A production method for preparing low noise and low iron loss oriented silicon steel by using secondary cold rolling

Abstract

The application discloses a production method for preparing low-noise and low-iron-loss oriented silicon steel by using secondary cold rolling, and comprises the following steps: S1, hot rolling a continuous casting billet to obtain a hot-rolled plate; S2, normalizing the hot-rolled plate to obtain a hot-rolled normalized plate; S3, cold rolling the hot-rolled normalized plate to obtain a primary cold-rolled plate; S4, feeding the primary cold-rolled plate into an annealing furnace for intermediate annealing to obtain an intermediate annealed plate; S5, cold rolling the intermediate annealed plate to obtain a secondary cold-rolled plate; S6, feeding the secondary cold-rolled plate into the annealing furnace for decarburization treatment to obtain a decarburized annealed plate; S7, uniformly coating the decarburized annealed plate with MgO release agent on one side or on both sides; S8, coiling the steel plate coated with the release agent and carrying out high-temperature annealing to obtain a high-temperature annealed plate; S9, pickling the high-temperature annealed plate and coating the same with an insulating coating; and S10, finely processing the steel plate coated with the insulating coating by on-line laser marking to obtain finished oriented silicon steel.

Description

Technical Field

[0001] This invention belongs to the field of grain-oriented silicon steel production technology, specifically relating to a production method for preparing low-noise, low-iron-loss grain-oriented silicon steel using secondary cold rolling. Background Technology

[0002] Grain-oriented silicon steel is a core soft magnetic material for power equipment such as transformers, reactors, and large motors. Its iron loss level directly determines the energy consumption of the equipment, while its plate shape quality and magnetic domain uniformity directly determine the level of operating noise. As power grids and new energy equipment upgrade towards high efficiency and low noise, there are dual requirements for grain-oriented silicon steel: low iron loss and low noise.

[0003] Chinese patent CN117737375A discloses a method for preparing thin-gauge oriented silicon steel, which uses thin slab continuous casting and rolling and secondary cold rolling processes. Although it can obtain products with high magnetic induction and low iron loss, the process has high precision requirements for continuous casting, hot rolling and cold rolling equipment, the process control is difficult, the mass production stability is insufficient, and the texture and magnetic domain orientation control is not carried out for the low noise requirement, so the noise reduction effect is limited.

[0004] Chinese patent CN105220071A discloses a low-noise grain-oriented silicon steel technology that reduces noise by controlling the Cu / S ratio and coating tension. However, it relies on a specific composition system and high-precision coating control, resulting in high costs. Furthermore, it only optimizes the coating and grain size without improving the plate shape and stress distribution from the rolling source, thus limiting the noise reduction and making it difficult to balance high magnetic induction and low iron loss.

[0005] In summary, existing technologies often suffer from high equipment requirements, complex composition, high cost, limited noise reduction, and difficulty in simultaneously achieving the requirements of low noise, high magnetic induction, and low iron loss, and therefore require improvement. Summary of the Invention

[0006] To address all or part of the aforementioned problems, the present invention aims to provide a production method for preparing low-noise, low-iron-loss oriented silicon steel using secondary cold rolling. This method optimizes the plate shape, achieves uniform microstructure, and perfects the Gaussian texture from the rolling source, eliminating the need for complex alloys and high-precision equipment. It is compatible with existing production lines and simultaneously achieves low noise, low iron loss, high magnetic induction, and high plate shape quality.

[0007] This invention provides a method for producing low-noise, low-iron-loss grain-oriented silicon steel using secondary cold rolling, comprising the following steps: S1, hot rolling of the continuously cast billet to obtain hot-rolled plate; S2, normalizing the hot-rolled plate to obtain a normalized hot-rolled plate; S3, cold rolling is performed on hot-rolled normalized plate to obtain primary cold-rolled plate; S4, the cold-rolled plate is fed into the annealing furnace for intermediate annealing to obtain an intermediate annealed plate; The annealing temperature is 820-860℃, the holding time is 6-10 min, and the atmosphere is a mixture of 15%-25% hydrogen and nitrogen. S5, cold rolling the intermediate annealed plate to obtain a secondary cold-rolled plate; S6, the secondary cold-rolled plate is sent into the annealing furnace for decarburization treatment to obtain a decarburized annealed plate; S7, uniformly coat one or both sides of the decarburized annealed plate with MgO release agent; S8, the steel plate coated with release agent is rolled up and subjected to high-temperature annealing to obtain a high-temperature annealed plate; S9, pickling and coating the high-temperature annealed plate with an insulating coating; S10 is a fine-grained online laser marking process for steel plates coated with insulating coatings to obtain finished grain-oriented silicon steel.

[0008] Optionally, in S1, conventional oriented silicon steel continuous casting billets are selected and heated to 1260-1350℃, with a hot rolling final rolling temperature of 920-960℃ and a coiling temperature of 550-650℃.

[0009] Optionally, in S2, the normalization temperature is 850–950℃ and the holding time is 2–4 min.

[0010] Optionally, in S3, the hot-rolled normalized plate is rolled in multiple passes with a total reduction of 60%-70%, rolled to an intermediate thickness of 0.60-0.70 mm, a first pass reduction of 25%-35%, a last pass reduction of 20%-25%, and a rolling speed of 300-600 m / min.

[0011] Optionally, in S5, the intermediate annealed plate is rolled in multiple passes with a total reduction of 55%-60%, a final flatness I-unit ≤ 5I, and a transverse thickness tolerance ≤ ±1μm.

[0012] Optionally, in S6, the decarbonization treatment temperature is 820-860℃, the holding time is 2-4 minutes, and the atmosphere inside the furnace is a humidified wet hydrogen atmosphere.

[0013] Optionally, in S7, the uniformity deviation of the MgO release agent coating thickness is ≤ ±1 μm.

[0014] Optionally, in S8, during the high-temperature annealing process, purification and recrystallization are carried out in the heating section, and the furnace is held at a high-temperature platform of 1100-1150℃ for 10-15 hours, while controlling the oxygen potential inside the furnace to be maintained at 10. -18 -10 -16 Pa.

[0015] Optionally, in S9, the plate surface is lightly acid-washed for 1-2 minutes using a 2-3% dilute nitric acid solution. After acid washing, it is rinsed clean with deionized water. Then, an insulating coating is applied to the bottom surface of the steel plate and cured at 200-250°C for 10-15 minutes.

[0016] Optionally, in S10, a high-power fiber laser is used to uniformly and directionally score the coating surface of the steel plate. The scoring mode is continuous parallel straight line scoring, and the scoring process parameters are as follows: The laser power is 80-120W, the scanning speed is 1500-2500mm / s, the scribe spacing is 3-6mm, the scribe depth is 5-15μm, and the scribe width is 20-40μm. The scribe is uniform throughout the process, without any breaks, overlaps, ablation, overheating, or coating peeling defects.

[0017] As can be seen from the above technical solution, the production method for preparing low-noise, low-iron-loss grain-oriented silicon steel using secondary cold rolling provided by the present invention has the following advantages: This production method optimizes the plate shape, uniform structure, and perfects the Gaussian texture from the rolling source. It does not require complex alloys and high-precision equipment, is compatible with existing production lines, and simultaneously achieves low noise, low iron loss, high magnetic induction, and high plate shape quality, thereby improving product quality.

[0018] Other features and advantages of the present invention will be set forth in the following description. Attached Figure Description

[0019] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0020] Figure 1 This is a flowchart of the production method in an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be arbitrarily combined with each other.

[0022] like Figure 1 The illustration shows an embodiment of the present invention, which discloses a method for producing low-noise, low-iron-loss grain-oriented silicon steel using secondary cold rolling, comprising the following steps: S1, hot rolling of continuously cast billets to obtain hot-rolled plates.

[0023] S2, normalizing the hot-rolled plate to obtain a normalized hot-rolled plate.

[0024] S3 involves cold rolling a hot-rolled normalized plate to obtain a primary cold-rolled plate.

[0025] S4, the cold-rolled plate is fed into the annealing furnace for intermediate annealing to obtain an intermediate annealed plate.

[0026] S5, cold rolling the intermediate annealed plate to obtain a secondary cold-rolled plate.

[0027] S6, the secondary cold-rolled plate is sent into the annealing furnace for decarburization treatment to obtain a decarburized annealed plate.

[0028] S7, uniformly coat one or both sides of the decarburized annealed plate with MgO release agent.

[0029] S8, the steel sheet coated with release agent is rolled up and subjected to high-temperature annealing to obtain a high-temperature annealed plate.

[0030] S9 involves pickling the high-temperature annealed plate and applying an insulating coating.

[0031] S10 is a fine-grained online laser marking process for steel plates coated with insulating coatings to obtain finished grain-oriented silicon steel.

[0032] The production method in this embodiment aims to overcome the shortcomings of existing single-stage cold rolling processes. It employs a synergistic control of secondary cold rolling and intermediate annealing. Secondary cold rolling significantly improves sheet flatness, reduces lamination gaps and vibration noise, meeting low-noise requirements. Simultaneously, it optimizes the initial recrystallization structure and Gaussian texture perfection, reducing hysteresis and eddy current losses to achieve low iron loss. Furthermore, this production method is compatible with existing production lines without adding new core equipment, balancing industrial feasibility, production efficiency, and economy. It improves surface quality and thickness uniformity, enhances the consistency of subsequent coatings and scoring, and comprehensively improves product stability and market competitiveness.

[0033] In S1, conventional grain-oriented silicon steel continuous casting billets are selected and heated to 1260-1350℃ to ensure that the alloying elements are fully dissolved. During the hot rolling process, the final rolling temperature is controlled at 920-960℃, and the coiling temperature is set at 550-650℃.

[0034] In S2, during the normalizing process, the normalizing temperature is controlled at 850-950℃ and held for 2-4 minutes to obtain a hot-rolled normalized plate with uniform structure and dispersed precipitation.

[0035] In S3, hot-rolled normalized plates undergo a single cold rolling process after pickling to thoroughly remove surface iron oxide scale. The hot-rolled normalized plates are rolled in multiple passes with a total reduction of 60%-70%, rolling to an intermediate thickness of 0.60-0.70 mm. Simultaneously, during the single cold rolling process, the first pass reduction is controlled at 25%-35%, the last pass at 20%-25%, and the rolling speed at 300-600 m / min to control plate shape deviations and prevent edge or center waviness defects.

[0036] In S4, after one cold rolling, the steel sheet is in a high-distortion energy storage state and then enters a continuous annealing furnace for intermediate annealing. During the annealing process, the annealing temperature is controlled at 820-860℃ and held for 6-10 minutes, with an atmosphere of 15%-25% hydrogen and nitrogen mixture.

[0037] In S5, after the intermediate annealed plate undergoes online electrolytic cleaning to remove surface residues, it is subjected to a crucial secondary cold rolling process. The intermediate annealed plate is rolled in multiple passes with a total reduction rate of 55%-60%, precisely rolling the plate thickness to the target finished thickness of 0.20-0.30 mm. During the secondary cold rolling process, a low-reduction-rate, multi-pass precision rolling mode is adopted, strictly controlling the rolling speed gradient of each pass. This is combined with fine adjustment of the work roll crown within the range of 0.10-0.20 mm, focusing on ensuring the quality of the plate shape and ensuring that the final plate flatness I-unit ≤ 5I and the transverse thickness tolerance ≤ ±1 μm.

[0038] In S6, during the decarburization process, the decarburization temperature is controlled at 820-860℃, and the holding time is 2-4 minutes, with the furnace atmosphere being a humidified wet hydrogen atmosphere. By precisely controlling the atmosphere dew point, a redox reaction occurs on the steel plate surface, removing the carbon content from the steel to below 30ppm. Simultaneously, the initial recrystallization process is completed inside the steel plate, forming appropriately sized and uniformly distributed inhibitor particles, preparing for subsequent secondary recrystallization.

[0039] In S7, the decarburized annealed steel plate is uniformly coated with high-purity MgO release agent on one or both sides, and the coating thickness is strictly controlled to ensure that the uniformity deviation is ≤±1μm.

[0040] In S8, high-temperature annealing employs a complex segmented temperature control curve. First, purification and recrystallization occur in the heating phase, followed by holding at a high-temperature plateau of 1100-1150℃ for 10-15 hours, during which the oxygen potential inside the furnace is strictly controlled to remain at 10%. -18 -10 -16 Extremely low Pa levels are used to ensure optimal secondary recrystallization growth and the formation of a uniform and dense glass film substrate.

[0041] In S9, a magnesium silicate underlayer is formed on the surface of the high-temperature annealed steel plate, with unreacted free MgO adhering to it. The plate surface is first lightly acid-washed with a 2-3% dilute nitric acid solution for 1-2 minutes to remove the free MgO, and then rinsed thoroughly with deionized water. Subsequently, an insulating coating is applied to the underlayer surface of the steel plate, and a curing treatment is performed at 200-250℃ for 10-15 minutes to form a uniform, insulating surface coating with tensile stress. Its uniformity directly depends on the smoothness and uniformity of the underlayer.

[0042] In S10, a high-power fiber laser is used to uniformly and directionally score the coating surface of the steel plate. The scoring mode is continuous parallel straight line scoring, and the scoring process parameters are as follows: The laser power is 80-120W, the scanning speed is 1500-2500mm / s, the scribe spacing is 3-6mm, the scribe depth is 5-15μm, and the scribe width is 20-40μm. The scribe is uniform throughout the process, without any breaks, overlaps, ablation, overheating, or coating peeling defects.

[0043] As described above, this production method, through secondary cold rolling precision leveling, improves the flatness of the sheet to ≤5I and the lamination factor to ≥0.98, significantly reducing air gaps and vibrations between core laminations. Actual operating noise is reduced by 3-6 dB(A) compared to conventional products, perfectly meeting the stringent requirements of high-end silent transformers and precision electrical components. Simultaneously, secondary cold rolling promotes the perfection and sharpening of the Gaussian texture, effectively reducing hysteresis and eddy current losses, significantly improving transformer energy efficiency, and demonstrating outstanding energy-saving and emission-reduction benefits throughout its entire life cycle.

[0044] In addition, this production method relies on multi-pass precision rolling and roll shape control, with the transverse thickness difference strictly controlled within ≤±1μm, and there are no edge or center defects. The extremely high dimensional consistency greatly improves the downstream cutting utilization rate and ensures the uniformity of subsequent laser marking and coating treatment.

[0045] Furthermore, this production method requires no additional expensive smelting or rolling equipment; it can be achieved simply by adjusting existing process parameters. This method boasts a high yield rate and strong production stability, adding high value to products without increasing extra investment costs, resulting in outstanding market competitiveness.

[0046] The present invention is further illustrated below by way of embodiments, but the present invention is not limited to the scope of the embodiments described herein, and the experimental methods in the following embodiments that do not specify specific conditions are in accordance with conventional methods and conditions.

[0047] Example 1 S1, the continuously cast billet is heated to 1280℃ and held for 2 hours, and then hot-rolled to obtain a 2.3mm thick hot-rolled plate.

[0048] S2, hot-rolled plate is normalized at 900℃ for 3 minutes to obtain hot-rolled normalized plate.

[0049] S3, hot-rolled normalized steel plate undergoes pickling followed by a five-pass single cold rolling process. During this single cold rolling process, the thickness is sequentially reduced from 2.30mm to 1.60mm, 1.60mm to 1.10mm, 1.10mm to 0.85mm, 0.85mm to 0.74mm, and 0.74mm to 0.68mm to obtain a single cold-rolled plate. Simultaneously, the reduction rates for each pass during the single cold rolling process are 30.4%, 31.3%, 22.7%, 12.9%, and 8.1%, respectively, with rolling speeds of 320m / min, 420m / min, 480m / min, 520m / min, and 400m / min, respectively. The total reduction rate for the single cold rolling is 67.0%, and the inlet tension is controlled at 10kg / mm². 2 Outlet tension 20 kg / mm 2 The emulsion provides cooling and lubrication, resulting in no obvious waviness defects in the rolled steel strip.

[0050] S4. The cold-rolled sheet is fed into an annealing furnace for intermediate annealing to obtain an intermediate annealed sheet. During the annealing process, the annealing temperature is controlled at 840℃ and held for 8 minutes. The atmosphere is 25% hydrogen by volume, with the remainder being nitrogen, to achieve complete recrystallization and eliminate internal stress.

[0051] S5, after intermediate annealing and electrolytic cleaning, undergoes four-pass secondary cold rolling precision rolling. The work roll crown of the mill is 0.14mm. During the secondary cold rolling process, the thickness is sequentially rolled from 0.68mm to 0.44mm, 0.44mm to 0.33mm, 0.33mm to 0.27mm, and 0.27mm to 0.23mm to obtain the secondary cold-rolled plate. Simultaneously, during the secondary cold rolling process, the reduction rates for each pass are 35.3%, 25.0%, 18.2%, and 14.8%, respectively, and the rolling speeds are 260m / min, 300m / min, 340m / min, and 280m / min, respectively. The total reduction rate of the secondary cold rolling is 66.2%. Closed-loop shape control is activated, and the post-rolling plate flatness is 4.2I, with a transverse thickness difference of ±0.8μm.

[0052] S6, the secondary cold-rolled plate is decarburized and annealed at 850℃ for 3 minutes, and the carbon in the steel is reduced to below 28ppm in a wet hydrogen atmosphere to obtain the decarburized annealed plate.

[0053] S7. Coat both sides of the decarburized annealed plate with MgO release agent evenly, and ensure a uniform deviation of 0.5μm.

[0054] S8, the steel plate coated with the release agent is rolled up and held at 1120℃ for 12 hours, while the oxygen potential inside the furnace is maintained at 10. -17 Pa level, to obtain high-temperature annealed plates.

[0055] S9, high-temperature annealed board is lightly acid-washed with 2.5% dilute nitric acid and cured with phosphate insulation coating at 230℃ for 12 minutes.

[0056] S10 is used for online laser marking refinement of steel plates coated with insulating coating, and the marking process parameters are controlled as follows: laser power 100W, scanning speed 2000mm / s, marking spacing 4mm, depth 10μm, and width 28μm, in order to obtain finished grain-oriented silicon steel.

[0057] The magnetic properties of the above-mentioned oriented silicon steel sheet were tested and found to be: magnetic induction intensity B800=1.89T, iron loss P1.7 / 50=1.05W / kg, lamination factor 0.982, and transformer simulated noise 42dB(A), which meet the production requirements.

[0058] Example 2 S1, the continuously cast billet is heated to 1300℃ and held for 1.5h, and then hot-rolled to obtain a 2.5mm thick hot-rolled plate.

[0059] S2, hot-rolled plate is normalized at 920℃ for 2.5 minutes to obtain hot-rolled normalized plate.

[0060] S3, hot-rolled normalized steel plate undergoes pickling followed by a five-pass single cold rolling process. During this single cold rolling, the thicknesses are sequentially reduced from 2.50mm to 1.72mm, 1.72mm to 1.21mm, 1.21mm to 0.92mm, 0.92mm to 0.76mm, and 0.76mm to 0.65mm to obtain the single cold-rolled plate. Simultaneously, the reduction rates for each pass during the single cold rolling process are 31.2%, 29.7%, 24.0%, 17.4%, and 14.5%, respectively, with rolling speeds of 300m / min, 400m / min, 460m / min, 500m / min, and 380m / min, respectively. The total reduction rate for the single cold rolling is 74.0%, and the inlet tension is controlled at 10kg / mm². 2 Outlet tension 20 kg / mm 2 The emulsion provides cooling and lubrication, resulting in no obvious waviness defects in the rolled steel strip.

[0061] S4. The cold-rolled sheet is fed into an annealing furnace for intermediate annealing to obtain an intermediate annealed sheet. During the annealing process, the annealing temperature is controlled at 860℃ and held for 6 minutes. The atmosphere is 20% hydrogen by volume, with the remainder being nitrogen, to achieve complete recrystallization and eliminate internal stress.

[0062] S5, after intermediate annealing and electrolytic cleaning, undergoes four-pass secondary cold rolling precision rolling. The work roll crown of the mill is 0.12mm. During the secondary cold rolling process, the rolling thicknesses are sequentially reduced from 0.65mm to 0.45mm, 0.45mm to 0.36mm, 0.36mm to 0.31mm, and 0.31mm to 0.27mm to obtain the secondary cold-rolled plate. Simultaneously, during the secondary cold rolling process, the reduction rates for each pass are 30.8%, 20.0%, 13.9%, and 12.9%, respectively, and the rolling speeds are 240m / min, 280m / min, 320m / min, and 260m / min, respectively. The total reduction rate of the secondary cold rolling is 58.5%. Closed-loop shape control is activated, resulting in a post-rolling plate flatness of 3.8I and a transverse thickness difference of ±0.7μm.

[0063] S6, the secondary cold-rolled plate is decarburized and annealed at 830℃ for 4 minutes, and the carbon in the steel is reduced to below 26ppm in a wet hydrogen atmosphere to obtain the decarburized annealed plate.

[0064] S7. Coat both sides of the decarburized annealed plate with MgO release agent evenly, and ensure a uniform deviation of 0.5μm.

[0065] S8, the steel plate coated with the release agent is rolled up and held at 1130℃ for 10 hours, while the oxygen potential inside the furnace is maintained at 10. -17 Pa level, to obtain high-temperature annealed plates.

[0066] S9, high-temperature annealed board is lightly acid-washed with 2.5% dilute nitric acid and cured with phosphate insulation coating at 220℃ for 14 minutes.

[0067] S10 is used for online laser marking refinement of steel plates coated with insulating coating, and the marking process parameters are controlled as follows: laser power 90W, scanning speed 18000mm / s, marking spacing 5mm, depth 9μm, and width 27μm, in order to obtain finished grain-oriented silicon steel.

[0068] The magnetic properties of the above-mentioned oriented silicon steel sheet were tested and found to be: magnetic induction intensity B800=1.89T, iron loss P1.7 / 50=1.02W / kg, lamination factor 0.984, and transformer simulated noise 41dB(A), which meet the production requirements.

[0069] Comparative Example 1 The continuously cast billet was heated to 1280℃ and held for 2 hours, then hot-rolled to obtain a 2.3mm hot-rolled plate. After normalizing, the hot-rolled plate was directly cold-rolled in five passes to a finished thickness of 0.23mm, with a total reduction rate of 90.0%. No intermediate annealing or secondary cold rolling process was performed. Subsequently, it was decarburized and annealed at 850℃ for 3 minutes in a 25% hydrogen atmosphere, coated with MgO, and then subjected to high-temperature annealing. The pickling, insulating coating, and laser marking process parameters were the same as in Example 1.

[0070] The magnetic properties of the above-mentioned oriented silicon steel sheet were tested and found to be: magnetic induction intensity B800=1.90T, iron loss P1.7 / 50=1.18W / kg, flatness of the sheet 11I, transverse thickness difference ±2.2μm, stacking factor 0.963, and noise 47dB(A), which do not meet the production requirements.

[0071] Comparative Example 2 The continuously cast billet was heated to 1280℃ and held for 2 hours, then hot-rolled to obtain a 2.3mm hot-rolled plate. After normalizing, the hot-rolled plate was directly cold-rolled to 0.23mm in a single pass, without intermediate annealing or a second cold-rolling process. Subsequent decarburization annealing, MgO coating, and high-temperature annealing processes were the same as in Comparative Example 1. After high-temperature annealing, a special high-tensile inorganic coating was used to replace the ordinary phosphate insulating coating, and the pickling and laser marking parameters were consistent with those in Example 1.

[0072] The magnetic properties of the above-mentioned oriented silicon steel sheet were tested and found to be: magnetic induction intensity B800=1.88T, iron loss P1.7 / 50=1.22W / kg, flatness of the sheet 10I, transverse thickness difference ±2.0μm, stacking factor 0.961, and noise 43dB(A), which do not meet the production requirements.

[0073] It should be noted that, unless otherwise stated, the technical or scientific terms used in this invention should have the ordinary meaning as understood by one of ordinary skill in the art.

[0074] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for producing low-noise, low-iron-loss grain-oriented silicon steel using secondary cold rolling, characterized in that, Includes the following steps: S1, hot rolling of the continuously cast billet to obtain hot-rolled plate; S2, normalizing the hot-rolled plate to obtain a normalized hot-rolled plate; S3, cold rolling is performed on hot-rolled normalized plate to obtain primary cold-rolled plate; S4, the cold-rolled plate is fed into the annealing furnace for intermediate annealing to obtain an intermediate annealed plate; The annealing temperature is 820-860℃, the holding time is 6-10 min, and the atmosphere is a mixture of 15%-25% hydrogen and nitrogen. S5, cold rolling the intermediate annealed plate to obtain a secondary cold-rolled plate; S6, the secondary cold-rolled plate is sent into the annealing furnace for decarburization treatment to obtain a decarburized annealed plate; S7, uniformly coat one or both sides of the decarburized annealed plate with MgO release agent; S8, the steel plate coated with release agent is rolled up and subjected to high-temperature annealing to obtain a high-temperature annealed plate; S9, pickling and coating the high-temperature annealed plate with an insulating coating; S10 is a fine-grained online laser marking process for steel plates coated with insulating coatings to obtain finished grain-oriented silicon steel.

2. The production method according to claim 1, characterized in that, In S1, conventional oriented silicon steel continuous casting billets are selected and heated to 1260-1350℃, with a hot rolling final rolling temperature of 920-960℃ and a coiling temperature of 550-650℃.

3. The production method according to claim 1, characterized in that, In S2, the normalization temperature is 850–950℃, and the holding time is 2–4 min.

4. The production method according to claim 1, characterized in that, In S3, hot-rolled normalized plates are rolled in multiple passes with a total reduction of 60%-70%, rolled to an intermediate thickness of 0.60-0.70 mm, a first pass reduction of 25%-35%, a last pass reduction of 20%-25%, and a rolling speed of 300-600 m / min.

5. The production method according to claim 1, characterized in that, In S5, the intermediate annealed plate is rolled in multiple passes with a total reduction of 55%-60%, a final plate flatness I-unit≤5I, and a transverse thickness tolerance≤±1μm.

6. The production method according to claim 1, characterized in that, In S6, the decarbonization treatment temperature is 820-860℃, the holding time is 2-4 minutes, and the atmosphere inside the furnace is a humidified wet hydrogen atmosphere.

7. The production method according to claim 1, characterized in that, In S7, the uniformity deviation of the MgO release agent coating thickness is ≤ ±1 μm.

8. The production method according to claim 1, characterized in that, In S8, during the high-temperature annealing process, purification and recrystallization are carried out in the heating section, and the furnace is held at a high-temperature platform of 1100-1150℃ for 10-15 hours, while maintaining the oxygen potential inside the furnace at 10. -18 -10 -16 Pa.

9. The production method according to claim 1, characterized in that, In S9, the plate surface is lightly acid-washed for 1-2 minutes using a 2-3% dilute nitric acid solution. After acid washing, it is rinsed clean with deionized water. Then, an insulating coating is applied to the bottom surface of the steel plate and cured at 200-250℃ for 10-15 minutes.

10. The production method according to claim 1, characterized in that, In S10, a high-power fiber laser is used to uniformly and directionally score the coating surface of the steel plate. The scoring mode is continuous parallel straight line scoring, and the scoring process parameters are as follows: The laser power is 80-120W, the scanning speed is 1500-2500mm / s, the scribe spacing is 3-6mm, the scribe depth is 5-15μm, and the scribe width is 20-40μm. The scribe is uniform throughout the process, without any breaks, overlaps, ablation, overheating, or coating peeling defects.

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