High magnetic induction non-oriented silicon steel and method for producing the same

Abstract

The application discloses a kind of high magnetic induction non-oriented silicon steel and production method thereof.The production method of high magnetic induction non-oriented silicon steel includes: converter smelting-RH refining-continuous casting-heating furnace heating-hot rolling-pickling-cold rolling-annealing-coating, and the chemical composition of the high magnetic induction non-oriented silicon steel is controlled as follows in percentage by mass: Si: 0.60-2.2%, Al: 0.10-0.42%, Mn: 0.21-0.95%, Nb≤0.0025%, V≤0.0020%, Ti≤0.0015%, Nb+V+Ti≤0.0045%, C≤0.0025%, N≤0.0020%, S: 0.0015-0.0035%, P≤0.02%, and the rest is iron and inevitable impurities.The application comprehensively designs components, hot rolling, annealing and normalizing process, aiming to improve product magnetic induction strength by simultaneously controlling precipitated phase and microstructure.At the same time, it has lower iron loss, effectively improves product B5000 magnetic induction 0.02T or more, realizes the purpose of improving magnetic properties, effectively reduces production cost, and has high energy and environmental friendliness.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and particularly relates to a high magnetic induction non-oriented silicon steel and its production method. Background Technology

[0002] Non-oriented silicon steel is a functional material, and its most important property is its magnetic properties. Non-oriented silicon steel is generally used as a core material for motors, and the quality or grade of its magnetic properties greatly affects motor performance. There are two main magnetic property indicators for silicon steel: iron loss and magnetic induction. Iron loss P1.5 / 50 is the loss when silicon steel is magnetized to 1.5T under a 50Hz alternating magnetic field. Magnetic induction B5000 is the magnetic induction intensity of the material corresponding to a magnetic field strength of 5000 A / m. As motor energy efficiency gradually improves and motors become more compact and efficient, silicon steel is required to have higher magnetic induction and lower iron loss. The increasing demands on the magnetic properties of silicon steel can also be seen in the product standards of different periods. For mainstream products with high market demand, the iron loss ranges from 2.6 to 4.3 W / kg. The current performance levels for each product level are as follows: when iron loss is 3.9 ≤ P1.5 / 50 ≤ 4.3 (W / kg), the magnetic induction of B5000 is approximately 1.71T; when iron loss is 3.4 ≤ P1.5 / 50 ≤ 3.7 (W / kg), the magnetic induction of B5000 is approximately 1.68T; when iron loss is 3.1 ≤ P1.5 / 50 ≤ 3.4 (W / kg), the magnetic induction of B5000 is approximately 1.66T; and when iron loss is 2.7 ≤ P1.5 / 50 ≤ 3.0 W / kg, the magnetic induction of B5000 is approximately 1.69T. The urgent requirement for these products is an increase in magnetic induction of at least 0.02T, while maintaining good cost-effectiveness.

[0003] In existing technologies, adding grain boundary segregating elements such as Sn and Sb can optimize the texture of the finished product and improve its magnetic properties. Treating the product with Ca during smelting or adding rare earth elements such as La and Ce can improve inclusions and also enhance magnetic properties. Even directly adding the magnetic element Ni can improve magnetic properties. However, these special elements are expensive, and their addition significantly increases product costs. For products with high market demand, this approach is not cost-effective. It also wastes special resources. Improving magnetic properties through high-temperature normalizing or secondary normalizing also increases product costs and is not conducive to energy conservation or carbon emission reduction. Directly using high-temperature normalizing processes for some mainstream products with high market demand is not the best choice. Moreover, the normalizing process involves the solid solution and re-precipitation of some precipitated phases, and the coarsening of others; the normalizing process is very delicate, otherwise it may adversely affect performance. Twin-roll thin-strip continuous casting technology is considered to be able to retain a favorable {100} surface texture and improve magnetic properties, but this technology is prone to surface quality defects and has not yet been widely adopted in the silicon steel field. Summary of the Invention

[0004] To address some or all of the technical problems existing in the prior art, the present invention provides a high magnetic induction non-oriented silicon steel and its production method.

[0005] The production method of high magnetic induction non-oriented silicon steel of the present invention includes: converter smelting - RH refining - continuous casting - furnace heating - hot rolling - pickling - cold rolling - annealing - coating. The chemical composition of the high magnetic induction non-oriented silicon steel is controlled by mass percentage as follows: Si: 0.60~2.2%, Al: 0.10~0.42%, Mn: 0.21~0.95%, Nb≤0.0025%, V≤0.0020%, Ti≤0.0015%, Nb+V+Ti≤0.0045%, C≤0.0025%, N≤0.0020%, S: 0.0015~0.0035%, P≤0.02%, with the remainder being iron and unavoidable impurities.

[0006] Converter smelting: smelting silicon steel in a converter;

[0007] RH refining: Refining molten steel after converter smelting with RH to control alloying and impurity element content;

[0008] Continuous casting: continuously casting molten steel refined with RH into steel billets;

[0009] Heating in a heating furnace: The steel billet is placed in the heating furnace and heated at a temperature T1 of 980℃-1080℃ for 2-4 hours.

[0010] Hot rolling: The heated steel billet is hot rolled at a final rolling temperature of 880℃-950℃, and the thickness of the hot-rolled steel is 2.6mm-3.0mm. The steel is then coiled.

[0011] Pickling: Pickling the coiled steel to remove the surface iron oxide scale;

[0012] Cold rolling: The pickled steel is cold rolled to a target thickness of 0.496mm-0.504mm;

[0013] Annealing: The cold-rolled steel is annealed in a continuous furnace at a speed of 120m / min-160m / min.

[0014] Coating: Applying a coating to the annealed steel.

[0015] Furthermore, in the above-mentioned method for producing high magnetic induction non-oriented silicon steel, the billet thickness is 210mm-240mm during continuous casting.

[0016] Furthermore, in the above-mentioned method for producing high magnetic induction non-oriented silicon steel, the relationship between heating temperature T1 and final rolling temperature T2 is 1.07≤T1 / T2≤1.16.

[0017] Furthermore, in the above-mentioned method for producing high magnetic induction non-oriented silicon steel, during the hot rolling process, the coiling temperature is 500℃-540℃ when coiling the steel.

[0018] Furthermore, in the above-mentioned method for producing high magnetic induction non-oriented silicon steel, the continuous furnace with a furnace length of 200m-215m is used in the annealing process.

[0019] Furthermore, in the above-mentioned method for producing high magnetic induction non-oriented silicon steel, during the annealing process, the annealing temperature T (°C) is adjusted according to the annealing speed C (m / min), and the relationship between the annealing temperature T (°C) and the annealing speed C (m / min) is: 178·ln(C)-0.54·C+107≤T≤178·ln(C)-0.54·C+137.

[0020] In a second aspect of the invention, a high magnetic induction non-oriented silicon steel is provided, which is produced using the high magnetic induction non-oriented silicon steel production method described above.

[0021] The high magnetic induction non-oriented silicon steel and its production method of the present invention have the following advantages and beneficial effects:

[0022] (1) Magnetic induction is enhanced through a dual approach of precipitate control and microstructure control. Regarding precipitates, the total amount and size of precipitates are controlled through impurity element content control, hot-rolling precipitation process control, and normalizing precipitation phase coarsening control. Regarding microstructure, the evolution of texture is controlled through the synergistic effect of hot-rolled, normalized, and annealed microstructures, thereby improving the favorable texture of the product. This invention can increase the magnetic induction of product B5000 by more than 0.02T.

[0023] (2) This invention does not use the addition of precious elements such as Sn, Sb, La, Ce, or special processes such as Ca treatment, high temperature normalization, secondary normalization, and double-roll thin belt. Based solely on the study of precipitated phase and texture, it achieves dual control of precipitated phase and texture by designing excellent matching of composition and process, thereby improving magnetic properties and effectively reducing production costs. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for further understanding of the embodiments of the present invention and constitute a part of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0025] Figure 1The above are metallographic images of the hot-rolled plate in Example 2, where a is the metallographic image of the hot-rolled plate after final rolling at 930°C in Example 4, and b is the metallographic image of the hot-rolled plate after final rolling at 850°C in Comparative Example 5.

[0026] Figure 2 The following are metallographic diagrams of the finished sheet metal in Example 3, where a is the metallographic diagram of the sheet metal after annealing at 910°C in Example 1, b is the metallographic diagram of the sheet metal after annealing at 880°C in Comparative Example 2, and c is the metallographic diagram of the sheet metal after annealing at 950°C in Example 4. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0028] The method used in this invention to achieve high magnetic induction is a combination of precipitate control and texture optimization. Precipitated phases pin grain boundaries and domain walls, hindering grain growth, inhibiting domain rotation, and deteriorating magnetic properties, especially the magnetic induction of the product. Moreover, the greater the quantity and the smaller the size of the precipitates, the greater the performance degradation. It is impossible to completely eliminate precipitates in non-oriented silicon steel; precipitate control is the only option. The direction of precipitate control is to reduce the total amount of precipitates and increase their size. Simply increasing the purity of the steel and reducing the content of impurity elements has limited effect on precipitate control because precipitate precipitation involves thermodynamic conditions and kinetic processes. Only by simultaneously matching and controlling the content of impurity elements and the production process can a better precipitate control effect be achieved. Texture is an important factor affecting the magnetic properties of silicon steel. If the product has a higher content of favorable textures, magnetization is relatively easier, and the magnetic induction is correspondingly higher.

[0029] This invention minimizes the total amount of precipitates by strictly controlling the content of precipitate-forming elements Nb, V, Ti, C, N, and S. It also employs specific hot rolling process parameters and a low-temperature normalizing process to ensure that the precipitates precipitate in the high-temperature section of hot rolling, preventing re-precipitation during the normalizing process and maximizing the size of the precipitates. Regarding texture optimization, it primarily utilizes the synergy of hot rolling and annealing processes, optimizing the microstructure before cold rolling and after annealing, to give the product more favorable textures and improve magnetic induction intensity. Combining the above methods, a class of high magnetic induction non-oriented silicon steel can be prepared. The performance of each grade of product can reach the following levels: when iron loss 3.9≤P1.5 / 50≤4.3 (W / kg), magnetic induction B5000≥1.73T; when iron loss 3.4≤P1.5 / 50≤3.7 (W / kg), magnetic induction B5000≥1.70T; when iron loss 3.1≤P1.5 / 50≤3.4 (W / kg), magnetic induction B5000≥1.68T; and when iron loss 2.7≤P1.5 / 50≤3.0W / kg, magnetic induction B5000≥1.71T.

[0030] The production method of high magnetic induction non-oriented silicon steel of the present invention includes: converter smelting - RH refining - continuous casting - furnace heating - hot rolling - pickling - cold rolling - annealing - coating. The chemical composition of the high magnetic induction non-oriented silicon steel is controlled by mass percentage as follows: Si: 0.60~2.2%, Al: 0.10~0.42%, Mn: 0.21~0.95%, Nb≤0.0025%, V≤0.0020%, Ti≤0.0015%, Nb+V+Ti≤0.0045%, C≤0.0025%, N≤0.0020%, S: 0.0015~0.0035%, P≤0.02%, with the remainder being iron and unavoidable impurities.

[0031] Si, Al, and Mn are the main alloying elements of the silicon steel in this invention, and they are non-ferromagnetic elements. Under the same process, as the content of the main alloying elements increases, the iron loss and magnetic induction of the silicon steel decrease simultaneously. The main alloying elements largely determine the iron loss level of the product. The total content of the main alloying elements is not high, which sets the basic conditions for improving the magnetic induction. Therefore, Si is required to be 0.60–2.2%, Al to be 0.10–0.42%, and Mn to be 0.21–0.95%.

[0032] Nb, V, Ti, C, N, and S are impurity elements and also precipitate-forming elements. The main precipitates involved are Nb, V, and Ti carbonitrides, AlN, and MnS. Among these, Nb, V, and Ti carbonitrides are predominantly carbides, as the high Al content causes N to primarily combine with Al. To reduce the total amount of Nb, V, and Ti carbide precipitation and prevent magnetic aging caused by C, the following concentrations are required: Nb ≤ 0.0025%, V ≤ 0.0020%, Ti ≤ 0.0015%, Nb+V+Ti ≤ 0.0045%, and C ≤ 0.0025%. To reduce AlN precipitation and prevent magnetic aging caused by N, N ≤ 0.0020%. To reduce MnS precipitation, S should be 0.0015–0.0035%. S should not be too low to ensure that the MnS precipitates are relatively large.

[0033] P has no clear effect on improving magnetic properties; in fact, intentionally adding P will degrade magnetic properties. P ≤ 0.02%

[0034] (a) Converter smelting:

[0035] Silicon steel is smelted into molten steel in a converter;

[0036] (II) RH Refining:

[0037] The molten steel after converter smelting is refined by RH refining to control alloying and impurity element content, so that the molten steel meets the target requirements. The RH refining process is the key process for alloying and impurity element content control. The molten steel meets the target requirements in this process. Impurity elements are related to the total amount of precipitated phases in the equilibrium state.

[0038] (III) Continuous casting:

[0039] The RH-refined molten steel is continuously cast into steel billets with a thickness of 210mm-240mm.

[0040] (iv) Heating in the heating furnace:

[0041] The steel billet is placed in a heating furnace and heated, causing some precipitated phases to dissolve and the remaining undissolved precipitates to aggregate and grow. The heating temperature T1 is 980℃-1080℃, and the heating time is 2h-4h, thus precipitating the billet. During the solidification and cooling of the billet, the precipitated phases are already present in the billet. The billet heating process is a process of some precipitated phases dissolving and the remaining undissolved precipitates aggregating and growing. It is desirable to minimize the amount of precipitated phase re-dissolving during the heating process, because the undissolved precipitates will fully aggregate and grow during high-temperature, long-term heating. The higher the heating temperature, the greater the amount of precipitated phase re-dissolving, so the heating temperature should not be too high. Too low a heating temperature will lead to difficulties in hot rolling.

[0042] (V) Hot rolling:

[0043] The heated steel billet is hot-rolled at a final rolling temperature T2 of 880℃-950℃, with a thickness of 2.6mm-3.0mm. The steel is then coiled at a coiling temperature of 500℃-540℃. The hot-rolling coiling temperature still affects the size of the precipitated phases. After final rolling reaches precipitation equilibrium, the billet is cooled to the coiling temperature, where the precipitated phase elements are once again in a supersaturated state, increasing the possibility of fine precipitation.

[0044] The thickness of hot-rolled material is related to hot-rolled energy storage. The smaller the hot-rolled thickness, the greater the hot-rolled energy storage, and the greater the amount of precipitation induced by the corresponding change. Controlling the hot-rolled thickness to 2.6-3.0 mm can effectively reduce the total amount of precipitation.

[0045] The relationship between heating temperature T1 and final rolling temperature T2 is 1.07 ≤ T1 / T2 ≤ 1.16. The hot rolling process after billet heating is accompanied by the rapid precipitation of impurity elements, especially in the finishing rolling stage. Under the influence of rolling energy storage (strain-induced precipitation) and precipitation Gibbs free energy, the precipitated phases have the conditions for rapid precipitation. In the finishing rolling stage, it is desirable for the precipitated phases to precipitate at high temperatures, because the diffusion rate of elements is higher at high temperatures, and the size of the precipitated phase is larger when precipitation is complete. Precipitated phases precipitated at high temperatures also possess the kinetic conditions for Ostwald ripening. In addition, the rolling process is accompanied by dynamic recovery and recrystallization of the microstructure. Higher final rolling temperatures result in a higher degree of recrystallization of the hot-rolled plate microstructure and larger grain size, which is beneficial for improving the texture of the finished product in subsequent cold rolling and annealing processes. However, the final rolling temperature should not be too high. If the final rolling temperature is too high, the precipitates will not precipitate sufficiently in the high-temperature section. Instead, they will precipitate in large quantities in small size during the cooling process after the final rolling. At the same time, the high final rolling temperature also increases the difficulty of the process. The hot rolling heating temperature and the final rolling temperature together determine the size of the precipitates.

[0046] (vi) Pickling:

[0047] The coiled steel is pickled to remove the surface iron oxide scale.

[0048] (vii) Cold rolling:

[0049] The pickled steel is then cold-rolled to a target thickness of 0.496mm-0.504mm;

[0050] (viii) Annealing:

[0051] The cold-rolled steel is annealed in a continuous furnace with a furnace length of 200m-215m and an annealing speed of 120m / min-160m / min. The annealing temperature T (°C) is adjusted according to the annealing speed C (m / min), and the relationship between annealing temperature T (°C) and annealing speed C (m / min) is: 178·ln(C)-0.54·C+107≤T≤178·ln(C)-0.54·C+137. The annealing process affects the grain size and texture of the product. The magnetic properties of the product are improved through precipitate control and texture control, with a target grain size of moderate quality. Excessive temperature results in excessively large grain size, deteriorated texture, and poor magnetic induction; excessively low temperature results in excessively small grain size and poor iron loss.

[0052] (ix) Coating:

[0053] The annealed steel is coated.

[0054] In the method for producing high-magnetic-induction non-oriented silicon steel of this invention, when the target iron loss P1.5 / 50 ≤ 3.0 W / kg is achieved, normalizing is required after hot rolling. The normalizing temperature is 750℃-800℃, the normalizing rate is 40m / min-60m / min, and the length of the continuous furnace used is 110m-120m. Normalized plates exhibit more complete recrystallization than hot-rolled plates, which is more beneficial for improving the texture and magnetic properties of the finished product. During the normalizing process, the precipitated phase undergoes both Ostwald ripening and remelting processes in parallel. The higher the normalizing temperature, the more severe the remelting of the precipitated phase, and after remelting, fine precipitates easily form during the cooling process after normalizing.

[0055] The above production method enables the production of high magnetic induction non-oriented silicon steel.

[0056] Example 1:

[0057] Converter smelting: smelting silicon steel in a converter;

[0058] RH refining: yielded Al: 0.26%, C: 0.002%, N: 0.0013%, S: 0.0022%, P: 0.007%;

[0059] Continuous casting: molten steel refined by RH is continuously cast into steel billets with a thickness of 230mm;

[0060] Heating in a heating furnace: The steel billet is placed in the heating furnace and heated at a temperature T1 of 1030℃ for 3 hours;

[0061] Hot rolling: The heated steel billet is hot rolled to a thickness of 29mm, and then finished to a thickness of 2.7mm after 7 finishing rollings. The final rolling temperature T2 is 910℃, and the steel is coiled at a temperature of 520℃.

[0062] When the target iron loss P1.5 / 50 ≤ 3.0 W / kg is produced, low-temperature normalization is carried out at a normalization temperature of 790℃ and a normalization rate of 50 m / min.

[0063] Pickling: Pickling the coiled steel to remove the surface iron oxide scale;

[0064] Cold rolling: Cold rolling the pickled steel to a target thickness of 0.50 mm;

[0065] Annealing: The cold-rolled steel is annealed in a continuous furnace at a speed of 130 m / min and a target annealing temperature of 920℃.

[0066] Coating: Applying a coating to the annealed steel.

[0067] The magnetic properties of the product were tested using an Epstein square ring, and the performance is shown in the table below. Those that do not meet the requirements of this invention are underlined.

[0068] Examples 1, 2, 3, and 4 of the invention meet the requirements of this invention in terms of impurity element content and key process parameters, exhibiting excellent magnetic induction and iron loss, and achieving the performance target.

[0069] The Ti content and total (Nb+V+Ti) of Comparative Example 5 exceeded the requirements of the invention; the Nb content of Comparative Example 6 exceeded the requirements of the invention; and the total (Nb+V+Ti) of Comparative Examples 7 and 8 exceeded the requirements of the invention. The magnetic properties were deviated, and the magnetic induction was significantly lower than that of Invention Examples 1 to 4 under the same iron loss level.

[0070] Table 1. Situation of Example 1

[0071]

[0072]

[0073] Example 2:

[0074] Converter smelting: smelting silicon steel in a converter;

[0075] RH refining: yielded Si: 1.51%, Al: 0.32%, Mn: 0.35%, C: 0.0019%, N: 0.0015%, P: 0.01%, S: 0.0028%, Nb: 0.0016%, V: 0.0013%, Ti: 0.0011%;

[0076] Continuous casting: molten steel refined by RH is continuously cast into steel billets with a thickness of 215mm;

[0077] Heating in a heating furnace: The steel billet is placed in the heating furnace and heated for 2.5 hours;

[0078] Hot rolling: The heated steel billet is hot rolled to a thickness of 33mm, and then finished to a thickness of 2.65mm after 7 finishing rollings. The steel is then coiled. The hot rolling heating temperature T1, the final rolling temperature T2 and the coiling temperature are set as shown in the table below.

[0079] Pickling: Pickling the coiled steel to remove the surface iron oxide scale;

[0080] Cold rolling: The pickled steel is cold rolled to a target thickness of 0.498 mm;

[0081] Annealing: The cold-rolled steel is annealed in a continuous furnace at a speed of 160 m / min and a target annealing temperature of 940℃.

[0082] Coating: Applying a coating to the annealed steel.

[0083] The magnetic properties of the product were tested using an Epstein square ring, and the performance is shown in the table below. Those that do not meet the requirements of this invention are underlined.

[0084] Table 2. Case Study 2

[0085]

[0086] In the above table of invention examples 1 to 4, the hot rolling heating temperature, final rolling temperature, ratio of heating temperature to final rolling temperature, and coiling temperature all meet the invention requirements, and the magnetic induction of all products with iron loss of 3.4≤P1.5 / 50≤3.7W / kg reaches the target of ≥1.70T.

[0087] The final rolling temperature of Comparative Example 5 is lower than the lower limit of the invention requirement; the ratio of heating temperature to final rolling temperature of Comparative Example 7 is higher than the upper limit of the invention requirement; and the winding temperature of Comparative Example 8 is higher than the upper limit of the invention requirement, resulting in magnetic deviation in the corresponding products. The ratio of heating temperature to final rolling temperature of Comparative Example 6 is lower than the upper limit of the invention requirement, making it unsuitable for mass production.

[0088] The metallographic features of the hot-rolled plates in Invention Example 4 and Comparative Example 5 above are shown in the table above. Figure 1 As shown in the figure. In Comparative Example 5, the hot rolling process did not meet the requirements of the invention. The precipitated phase was in a fine precipitate state, and the recrystallization of the hot-rolled plate was significantly deviated, which was the main reason for the poor magnetic induction.

[0089] Example 3:

[0090] Converter smelting: smelting silicon steel in a converter;

[0091] RH refining: yielded Si: 1.561%, Al: 0.32%, Mn: 0.91%, C: 0.0015%, N: 0.0017%, P: 0.008%, S: 0.0025%, Nb: 0.0014%, V: 0.0017%, Ti: 0.0013%;

[0092] Continuous casting: molten steel refined by RH is continuously cast into steel billets with a thickness of 225mm;

[0093] Heating in the heating furnace: The steel billet is placed in the heating furnace and heated at a temperature T1 of 1060℃ for 3.5 hours.

[0094] Hot rolling: The heated steel billet is hot rolled to a thickness of 31mm, and then finished to a thickness of 2.9mm after 7 finishing rollings. The final rolling temperature T2 is 920℃, and the steel is coiled at a temperature of 530℃.

[0095] Pickling: Pickling the coiled steel to remove the surface iron oxide scale;

[0096] Cold rolling: The pickled steel is cold rolled to a target thickness of 0.502 mm;

[0097] Annealing: The cold-rolled steel is annealed in a continuous furnace. The annealing speed and target annealing temperature are shown in the table below.

[0098] Coating: Applying a coating to the annealed steel.

[0099] The magnetic properties of the product were tested using an Epstein square ring, and the performance is shown in the table below. Those that do not meet the requirements of this invention are underlined.

[0100] Table 3. Case Study 3

[0101]

[0102] Examples 1, 3, and 5 in the table above satisfy the matching relationship between annealing temperature and annealing speed of the present invention, and the magnetic induction of all products with iron loss 3.1≤P1.5 / 50≤3.4W / kg level reaches the target of ≥1.68T.

[0103] Comparative Examples 2 and 4 show that the annealing temperature and annealing speed do not meet the matching requirements of this invention. When the annealing temperature is below the lower limit, the iron loss deviates; when the annealing temperature is above the upper limit, the magnetic induction does not meet the objectives of this invention.

[0104] The metallographic structures of the finished plates corresponding to Invention Example 1, Comparative Example 2, and Comparative Example 4 in the table above are as follows: Figure 2 As shown. In Comparative Example 2, the finished plate had excessively small grain size, resulting in poor iron loss. In Comparative Example 4, the high annealing temperature led to excessively large grain size, resulting in deteriorated texture, which was the main reason for poor magnetic induction.

[0105] In summary, compared with the prior art, the high magnetic induction non-oriented silicon steel and its production method of the present invention have the following advantages and beneficial effects:

[0106] (1) Magnetic induction is enhanced through a dual approach of precipitate control and microstructure control. Regarding precipitates, the total amount and size of precipitates are controlled through impurity element content control, hot-rolling precipitation process control, and normalizing precipitation phase coarsening control. Regarding microstructure, the evolution of texture is controlled through the synergistic effect of hot-rolled, normalized, and annealed microstructures, thereby improving the favorable texture of the product. This invention can increase the magnetic induction of product B5000 by more than 0.02T.

[0107] (2) This invention does not use the addition of precious elements such as Sn, Sb, La, Ce, or special processes such as Ca treatment, high temperature normalization, secondary normalization, and double-roll thin belt. Based solely on the study of precipitated phase and texture, it achieves dual control of precipitated phase and texture by designing excellent matching of composition and process, thereby improving magnetic properties and effectively reducing production costs.

[0108] It should be noted that, unless otherwise expressly specified and limited, the term "connection" or its synonyms should be interpreted broadly in this document. For example, "connection" can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, expressions such as "first" and "second" are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Meanwhile, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. In addition, the terms "front," "rear," "left," "right," "upper," and "lower" in this document refer to the placement states shown in the accompanying drawings.

[0109] 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing high magnetic induction non-oriented silicon steel, characterized in that, The production method of the high magnetic induction non-oriented silicon steel includes: converter smelting - RH refining - continuous casting - heating furnace heating - hot rolling - pickling - cold rolling - annealing - coating. The chemical composition of the high magnetic induction non-oriented silicon steel is controlled by mass percentage as follows: Si: 0.60~2.2%, Al: 0.10~0.42%, Mn: 0.21~0.95%, Nb≤0.0025%, V≤0.0020%, Ti≤0.0015%, Nb+V+Ti≤0.0045%, C≤0.0025%, N≤0.0020%, S: 0.0015~0.0035%, P≤0.02%, with the remainder being iron and unavoidable impurities. Converter smelting: smelting silicon steel in a converter; RH refining: Refining molten steel after converter smelting with RH to control alloying and impurity element content; Continuous casting: molten steel refined by RH is continuously cast into steel billets with a thickness of 210mm-240mm; Heating in a heating furnace: The steel billet is placed in the heating furnace and heated at a temperature T1 of 980℃-1080℃ for 2-4 hours. Hot rolling: The heated steel billet is hot rolled at a final rolling temperature of 880℃-950℃, and the thickness of the hot-rolled steel is 2.6mm-3.0mm. The steel is then coiled at a coiling temperature of 500℃-540℃. The relationship between heating temperature T1 and final rolling temperature T2 is 1.07 ≤ T1 / T2 ≤ 1.16; When the target iron loss P1.5 / 50 is ≤3.0W / kg, normalization is required after hot rolling. The normalization temperature is 750℃-800℃, the normalization speed is 40m / min-60m / min, and the length of the continuous furnace used is 110m-120m. Pickling: Pickling the coiled steel to remove the surface iron oxide scale; Cold rolling: The pickled steel is cold rolled to a target thickness of 0.496mm-0.504mm; Annealing: The cold-rolled steel is annealed in a continuous furnace at a speed of 120m / min - 160m / min. The length of the continuous furnace used in the annealing equipment is 200m-215m. The annealing temperature T (°C) is adjusted according to the annealing speed C (m / min). The relationship between the annealing temperature T (°C) and the annealing speed C (m / min) is: 178•ln(C) -0.54•C+107≤T≤178•ln(C) -0.54•C+137; Coating: Applying a coating to the annealed steel.

2. A high-magnetic-induction non-oriented silicon steel, characterized in that, The high magnetic induction non-oriented silicon steel is produced using the high magnetic induction non-oriented silicon steel production method described in claim 1.

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