High-magnetic-induction oriented silicon steel and manufacturing method thereof

Abstract

The invention discloses high-magnetic-induction oriented silicon steel, which contains Fe and inevitable impurities, and also contains the following chemical elements in percentage by mass: Clt; 0.001% of the total weight; 2.5 to 4.0% of Si; mn: 0.05 to 0.20%; slt; 0.0005%, 0.0005%; the content of Als is 0.015 to 0.045 percent; nlt; 0.005% of the total amount of the raw materials; 0.03% to 0.3% of Cu; and at least one of the following chemical elements: 0 < = 0.03% of P, 0.01-0.40% of Cr, 0.03-0.30% of Sn, 0.001-0.1% of Sb, 0 < = 0.008% of Ti, and 0.001-0.1% of Nb. The invention also discloses a manufacturing method of the silicon steel, which comprises the following steps of: smelting and continuously casting and rolling a thin slab to obtain the thin slab; plate blank heating and hot rolling; normalizing and annealing; cold rolling; decarburization annealing; directly coating an annealing isolating agent without nitriding annealing, and carrying out high-temperature annealing; and insulating coating and flattening annealing.

Description

Technical Field

[0001] This invention relates to a silicon steel and its manufacturing method, and more particularly to an oriented silicon steel and its manufacturing method. Background Technology

[0002] Grain-oriented silicon steel is the basic material for manufacturing the cores of transmission and distribution transformers. The core of its manufacturing technology lies in achieving primary recrystallization with Goss orientation ({011}). <100> Under the action of the second-phase inhibitor, the grains undergo secondary recrystallization, forming a single texture component within the strip. Currently, industrial production of grain-oriented silicon steel primarily employs conventional thick slab processes. However, this process presents numerous insurmountable challenges during the continuous casting to hot rolling stages. For instance, the low slab casting speed (0.8–1.5 m / min) and thick slab (200–250 mm) in the continuous casting stage lead to uneven cooling within the slab, affecting the uniform distribution of the inhibitor. The long holding time in the hot rolling stage impacts slab burn-off and production efficiency, and the high rolling reduction rate (approximately 99%) also increases the difficulty of rolling.

[0003] To overcome the limitations of current steel production technology, existing technologies include solutions for producing silicon steel products using a short casting and rolling process. Among these, the thin slab continuous casting and rolling (CSP) technology, with its unique production characteristics, overcomes many disadvantages of conventional thick slab processes in the continuous casting, slab heating, and hot rolling stages. Slab drawing speeds can reach 6 m / min, and the slab thickness is generally less than 100 mm. After exiting the casting machine, the thin slab can directly enter the heating furnace at a high temperature (up to 900℃), and after approximately 20–40 minutes of heating, it directly enters the hot finishing mill, obtaining hot-rolled coils under relatively low hot rolling reduction conditions, demonstrating significant technological advantages.

[0004] In the prior art, existing patent documents cover the above-mentioned technical fields:

[0005] For example, Chinese patent document CN103774042A, published on May 7, 2014, entitled "A Thin Slab Continuous Casting and Rolling High Magnetic Induction Oriented Silicon Steel and Its Preparation Method," discloses a thin slab continuous casting and rolling high magnetic induction oriented silicon steel and its preparation method. This technical solution uses an AlN+Cu2S composite inhibitor system combined with the grain boundary segregating element Sn. The slab composition contains, by mass%, Al: 0.02–0.04%, N: 0.009–0.013%, and Sn: 0.1–0.2%. The slab soaking furnace process involves holding at 1150–1180℃ for 30–60 min, combined with a two-stage normalizing annealing treatment (high-temperature stage 1050–1150℃, holding for 2–5 min; low-temperature stage 900–950℃, holding for 2–4 min), yielding a finished product with a magnetic induction of B. 800 ≥1.89T, iron loss P 1.7 / 50High magnetic induction oriented silicon steel with a strength of ≤1.2W / kg.

[0006] For example, Chinese patent document CN107002157A, published on August 1, 2017, entitled "Process for Manufacturing Grain-Oriented Electrical Steel Strip and Grain-Oriented Electrical Steel Strip Obtained According to the Process," discloses a process for manufacturing grain-oriented electrical steel strip and a scheme for obtaining grain-oriented electrical steel strip according to the process. This scheme emphasizes feeding the thin slab to a high-frequency induction heating device before hot rolling and homogenizing it at a temperature of approximately 1350–1380°C for a few seconds to effectively activate the inherent inhibitors of MnS and AlN, thereby enhancing the inhibition of secondary recrystallization. However, the effect of induction heating on the uniformity of temperature within the slab and the effective solidification degree of the inhibitors remain uncertain, and the investment in induction heating equipment for production line modification is substantial. Summary of the Invention

[0007] One of the objectives of this invention is to provide a high magnetic induction oriented silicon steel. This oriented silicon steel is based on a thin slab continuous casting and rolling process. Through the coordinated matching of process and alloy composition, it achieves effective solid solution of AlN+Cu2S as the main inhibitor in the thin slab, and finer and more dispersed precipitation of the primary inhibitor in the hot-rolled plate.

[0008] To achieve the above objectives, the present invention provides a high magnetic induction oriented silicon steel, which contains Fe and unavoidable impurities, and further contains the following chemical elements in the following mass percentages:

[0009] C < 0.001%; ​​Si: 2.5–4.0%; Mn: 0.05–0.20%; S < 0.0005%; Als: 0.015–0.045%; N < 0.005%; Cu: 0.03%–0.3%; and

[0010] At least one of the following chemical elements: 0 < P ≤ 0.03%, Cr: 0.01–0.40%, Sn: 0.03–0.30%, Sb: 0.001–0.1%, 0 < Ti ≤ 0.008%, Nb: 0.001–0.1%.

[0011] Furthermore, in the high magnetic induction oriented silicon steel described in this invention, the mass percentage content of each chemical element is as follows:

[0012] C < 0.001%; ​​Si: 2.5–4.0%; Mn: 0.05–0.20%; S < 0.0005%; Als: 0.015–0.045%; N < 0.005%; Cu: 0.03%–0.3%; and

[0013] At least one of the following chemical elements: 0 < P ≤ 0.03%, Cr: 0.01–0.40%, Sn: 0.03–0.30%, Sb: 0.001–0.1%, 0 < Ti ≤ 0.008%, Nb: 0.001–0.1%;

[0014] The balance is Fe and unavoidable impurities.

[0015] Furthermore, in the high magnetic induction oriented silicon steel described in this invention, the average grain diameter is 1 to 5 cm.

[0016] Furthermore, in the high magnetic orientation silicon steel described in this invention, the grain size aspect ratio is 1.5 to 6, wherein the grain size aspect ratio is the ratio of the average size of the grain along the rolling direction to the average size of the grain along the width direction of the plate.

[0017] Furthermore, the iron loss P of the high magnetic induction oriented silicon steel described in this invention... 17 / 50 ≤0.97W / kg, magnetic induction B 800 ≥1.93T.

[0018] Another objective of this invention is to provide a method for manufacturing high magnetic induction oriented silicon steel, which eliminates the need for nitriding treatment and secondary inhibitor supplementation, thereby greatly simplifying the production process and yielding a finished product with excellent magnetic properties.

[0019] To achieve the above objectives, the present invention provides a method for manufacturing high magnetic induction oriented silicon steel, comprising the following steps:

[0020] The slab is smelted and continuously cast and rolled to obtain a thin slab; the mass percentage of each chemical element in the slab is as follows: C: 0.03-0.1%; Si: 2.5-4.0%; Mn: 0.05-0.20%; S: 0.01-0.08%; Als: 0.015-0.045%; N: 0.006-0.03%; Cu: 0.03%-0.3%; and at least one of the following chemical elements: 0 < P ≤ 0.03%, Cr: 0.01-0.40%, Sn: 0.03-0.30%, Sb: 0.001-0.1%, 0 < Ti ≤ 0.008%, Nb: 0.001-0.1%; and the mass percentage of Cu and S satisfies 3 ≤ Cu / S ≤ 6; the mass percentage of Al and N satisfies 1 ≤ Al / N ≤ 4;

[0021] Heating and hot rolling of thin slabs;

[0022] Normalizing annealing;

[0023] Cold rolling;

[0024] Decarburization annealing; the average grain size of the primary recrystallized grains after decarburization annealing is 8-15 μm, and the primary recrystallized grain size inhomogeneity factor is less than 3.5, where the primary recrystallized grain size inhomogeneity factor = the maximum grain size of the primary recrystallized grains / the average grain size of the primary recrystallized grains.

[0025] Instead of nitriding annealing, an annealing release agent is directly applied, followed by high-temperature annealing;

[0026] Insulating coating and smoothing annealing.

[0027] The inventors in this case analyzed the evolution characteristics of primary inhibitors in existing thick slab processes and found that the inhibitors within the slab are affected by the continuous casting process, exhibiting a relatively coarse precipitation state. This makes it more difficult to resolidify the inhibitors during subsequent slab heating. In particular, for low-temperature heating processes using AlN as the main inhibitor, the relatively low slab heating temperature exacerbates the above problems, making it difficult to achieve a fine, dispersed, and uniform precipitation effect for the primary inhibitors in hot-rolled plates. Moreover, this effect is inherited in the initial recrystallization process.

[0028] For the primary recrystallization process, the relatively weak pinning effect of the primary inhibitor weakens the inhibitor's constraint on grain growth, resulting in an increase in the average size of the primary recrystallized grains and a decrease in their uniformity of distribution. Correspondingly, during the annealing process before secondary recrystallization, the matrix grain size is difficult to control stably. On the one hand, the larger average size of the primary recrystallized grains tends to increase the initiation temperature of secondary recrystallization, weakening the driving force for grain growth and affecting the completeness of secondary recrystallization. On the other hand, the uneven distribution of grain size tends to cause larger grains to grow preferentially, and the crystal orientation of these large grains is often not Goss orientation, hindering the secondary recrystallization process of Goss-oriented grains and resulting in a poorer orientation in the finished product. All of these effects will degrade the magnetic properties of the finished product, and may even lead to its scrapping.

[0029] To address the numerous adverse effects caused by the matrix grain size characteristics during the initial recrystallization stage, introducing a secondary inhibitor through nitriding can effectively enhance the matrix inhibition effect. This stabilizes non-Goss-oriented matrix grains before secondary recrystallization of Goss-oriented grains occurs, improving the completeness of secondary recrystallization and the orientation of the finished product, thereby optimizing the product's magnetic properties. However, the application of this technology requires comprehensive matching of decarburization and nitriding processes, including factors such as temperature, time, and atmosphere, and demands even higher precision in element control during alloy smelting.

[0030] To optimize the aforementioned challenges and problems associated with the low-temperature heating and nitriding process for thick slabs, this invention combines the CSP process with an AlN+Cu2S inhibitor system. This system fully utilizes the high slab casting speed and high cooling rate during the continuous casting stage of the CSP process, enabling the formation of finely dispersed inhibitors during the solidification process of thin slabs in the crystallizer and cooling section. This effectively optimizes the inhibitor content within the slab. Simultaneously, the high casting speed ensures that the slab enters the furnace at a relatively high temperature after exiting the casting machine, reducing slab temperature loss and preventing the coarsening of the finely dispersed inhibitors precipitated during continuous casting.

[0031] From the perspective of slab composition design, the design principles of each chemical element in the slab are as follows:

[0032] Carbon (C): As an element that expands the γ-phase region in steel, C enables the formation of a certain amount of γ-phase during the slab heating process before hot rolling. During hot rolling, combined with hot deformation and the γ→α phase transformation, a corresponding microstructure gradient is achieved within the slab, refining the grain structure, especially in the central region along the thickness direction. This facilitates microstructure control in subsequent processes, optimizing secondary recrystallization. For silicon steel, the higher Si content increases its α-phase region. Therefore, the addition of C must be matched with the Si content in the steel to ensure an appropriate proportion of γ-phase is obtained during manufacturing. Accordingly, this invention requires that the amount of C added be no less than 0.03%, and the amount of C added must be controlled within 0.1% to prevent the formation of large-sized carbide deposits, which would be difficult to remove effectively during subsequent decarburization, affecting the manufacturing process and performance stability of the product.

[0033] Silicon (Si): As a core element in oriented silicon steel to improve resistivity and reduce losses, the amount of Si added in this invention needs to be controlled between 2.5% and 4.0%. Too low an addition (<2.5%) will reduce the resistivity of the material and make it difficult to obtain excellent magnetic properties; too high an addition (>4.0%) will make the material difficult to process, worsen its rollability, and also significantly increase the difficulty of controlling the stability of the microstructure, which can easily cause unstable secondary recrystallization of the product, abnormal magnetic properties, and even product performance failure.

[0034] Manganese (Mn): Similar to silicon (Si), Mn in silicon steel can increase resistivity and reduce losses. In this invention, Mn plays two main roles: firstly, it expands the γ-phase region, improving the ability to uniformly control the hot-rolled microstructure; secondly, it improves the hot-working properties of silicon steel, preventing quality problems such as cracking and fissures during hot rolling. When the Mn content is below 0.05%, it cannot effectively exert the above effects; while above 0.20%, it easily causes phase transformation instability, affecting microstructure uniformity, impacting the uniform control of the primary recrystallization microstructure, and causing instability in secondary recrystallization.

[0035] Copper (Cu) and Sulfur (S): Cu and S are the main inhibitor-forming elements in this invention. During the hot rolling stage, they can form Cu₂S inhibitor precipitation. Their addition amounts need to be coordinated and matched to achieve effective solid solution control and obtain a fine and dispersed inhibitor precipitation effect during hot rolling. Cu, in particular, not only forms inhibitors but also, as a γ-forming element, expands the γ-phase region and optimizes the hot-rolled microstructure. In this invention, when the Cu content is below 0.03%, it cannot exert the above-mentioned effects; when its content is above 0.3%, it increases manufacturing costs and is detrimental to the effective solid solution and precipitation control of the inhibitor, which is not conducive to optimizing magnetic properties. For S, if the S content is <0.01%, the number of Cu₂S inhibitors formed is insufficient, the inhibitory ability of the primary inhibitor is weakened, and the stable control of the primary recrystallization grain size is affected; when the S content is >0.08%, the Cu₂S inhibitor solid solution becomes unstable, and the primary and secondary recrystallization easily become unstable, leading to a deterioration in product performance. At the same time, a high sulfur content makes it difficult to remove sulfur during the high-temperature annealing process of the essence, increasing manufacturing difficulty and cost.

[0036] Aluminum (Als) and Nitrogen (N): Als and N are also the main inhibitor-forming elements in this invention, capable of forming AlN as a primary inhibitor that precipitates during the hot rolling stage, enhancing the inhibition effect during the primary and secondary recrystallization processes. When the Als content is below 0.015%, the amount of inhibitor precipitated is insufficient, making it difficult to achieve adequate inhibition; when the Als content is above 0.045%, Als remains, and since this invention does not involve nitriding, Als can easily cause adverse effects during the formation of the bottom layer, resulting in poor surface quality. For N, when the content is below 0.006%, the primary inhibitor is insufficient, and the primary recrystallization cannot be stably controlled; when the content exceeds 0.03%, the steelmaking load increases, and bubble-like defects are easily formed in the continuously cast billet.

[0037] Phosphorus (P): P has a certain grain boundary segregation effect in steel, which can delay the coarsening of inhibitors during secondary recrystallization annealing. However, excessive P content will affect the uniformity of inhibitor precipitation and the stability of secondary recrystallization. In addition, P in steel tends to have an adverse effect on the rollability of the material, especially for materials with relatively high Si content such as grain-oriented silicon steel. Therefore, its content needs to be limited. This invention controls it to be below 0.03%.

[0038] Chromium (Cr): Cr helps improve the resistivity of silicon steel and also has a certain effect on improving mechanical properties. Simultaneously, the addition of Cr promotes oxidation of the steel plate during decarburization annealing, resulting in better oxygen adhesion on the surface. After high-temperature annealing, it promotes a more uniform magnesium silicate underlayer, thus improving the surface quality of the product. However, excessive Cr content can adversely affect the decarburization and nitriding processes; therefore, this invention limits its content to 0.01–0.40%.

[0039] Tin (Sn) and Antimony (Sb): Both Sn and Sb are grain boundary segregating elements, which have an auxiliary inhibitory effect. They can segregate at the interface between the inhibitor particles and the matrix, thereby reducing the interfacial energy of the inhibitor particles and preventing premature ripening and growth of the inhibitor during secondary recrystallization annealing, thus maintaining the inhibitory ability and ensuring the stable occurrence of secondary recrystallization. However, there is a certain upper limit to the amount of these elements added. Due to their surface segregation effect, they can adversely affect the decarburization and nitriding processes, and can also deteriorate the quality of the underlying layer, resulting in poor insulation film quality, reduced adhesion, and affecting the overall performance evaluation of the product. Based on the above advantages and disadvantages, the amount of Sn or Sb added needs to be limited. For Sn, its mass percentage can preferably be set to 0.03-0.30%; for Sb, its mass percentage can preferably be set to 0.001-0.1%.

[0040] Titanium (Ti) and Niobium (Nb): Both Ti and Nb can form precipitates with C and N, respectively. TiN precipitates at relatively high temperatures during continuous casting. In conventional thick slab processes, TiN precipitates in combination with inhibitors such as MnS, forming large particles that are detrimental to the stable control of secondary recrystallization. For Nb, the precipitation temperature for NbN formation is relatively low, which can help stabilize the grain size during initial recrystallization. However, the precipitates formed by Ti and Nb with C can hinder the decarburization process, and these compounds have relatively high decomposition temperatures, affecting the purification effect during high-temperature purification annealing. Therefore, this invention limits their content, with the Ti mass percentage set to below 0.008% and the Nb mass percentage set to 0.001–0.1%.

[0041] In this invention, the mass percentages of Cu and S in the slab satisfy 3≤Cu / S≤6; and the mass percentages of Al and N satisfy 1≤Al / N≤4. This is to ensure that the thin slab can achieve sufficient solid solution of AlN and Cu2S inhibitors without using excessively high heating temperatures during the heating process, and to obtain finer and more dispersed inherent inhibitors in the subsequent hot-rolled plate.

[0042] Furthermore, after the decarburization annealing step, this invention eliminates the need for nitriding annealing. It can directly proceed through coating an annealing release agent, slow heating and high-temperature purification annealing, and insulating coating and leveling annealing steps to complete the secondary recrystallization annealing and related processes. This is because by matching the alloy composition design with the slab heating process of continuous casting and rolling (CSP) technology, fine and dispersed precipitation of precipitates within the continuously cast slab is promoted. Combined with optimized adjustments to the slab heating process, effective solid solution of inhibitors within the slab is achieved. This reduces the slab heating temperature while simultaneously achieving fine and dispersed precipitation of primary inhibitors within the hot-rolled slab. Therefore, based on this, secondary recrystallization of accurately oriented Goss-oriented grains can be obtained without nitriding treatment.

[0043] In summary, this invention achieves effective control of primary inhibitors through alloy design under the CSP process, thin slab continuous casting, and coordinated matching of various processes. This eliminates the need for supplementing inhibitors during nitriding treatment, and successfully manufactures high-magnetic-induction and even ultra-high-magnetic-induction oriented silicon steel products.

[0044] Based on this, the present invention further employs a laser scribing step to refine the magnetic domains after the insulating coating and leveling annealing steps, which can further obtain products with lower iron loss and better magnetic properties.

[0045] Furthermore, in the manufacturing method described in this invention, the mass percentages of Cu and S in the slab satisfy 3 ≤ Cu / S ≤ 5; and the mass percentages of Al and N satisfy 1 ≤ Al / N ≤ 3.

[0046] The present invention controls the mass percentage of Cu and S in the slab to satisfy 3≤Cu / S≤5; and the mass percentage of Al and N to satisfy 1≤Al / N≤3. This is so that the thin slab can achieve sufficient solid solution of AlN and Cu2S inhibitors without using excessively high heating temperatures during the heating process, and can obtain more finely dispersed inherent inhibitors in the subsequent hot-rolled plate.

[0047] However, the inventors also discovered through research that when the slab drawing speed reaches 4.5 m / s or higher during the smelting and thin slab continuous casting and rolling steps, and the slab furnace temperature reaches 950°C or higher, the addition amount of inhibitor alloying elements in the slab can be relaxed to meet the above-mentioned requirement that "the mass percentage of Cu and S meets 3 ≤ Cu / S ≤ 6; the mass percentage of Al and N meets 1 ≤ Al / N ≤ 4". This is because the slab can achieve a relatively higher cooling rate under higher drawing speed conditions, which is conducive to the fine precipitation of inhibitors. At the same time, the high furnace temperature can avoid coarsening of precipitates and facilitate more complete solidification in the heating furnace. Increasing the amount of inhibitor elements added will not significantly affect their effect, so this limitation condition can be appropriately relaxed.

[0048] Furthermore, in the manufacturing method described in this invention, the atomic ratio of Cu to S in the slab satisfies: 1.5 ≤ n Cu :n S ≤3; the ratio of Al to N atoms satisfies: 0.6≤n Al :n N ≤1.5.

[0049] In this invention, the inhibitor-related alloying elements used in the slab include Al, N, Cu, and S. To ensure sufficient solid solution of the AlN and Cu2S inhibitors during the heating process of the thin slab without using excessively high heating temperatures, and to obtain finer, more dispersed inherent inhibitors in the subsequent hot-rolled plate, the atomic ratio can be further controlled within the range of 1.5 ≤ n. Cul :n S ≤3; 0.6≤n Al :n N ≤1.5.

[0050] Furthermore, in the thin slab continuous casting and rolling step of the manufacturing method described in this invention, the slab drawing speed is controlled at 3.0 to 5.5 m / min, and the obtained slab thickness is 50 to 90 mm.

[0051] Furthermore, in the slab heating and hot rolling steps of the manufacturing method described in this invention, the slab temperature entering the furnace is controlled at 850-1000°C, the slab time in the furnace is controlled at 15-40 minutes, and the slab temperature exiting the heating furnace is controlled at 1100-1300°C.

[0052] For the heating process of thin slabs, this invention adjusts the addition amount of AlN+Cu2S inhibitor-related elements during the alloy smelting stage to match the above heating process. With the assistance of the fine and dispersed inhibitor precipitation effect within the slab, it promotes a high proportion of inhibitor solution to be completed in a short time at a temperature lower than the complete solution temperature. Furthermore, by controlling the furnace exit temperature, stable control of the hot rolling start temperature is achieved to ensure that the inhibitor precipitates more finely and dispersedly during the hot deformation process in the hot rolling stage.

[0053] Furthermore, in the normalizing annealing step of the manufacturing method described in this invention, a normalizing annealing is performed at a temperature of 800–1200°C for a time of 80–150 seconds.

[0054] Furthermore, in the decarburization annealing step of the manufacturing method described in this invention, decarburization annealing is performed at a temperature of 780–850°C for a time of 90–140 seconds.

[0055] The high magnetic induction oriented silicon steel and its manufacturing method described in this invention have the following advantages and beneficial effects:

[0056] The high-magnetic-induction grain-oriented silicon steel and its manufacturing method described in this invention are based on high-magnetic-induction grain-oriented silicon steel products manufactured using the CSP process. By matching the alloy composition design with the CSP slab heating process, fine and dispersed precipitation of precipitates within the continuously cast slab is promoted. Combined with optimized adjustments to the slab heating process, effective solid solution of inhibitors within the slab is achieved, reducing the slab heating temperature while simultaneously obtaining the effect of fine and dispersed precipitation of primary inhibitors within the hot-rolled slab. Based on this, secondary recrystallization of accurately oriented Goss grains can be obtained without nitriding treatment, thereby obtaining grain-oriented silicon steel products with high and even ultra-high magnetic induction properties.

[0057] In some implementations, its iron loss P 17 / 50 ≤0.97W / kg, magnetic induction B 800 ≥1.93T. Detailed Implementation

[0058] The high magnetic induction oriented silicon steel and its manufacturing method described in this invention will be further explained and described below with reference to specific embodiments. However, this explanation and description do not constitute an improper limitation on the technical solution of this invention.

[0059] Examples 1-10 and Comparative Examples 1-4

[0060] The high magnetic induction oriented silicon steels of Examples 1-10 of this invention were all prepared using the following steps:

[0061] (1) Smelting and continuous casting and rolling of thin slabs to obtain thin slabs: The molten steel obtained from smelting is cast into thin slabs. During the casting process, the slab drawing speed is controlled at 3.0 to 5.5 m / min, and the slab thickness is 50 to 90 mm. Tables 1-1 and 1-2 list the chemical element mass percentages of the slabs of Examples 1-10 and Comparative Examples 1-4.

[0062] (2) Heating and hot rolling of thin slabs: After the thin slabs obtained from continuous casting are cut, they are quickly put into the tunnel furnace for heating and heat preservation. The temperature of the slab entering the furnace is controlled at 850-1000℃, the time of the slab in the furnace is controlled at 15-40min, the temperature of the slab exiting the heating furnace is controlled at 1100-1300℃, and hot rolling is completed above 850℃ to obtain oriented silicon steel hot-rolled plates with a thickness of 1.5-3.5mm.

[0063] (3) Normalizing annealing: The hot-rolled plate is subjected to normalizing annealing at a temperature of 800-1200℃, and the normalizing annealing time is controlled at 80-150s.

[0064] (4) Cold rolling: The normalized plate after pickling is subjected to a single cold rolling process with a large reduction rate to obtain oriented silicon steel strip. The cold rolling reduction rate can be greater than 85% to roll the normalized plate into a cold-rolled plate with a thickness of 0.3 mm.

[0065] (5) Decarburization annealing: The cold-rolled strip is subjected to decarburization annealing at 780-850℃ for 90-140s. After decarburization annealing, the average grain size of the primary recrystallized grains is 8-15μm, and the primary recrystallized grain size inhomogeneity factor is less than 3.5, where the primary recrystallized grain size inhomogeneity factor = maximum grain size of primary recrystallized grains / average grain size of primary recrystallized grains.

[0066] (6) Apply annealing release agent directly without nitriding annealing and perform high temperature annealing: After applying annealing release agent mainly composed of MgO, slow heating and high temperature purification annealing treatment can be carried out according to the conventional process.

[0067] (7) Insulating coating and smoothing annealing: The finished product is obtained after applying the insulating coating and hot stretching and smoothing annealing. Tables 1-3 and 1-4 list the chemical element mass percentages of the high magnetic induction oriented silicon steel products of Examples 1-10 and the silicon steel products of Comparative Examples 1-4.

[0068] In some implementations, step (8) laser marking can also be performed to obtain oriented silicon steel with better performance.

[0069] It should be noted that although the comparative steels of Comparative Examples 1-4 were also prepared using the above steps, their chemical composition ratios or process parameters did not meet the design requirements of this invention.

[0070] Table 1-1. Chemical composition (wt%, balance: Fe and other unavoidable impurities) of slabs in various embodiments and comparative examples of the present invention.

[0071] serial number C Si Mn S Als N Cu Example 1 0.099 3.98 0.060 0.039 0.031 0.028 0.165 Example 2 0.044 3.04 0.194 0.068 0.041 0.027 0.252 Example 3 0.087 3.77 0.093 0.080 0.038 0.021 0.064 Example 4 0.093 3.87 0.179 0.038 0.045 0.022 0.119 Example 5 0.073 3.55 0.086 0.010 0.031 0.018 0.030 Example 6 0.069 3.35 0.068 0.045 0.015 0.006 0.170 Example 7 0.032 2.50 0.123 0.062 0.036 0.019 0.290 Example 8 0.058 3.29 0.181 0.059 0.031 0.011 0.261 Example 9 0.076 3.59 0.112 0.046 0.028 0.023 0.258 Example 10 0.053 3.24 0.098 0.041 0.042 0.011 0.147 Comparative Example 1 0.029 3.11 0.046 0.014 0.039 0.015 0.084 Comparative Example 2 0.055 2.43 0.167 0.042 0.017 0.021 0.130 Comparative Example 3 0.033 2.85 0.23 0.025 0.030 0.014 0.199 Comparative Example 4 0.11 4.25 0.135 0.045 0.039 0.011 0.120

[0072] Table 1-2. Chemical composition of slabs in various embodiments and comparative examples of the present invention (wt%, balance being Fe and other unavoidable impurities).

[0073]

[0074]

[0075] Table 1-3. (wt%, balance is Fe and unavoidable impurities)

[0076]

[0077]

[0078] Table 1-4. (wt%, balance is Fe and unavoidable impurities)

[0079] serial number P Cr Sn Sb Nb Ti Example 1 0.029 0.257 0.209 0.004 0.030 0 Example 2 0 0.400 0.031 0.060 0.100 0.003 Example 3 0.029 0.237 0.300 0 0.064 0.002 Example 4 0.025 0.347 0.239 0 0.077 0.004 Example 5 0.006 0.350 0 0.092 0.015 0.002 Example 6 0.025 0 0.125 0.088 0.069 0.003 Example 7 0.022 0.010 0.082 0.097 0.051 0 Example 8 0 0.226 0.141 0.006 0.001 0.001 Example 9 0.009 0.031 0.090 0.008 0 0.008 Example 10 0.011 0 0.211 0.021 0.052 0.002 Comparative Example 1 0.035 0.124 0.294 0 0.061 0.002 Comparative Example 2 0.013 0.339 0.096 0.023 0.077 0 Comparative Example 3 0.012 0.007 0 0.010 0.033 0.003 Comparative Example 4 0.028 0.282 0.120 0 0.110 0.002

[0080] Tables 2-1 and 2-2 list the specific process parameters for the high magnetic induction oriented silicon steel of Examples 1-10 and the comparative steel of Comparative Examples 1-4 of the present invention.

[0081] Table 2-1.

[0082]

[0083]

[0084] Table 2-2.

[0085] serial number Normalizing temperature (°C) Normalization time (s) Decarbonization temperature (°C) Decarbonization time (s) Example 1 800 95 820 105 Example 2 1130 115 795 90 Example 3 970 85 850 100 Example 4 1140 105 810 130 Example 5 1200 135 780 105 Example 6 870 80 835 120 Example 7 890 120 825 125 Example 8 950 135 820 115 Example 9 920 150 835 100 Example 10 970 115 830 140 Comparative Example 1 960 80 825 125 Comparative Example 2 900 105 810 110 Comparative Example 3 950 130 835 120 Comparative Example 4 1120 100 800 100

[0086] Samples were taken from the high magnetic induction oriented silicon steels of Examples 1-10 and the comparative steels of Comparative Examples 1-4. The samples from each example and comparative example steel plate were observed, and various relevant properties were tested. The results of the observations and related performance tests are listed in Table 3. The specific testing methods for the relevant properties are described below:

[0087] Microstructure testing: For microstructure testing, metallographic preparation of the initial recrystallization sample was performed according to GB / T 15125-2009; for macrostructure testing, the sample was prepared by acid washing of the finished sample. Subsequently, grain size was measured according to GB / T 6394-2017, and the micro and macro grain sizes were statistically analyzed. Simultaneously, the aspect ratio of the macro grain size was measured and statistically analyzed along the rolling direction and along the width direction of the plate, referring to the straight-line intercept method described in GB / T 6394-2017.

[0088] Magnetic property testing: Iron loss P 17 / 50 and magnetic induction intensity B800 The method for measuring the magnetic properties of electrical steel sheets (strips) using the Epstein square method specified in standard GB / T 3655-2022 was adopted.

[0089] Table 3 lists the test results of various properties of the high magnetic induction oriented silicon steel of Examples 1-10 and the comparative steel of Comparative Examples 1-4 of the present invention.

[0090] Table 3.

[0091]

[0092] Based on the data listed in Tables 1-1, 1-21, 1-3, 1-4, 2-1, 2-2, and 3, it can be seen that the high magnetic induction oriented silicon steel products prepared in Examples 1-8 of this invention have alloy compositions and manufacturing processes that meet the requirements of this invention, and their corresponding microstructures also meet the requirements of this invention. The corresponding magnetic induction intensity B... 800 All of them achieved magnetic performance levels of 1.93T and above, with some process performance reaching 1.95T and above, demonstrating ultra-high magnetic induction performance.

[0093] Based on the relevant data from Comparative Examples 1-5, it can be seen that when the alloy composition and manufacturing process do not meet the requirements of this invention, the initial recrystallization grain size data may not reach the required value range, resulting in large fluctuations in the magnetic properties of the oriented silicon steel product obtained from the trial production, and the secondary recrystallization of Goss oriented grains may not be able to occur stably.

[0094] It should be noted that embodiments 9-10 of this case employed a higher billet pulling speed, resulting in a higher slab entry temperature into the furnace. Therefore, the mass percentage of high-proportion inhibitor elements within the slab was achieved, satisfying 3≤Cu / S≤6, 1≤Al / N≤4, and B was also obtained. 800 Magnetic properties >1.93T.

[0095] It should be noted that the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0096] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A high-magnetic-induction grain-oriented silicon steel, containing Fe and unavoidable impurities, characterized in that, It also contains the following chemical elements in the following mass percentages: C<0.001%; ​​Si: 2.5~4.0%; Mn: 0.05~0.20%; S<0.0005%; Als: 0.015~0.045%; N<0.005%; Cu: 0.03%~0.3%; as well as At least one of the following chemical elements: 0 < P ≤ 0.03%, Cr: 0.01–0.40%, Sn: 0.03~0.30%, Sb: 0.001~0.1%, 0<Ti≤0.008%, Nb: 0.001~0.1%.

2. The high magnetic induction oriented silicon steel as described in claim 1, characterized in that, Its mass percentage content of each chemical element is as follows: C<0.001%; ​​Si: 2.5~4.0%; Mn: 0.05~0.20%; S<0.0005%; Als: 0.015~0.045%; N<0.005%; Cu: 0.03%~0.3%; as well as At least one of the following chemical elements: 0 < P ≤ 0.03%, Cr: 0.01–0.40%, Sn: 0.03~0.30%, Sb: 0.001~0.1%, 0<Ti≤0.008%, Nb: 0.001~0.1%; The balance is Fe and unavoidable impurities.

3. The high magnetic induction oriented silicon steel as described in claim 1 or 2, characterized in that, Its average grain diameter is 1–5 cm.

4. The high magnetic induction oriented silicon steel as described in claim 1 or 2, characterized in that, The grain size aspect ratio is 1.5 to 6, where the grain size aspect ratio is the ratio of the average size of the grain along the rolling direction to the average size of the grain along the width of the plate.

5. The high magnetic induction oriented silicon steel as described in claim 1 or 2, characterized in that, Its iron loss P 17 / 50 ≤0.97W / kg, magnetic induction B 800 ≥1.93T.

6. The method for manufacturing high magnetic induction oriented silicon steel according to any one of claims 1-5, characterized in that, Including the following steps: The smelting and continuous casting and rolling of thin slabs are used to obtain thin slabs; the mass percentage of each chemical element in the slabs is: C: 0.03-0.1%; Si: 2.5-4.0%; Mn: 0.05-0.20%; S: 0.01~0.08%; Als: 0.015~0.045%; N: 0.006–0.03%; Cu: 0.03%–0.3%; and at least one of the following chemical elements: 0 < P ≤ 0.03%, Cr: 0.01–0.40%. Sn: 0.03~0.30%, Sb: 0.001~0.1%, 0<Ti≤0.008%, Nb: 0.001~0.1%; and the mass percentage of Cu and S satisfies 3≤Cu / S≤6; the mass percentage of Al and N satisfies 1≤Al / N≤4; Heating and hot rolling of thin slabs; Normalizing annealing; Cold rolling; Decarburization annealing; the average grain size of the primary recrystallized grains after decarburization annealing is 8-15 μm, and the primary recrystallized grain size inhomogeneity factor is less than 3.5, where the primary recrystallized grain size inhomogeneity factor = the maximum grain size of the primary recrystallized grains / the average grain size of the primary recrystallized grains. Instead of nitriding annealing, an annealing release agent is directly applied, followed by high-temperature annealing; Insulating coating and smoothing annealing.

7. The manufacturing method as described in claim 6, characterized in that, The mass percentages of Cu and S in the slab satisfy 3 ≤ Cu / S ≤ 5; the mass percentages of Al and N satisfy 1 ≤ Al / N ≤ 3.

8. The manufacturing method as described in claim 6, characterized in that, The atomic ratio of Cu to S in the slab satisfies: 1.5 ≤ n Cu :n S ≤3; the ratio of Al to N atoms satisfies: 0.6≤n Al :n N ≤1.

5.

9. The manufacturing method as described in claim 6, characterized in that, In the thin slab continuous casting and rolling process, the slab drawing speed is controlled at 3.0 to 5.5 m / min, and the obtained slab thickness is 50 to 90 mm.

10. The manufacturing method as described in claim 6, characterized in that, In the slab heating and hot rolling steps, the slab temperature entering the furnace is 850-1000℃, the slab time in the furnace is controlled at 15-40 minutes, and the slab temperature exiting the heating furnace is controlled at 1100-1300℃.

11. The manufacturing method as described in claim 6, characterized in that, In the normalizing annealing step, normalizing annealing is carried out at a temperature of 800–1200℃ for 80–150 seconds.

12. The manufacturing method as described in claim 6, characterized in that, In the decarburization annealing step, decarburization annealing is carried out at a temperature of 780–850℃ for a time of 90–140s.

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