the present invention, so the insulation effect is relatively poor, and there are safety risks during the service of the transformer.

[0106] The sum of the coating thicknesses of Comparative Example 3 exceeds the required range of the present invention, resulting in a lower stacking factor of the finished product than that of the preferred embodiment of the present invention.

[0107] It should be noted that the prior art in the protection scope of the present invention is not limited to the embodiments given in the present application documents. All prior art that does not contradict the scheme of the present invention, including but not limited to prior patent documents, prior public publications, prior public uses, etc., can be included in the protection scope of the present invention.

[0108] In addition, the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0109] It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with the contents disclosed by those skilled in the art from the present invention, and all should belong to the protection scope of the present invention.

Claims

1. A heat-resistant magnetic domain-refined low iron loss oriented silicon steel sheet, the surface of which has a scoring area formed by laser scoring; characterized in that: The depth of the melt-solidified layer in the notched area is between 8 and 30 μm; the width of the melt-solidified layer in the notched area is between 20 and 100 μm; the height S of the surface protrusion in the notched area is a ≤3μm.

2. The heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet according to claim 1, characterized in that: The line roughness R at the center of the notch area a ≤3μm.

3. The heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet according to claim 1, characterized in that: The thickness of the insulating coating at the center of the notch area is t c ≥0.2μm, and the thickness of the insulating coating in the non-scratched area is t n The sum satisfies: 0.8μm≤t c +t n ≤3.5μm。 4. The heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet according to claim 1, characterized in that: The spacing between the notched areas in the rolling direction is 4-20 mm.

5. The heat-resistant magnetic domain refined low iron loss oriented silicon steel sheet according to claim 1, characterized in that: Its lamination coefficient is ≥95%.

6. A laser scoring method for the heat-resistant magnetic domain-refined low iron loss oriented silicon steel sheet as claimed in any one of claims 1 to 5, characterized in that: Laser scoring is performed on the surface of a steel plate using a laser with an annular spot.

7. The laser scoring method according to claim 6, characterized in that: The total power density of the laser is 16 kW / mm 2 -80kW / mm 2 .

8. The laser scoring method according to claim 6, wherein: The energy ratio between the central light beam and the outer ring light beam of the laser with the annular light spot is 1-9.

9. The laser scoring method according to claim 6, wherein: The diameter a of the annular light spot in the rolling direction is 20-100 μm.

10. The laser scoring method according to claim 6, characterized in that: The diameter b of the annular light spot in the laser scoring scanning direction is 1-10 mm.

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