Low-noise non-oriented silicon steel for new energy automobile driving motor and production method of low-noise non-oriented silicon steel

Abstract

The invention discloses a production method of low-noise non-oriented silicon steel for a driving motor of a new energy automobile, and the non-oriented silicon steel with the thickness ranging from 0.20 mm to 0.30 mm is prepared through steelmaking, continuous casting, hot rolling, normalizing, acid pickling, cold rolling, annealing and coating which are carried out in sequence. According to the low-noise non-oriented silicon steel for the driving motor of the new energy automobile, the texture of a finished product is controlled by adjusting alloy components, controlling the thickness of a hot rolled plate and optimizing the reduction distribution and the strain rate of each pass of cold rolling, the low-noise non-oriented silicon steel for the driving motor of the new energy automobile is finally obtained, the thickness of the product ranges from 0.20 mm to 0.30 mm, the performance index meets 400 Hz, and the production cost is low. The average magnetostriction coefficient lambda p-p which is parallel to the rolling direction and forms an angle of 55 degrees with the rolling direction under 1.0 T is less than or equal to 10 * 10 <-6 >, the average weighted sound level decibel value AWV (dBA) is less than or equal to 100, and the average loss P1.0 / 400 is less than or equal to 10 + 40 * t2W / kg (t is the thickness of a finished product, and t is more than or equal to 0.20 mm and less than or equal to 0.30 mm).

Description

Technical Field

[0001] The present invention belongs to the technical field of manufacturing non-oriented silicon steel, and specifically relates to low-noise non-oriented silicon steel for a new energy vehicle drive motor and a production method thereof. Background Art

[0002] In recent years, new energy vehicles are changing the global automotive industry at an unprecedented speed, depth and breadth, which not only provides new impetus for the development of the global automotive industry, but also brings historic opportunities to reshape the world's automotive energy structure, respond to global climate change, and achieve sustainable development of the automotive industry. As the heart of new energy vehicles, the performance of the drive motor is directly related to the endurance and driving performance of new energy vehicles.

[0003] Noise is one of the important indicators of drive motors, which can be roughly divided into mechanical noise, electromagnetic noise, and aerodynamic noise. Among them, the mechanism of electromagnetic noise is relatively complex, the sound quality is poor, and it often manifests as high-frequency howling, which can easily cause discomfort to people. Electromagnetic noise is one of the main sources of noise in speed-regulating permanent magnet synchronous motors. The air gap magnetic field of the motor acts on the stator core of the motor to generate electromagnetic force, which causes the vibration of the stator core and then causes electromagnetic noise. The main sources of electromagnetic noise are Maxwell force and magnetostrictive force. Maxwell force mainly exists between the air gaps, where the relative magnetic permeability of the material is discontinuously distributed. The Maxwell force acting on the top of the stator teeth is the main cause of the vibration of the stator core of the rotating motor. When the core material non-oriented silicon steel is magnetized, the size of the material will change due to magnetostrictive force. Therefore, magnetostriction is an important source of core vibration and noise. The magnetostrictive properties of non-oriented silicon steel used in drive motors are crucial for motor noise control.

[0004] Patent CN 116121653 A discloses a low-noise non-oriented silicon steel and its production method and application, with the composition of C≤0.0025%, 2.15%≤Si≤2.90%, 0.25%≤Mn≤0.65%, P≤0.25%, 0.3%≤Als≤0.6%, S≤0.0030%, N≤0.0030%, Ti≤0.0030%, and the rest is Fe and unavoidable impurities; in terms of method, it is required to control the thickness of the insulating coating to achieve the purpose of controlling the surface tension of the silicon steel, thereby reducing the noise, and the working noise is ≤55dB. This technology mainly adjusts the alloy composition and controls the thickness of the insulating coating for the needs of arc suppression coils. It usually works at a frequency of several kilohertz to several tens of kilohertz, and has no special requirements for the magnetic properties of silicon steel sheets, so its Si+Al content is low, but its loss level is difficult to meet the requirements of new energy vehicle drive motors.

[0005] Patent CN 109943766 A discloses a non-oriented silicon steel for transformer and its preparation method. The chemical composition of the non-oriented silicon steel is C≤0.0040%, Si 2.80%~3.20%, Mn 0.10%~0.60%, P≤0.050%, Als 0.50%~0.90%, Sb 0.0030%~0.020%, S≤0.0020%, N≤0.0020%, Ti≤0.0020%, Cu≤0.050%, Nb≤0.0020%, V≤0.0020%, and the rest is Fe and unavoidable impurities; the preparation process includes molten iron pretreatment → converter smelting → RH refining → continuous casting → hot rolling → normalizing → pickling → cold rolling → continuous annealing → coating → silicon steel finished product. The non-oriented silicon steel produced by the method has an iron loss P 1.5 / 50 ≤2.20W / kg, magnetic induction intensity B 50 ≥1.66T. This non-oriented silicon steel is mainly used for transformer cores, and its operating frequency is generally 50-60Hz. Its assessment indicators are essentially different from those of new energy vehicle drive motors, and do not involve special processes to improve the level of noise control; moreover, since the transformer is in a static state, its performance requirements for non-oriented silicon steel can actually only be in a fixed direction.

[0006] The operating frequency of new energy vehicle drive motors generally ranges from 50Hz to several thousand Hz. The national standard "Cold-rolled non-oriented electrical steel strip for electric vehicle drive motors" clearly proposes the loss standard of silicon steel sheets at 400Hz and 1.0T. Therefore, the magnetostriction level of silicon steel sheets at 400Hz and 1.0T can be used as an important reference for the noise level of non-oriented silicon steel used in new energy vehicle drive motors. At present, there are no low-noise non-oriented silicon steel products on the market that can meet the working conditions of new energy vehicle drive motors. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a low-noise non-oriented silicon steel and a production method thereof in view of the deficiencies in the above-mentioned prior art. By adjusting the alloy composition, controlling the thickness of the hot-rolled plate, optimizing the reduction distribution and strain rate of each cold rolling pass, the texture of the finished product is controlled, and finally a low-noise non-oriented silicon steel is obtained, which can meet the use requirements of new energy vehicle drive motors.

[0008] The technical solution adopted by the present invention to solve the above-mentioned problems is:

[0009] A method for producing low-noise non-oriented silicon steel for new energy vehicle drive motors, wherein non-oriented silicon steel with a thickness of 0.20 mm to 0.30 mm is prepared by sequentially performing steelmaking, continuous casting, hot rolling, normalizing, pickling, cold rolling, annealing, and coating. Specifically, the method comprises the following steps:

[0010] 1) For molten steel smelting and continuous casting, the chemical composition of non-oriented silicon steel ingots includes, by mass percentage: 3.4%≤(Si+Al)≤5.0%, Mn 0.2%~1.0%, 0.03%≤(Sn+Sb)≤0.15%, (Nb+V+Ti)≤0.006%, (C+N)≤0.005%, S≤0.002%, and the rest is Fe and unavoidable inclusions;

[0011] 2) The non-oriented silicon steel ingot is heated, and then subjected to multiple passes of rough rolling and finish rolling, with the outlet thickness of the finish rolling being 1.4-2.2 mm (i.e., the thickness of the hot-rolled plate), and then subjected to laminar cooling and coiling into a hot-rolled coil;

[0012] 3) The hot rolled coil is normalized, pickled, and then cold rolled once to obtain a cold rolled coil; wherein the cold rolling parameter M represents the reduction distribution and strain rate of each cold rolling pass, and the value range of M is 3.5 to 8, and the calculation formula is as follows:

[0013]

[0014] In the above formula, n is the rolling pass, H i is the entrance thickness of the i-th pass, H i+1 is the exit thickness of the i-th pass (i.e. the entrance thickness of the i+1-th pass), Ri is the roller diameter of the working roll; in this formula, H i , H i+1 The same length unit is used as Ri;

[0015] 4) The cold rolled coil is annealed and coated to finally obtain non-oriented silicon steel with a thickness ranging from 0.20 mm to 0.30 mm.

[0016] Further preferably, in step 1), the chemical composition of the non-oriented silicon steel ingot also needs to satisfy Si 2.5%-3.8%, 0≤Sn≤0.10%, Ti≤0.0015%, Nb≤0.0020%, and N≤0.0025%.

[0017] Further preferably, in step 1), during the continuous casting stage, the crystallizer pulling speed is 0.8-1.2 m / min, and the thickness of the cast billet is 180-250 mm.

[0018] According to the above scheme, in step 2), the heating temperature of the ingot is 1050-1150°C, and the time in the furnace is 150-250 min; the hot rolling includes 3-5 rough rolling passes and 7 finishing rolling passes, wherein the starting temperature of the rough rolling is ≥1020°C, the thickness of the rough rolling intermediate billet is 25-35 mm, the starting temperature of the finishing rolling is ≥950°C, and the final rolling temperature is ≥850°C; the coiling temperature is generally in the range of 550-700°C.

[0019] According to the above scheme, in step 3), the normalized soaking temperature is 860-960°C, the hydrochloric acid concentration in the pickling tank is 8-12%, and the hot-rolled coil after normalized pickling is induction heated to ensure that the cold rolling mill entrance rolling temperature is 80-200°C.

[0020] According to the above scheme, the coating generally adopts a phosphate coating, and the coating is controlled at 0.3 to 0.8 μm.

[0021] The low-noise non-oriented silicon steel produced by the above method has a product thickness in the range of 0.20mm to 0.30mm and its performance indicators are as follows: the average magnetostriction coefficient λp-p parallel to the rolling direction and at 55° to the rolling direction at 400Hz, 1.0T is ≤10×10 -6 , average weighted sound level decibel value AWV (dBA) ≤ 100, average loss P 1.0 / 400 ≤10+40×t 2 W / kg (t is the thickness of the finished product, and 0.20mm≤t≤0.30mm), that is, P 1.0 / 400 11.6~13.6W / kg.

[0022] When designing the ingredients of the present invention, the conception of each element is as follows:

[0023] Si+Al: Si is an effective additive element for increasing resistivity and reducing iron loss; Al has a similar effect on magnetic properties as silicon, increasing the resistivity of steel sheets, causing grain growth, and reducing iron loss in finished products. However, as the (Si+Al) content increases, the saturation magnetic induction decreases, the cold rolling performance decreases, and stable batch production is difficult. As the Al content increases, fine AlN will precipitate when the hot-rolled sheet is cooled, which will hinder grain growth and deteriorate iron loss. Therefore, the Al content cannot be too high, and the (Si+Als) content in the present invention is limited to 3.2% to 4.8%.

[0024] Mn: Adding an appropriate amount of Mn is beneficial to improving the resistivity of electrical steel, reducing iron loss, improving the rollability of hot-rolled plates, inhibiting hot brittleness caused by S, promoting MnS coarsening, and facilitating grain growth. If Mn is too high, it is easy to combine with S to precipitate fine MnS during hot rolling, which will lead to a decrease in magnetic induction intensity and an increase in iron loss. Therefore, the Mn content of the present invention is set to 0.2-1.0%.

[0025] C+N: C, whether in the form of solid solution or cementite, will damage the magnetic properties of the steel plate; N will deteriorate the magnetic properties and the grain growth during the final annealing through the precipitation of TiN, AlN, etc., so its content is reduced as much as possible. The present invention controls C+N≤0.005%.

[0026] S: fine MnS is precipitated during the hot rolling process, which will lead to a decrease in magnetic induction intensity and an increase in iron loss. The present invention controls S to be ≤ 0.002%.

[0027] Nb+V+Ti: Adding these elements will form fine precipitates with C / N atoms in the steel, and these precipitates strongly hinder the growth of grains during annealing. Therefore, the upper limit of the content of the microalloying elements Nb+V+Ti in the present invention is set to 0.006%.

[0028] Sn+Sb: Sn and Sb are grain boundary segregation elements, which can significantly reduce the proportion of {111} unfavorable textures, which is beneficial to improving the magnetic induction intensity of the finished product. However, in addition to segregation at the grain boundaries, Sn and Sb also segregate on the surface. Their segregation on the surface is related to temperature. As the temperature rises, the amount of segregation gradually increases and reaches a peak at 700°C. Furthermore, the segregation of Sn and Sb on the surface is orientation-dependent. However, when the amount of surface segregation is too large, the surface energy of almost all oriented grains will be significantly reduced. This phenomenon directionally reduces the surface energy of {100} grains, and {100} grains will not be able to obtain the right to preferential growth at this time. In the present invention, 0.03-0.15% of Sn+Sb is added.

[0029] When designing the production method of the present invention, the key process is conceived as follows:

[0030] The formation and development of recrystallization texture in steel after annealing is related to the content of the corresponding deformation texture component, but more depends on the strain energy storage of the deformation texture component. The orientation characteristics of the nucleus during recrystallization nucleation and the orientation of the nucleus that can grow determine the type of recrystallization texture. In the present invention, the production of non-oriented silicon steel adopts a single cold rolling process (large reduction rate), the hot rolled plate thickness is 1.4 to 2.2 mm, the finished plate thickness is 0.20 to 0.30 mm, the cold rolling reduction rate range is 78.6% to 90.9% (calculated based on the hot rolled plate thickness and the finished plate thickness), and the deformation texture after cold rolling is mainly composed of α ( <110> / / RD) fiber texture and complete γ( <111> / / RD) fiber texture composition. When the thickness of the finished plate is constant, the hot-rolled plate becomes thicker, the cold-rolling reduction rate increases, and the strength of the α fiber texture and the γ fiber texture increases; during the annealing process of the cold-rolled plate, the annealing structure is hereditary. Since the γ-oriented grains have the highest storage energy and the γ recrystallized grains have directional nucleation, the γ deformed grains are the first to recrystallize during the final annealing of the cold-rolled plate, and have size and quantity advantages. Therefore, as the hot-rolled plate becomes thicker, the proportion of the {112} and {111} surface textures of the annealed plate increases, magnetization becomes increasingly difficult, the magnetostriction coefficient becomes larger, and the weighted sound level decibel value becomes larger. However, when the thickness of the finished plate is constant, if the thickness of the hot-rolled plate is too thin, it will lead to insufficient total cold-rolling reduction rate and insufficient cold-rolling deformation energy storage, especially the favorable orientation {110} <110> and {001} <110> The cold-deformed grains have low storage energy, and the recrystallization annealing growth power is insufficient, so it is not easy to form recrystallization nuclei, and it is not easy to grow in the later annealing, which further deteriorates the magnetostriction coefficient and iron loss of the finished product. Therefore, the thickness of the hot-rolled plate in the present invention is set to 1.4-2.2 mm.

[0031] The shear band formed during cold rolling is a concentrated deformation area caused by uneven deformation. It is a common recrystallization nucleation site and a very important microstructure in the large deformation organization of cold rolling. During the recrystallization annealing process, Goss oriented grains are mainly in the {111} <112> 、{1l1} <110> and {112} <110> The cubic oriented grains also nucleate on these shear bands, but the number of nuclei is lower than that of the Gaussian oriented {111} <112> The grains oriented in {111} <110> Nucleation in oriented grains, {1l1} <110> Oriented grains are in {111} <112> Therefore, if the characteristics of the shear band can be effectively controlled, the development of the recrystallized Goss texture and cubic texture can be controlled, thereby effectively improving the magnetic properties of the product. The main factors affecting the formation of the cold rolling shear band include the cold rolling strain rate, the cold rolling reduction rate, etc., and the work roll diameter directly affects the cold rolling strain rate.

[0032] In the present invention, the cold rolling work roll diameter and the cold rolling reduction rate of each pass are comprehensively considered and summarized as the cold rolling parameter M. When M < 3.5, the shear band density is insufficient, the Goss-oriented grains and the cubic-oriented grains cannot grow fully after annealing, the average magnetostriction coefficient is too high, and the iron loss is too high. When M > 8, the shear band density is too high, {111} <112> , {111} <110> The unfavorable oriented grains nucleate in large quantities on the shear band, have size advantages after annealing, and swallow up nearby Goss oriented grains and cubic orientations, resulting in an excessively high average magnetostriction coefficient and excessively high iron loss. Therefore, the present invention controls M within the range of 3.5 to 8.0.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] In view of the demand for improving the noise level of new energy vehicle drive motors, the present invention, under the premise of considering the feasibility of non-oriented silicon steel production, optimizes the non-oriented silicon steel component design and hot-rolled plate thickness, and controls the cold rolling parameters according to the cold rolling passes, the roller diameter and the thickness of each pass at the entrance and exit, to obtain a low-loss, low-noise non-oriented silicon steel for new energy vehicle drive motors. The finished plate thickness is in the range of 0.20mm to 0.30mm, and the average magnetostriction coefficient λp-p parallel to the rolling direction and at 55° to the rolling direction at 400Hz and 1.0T is ≤10×10 -6 , average weighted sound level decibel value AWV (dBA) ≤ 100, average loss 11.6 ≤ P 1.0 / 400 ≤13.6W / kg. Moreover, the relevant production process of the present invention is highly operable and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the orientation distribution function (ODF) diagram of the finished plate of Example 2-3;

[0036] Figure 2 It is the orientation distribution function (ODF) diagram of the finished plate of comparative example 2-3. DETAILED DESCRIPTION

[0037] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the present invention is not limited to the following embodiments.

[0038] In the following embodiments, the method for producing low-noise non-oriented silicon steel for new energy vehicle drive motors comprises the following steps:

[0039] 1) Molten steel smelting and continuous casting, the continuous casting crystallizer pulling speed is 1.0-1.1 m / min, the ingot thickness is 215±5 mm, and the chemical composition of the non-oriented silicon steel ingot includes, by mass percentage: Si 2.5%-3.6%, 3.6%≤(Si+Al)≤4.5%, Mn0.2%-0.7%, 0≤Sn≤0.05%, 0≤Sb≤0.06%, 0.05%≤(Sn+Sb)≤0.10%, 0.0014≤Nb≤0.0021%, 0.0013≤V≤0.0024%, 0.0013≤Ti≤0.0022%, (Nb+V+Ti)≤0.006%, N≤0.0025%, (C+N)≤0.005%, S≤0.002%, and the rest is Fe and unavoidable inclusions;

[0040] 2) The non-oriented silicon steel ingot is heated at a temperature of 1050-1150°C and a furnace time of 150-250 min, and then subjected to 3-5 rough rolling and 7 finishing rolling, wherein the rough rolling start temperature is ≥1020°C, the rough rolling intermediate slab thickness is 25-35 mm, the finishing rolling start temperature is ≥950°C, the final rolling temperature is ≥850°C, the finishing rolling outlet thickness is 1.4-2.2 mm (i.e., the hot-rolled plate thickness), and then subjected to laminar cooling and coiling into a hot-rolled coil, wherein the coiling temperature is 590±5°C;

[0041] 3) The hot rolled coil is normalized, the normalized soaking temperature is 860-960°C, the normalized hot rolled coil is pickled, the pickling hydrochloric acid concentration is 9-10%, the hot rolled coil after normalized pickling is induction heated to, the cold rolling mill entrance rolling temperature is 140±10°C, and then cold rolling is performed once to obtain a cold rolled coil; wherein, the cold rolling parameter M represents the control of the pressure distribution and strain rate of each cold rolling pass, the value range of M is 3.5-8, and the calculation formula is as follows:

[0042]

[0043] Where n is the rolling pass, H i is the entrance thickness of the i-th pass, H i+1 is the exit thickness of the i-th pass (i.e. the entrance thickness of the i+1-th pass), and Ri is the diameter of the working roll.

[0044] 4) After the cold rolled coil is annealed, conventional phosphate coating is performed. The plate temperature in the coating drying stage is generally 155-165°C, the plate temperature in the sintering stage is generally 330-340°C, and the film thickness is generally about 0.3-0.6 μm. Finally, a non-oriented silicon steel finished plate with a thickness in the range of 0.20 mm to 0.30 mm is obtained.

[0045] Example 1

[0046] The composition of the non-oriented silicon steel ingots of Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-6 is shown in Table 1-1. The ingots were heated at 1080°C, kept in the furnace for 185min, and subjected to 5 rough rollings, with the start rolling temperature of the rough rolling at 1030°C and the intermediate ingot thickness of 32mm. The ingots were subjected to 7 finish rollings, with the start rolling temperature of the finish rolling at 990°C and the final rolling temperature at 890°C. Finally, they were subjected to laminar cooling and coiled into hot-rolled coils, with the final rolling temperature at 670°C and the hot-rolled plate thickness at 1.85mm. The hot-rolled coils were normalized and pickled at 880°C, and cold-rolled on the rolling mill to a thickness of 0.30mm (because the coating thickness is relatively thin, the finished product thickness can generally be controlled according to the cold rolling thickness, and the effect of the coating thickness on the finished product thickness is negligible), and the cold rolling parameter M is 4.5; the obtained cold-rolled coils were subjected to soaking annealing at 960°C in a continuous annealing furnace, and coated to obtain non-oriented silicon steel finished coils with a thickness of about 0.30mm.

[0047] Table 1-1 Chemical composition of the castings of Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-6 (wt, %)

[0048] serial number Si Al Mn Sn Sb Nb V Ti C N S Si+Al Sn+Sb Nb+V+Ti C+N Example 1-1 3.2 0.5 0.5 0.03 0.04 0.0021 0.0013 0.0022 0.0018 0.0022 0.0012 3.7 0.07 0.0056 0.0040 Example 1-2 2.6 1.1 0.3 0.05 / 0.0014 0.0017 0.0019 0.0021 0.0018 0.0015 3.7 0.05 0.005 0.0039 Examples 1-3 2.9 1.2 0.7 / 0.06 0.0018 0.0015 0.0013 0.0017 0.0015 0.0009 4.1 0.06 0.0046 0.0032 Examples 1-4 3.4 0.2 0.6 0.05 0.05 0.0021 0.0014 0.0016 0.0021 0.0017 0.0011 3.6 0.1 0.0051 0.0038 Examples 1-5 3.6 0.9 0.5 0.03 0.06 0.0017 0.0021 0.0015 0.0017 0.0012 0.0016 4.5 0.09 0.0053 0.0029 Examples 1-6 2.5 1.3 0.2 0.04 0.03 0.002 0.0024 0.0013 0.0012 0.0018 0.0012 3.8 0.07 0.0057 0.0030 Comparative Example 1-1 2.5 0.4 0.6 0.02 0.05 0.0016 0.0014 0.0016 0.0021 0.0017 0.0011 2.9 0.07 0.0046 0.0038 Comparative Example 1-2 4.2 1.2 0.2 0.03 0.06 0.0025 0.0021 0.0015 0.0017 0.0014 0.0016 5.4 0.09 0.0061 0.0031 Comparative Examples 1-3 3.3 0.7 0.5 0.12 0.11 0.0014 0.0017 0.0019 0.0021 0.0018 0.0015 4.0 0.23 0.005 0.0039 Comparative Examples 1-4 3.0 1.2 0.7 / / 0.0016 0.0014 0.0016 0.0021 0.0017 0.0011 4.2 / 0.0046 0.0038 Comparative Examples 1-5 3.2 0.5 0.4 0.07 0.08 0.0024 0.0027 0.0033 0.0021 0.0018 0.0012 3.7 0.15 0.0084 0.0039 Comparative Examples 1-6 3.4 0.9 0.3 0.1 0.03 0.0014 0.0019 0.0015 0.0033 0.0042 0.0025 4.3 0.13 0.0048 0.0075

[0049] Note: The balance is Fe and unavoidable impurities.

[0050] The magnetostriction coefficient λp-p of the sample parallel to the rolling direction and 55° to the rolling direction at 400Hz and 1.0T is tested on the MPG-200D magnetic test system according to IEC60404-17, and the weighted sound level decibel value AWV is tested. The iron loss P at 400Hz and 1.0T is tested with the Epstein square ring according to GB / T3655-2022. 1.0 / 400 The magnetostriction coefficient test sample size is 600×100 mm, and the iron loss test sample size is 320×30 mm (half the number in each direction), and the average value of the measured values ​​in different directions is calculated. Table 1-2 shows the finished product properties of Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-6.

[0051] The existing standards do not specify the magnetostrictive properties of non-oriented silicon steel. The 55° direction is the most difficult to magnetize, so theoretically its magnetostriction coefficient is the largest, while the rolling direction is the most difficult to magnetize, so its magnetostriction coefficient is the smallest. Considering the specific working conditions of motor rotation, it is more reasonable to select the average values ​​of the rolling direction and the 55° direction for consideration. The λp-p of the present invention is the peak-to-peak amplitude of the magnetostrictive butterfly curve, which is a currently recognized parameter for evaluating the magnetostriction coefficient of a material.

[0052] Table 1-2 Finished product properties of Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-6

[0053]

[0054] Note: λp-p in 55° direction indicates the magnetostriction coefficient at an angle of 55° to the rolling direction.

[0055] It can be seen from Table 1-1 and Table 1-2 that the composition range, hot rolled coil thickness and cold rolling parameters of Examples 1-1 to 1-6 are all within the scope of the invention, and the average magnetostriction coefficient λp-p of the finished product is ≤10×10 -6 , the average weighted sound level decibel value AWV (dBA) ≤ 100, the average iron loss P1.0 / 400 ≤ 13.5W / kg, it has advantages in magnetostrictive characteristics, noise performance and iron loss level, and can meet the use requirements of new energy vehicle drive motors. Comparative Example 1-1 has too low (Si+Al)% and low resistivity, resulting in too high average iron loss of the finished product. Comparative Example 1-2 has too high (Si+Al)% and reduced saturation magnetic induction, resulting in a decrease in the average magnetostriction coefficient λp-p and the average weighted sound level decibel value AWV of the finished product. Comparative Example 1-3 has too high (Sn+Sb)%, which reduces the surface energy of the {100} grains, and the {100} grains cannot obtain the right to preferential growth, resulting in a decrease in the average magnetostriction coefficient λp-p and the average weighted sound level decibel value AWV of the finished product. Since no Sn and Sb are added to Comparative Examples 1-4, the proportion of {111} unfavorable texture is high, the saturation magnetic induction is reduced, and the average magnetostriction coefficient λp-p and the average weighted sound level decibel value AWV of the finished product are reduced. Since the (Nb+V+Ti)% of Comparative Examples 1-5 is high, fine and harmful second phases will be precipitated, the finished product structure will be deteriorated, the iron loss will be high, the magnetic induction will be low, and the average magnetostriction coefficient λp-p and the average weighted sound level decibel value AWV of the finished product will be reduced. Since the (C+N)% of Comparative Examples 1-6 is high, a large number of fine carbonitrides will be precipitated, the finished product structure will be deteriorated, the iron loss will be high, the magnetic induction will be low, and the average magnetostriction coefficient λp-p and the average weighted sound level decibel value AWV of the finished product will be reduced.

[0056] Example 2

[0057] The non-oriented silicon steel ingot of Example 1-1 in Example 1 was used as the raw material. The ingot was heated at 1130°C, and in the furnace for 210 minutes, and then subjected to 5 rough rollings, with the rough rolling start temperature at 1060°C and the intermediate billet thickness at 29mm. The rough rolling was subjected to 7 finish rollings, with the finish rolling start temperature at 1010°C and the final rolling temperature at 920°C. Finally, laminar cooling was performed, and the hot-rolled coil was coiled, with the final rolling temperature at 630°C. The hot-rolled plate thickness was the first pass entry plate thickness in Table 2-1. The hot-rolled coil was normalized and pickled at 920°C, and then cold-rolled to a thickness of 0.20mm in multiple passes on the rolling mill. The specific cold rolling process parameters are shown in Table 2-1. The obtained cold-rolled coil was subjected to 980°C soaking annealing in a continuous annealing furnace, and then coated to obtain a non-oriented silicon steel sample. The finished product performance was tested according to the method of Example 1.

[0058] Table 2-1 and Table 2-2 respectively give the cold rolling process parameters and finished product properties of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3.

[0059] Table 2-1 Cold rolling process parameters of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3

[0060]

[0061]

[0062] Table 2-2 Finished product properties of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3

[0063]

[0064] It can be seen from Table 2-1 and Table 2-2 that the hot rolled coil thickness and cold rolling parameters of Examples 2-1 to 2-3 are within the scope of the invention, and the average magnetostriction coefficient λp-p (≤6×10 -6 ), average weighted sound level decibel value AWV (≤85) and average iron loss (P 1.0 / 400 ≤11.2W / kg) are maintained at a relatively low level, which can meet the use requirements of new energy vehicle drive motors. Comparative Example 2-1 The hot-rolled coil is too thick, the proportion of {112} and {111} surface textures of the annealed plate is increased, the average magnetostriction coefficient λp-p and the average weighted sound level decibel value AWV of the finished product are too high, and the average iron loss is also relatively high. Comparative Example 2-2 The cold rolling parameter M>8, the unfavorable orientation grain size after annealing is large, the average magnetostriction coefficient λp-p and the average weighted sound level decibel value AWV of the finished product are too high, and the average iron loss is also relatively high. Comparative Example 2-3 The cold rolling parameter M<3.5, the shear band density is insufficient, the Goss-oriented grains and cubic-oriented grains cannot grow fully after annealing, the average magnetostriction coefficient λp-p and the average weighted sound level decibel value AWV are too high, and the average iron loss is also relatively high.

[0065] Depend on Figure 1 and Figure 2 It can be seen that the working roll diameter of Example 2-3 is significantly larger than that of Comparative Example 2-3, and its cold rolling strain rate is higher, resulting in its cold rolling parameters (M=4.4) being higher than that of Comparative Example 2-3 (M=3.4). Therefore, the {111} fiber texture strength in its finished plate is significantly lower than that of Comparative Example 2-3.

[0066] Example 3

[0067] The non-oriented silicon steel ingots of Examples 1-4 in Example 1 were used as raw materials. The ingots were heated at 1080°C, and in the furnace for 225 minutes, and subjected to 5 rough rolling passes, with the rough rolling start temperature at 1030°C, the intermediate billet thickness at 33mm, and 7 finishing rolling passes, with the finishing rolling start temperature at 980°C, the final rolling temperature at 870°C, and the hot-rolled plate thickness being the first pass entry plate thickness in Table 3-1. Finally, laminar cooling was performed, and the hot-rolled coils were coiled at a coiling temperature of 590°C. The hot-rolled coils were normalized and pickled at 890°C, and cold-rolled in a rolling mill to a finished product thickness of 0.25mm. The specific cold rolling process parameters are shown in Table 3-1; all cold-rolled coils were subjected to 980°C soaking annealing in a continuous annealing furnace, and coated to obtain non-oriented silicon steel samples. The finished product performance was tested according to the method of Example 1.

[0068] Table 3-1 and Table 3-2 respectively give the cold rolling process parameters and finished product properties of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-3.

[0069] Table 3-1 Cold rolling process parameters of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-3

[0070]

[0071]

[0072] Table 3-2 Finished product properties of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-3

[0073]

[0074] As can be seen from Table 3-1 and Table 3-2, the hot-rolled coil thickness and cold-rolling parameters of Examples 3-1 to 3-3 are all within the scope of the invention, and the average magnetostriction coefficient λp-p, average weighted sound level decibel value AWV and average iron loss of the finished product are all maintained at a relatively low level, which can meet the use requirements of new energy vehicle drive motors. The hot-rolled coil of Comparative Example 3-1 is too thin, the total cold rolling reduction is insufficient, and the recrystallization annealing growth power is insufficient, resulting in the average magnetostriction coefficient λp-p and average weighted sound level decibel value AWV of the finished product being too high, and the average iron loss is also relatively high. The cold rolling parameters of Comparative Example 3-2 are M>8, and the unfavorable orientation grain size after annealing is large, and the average magnetostriction coefficient λp-p, average weighted sound level decibel value AWV and average iron loss of the finished product are all too high. In comparative example 3-3, the cold rolling parameter M is less than 3.5, the shear band density is insufficient, the Goss-oriented grains and cubic-oriented grains cannot grow fully after annealing, and the average magnetostriction coefficient λp-p, the average weighted sound level decibel value AWV and the average iron loss of the finished product are all too high.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and changes without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for producing low-noise non-oriented silicon steel for new energy vehicle drive motors, characterized in that: The steps include: 1) For molten steel smelting and continuous casting, the chemical composition of non-oriented silicon steel ingots includes, by mass percentage: (Si+Al) 3.4%-5.0%, Mn 0.2%-1.0%, 0.03%≤(Sn+Sb)≤0.15%, (Nb+V+Ti)≤0.006%, (C+N)≤0.005%, S≤0.002%, and the rest is Fe and unavoidable inclusions; 2) The non-oriented silicon steel ingot is heated, and then rough rolled and finish rolled to obtain a hot rolled coil; 3) The hot rolled coil is normalized, pickled, and then cold rolled once to obtain a cold rolled coil; wherein the cold rolling parameter M represents the reduction distribution and strain rate of each cold rolling pass, and the value range of M is 3.5 to 8, and the calculation formula is as follows: In the above formula, n is the rolling pass, H i is the entrance thickness of the i-th pass, H i+1 is the exit thickness of the i-th pass, Ri is the roller diameter of the working roll; H i , H i+1 The same length unit is used as Ri; 4) The cold-rolled coil is annealed and coated to obtain the low-noise non-oriented silicon steel for the new energy vehicle drive motor.

2. The method for producing low-noise non-oriented silicon steel for new energy vehicle drive motor according to claim 1, characterized in that: The thickness of the low-noise non-oriented silicon steel produced is in the range of 0.20mm to 0.30mm, and its performance indicators are as follows: average magnetostriction coefficient λp-p ≤ 10×10 at 400Hz, 1.0T parallel to the rolling direction and at 55° to the rolling direction -6 , average weighted sound level decibel value AWV (dBA) ≤ 100, average loss P 1.0 / 400 11.6~13.6W / kg.

3. The method for producing low-noise non-oriented silicon steel for new energy vehicle drive motor according to claim 1, characterized in that: In step 2), the finishing rolling outlet thickness is 1.4-2.2 mm; in step 4), the finished plate thickness of the low-noise non-oriented silicon steel for new energy vehicle drive motor obtained is in the range of 0.20 mm to 0.30 mm.

4. The method for producing low-noise non-oriented silicon steel for new energy vehicle drive motor according to claim 1, characterized in that: In step 1), the chemical composition of the non-oriented silicon steel ingot also needs to satisfy Si 2.5% to 3.8%, 0≤Sn≤0.10%, Ti≤0.0015%, Nb≤0.0020%, and N≤0.0025%.

5. The method for producing low-noise non-oriented silicon steel for new energy vehicle drive motor according to claim 1, characterized in that: In step 1), during the continuous casting stage, the crystallizer pulling speed is 0.9-1.2 m / min, and the thickness of the cast billet is 180-250 mm.

6. The method for producing low-noise non-oriented silicon steel for new energy vehicle drive motor according to claim 1, characterized in that: In step 2), the heating temperature of the cast billet is 1050-1150°C, and the time in the furnace is 150-250 min; the hot rolling includes 3-5 rough rolling passes and 7 finishing rolling passes, wherein the starting temperature of the rough rolling is ≥1020°C, the thickness of the rough rolling intermediate billet is 25-35 mm, the starting temperature of the finishing rolling is ≥950°C, and the final rolling temperature is ≥850°C.

7. The method for producing low-noise non-oriented silicon steel for new energy vehicle drive motor according to claim 1, characterized in that: In step 3), the normalized soaking temperature is 860-960°C.

8. The method for producing low-noise non-oriented silicon steel for new energy vehicle drive motor according to claim 1, characterized in that: The coating is a phosphate coating with a thickness of 0.3 to 0.8 μm.

9. Low-noise non-oriented silicon steel produced by the method of any one of claims 1 to 8.

10. Application of the low-noise non-oriented silicon steel according to claim 9 in driving motors of new energy vehicles.

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