Magnesium-silicate-bottom-layer-free high-magnetic-induction oriented silicon steel prepared through laser technology and method

Abstract

Magnesium silicate bottom layer-free high-magnetic-induction oriented silicon steel prepared by a laser process comprises the following components in percentage by weight: 0.015 to 0.095 percent of C, 2.50 to 4.50 percent of Si, 0.010 to 0.040 percent of Als, 0.0050 to 0.0100 percent of N, 0.010 to 1.00 percent of Mn, 0.0030 to 0.0300 percent of S, and at least any two of P, Cu, Sn, Sb, Cr and As, wherein the condition that (P + Cu + Sn + Sb + Cr + As) is less than or equal to 1.80 percent is met. The preparation method comprises the following steps: smelting, carrying out vacuum treatment and casting into a blank; heating the casting blank; hot rolling; performing coiling; normalizing is conducted; performing primary cold rolling; carrying out decarburization annealing; nitriding treatment is carried out; coating a conventional high-temperature annealing isolating agent which takes MgO as a main component; performing high-temperature annealing; uncoiling and carrying out laser treatment under a protective atmosphere; and stretching, flattening and annealing. The finished product is excellent in magnetic performance, the magnetic induction B800 is equal to 1.89-1.93 T, the iron loss P17 / 50 is equal to 1.25-1.45 W / kg, the stamping machinability and weldability of the finished product are excellent (no magnesium silicate bottom layer exists on the whole plate surface), the finished product has high magnetic induction performance, and the whole plate surface is smooth and clean (the smoothness of the plate surface can reach 100%).

Description

Technical Field

[0001] The present invention relates to an oriented electrical steel and a production method, and more particularly to a method for preparing a high magnetic induction oriented electrical steel without a magnesium silicate bottom layer by using a laser process. Background Art

[0002] Oriented electrical steel is mainly used as the core of a transformer and is the "heart" material of various power transmission and transformation transformers. It is an important soft magnetic alloy indispensable in the power and electronics industries. The quality grade of oriented electrical steel plays a decisive role in the development of the national power industry. Oriented electrical steel is regarded as an important symbol of the steel manufacturing technology level because of its most complex manufacturing process, high technical content, and high added value. Oriented electrical steel can be divided into ordinary oriented electrical steel (CGO) and high magnetic induction oriented electrical steel (HiB) according to the manufacturing process and magnetic induction. Typically, ordinary oriented electrical steel is the oriented electrical steel developed by the Upper Iset and Novolipetsk Steel Works in Russia, etc., with Cu2S as the main inhibitor. Typically, high magnetic induction oriented electrical steel is the high magnetic induction oriented electrical steel (HiB) with higher magnetic induction and lower iron loss first produced by Nippon Steel using the single large reduction cold rolling method, with AlN as the main and MnS as the auxiliary inhibitor. Later, the Yawata Works of Nippon Steel first proposed not to use the pre-precipitated AlN as an inhibitor before decarburization annealing, that is, not to use the "inherent inhibitor", but to perform nitriding treatment after decarburization annealing to form an inhibitor by N and Als in the steel, that is, to rely on the inhibitor obtained in the subsequent process, which can reduce the slab heating temperature to 1150-1200°C. Energy conservation and environmental protection have become a global trend today. At the same time, with the large-scale power construction in China, the domestic demand for oriented electrical steel is increasing, and there is a huge market space. Therefore, the development of high-performance oriented electrical steel is becoming more and more urgent, and higher magnetic induction and lower iron loss have always been the pursuit and goal of oriented electrical steel production.

[0003] Most domestic and foreign wind power motors, thermal power motors, and nuclear power motors use high-grade non-oriented electrical steel. However, in recent years, with the rapid development of the motor industry, in order to further improve the efficiency of the motor, some users have improved the design and selected high magnetic polarization intensity oriented electrical steel as the main material for the core or other components. At the same time, in addition to meeting excellent electromagnetic performance, in order to meet the requirements of punching processing, it is required that the surface of the oriented electrical steel sheet used for large motors has no magnesium silicate bottom layer. However, when used as the main material for the core, an insulating isolation coating still needs to be applied to meet insulation, adhesion, low surface hardness, etc., and when used for other components, the surface of the steel sheet needs to be completely without a magnesium silicate bottom layer to ensure excellent welding performance. At the same time, the finished product of the magnesium silicate bottom layer-free oriented electrical steel without an insulating coating can be used as the base material for preparing an oriented electrical steel ultra-thin strip with a thickness of 0.03-0.10 mm.

[0004] After retrieval:

[0005] The document with the Chinese patent application number CN109112395A discloses "A non-bottom-layer-oriented ultra-thin strip base material and its preparation method". The raw material components of the base material are C 0.035 - 0.075%, Si 2.8% - 3.4%, Cu 0.20 - 0.45%, Sn 0.1 - 0.2%, Als 0.02% - 0.03%, S 0.015 - 0.03%, Mn 0.04 - 0.08%, N 0.005 - 0.01%, Sb 0.03 - 0.09%, and the balance is Fe. The preparation method includes continuous casting, hot rolling, normalizing, pickling, cold rolling, decarburizing annealing, coating an isolation layer (Al2O3, SiO2, etc.), high-temperature annealing, etc. to obtain a non-magnesium silicate bottom-layer-oriented silicon steel base material that can be directly used for the preparation of oriented silicon steel ultra-thin strips without pickling. Although this document can obtain oriented silicon steel without forming a magnesium silicate bottom layer, due to the inclusion of Al2O3, SiO2, etc. in the isolation coating (which destroys the formation of the magnesium silicate bottom layer), the inhibitor is unstable during the high-temperature annealing process, resulting in unstable magnetic properties of the finished product and it is difficult to obtain a non-magnesium silicate bottom-layer-oriented silicon steel with a smooth surface across the entire plate.

[0006] The document with the Chinese patent application number CN113215374A discloses "A preparation method of non-bottom-layer-oriented silicon steel", which includes production steps such as pickling of hot-rolled billets, cold rolling, decarburizing annealing, coating an isolation agent, high-temperature annealing, stretch leveling, laser removal of the magnesium silicate bottom layer, stress relief annealing, etc. This invention uses the laser method to prepare non-bottom-layer-oriented silicon steel, replacing the traditional method of removing the magnesium silicate bottom layer by acid or adding special additives (Al2O3, SiO2, etc.) in the MgO coating solution. The prepared oriented silicon steel strip has a bright surface and does not contain a magnesium silicate bottom layer. However, this invention does not disclose the manufacturing components and electromagnetic properties of the prepared non-magnesium silicate bottom-layer-oriented silicon steel strip (only the electromagnetic properties of the 0.03 - 0.10 mm thick oriented silicon steel ultra-thin strip prepared using this non-magnesium silicate bottom-layer-oriented silicon steel as the base material), and after laser removal of the magnesium silicate bottom layer, a stress relief annealing process needs to be added. The protective atmosphere for stress relief annealing needs to be heated to 600 - 800 °C, and the protective atmosphere is a mixed gas of hydrogen and nitrogen with a volume ratio of 1 - 3:1, and the flow rate is 3 - 10 Nm 3 / h, and the annealing holding time is 1 - 10 h, which increases the preparation process (and related equipment) and significantly increases the manufacturing cost of non-magnesium silicate bottom-layer-oriented silicon steel.

[0007] It can be seen that in the above-mentioned documents such as CN109112395A, during the process of coating the MgO coating solution in the production process of grain-oriented electrical steel, special additives (such as Al2O3, SiO2, etc.) are added to the MgO coating solution to achieve the effect of removing the magnesium silicate bottom layer. However, such traditional processes for preparing grain-oriented electrical steel without a magnesium silicate bottom layer will cause instability of the inhibitor during high-temperature annealing, resulting in unstable magnetic properties of the finished grain-oriented electrical steel, and it is difficult to obtain grain-oriented electrical steel without a magnesium silicate bottom layer with a smooth surface across the entire plate (it cannot meet the requirements of having no magnesium silicate bottom layer on the surface of some components of large motors and excellent weldability); another type of document such as CN113215374A prepares grain-oriented electrical steel without a bottom layer through a laser method, replacing the traditional method of removing the magnesium silicate bottom layer of grain-oriented electrical steel. However, this invention does not disclose the electromagnetic properties of the grain-oriented electrical steel strip without a magnesium silicate bottom layer, and after laser removal of the magnesium silicate bottom layer, a stress-relieving annealing process needs to be added (the protective atmosphere for stress-relieving annealing needs to be heated to 600 - 800 °C, the protective atmosphere is a mixture of hydrogen and nitrogen with a volume ratio of 1 - 3:1, the flow rate is 3 - 10 Nm 3 / h, and the annealing holding time is 1 - 10 h), resulting in too high manufacturing costs for grain-oriented electrical steel without a magnesium silicate bottom layer. SUMMARY OF THE INVENTION

[0008] The present invention aims to overcome the deficiencies existing in the prior art and provides a grain-oriented electrical steel without a magnesium silicate bottom layer with a high magnetic induction B 800 = 1.89 - 1.93 T, iron loss P 17 / 50 = 1.25 - 1.45 W / kg, excellent stamping processability and weldability for the finished product (no magnesium silicate bottom layer across the entire plate surface), with high magnetic induction performance and a smooth surface across the entire plate (the surface smoothness reaches 100%), and a method for preparing the same using a laser process.

[0009] Measures to achieve the above object:

[0010] A grain-oriented electrical steel without a magnesium silicate bottom layer with a high magnetic induction prepared using a laser process, the components and their weight percentage contents are: C: 0.015 - 0.095%, Si: 2.50 - 4.50%, Als: 0.010 - 0.040%, N: 0.0050 - 0.0100%, Mn: 0.010 - 1.00%, S: 0.0030 - 0.0300%, any at least two of P, Cu, Sn, Sb, Cr, and As and satisfying (P + Cu + Sn + Sb + Cr + As) ≤ 1.80%, and the rest are iron and inevitable impurities.

[0011] A method for preparing a grain-oriented electrical steel without a magnesium silicate bottom layer with a high magnetic induction using a laser, the steps are as follows:

[0012] 1) After smelting, vacuum treatment, and casting into billets;

[0013] 2) Heat the continuous casting billet, and control the heating temperature at 1100 - 1400 °C;

[0014] 3) Conduct hot rolling, control the finish rolling temperature at 850 - 1100 °C, and the thickness of the hot rolled sheet at 2.0 - 2.8 mm;

[0015] 4) Conduct coiling, and control the coiling temperature not exceeding 600 °C;

[0016] 5) Conduct normalizing, control the normalizing temperature at 1000 - 1150 °C, and hold for 30 - 180 s at this temperature;

[0017] 6) Conduct one - pass cold rolling, and perform at least one - pass aging rolling during cold rolling, control the aging temperature at 160 - 250 °C, and the finished product thickness at 0.15 - 0.35 mm;

[0018] 7) Conduct decarburization annealing under a wet protective atmosphere, control the decarburization annealing temperature at 750 - 900 °C, hold for 60 - 180 s at this temperature, the dew point is 25 °C, the protective atmosphere is a mixed gas of wet H₂ and N₂, and the volume content of H₂ is 15 - 80%;

[0019] 8) Conduct nitriding treatment:

[0020] When the heating temperature of the continuous casting billet is not lower than 1260 °C, nitriding is not required;

[0021] When the heating temperature of the continuous casting billet is lower than 1260 °C, nitriding is required. The nitriding atmosphere is a mixed gas of wet H₂, N₂ and NH₃, the volume content of H₂ is 15 - 80%, and control the nitrogen penetration amount at 50 - 350 PPm;

[0022] 9) Coat a conventional high - temperature annealing release agent with MgO as the main component;

[0023] 10) Conduct conventional high - temperature annealing;

[0024] 11) Uncoil and conduct laser treatment under a protective atmosphere:

[0025] Laser treatment parameters: The average power of the continuous laser is 20 - 3500 W; the laser pulse repetition frequency is 1 -

[0026] 160 kHz; the laser pulse width is 1 - 10 ms; the filling line spacing is 0.01 - 0.06 mm; the scanning rate is

[0027] 10 - 8000 mm / s; the focus of the light beam is focused on the surface of the steel plate; the protective gas is nitrogen or argon, and the protective gas flow rate is 1 - 50 L / min;

[0028] 12) Conduct conventional stretch - leveling annealing treatment on the steel strip.

[0029] Preferably, the average power of the continuous laser is 45 - 3420 W.

[0030] Preferably, the repetition frequency of the laser pulses is 8 - 145 kHz.

[0031] Preferably, the pitch of the filler wire is 0.02 - 0.05 mm.

[0032] Preferably, the scanning rate is 20 - 7750 mm / s.

[0033] Preferably, the width of the laser pulse is 1.6 - 9.2 ms.

[0034] Functions and mechanisms of the main processes in the present invention

[0035] The reason why the present invention controls the heating temperature of the slab at 1100°C ≤ ST ≤ 1400°C is to ensure hot rolling within a relatively high temperature range and a relatively high final rolling temperature, so that no large - sized second - phase particles such as AlN precipitate during hot rolling.

[0036] The reason why the present invention controls the normalizing temperature at 1000 - 1150°C and holds at this temperature for 30 - 180 s is to ensure that second - phase particles of AlN with appropriate sizes complete solid solution to form (or form during nitriding treatment) favorable second phases. When normalizing at a temperature lower than 1000°C, since the temperature is low, it is difficult for AlN to solidify; when higher than 1150°C, the grains of the steel strip coarsen, resulting in grain growth after primary recrystallization annealing and increasing costs at the same time.

[0037] The reason why the present invention controls at least one pass of aging rolling at 160 - 250°C during cold rolling is that cold - rolling aging can increase the content of dissolved carbon and nitrogen in the steel. During cold rolling, the dissolved carbon and nitrogen accumulate at dislocations, hinder dislocation movement, change the normal slip system, promote the formation of more transition zones, and form more favorable primary recrystallization texture components after cold rolling and annealing.

[0038] The reason why the present invention controls the decarburizing annealing temperature at 750 - 900°C and holds at this temperature for 60 - 180 s is to complete primary recrystallization, so that there are a sufficient number of

[110] (001) grains (secondary nuclei) in the matrix and a primary recrystallization structure and texture conducive to their growth; to reduce the carbon content in the steel to less than 0.0030% to ensure a single α - phase during subsequent high - temperature annealing; and to form a dense and uniform SiO2 film on the surface of the steel strip.

[0039] When the heating temperature of the continuous casting billet is controlled within the range of 1100 - 1260°C in the present invention, nitriding treatment must be carried out in the subsequent processes. When the heating temperature is within the range of 1260 - 1400°C, nitriding treatment is not required in the subsequent processes. This is because when the heating temperature of the continuous casting billet is within the range of 1100 - 1260°C, only partial solid solution of AlN in the billet can occur. Nitriding treatment must be carried out in the annealing process to increase the content of AlN second-phase particles, ensuring sufficient inhibitory force to obtain a perfect secondary recrystallization structure and texture. When the heating temperature is within the range of 1260 - 1400°C, AlN in the billet can be completely and fully solid-solved. Sufficient amounts of AlN second-phase particles can be obtained in the normalizing and annealing processes of the hot-rolled sheet, ensuring sufficient inhibitory force to obtain a perfect secondary recrystallization structure and texture. Therefore, nitriding treatment is not required.

[0040] The purpose of nitriding treatment is to ensure that there is sufficient nitrogen content in the steel to form AlN and (Si,Al)N, forming a favorable second phase, inhibiting the normal growth of primary grains during high-temperature annealing, and promoting the perfection of secondary recrystallization.

[0041] In the present invention, a high-temperature annealing isolation agent with MgO as the main component is coated, which plays a role in isolating the layers of the steel coil during high-temperature annealing.

[0042] In the present invention, the laser processing parameters are controlled as follows: the average power of the continuous laser is within the range of 20 - 3500 W; the laser pulse repetition frequency is within the range of 1 - 160 kHz; the laser pulse width is within the range of 1 - 10 ms; the filling line spacing is within the range of 0.01 - 0.06 mm; the scanning speed is within the range of 10 - 8000 mm / s; the focus of the light beam is focused on the surface of the steel plate; the protective gas is nitrogen or argon, and the flow rate of the protective gas is within the range of 1 - 50 L / min. Based on the difference in the damage threshold between the magnesium silicate bottom layer and the substrate, the removal of the magnesium silicate bottom layer with low damage and smooth surface on the whole plate of grain-oriented silicon steel is realized through processes such as precise ablation of the magnesium silicate bottom layer by high-energy pulsed laser, rapid scanning by a galvanometer scanner, purging with protective gas, and filtering by a smoke absorber. Its characteristic is that the position of the galvanometer scanner can be adjusted longitudinally, enabling the focus of the light beam to be focused on the surface of the steel plate, achieving high efficiency in removing the magnesium silicate bottom layer, being easy to automate control, and having a smooth surface effect on the whole plate. By carrying out tension leveling annealing treatment on the steel strip, grain-oriented silicon steel with a smooth surface and no magnesium silicate bottom layer and high magnetic induction is obtained.

[0043] However, when the average power of the laser is lower than 20 W, incomplete removal of the underlying magnesium silicate in the final product will occur, and full-surface smoothness cannot be achieved (poor steel plate stamping processability and weldability); when the average power of the laser is higher than 3500 W, local heating of the steel strip will cause plastic deformation, resulting in poor plate shape; when the laser pulse repetition frequency is lower than 1 kHz, incomplete removal of the underlying magnesium silicate in the final product will occur, and full-surface smoothness cannot be achieved (poor steel plate stamping processability and weldability); when the average power of the laser is higher than 160 kHz, local heating of the steel strip will cause plastic deformation, resulting in poor plate shape; when the laser pulse width is lower than 1 ms, incomplete removal of the underlying magnesium silicate in the final product will occur, and full-surface smoothness cannot be achieved (poor steel plate stamping processability and weldability); when the laser pulse width is higher than 10 ms, local heating of the steel strip will cause plastic deformation, resulting in poor plate shape; when the laser pulse filling line spacing is lower than 0.01 mm, local heating of the steel strip will cause plastic deformation, resulting in poor plate shape; when the laser filling line spacing is higher than 0.06 mm, incomplete removal of the underlying magnesium silicate in the final product will occur, and full-surface smoothness cannot be achieved (poor steel plate stamping processability and weldability); when the laser scanning rate is lower than 10 mm / s, incomplete removal of the underlying magnesium silicate in the final product will occur, and full-surface smoothness cannot be achieved (poor steel plate stamping processability and weldability); when the laser scanning rate is higher than 8000 mm / s, local heating of the steel strip will cause plastic deformation, resulting in poor plate shape.

[0044] Compared with the prior art, the finished product of the present invention has excellent magnetic properties, magnetic induction B 800 = 1.89 - 1.93 T, iron loss P 17 / 50 = 1.25 - 1.45 W / kg, excellent stamping processability and weldability of the finished product (no underlying magnesium silicate on the full surface), high magnetic induction performance and full-surface smoothness (surface smoothness can reach 100%). Detailed implementation manners

[0045] The present invention will be described in detail below:

[0046] Table 1 shows the chemical composition lists of each embodiment and comparative example of the present invention;

[0047] Table 2 shows the main process value lists of each embodiment and comparative example of the present invention;

[0048] Table 3 shows the performance test lists of each embodiment and comparative example of the present invention.

[0049] Each embodiment of the present invention is produced according to the following steps:

[0050] 1) After smelting, vacuum treatment, and casting into billets;

[0051] 2) Heating the billets, with the heating temperature controlled at 1100 - 1400 °C;

[0052] 3) Perform hot rolling, control the finish rolling temperature at 850 - 1100 °C, and the thickness of the hot rolled sheet at 2.0 - 2.8 mm;

[0053] 4) Perform coiling, control the coiling temperature not exceeding 600 °C;

[0054] 5) Perform normalizing, control the normalizing temperature at 1000 - 1150 °C, and hold at this temperature for 30 - 180 s;

[0055] 6) Perform first cold rolling, carry out at least one pass of aging rolling during cold rolling, control the aging temperature at 160 - 250 °C, and the finished product thickness at 0.15 - 0.35 mm;

[0056] 7) Carry out decarburization annealing under a wet protective atmosphere, control the decarburization annealing temperature at 750 - 900 °C, and hold at this temperature for 60 - 180 s, with a dew point of 25 °C; the protective atmosphere is a mixed gas of wet H2 and N2, where the volume content of H2 is 15 - 80%;

[0057] 8) Carry out nitriding treatment:

[0058] When the heating temperature of the continuous casting billet is not lower than 1260 °C, nitriding is not required;

[0059] When the heating temperature of the continuous casting billet is lower than 1260 °C, nitriding is required. The nitriding atmosphere is a mixed gas of wet H2, N2 and NH3, where the volume content of H2 is 15 - 80%, and control the amount of infiltrated nitrogen at 50 - 350 PPm;

[0060] 9) Coat with a conventional high - temperature annealing release agent mainly composed of MgO;

[0061] 10) Carry out conventional high - temperature annealing;

[0062] 11) Uncoil and perform laser treatment under a protective atmosphere:

[0063] Laser treatment parameters: the average power of the continuous laser is 20 - 3500 W; the laser pulse repetition frequency is 1 -

[0064] 160 kHz; the laser pulse width is 1 - 10 ms; the filling line spacing is 0.01 - 0.06 mm; the scanning rate is

[0065] 10 - 8000 mm / s; the focus of the light beam is focused on the steel plate surface; the protective gas is nitrogen or argon, and the protective gas flow rate is 1 - 50 L / min;

[0066] 12) Carry out conventional tension leveling annealing treatment on the steel strip.

[0067] Description: The high-temperature annealing release agent is a conventional release agent mainly composed of MgO.

[0068] Table 1 Value list of each example and comparative example of the present invention (wt%)

[0069]

[0070]

[0071] As can be seen from Table 1, in Comparative Example Q1, Als < 0.010%, the Als content is low, the number of AlN precipitates after decarburization (nitriding) decreases, the inhibitory force during high-temperature annealing decreases, and the magnetic properties of the finished product decrease; in Comparative Example Q2, Als > 0.040%, the solubility product of Als and N is high, and it is difficult to completely dissolve during heating at 1100°C to 1400°C, resulting in a decrease in the effective precipitation quantity after decarburization (nitriding), thereby leading to a decrease in the inhibitory force during high-temperature annealing and a decrease in the magnetic properties of the finished product; in Comparative Example Q3, (P + Cu + Sn + Sb + Cr + As) > 1.80%, the content of interface enrichment elements is too high, and the hot-rolled edge cracking is extremely large, making it difficult to carry out production smoothly.

[0072] Table 2 List of main process parameters of each example and comparative example of the present invention

[0073]

[0074]

[0075] Continued Table 2

[0076]

[0077] Description: In Table 2, the protective gas is nitrogen or argon, and the two can be interchanged.

[0078] In Table 2:

[0079] In comparative example Q1, the slab hot rolling heating temperature is less than 1100°C, the final rolling temperature is less than 850°C, AlN cannot be completely dissolved during the heating process, and the final rolling temperature is low, large particles of AlN will be precipitated, and the effective AlN precipitation in the subsequent process will be reduced. The normalization time is less than 30s, small particles of AlN cannot be completely dissolved, and the effective precipitation amount after decarburization (nitriding) is reduced, resulting in reduced inhibition during high-temperature annealing and reduced magnetic properties of the finished product; in comparative example Q2, the slab hot rolling heating temperature is greater than 1400°C, the heating temperature is high, the ingot grain size grows, resulting in the hot-rolled plate and the primary recrystallization annealed plate grain size At the same time, if the heating temperature is too high, the burning loss of the ingot will be aggravated, the yield rate will be reduced, and the normalizing time is greater than 180s. If the normalizing time is too long, the favorable precipitation will be aggregated and coarsened, thereby reducing the inhibition force in the subsequent annealing process. At the same time, if the heating time is too long, the grains of the hot-rolled plate will grow, which will lead to the growth of the grain size of the primary recrystallization annealing plate, the instability of the secondary recrystallization, and the reduction of the magnetic properties of the finished product; in the comparative example Q3, the normalizing temperature is less than 1000℃, and the small particles of AlN in the normalizing are difficult to dissolve, and the number of effective precipitations after decarburization (nitriding) is reduced, which leads to the reduction of inhibition force in high-temperature annealing and the reduction of the magnetic properties of the finished product.

[0080] In comparative example Q1, the average power is less than 20W, the laser pulse repetition frequency is less than 1kHz, the pulse width is less than 1ms, and the scanning rate is less than 10mm / s, resulting in incomplete removal of the magnesium silicate bottom layer of the final product, and the entire plate surface cannot be smooth. The stamping processability and weldability of the steel plate are poor, the filling line spacing is less than 0.01mm, and the steel strip is locally heated to produce plastic deformation, resulting in poor plate shape; in comparative example Q2, the average power is less than 20W, the laser pulse repetition frequency is less than 1kHz, the pulse width is less than 1ms, and the scanning rate is less than 10mm / s, resulting in the removal of the magnesium silicate bottom layer of the final product. It is incomplete, and the entire plate surface cannot be smooth. The stamping processability and weldability of the steel plate are poor. The filling line spacing is less than 0.01mm. Local heating of the steel strip produces plastic deformation, resulting in poor plate shape. In comparative example Q3, the average power is greater than 3500W, the laser pulse repetition frequency is greater than 160kHz, the pulse width is greater than 10ms, and the scanning rate is greater than 8000mm / s. Local heating of the steel strip produces plastic deformation, resulting in poor plate shape. The filling line spacing is greater than 0.06mm. The magnesium silicate bottom layer of the product is not completely removed, and the entire plate surface cannot be smooth. The stamping processability and weldability of the steel plate are poor.

[0081] Table 3 Performance test results of various embodiments of the present invention and comparative examples

[0082]

[0083]

[0084] It can be seen from Table 3 that the magnetic induction B of the finished product in comparative example Q1 is 800 <1.89T, loss P 17 / 50> 1.45 W / kg, there is a residual magnesium silicate bottom layer on the plate surface, the plate shape is poor, and the stamping processability and weldability are poor; the finished product magnetic induction B in Comparative Example Q2 800 < 1.89 T, loss P 17 / 50 > 1.45 W / kg, there is a residual magnesium silicate bottom layer on the plate surface, the plate shape is poor, and the stamping processability and weldability are poor; in Comparative Example Q3, since the sum of (P + Cu + Sn + Sb + Cr + As) > 1.80%, the production process cannot proceed and it is a waste product.

[0085] The specific implementation manners are only the best examples and are not restrictive implementations of the technical solutions of the present invention.

Claims

1. A high magnetic induction oriented silicon steel without magnesium silicate bottom layer prepared by laser process, wherein the components and weight percentage contents are as follows: C: 0.015-0.095%, Si: 2.50-4.50%, Als: 0.010-0.040%, N: 0.0050-0.0100%, Mn: 0.010-1.00%, S: 0.0030-0.0300%, any at least two of P, Cu, Sn, Sb, Cr and As and satisfying (P+ Cu+ Sn+ Sb+ Cr+ As)≤1.80%, and the rest are iron and unavoidable impurities.

2. A method for preparing high magnetic induction oriented silicon steel without magnesium silicate bottom layer by laser process as claimed in claim 1, wherein the steps are as follows: 1) After smelting, vacuum treatment, and casting into billets; 2) Heat the ingot, and control the heating temperature at 1100-1400℃; 3) Hot rolling is performed, the final rolling temperature is controlled at 850-1100°C, and the thickness of the hot rolled plate is 2.0-2.8 mm; 4) Coil the steel sheet and control the coiling temperature not to exceed 600°C; 5) Normalize the product at a temperature of 1000-1150°C and keep the temperature at this temperature for 30-180 seconds; 6) Perform one cold rolling, perform at least one aging rolling in the cold rolling, control the aging temperature at 160-250°C, and the finished product thickness at 0.15-0.35mm; 7) Carry out decarburization annealing under wet protective atmosphere, control the decarburization annealing temperature at 750-900°C, and keep it at this temperature for 60-180s, the dew point is 25°C, and the protective atmosphere is a mixed gas of wet H2 and N2, in which the volume content of H2 is 15-80%; 8) Perform nitriding treatment: When the heating temperature of the ingot is not less than 1260℃, nitriding is not required; When the heating temperature of the ingot is lower than 1260℃, nitriding is required. The nitriding atmosphere is a wet H2, N2 and NH3 mixed gas, in which the volume content of H2 is 15-80%, and the amount of nitrogen infiltration is controlled at 50-350PPm. 9) Applying a conventional high temperature annealing separator with MgO as the main component; 10) Perform conventional high temperature annealing; 11) Unwind and laser process under protective atmosphere: Laser processing parameters: the average power of continuous laser is 20-3500W; the laser pulse repetition frequency is 1-160kHz; the laser pulse width is 1-10ms; the filling line spacing is 0.01-0.06mm; the scanning rate is 10-8000mm / s; the focus of the light beam is on the surface of the steel plate; the protective gas is nitrogen or argon, and the protective gas flow rate is 1-50L / min; 12) The steel strip is subjected to conventional stretching and flattening annealing treatment.

3. A method for preparing high magnetic induction oriented silicon steel without magnesium silicate bottom layer by laser process as claimed in claim 2, characterized in that: The average power of continuous laser is between 45 and 3420W.

4. A method for preparing high magnetic induction oriented silicon steel without magnesium silicate bottom layer by laser process as claimed in claim 2, characterized in that: The laser pulse repetition frequency is between 8 and 145 kHz.

5. The method for preparing high magnetic induction oriented silicon steel without magnesium silicate bottom layer by laser process as claimed in claim 2, characterized in that: The spacing between the filling lines is 0.02 to 0.05 mm.

6. The method for preparing high magnetic induction oriented silicon steel without magnesium silicate bottom layer by laser process as claimed in claim 2, characterized in that: The scanning rate is between 20 and 7750 mm / s.

7. The method for preparing high magnetic induction oriented silicon steel without magnesium silicate bottom layer by laser process as claimed in claim 2, characterized in that: The laser pulse width is between 1.6 and 9.2 ms.

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