Electrical steel and method of manufacturing the same

Abstract

The application discloses an electrical steel and a manufacturing method thereof. The manufacturing method of the electrical steel comprises smelting rolling, thickness collection, cross-section parameter acquisition and detection screening. The smelting rolling comprises adopting a non-oriented electrical steel with a preset chemical composition ratio, and obtaining a hot-rolled strip through the processes of molten iron pre-desulfurization, converter smelting, RH vacuum treatment, continuous casting, slab heating, rough rolling and finish rolling. The detection screening comprises detecting unqualified strip steel according to the cross-section convexity C100 and the local high point thickness difference, and rejecting and blocking the flow into the cold rolling process. The local high point thickness difference LH in any continuous 40 mm length in the width direction of the strip steel is less than or equal to 10 microns, and the convexity of the strip steel at the position of 100 mm of the edge part is greater than or equal to 5 microns and less than or equal to 25 microns. The technical scheme of the application can effectively prevent the cold-rolled product from being ribbed due to the hot-rolled profile defects through the accurate detection and screening of the cross-section convexity and the local high point thickness difference of the hot-rolled strip, so as to improve the product quality and the qualified rate of the electrical steel.

Description

Technical Field

[0001] This application relates to the field of iron and steel smelting, and in particular to an electrical steel and a method for manufacturing the same. Background Technology

[0002] Electrical steel, also known as silicon steel, is a soft magnetic alloy of iron and silicon with a silicon content within a specific range. Due to its extremely high permeability and extremely low coercivity, it can generate strong magnetic induction intensity in alternating magnetic fields while minimizing iron losses. Electrical steel is widely used in core areas such as drive motors for new energy vehicles, ultra-high voltage transformers, and high-efficiency industrial motors. In particular, high-grade non-oriented electrical steel directly determines the energy efficiency rating and power density of end-use equipment.

[0003] The current production process for electrical steel typically involves complex steps such as hot metal pretreatment, converter smelting, RH vacuum refining, continuous casting, slab heating, hot rolling, and cold rolling annealing. However, in existing production processes, visible strip-like protrusions, known as "ribs," often form on the surface of the finished product. This not only leads to product downgrading but also severely affects the stacking coefficient and magnetic properties of the motor core. Summary of the Invention

[0004] In view of the above problems, this application provides an electrical steel and its manufacturing method, which can effectively prevent the cold-rolled finished product from developing ribs due to hot-rolled profile defects by accurately detecting and screening the convexity of the hot-rolled strip cross section and the thickness difference of local high points, thereby improving the finished product quality and pass rate of electrical steel.

[0005] In one aspect, this application provides a method for manufacturing electrical steel, including smelting and rolling, thickness acquisition, cross-sectional parameter acquisition, and inspection and screening. Smelting and rolling includes using non-oriented electrical steel with a preset chemical composition, and rolling it into hot-rolled strip steel through hot metal pre-desulfurization, converter smelting, RH vacuum treatment, continuous casting, slab heating, roughing, and finishing rolling processes. Thickness acquisition includes real-time acquisition of the cross-sectional thickness data of the strip steel at the exit of the hot-rolling finishing mill. Cross-sectional parameter acquisition includes obtaining the cross-sectional convexity C100 and the thickness difference LH of local high points within any continuous 40mm length in the width direction of the strip steel based on the cross-sectional thickness data. Inspection and screening includes detecting unqualified strip steel based on the cross-sectional convexity C100 and the thickness difference of local high points, rejecting it, and preventing it from flowing into the cold rolling process. Specifically, the thickness difference LH of local high points within any continuous 40mm length in the width direction of the strip steel is ≤10μm, and the convexity at the edge of the strip steel is 5μm ≤ C100 ≤ 25μm.

[0006] In some embodiments, the section parameter acquisition step further includes: acquiring a wedge-shaped W40 at a position 40mm from the edge of the strip based on the cross-sectional thickness data. The inspection and screening step further includes: comparing the wedge-shaped W40 with a preset standard to determine whether the strip is qualified. The preset standard further includes: -20μm ≤ W40 ≤ 20μm.

[0007] In some embodiments, the section parameter acquisition step further includes: acquiring a wedge-shaped W100 at a position 100mm from the edge of the strip based on the cross-sectional thickness data. The inspection and screening step further includes comparing the wedge-shaped W100 with a preset standard to determine whether the strip is qualified. The preset standard further includes: -15μm ≤ W100 ≤ 15μm.

[0008] In some embodiments, the section parameter acquisition step further includes: obtaining the maximum thickness value H within a 100mm interval in the middle of the strip based on the cross-sectional thickness data. midmax And the maximum thickness H within a 200mm interval on each side of the strip. edgemax The detection and screening steps also include... midmax With H edgemax A comparison is made. The preset criteria also include: H midmax >H edgemax .

[0009] In some embodiments, the formula for calculating the cross-sectional convexity C100 is: C100 = T center (T edge_WS +T edge_DS ) / 2; where T center T represents the thickness at the center point of the strip. edge_WS T is the thickness at 100mm from the working side edge of the strip. edge_DS The thickness is located 100mm from the drive side of the strip.

[0010] In some embodiments, the quality determination step further includes: generating a rejection signal and sending it to a coiler or slitting shear downstream of the finishing mill. Based on the position coordinates of the defective product along the length of the strip, the coiler is controlled not to coil or the slitting shear is controlled to physically cut the defective product, thus separating it from the production line.

[0011] In some embodiments, during the slab heating process, the heating temperature of the slab is controlled at 1130°C to 1170°C, and the furnace exit temperature of the slab is controlled at 1100°C to 1140°C.

[0012] In some embodiments, after the qualified hot-rolled strip enters the cold rolling process, it undergoes pickling and continuous rolling treatment. The single-sided edge trimming amount in the pickling and continuous rolling process is controlled to be 20mm to 40mm to remove areas with abnormal edge thickness.

[0013] Secondly, this application also provides an electrical steel, which is obtained by cold rolling hot-rolled strip steel produced by the manufacturing method of electrical steel as described in the above embodiments. The chemical composition of the electrical steel, by weight percentage, is: C≤0.0055%, 0.20%≤Si≤3.50%, 0.10%≤Mn≤0.90%, P≤0.15%, S≤0.006%, 0.15%≤Als≤1.50%, with the balance being iron and unavoidable trace elements.

[0014] In some embodiments, the thickness of the electrical steel is 0.20 mm to 0.50 mm, and the rate of grade reduction of the rib defects of the electrical steel is ≤ 0.05%.

[0015] The method for manufacturing electrical steel provided in this application collects strip cross-sectional thickness data in real time at the hot-rolled finishing mill exit and performs online detection and rejection based on two key parameters: cross-sectional convexity C100 and local high-point thickness difference LH. This achieves the goal of preventing hot-rolled strips with abnormal cross-sectional profiles from flowing into the cold-rolling process at the source. This technique effectively avoids the "ribbed" defect in finished products caused by the amplification of local thickness fluctuations in hot-rolled strips under the large reduction rate of cold rolling. It significantly reduces the downgrading rate of finished electrical steel products due to plate shape issues, improves the product quality consistency and production stability of high-grade non-oriented electrical steel, and provides a high-quality raw material guarantee with controllable profile quality for subsequent cold-rolling processes.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which the same or similar reference numerals denote the same or similar features, and the drawings are not drawn to scale.

[0018] Figure 1 This application provides a process flow diagram of a method for manufacturing electrical steel according to one embodiment. Detailed Implementation

[0019] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0020] It should be noted that, in this document, relational terms such as "first" and "second" are used merely 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. Furthermore, 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. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0021] It should be understood that when describing the structure of a component, when referring to a layer or region as being "above" or "on top of" another layer or region, it can mean that it is directly above the other layer or region, or that it contains other layers or regions between it and the other layer or region. Furthermore, if the component is flipped over, that layer or region will be located "below" or "under" the other layer or region.

[0022] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. Furthermore, the features, structures, or characteristics described below may be combined in any suitable manner in one or more embodiments.

[0023] In the hot-rolling finishing process of non-oriented electrical steel, the formation of the "center-convex" structure of the strip mainly stems from the bending and thermal expansion of the rolls. When a huge rolling force is applied to the rolls, the center of the roll body undergoes elastic bending deformation. At the same time, the heat transferred by the high-temperature strip causes the thermal expansion in the center of the roll to be greater than that at the edges, resulting in an actual roll gap that is "wider in the middle and narrower at the edges." Therefore, the rolled strip naturally exhibits a convex characteristic of being slightly thicker in the middle and slightly thinner at the edges. Maintaining a moderate degree of convexity also prevents the edges of the strip from becoming too thin, resulting in waviness or edge cracking.

[0024] These minute anomalies in the profile of the hot-rolled strip are the root cause of the "rib formation" defect in subsequent cold rolling. Cold rolling is a high-reduction rolling process. According to the law of constant metal volume, the thinner the strip, the greater the elongation, and the thicker the strip, the smaller the elongation. If there are tiny local high points on the surface of the hot-rolled strip, during cold rolling, the elongation of the high-point area will be significantly less than that of the thinner areas on both sides because the high-point area is relatively thicker.

[0025] This uneven lateral extension can lead to severe plate instability. Because the thinner areas on both sides extend rapidly, they exert enormous compressive stress on the thicker areas in the middle, which extend more slowly. When this compressive stress exceeds a critical value, compressive instability occurs in the local high-point areas, forcing them to bulge outwards and form strip-like waves. These waves cannot be completely eliminated after subsequent leveling or annealing, eventually forming visible light and dark stripes on the steel plate surface, known as "ribbed" defects.

[0026] Based on the above research, embodiments of this application provide a method for manufacturing electrical steel. By collecting strip cross-sectional thickness data in real time at the hot-rolled finishing mill exit and performing online detection and rejection based on two key parameters—cross-sectional convexity C100 and local high-point thickness difference LH—it effectively prevents hot-rolled strips with abnormal cross-sectional profiles from flowing into the cold-rolling process. This technique effectively avoids the "ribbed" defect in finished products caused by the amplification of local thickness fluctuations in hot-rolled strips under high reduction rates in cold rolling. It effectively reduces the downgrading rate of finished electrical steel products due to plate shape issues, improves the product quality consistency and production stability of high-grade non-oriented electrical steel, and provides a high-quality raw material guarantee with controllable profile quality for subsequent cold-rolling processes.

[0027] The electrical steel and its manufacturing method provided in the embodiments of this application are described in detail below.

[0028] like Figure 1 As shown, an embodiment of this application provides a method for manufacturing electrical steel, comprising: S1: Smelting and rolling, using non-oriented electrical steel with a preset chemical composition ratio, hot-rolled strip steel is obtained through hot iron pre-desulfurization, converter smelting, RH vacuum treatment, continuous casting, slab heating, rough rolling and finish rolling processes; S2: Thickness acquisition: Real-time acquisition of cross-sectional thickness data of strip steel at the exit of the hot rolling mill; S3: Section parameter acquisition: Based on the cross-sectional thickness data, obtain the cross-sectional convexity C100 of the strip and the thickness difference LH of local high points within any continuous 40mm length in the width direction of the strip; S4: Inspection and screening: Based on the cross-sectional convexity C100 and the thickness difference of local high points, unqualified strip steel is detected, rejected, and blocked from flowing into the cold rolling process; wherein, the thickness difference of local high points within any continuous 40mm length in the width direction of the strip steel is LH≤10μm, and the convexity of the strip steel at the edge of 100mm position is 5μm≤C100≤25μm.

[0029] This application proposes a method for manufacturing electrical steel based on precise control of the hot-rolled exit section profile. Its core process covers four stages: smelting and rolling, thickness acquisition, section parameter acquisition, and detection and screening.

[0030] In the smelting and rolling stage, non-oriented electrical steel with a preset chemical composition is used and sequentially processed through hot-rolled strip steel via hot metal pre-desulfurization, converter smelting, RH vacuum treatment, continuous casting, slab heating, rough rolling, and finish rolling. The key improvement lies in quality control after the finish rolling process: real-time data on the cross-sectional thickness of the strip steel is collected at the exit of the hot-rolled finish mill, and the cross-sectional convexity C100 and the thickness difference LH of local high points within any continuous 40mm length in the width direction are calculated based on this data.

[0031] The system performs online detection and screening based on specific standards, requiring that the thickness difference (LH) of local high points within any continuous 40mm length in the width direction of the strip be ≤10μm, and the convexity at the edge of the strip within 100mm be controlled within 5μm≤C100≤25μm. Once the detection data exceeds these ranges, the system determines the strip to be unqualified, immediately triggers a rejection command, and prevents it from flowing into the subsequent cold rolling process.

[0032] This solution addresses the industry-wide problem of "rib formation" in cold-rolled finished products by establishing a strict cross-sectional profile interception mechanism at the end of hot rolling. Firstly, by limiting the thickness difference at local high points (LH) to ≤10μm, it effectively eliminates uneven elongation caused by sudden changes in local thickness during hot rolling under high reduction rates in cold rolling, preventing localized thick areas from bulging and forming ribs due to instability caused by delayed elongation under pressure. Simultaneously, controlling the edge convexity (C100) within a small range of 5μm to 25μm ensures the stability of the strip edge while avoiding elongation differences in the center caused by excessive convexity. This refined pre-control significantly reduces the plate shape defect rate and downgrade rate of electrical steel finished products, greatly improving the production stability and final product quality of high-grade non-oriented electrical steel.

[0033] In some embodiments of this application, the section parameter acquisition step further includes: acquiring a wedge-shaped W40 at a position 40mm from the edge of the strip based on the cross-sectional thickness data. The inspection and screening step further includes: comparing the wedge-shaped W40 with a preset standard to determine whether the strip is qualified. The preset standard further includes: -20μm ≤ W40 ≤ 20μm.

[0034] During the thickness acquisition and parameter acquisition stage, the cross-sectional thickness data of the strip is collected in real time at the exit of the hot rolling mill, and three key dimension parameters are calculated based on this data: the cross-sectional convexity C100 at the 100mm position of the strip edge, the thickness difference LH of local high points within any continuous 40mm length in the width direction, and the wedge shape W40 at the 40mm position of the strip edge.

[0035] During the inspection and screening stage, the system implements strict admission criteria: the thickness difference at local high points LH ≤ 10μm, the edge convexity 5μm ≤ C100 ≤ 25μm, and the edge wedge shape -20μm ≤ W40 ≤ 20μm. If any parameter exceeds the preset standard, the strip is judged as unqualified, and a rejection command is immediately triggered to prevent it from flowing into the cold rolling process.

[0036] This solution, based on the original control of convexity and local high points, further introduces the control of edge wedge W40, realizing three-dimensional interception of the transverse thickness distribution of hot-rolled strip steel.

[0037] In some embodiments of this application, the section parameter acquisition step further includes: acquiring a wedge-shaped W100 at a position 100mm from the edge of the strip based on the cross-sectional thickness data. The inspection and screening step further includes comparing the wedge-shaped W100 with a preset standard to determine whether the strip is qualified. The preset standard further includes: -15μm ≤ W100 ≤ 15μm.

[0038] During the thickness acquisition and parameter acquisition stage, the cross-sectional thickness data of the strip is collected in real time at the exit of the hot rolling mill, and four key dimension parameters are calculated based on this data: the cross-sectional convexity C100 at the 100mm position of the strip edge, the thickness difference LH of local high points within any continuous 40mm length in the width direction, the wedge shape W40 at the 40mm position of the strip edge, and the wedge shape W100 at the 100mm position of the strip edge.

[0039] During the inspection and screening phase, the system implements strict entry criteria: the thickness difference at local high points LH ≤ 10μm, the edge convexity 5μm ≤ C100 ≤ 25μm, the edge wedge shape -20μm ≤ W40 ≤ 20μm, and the edge wedge shape -15μm ≤ W100 ≤ 15μm. If any parameter exceeds the preset standard, the strip is judged as unqualified, and a rejection command is immediately triggered, preventing it from entering the cold rolling process.

[0040] Based on the existing control of convexity, local high points, and 40mm wedge at the edge, this solution further introduces a wedge W100 control at the 100mm position at the edge, realizing a refined three-dimensional interception of the transverse thickness distribution of hot-rolled strip steel.

[0041] By limiting the thickness difference at local high points (LH) to ≤10μm, uneven cold-rolling elongation caused by sudden changes in local thickness is eliminated. Controlling the edge convexity (C100) within 5μm~25μm balances strip straightness and edge stability. The dual wedge control of W40 and W100 (-20μm≤W40≤20μm, -15μm≤W100≤15μm) establishes a double defense against edge thickness gradients, effectively suppressing asymmetrical tilting of the strip edges and preventing cold-rolling deviation, edge waviness, and misalignment defects caused by excessively thin or thick edges on one side. This multi-dimensional, pre-emptive, and refined control significantly reduces the strip shape defect rate of high-grade non-oriented electrical steel and greatly improves yield and the uniformity of product magnetic properties.

[0042] In some embodiments of this application, the step of obtaining cross-sectional parameters further includes: obtaining the maximum thickness value H within a 100mm interval in the middle of the strip based on the cross-sectional thickness data. midmax And the maximum thickness H within a 200mm interval on each side of the strip. edgemax The detection and screening steps also include... midmax With H edgemax A comparison is made. The preset criteria also include: H midmax >H edgemax .

[0043] During the thickness acquisition and parameter acquisition stage, the cross-sectional thickness data of the strip is collected in real time at the exit of the hot rolling mill, and key dimensional parameters are calculated based on this data. In addition to the original cross-sectional crown C100, local high-point thickness difference LH, edge wedge W40, and W100, this scheme further extracts the maximum thickness value H within a 100mm interval in the middle of the strip. midmax And the maximum thickness H within a 200mm interval on each side of the strip. edgemax .

[0044] During the screening phase, the system implements strict admission criteria: the thickness difference at local high points LH ≤ 10μm, the edge convexity 5μm ≤ C100 ≤ 25μm, the edge wedge shape -20μm ≤ W40 ≤ 20μm, -15μm ≤ W100 ≤ 15μm, and the maximum thickness at the center must be greater than the maximum thickness at the edge (H). midmax >H edgemax If any parameter exceeds the preset standard, the strip is deemed unqualified, and a rejection instruction is immediately triggered to prevent it from flowing into the cold rolling process.

[0045] The technical solution of this application, based on the original control of convexity, local high points, and edge wedge shape, innovatively introduces the determination of the relative magnitude of the maximum thickness value between the middle and the edge (H). midmax >H edgemax This established the absolute profile benchmark of hot-rolled strip steel being "thick in the middle and thin at both sides".

[0046] By limiting H midmax >H edgemax Logically, this prevents substandard strip shapes with "edge waviness" or "edge thickening" from flowing into the next process. During cold rolling, if the edge thickness is greater than the center, it easily leads to edge extension exceeding the center, resulting in severe center waviness or strip breakage. This judgment standard, combined with local high point, crown, and wedge shape control, constructs a three-dimensional quality defense line from local points to the overall area, effectively ensuring the uniformity of strip thickness and the stability of the strip shape, significantly improving the rolling safety and finished magnetic properties of high-grade non-oriented electrical steel.

[0047] In some embodiments of this application, the formula for calculating the cross-sectional convexity C100 is: C100 = T center (T edge_WS +T edge_DS ) / 2; where T center T represents the thickness at the center point of the strip. edge_WS T represents the thickness at a distance of 4100 mm from the working side edge of the strip. edge_DS The thickness is located 100mm from the drive side of the strip.

[0048] During the thickness acquisition and parameter acquisition stage, strip cross-sectional thickness data are collected in real time at the exit of the hot-rolled finishing mill, and key dimensional parameters are calculated based on this data. In addition to the local high-point thickness difference LH, edge wedges W40 and W100, and the relationship between the maximum thickness values ​​at the center and edge, this scheme clarifies the calculation logic for the cross-sectional convexity C100: C100 = T center - (T edge_WS +T edge_DS ) / 2. Where, T center T represents the thickness at the center point of the strip. edge_WS T is the thickness at 100mm from the working side edge of the strip. edge_DS The thickness is located 100mm from the drive side of the strip.

[0049] During the detection and screening phase, the system implements strict admission criteria: local high-point thickness difference LH ≤ 10μm, edge wedge thickness -20μm ≤ W40 ≤ 20μm, -15μm ≤ W100 ≤ 15μm, satisfying H... midmax >H edgemax Furthermore, the cross-sectional convexity must be controlled within 5μm≤C100≤25μm. If any parameter exceeds the preset standard, the strip is deemed unqualified, and a rejection command is immediately triggered to prevent it from flowing into the cold rolling process.

[0050] This solution standardizes the evaluation criteria for strip shape quality by clarifying the calculation formula for C100. The formula uses the difference between the thickness at the center point and the average thickness at both sides (100mm from the edge on the working side and the drive side) to define convexity. This can accurately quantify the degree of "bulging" of the strip cross-section and effectively eliminate the interference of measurement errors on one side of the edge on the overall convexity determination.

[0051] Combining the defined range of 5μm ≤ C100 ≤ 25μm, this technical solution ensures that the strip maintains a "thick middle and thinner sides" profile (in conjunction with H). midmax >H edgemax Based on the judgment, excellent lateral stiffness and flatness of the sheet were maintained. This refined convexity control, combined with the comprehensive management of local high points and wedges, significantly reduced the risk of sheet shape defects during cold rolling, ensuring the consistency of thickness and the stability of magnetic properties of high-grade non-oriented electrical steel products.

[0052] In some embodiments of this application, the quality judgment step further includes: generating a rejection signal and sending it to the coiler or slitting shear downstream of the finishing mill. Based on the position coordinates of the defective product along the length of the strip, the coiler is controlled not to coil or the slitting shear is controlled to physically cut the defective product, thus separating it from the production line.

[0053] The rejection signal is sent to the downstream actuator (coiler or slitting shear) of the finishing mill. Based on the specific coordinates of the defective product along the length of the strip, the system precisely controls the coiler to stop coiling, or controls the slitting shear to physically cut the defective product before or after the defective section, directly separating and removing the defective product from the production line, ensuring that only qualified strip enters the next process.

[0054] By generating a rejection signal and linking it to the downstream winding machine or slitting shear, this solution can perform targeted removal of defective products based on their precise length coordinates. This mechanism completely prevents rejection of products with abnormal convexity, excessive wedge shape, or edge thickening (H). midmax ≤H edgemax Defective hot-rolled coils (such as those with defects) are allowed to flow into the cold rolling process, avoiding a chain of quality problems caused by raw material defects, such as cold-rolled strip breakage, roll damage, and substandard magnetic properties of finished products. This automatic rejection function significantly improves the intelligence level and yield of the production line, and greatly reduces the cost and energy consumption of waste disposal in subsequent processes.

[0055] In some embodiments of this application, during the slab heating process, the heating temperature of the slab is controlled at 1130℃~1170℃, and the furnace exit temperature of the slab is controlled at 1100℃~1140℃.

[0056] This solution, building upon existing cross-sectional profile control, further pinpoints the critical temperature windows for slab heating and unloading, ensuring stability and microstructure uniformity throughout the rolling process from the outset. Controlling the slab heating temperature between 1130℃ and 1170℃ and the unloading temperature between 1100℃ and 1140℃ effectively prevents excessively high temperatures leading to coarse grains or excessively low temperatures causing a surge in rolling load. This temperature range ensures the slab achieves a uniform austenitic structure and suitable plasticity before rolling, significantly reducing transverse thickness fluctuations in strip steel (such as abnormal C100 crown) and the risk of edge cracks caused by slab temperature differences. Combined with precise downstream inspection and automatic rejection mechanisms, this solution achieves a closed-loop quality control system from the "heating source" to the "rolling end," significantly improving the yield and magnetic property consistency of high-grade electrical steel.

[0057] In some embodiments of this application, after the hot-rolled strip steel that has passed the test enters the cold rolling process, it undergoes pickling and continuous rolling treatment. The single-sided edge trimming amount in the pickling and continuous rolling process is controlled to be 20mm to 40mm in order to remove areas with abnormal edge thickness.

[0058] This solution targets qualified hot-rolled strip steel and implements specific edge trimming process control during its pickling and continuous rolling process in the cold rolling mill. Specifically, during the operation of the pickling and continuous rolling mill, the parameters of edge trimming equipment such as disc shears are adjusted to strictly control the single-sided trimming amount of the strip steel within the range of 20mm to 40mm. This solution does not change the rolling deformation process of the strip steel itself, but focuses on quantitative physical trimming of the strip steel's edge areas to ensure that the trimming width covers the edge areas where thickness fluctuations may occur during hot rolling.

[0059] The core effect of this technical solution lies in effectively eliminating abnormal thickness areas at the edges of the strip. The edges of hot-rolled strip are often the weakest points in thickness control, most prone to localized high points or uneven thickness. If these defects are retained during subsequent precision cold rolling, they can easily lead to strip breakage or a decline in finished product quality. By removing 20mm to 40mm of edge material from each side, these potential edge geometric defects can be completely eliminated, significantly improving the shape quality and thickness accuracy of the cold-rolled product. Simultaneously, it reduces rolling stability issues caused by edge defects, thereby ensuring high performance and a high yield rate for the final product.

[0060] An embodiment of this application also provides an electrical steel, which is obtained by cold rolling hot-rolled strip steel produced by the manufacturing method of electrical steel as described in the above embodiments. The chemical composition of the electrical steel, by weight percentage, is: C≤0.0055%, 0.20%≤Si≤3.50%, 0.10%≤Mn≤0.90%, P≤0.15%, S≤0.006%, 0.15%≤Als≤1.50%, with the balance being iron and unavoidable trace elements.

[0061] The electrical steel provided in this application embodiment is prepared using a specific chemical composition system. The raw materials are processed into hot-rolled strip steel using the manufacturing method described in the preceding embodiments, and then finally produced through a cold rolling process. The chemical composition of this electrical steel is strictly controlled by weight percentage as follows: carbon (C) content not exceeding 0.0055%, silicon (Si) content between 0.20% and 3.50%, manganese (Mn) content between 0.10% and 0.90%, phosphorus (P) content not exceeding 0.15%, sulfur (S) content not exceeding 0.006%, acid-soluble aluminum (Als) content between 0.15% and 1.50%, with the balance being iron and unavoidable trace elements.

[0062] This technical solution significantly improves the electromagnetic and processing properties of electrical steel by optimizing the chemical composition ratio. By strictly controlling the content of harmful impurities such as carbon, sulfur, and phosphorus, the magnetic aging tendency and hysteresis loss within the material are effectively reduced. Simultaneously, the reasonable adjustment of the silicon and acid-soluble aluminum content not only helps to increase the material's resistivity to reduce eddy current losses but also promotes the formation of favorable textures. Thus, while ensuring excellent stamping processing performance, it achieves superior magnetic properties with low iron loss and high magnetic induction.

[0063] In some embodiments of this application, the thickness of the electrical steel is 0.20mm to 0.50mm, and the rate of degradation of the rib defects of the electrical steel is ≤ 0.05%.

[0064] Specifically, the finished thickness of the electrical steel is controlled within a thin specification range of 0.20mm to 0.50mm to meet the lightweight material requirements of high-end power and electronic equipment. At the same time, the solution imposes stringent restrictions on "rib formation" quality defects that are highly prone to occur during the production process, requiring that the rate of rib formation defects within this thickness range be controlled to 0.05% or less, ensuring that the product possesses extremely high surface smoothness and thickness uniformity.

[0065] This technical solution improves the finished product quality and performance of ultra-thin electrical steel. By precisely controlling the thickness to 0.20mm~0.50mm and suppressing rib defects, it not only significantly reduces eddy current losses and iron losses in practical applications (such as transformers and motor cores), improving the overall energy efficiency of the equipment; but also, the extremely low degradation rate means that the strip has excellent flatness, effectively avoiding problems such as die jamming and uneven stacking during subsequent customer processing and stamping, greatly improving the material utilization rate and production efficiency of downstream users. Specific Implementation The following specific embodiments illustrate this application. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0067] Example 1 (1) Smelting and rolling Non-oriented electrical steel with the following chemical composition ratio is rolled into hot-rolled strip steel through processes such as hot iron pre-desulfurization, converter smelting, RH vacuum treatment, continuous casting, slab heating, rough rolling, and finish rolling. Table 1

[0068] (2) Thickness acquisition, cross-sectional parameter acquisition and detection screening Thickness acquisition: Real-time acquisition of the cross-sectional thickness data of the strip at the exit of the hot rolling mill.

[0069] Table 2

[0070] Section parameter acquisition: Based on the cross-sectional thickness data, the cross-sectional convexity C100 of the three strips and the thickness difference LH of the local high points within any continuous 40mm length of the strip are obtained respectively; Inspection and screening: Unqualified strip steel is detected based on the cross-sectional convexity C100 and the thickness difference of local high points, and is rejected and blocked from entering the cold rolling process; among them, the thickness difference of local high points LH within any continuous 40mm length in the width direction of the strip steel is ≤10μm, and the convexity of the strip steel at the edge of 100mm position is 5μm≤C100≤25μm.

[0071] (3) Pickling and cold rolling After trimming the hot-rolled substrate, it was rolled to the target thickness, ensuring the sheet shape and surface quality. The surface quality inspection results of the three steel coils after cold rolling are as follows: Table 3

[0072] Steel coil 1, which was initially deemed substandard, subsequently developed ribs, leading to a downgrade in product grade.

[0073] Example 2 (1) Smelting and rolling Non-oriented electrical steel with the following chemical composition ratio is rolled into hot-rolled strip steel through processes such as hot iron pre-desulfurization, converter smelting, RH vacuum treatment, continuous casting, slab heating, rough rolling, and finish rolling. Table 4

[0074] (2) Thickness acquisition, cross-sectional parameter acquisition and detection screening Thickness acquisition: Real-time acquisition of the cross-sectional thickness data of the strip at the exit of the hot rolling mill.

[0075] Section parameters are obtained: Based on the cross-sectional thickness data, the cross-sectional convexity C100 of the three strips, the thickness difference LH of the local high points within any continuous 40mm length of the strip, the wedge W40 at the 40mm position of the strip edge, and the wedge W100 at the 100mm position of the strip edge are obtained respectively.

[0076] Inspection and screening: Unqualified strip steel is detected based on the cross-sectional convexity C100 and the thickness difference of local high points, and is rejected and blocked from entering the cold rolling process; among them, the thickness difference of local high points within any continuous 40mm length of the strip steel is LH≤10μm, and the convexity of the strip steel at the edge of 100mm position is 5μm≤C100≤25μm, -20μm≤W40≤20μm, and -15μm≤W100≤15μm.

[0077] Table 5

[0078] (3) Pickling and cold rolling After trimming the hot-rolled substrate, it was rolled to the target thickness, ensuring the sheet shape and surface quality. The surface quality inspection results of the three steel coils after cold rolling are as follows: Table 6

[0079] Steel coil 6, which was deemed substandard, developed ribs after pickling and cold rolling, leading to a decrease in product grade. Steel coils deemed acceptable did not exhibit the aforementioned defects.

[0080] Therefore, the method of this application can effectively reduce the defects of subsequent rib formation, remove unqualified products in the cold rolling stage, effectively improve the product qualification rate and grade, and reduce the input cost of unqualified products.

[0081] Comparative Example 1 (1) Smelting and rolling Non-oriented electrical steel with the following chemical composition ratio is rolled into hot-rolled strip steel through processes such as hot iron pre-desulfurization, converter smelting, RH vacuum treatment, continuous casting, slab heating, rough rolling, and finish rolling. Table 7

[0082] (2) Obtaining cross-sectional parameters The cross-sectional shape is obtained by visual observation.

[0083] Table 8

[0084] (3) Pickling tandem cold rolling The hot-rolled substrate is trimmed and then rolled to the target thickness to ensure the plate shape and surface quality. After the cold rolling is completed, the surface quality inspection results of the three steel coils are as follows: Table 9

[0085] In this comparative example, it was observed by naked eye that steel coil 7 was unqualified, and steel coils 8, 9, and 10 were all qualified. Then after the subsequent pickling tandem cold rolling process, steel coils 8, 9, and 10 all showed "ribbing" defects and were all unqualified. Therefore, the method of judging by naked eye cannot effectively screen out unqualified products, has a low error rate, reduces the product qualification rate, and increases the input cost for defective products.

[0086] According to the embodiments of the present application as described above, these embodiments do not exhaustively describe all the details, nor do they limit the application to the specific embodiments described. Obviously, many modifications and variations are possible in light of the above description. The specification selects and specifically describes these embodiments to better explain the principles and practical applications of the present application, so that those skilled in the art can well utilize the present application as well as the modifications based on the present application. The present application is limited only by the claims and the full scope of equivalents thereof.

Claims

1. A method for manufacturing electrical steel, characterized in that, include: The smelting and rolling process involves using non-oriented electrical steel with a pre-set chemical composition ratio, and then rolling it through processes such as hot iron pre-desulfurization, converter smelting, RH vacuum treatment, continuous casting, slab heating, rough rolling, and finish rolling to obtain hot-rolled strip steel. Thickness acquisition: Real-time acquisition of cross-sectional thickness data of strip steel at the exit of the hot rolling mill; Section parameter acquisition: Based on the cross-sectional thickness data, the cross-sectional convexity C100 of the strip and the thickness difference LH of local high points within any continuous 40mm length in the width direction of the strip are obtained; Inspection and screening: Based on the cross-sectional convexity C100 and the thickness difference of local high points, unqualified strip steel is detected, rejected, and blocked from entering the cold rolling process; wherein, the thickness difference of local high points LH within any continuous 40mm length of the strip steel is ≤10μm, and the convexity of the strip steel at the edge 100mm position is 5μm≤C100≤25μm.

2. The method for manufacturing electrical steel according to claim 1, characterized in that, The step of obtaining the cross-sectional parameters further includes: obtaining the wedge-shaped W40 at a position of 40mm on the edge of the strip based on the cross-sectional thickness data; The detection and screening step further includes: comparing the wedge-shaped W40 with the preset standard to determine whether the strip steel is qualified; The preset standard also includes: -20μm ≤ W40 ≤ 20μm.

3. The method for manufacturing electrical steel according to claim 2, characterized in that, The step of obtaining the cross-sectional parameters further includes: obtaining the wedge-shaped W100 at a position 100mm from the edge of the strip based on the cross-sectional thickness data; The detection and screening step further includes comparing the wedge-shaped W100 with the preset standard to determine whether the strip steel is qualified; The preset standard also includes: -15μm ≤ W100 ≤ 15μm.

4. The method for manufacturing electrical steel according to claim 1, characterized in that, The step of obtaining the cross-sectional parameters further includes: obtaining the maximum thickness value H within a 100mm range in the middle of the strip based on the cross-sectional thickness data. midmax And the maximum thickness H within a 200mm interval on each side of the strip. edgemax ; The detection and screening steps also include H midmax With H edgemax Compare; The preset standard also includes: H midmax >H edgemax .

5. The method for manufacturing electrical steel according to any one of claims 1-4, characterized in that, The formula for calculating the convexity C100 of the cross section is: C100 = T center (T edge_WS +T edge_DS ) / 2; Among them, T center T represents the thickness at the center point of the strip. edge_WS T is the thickness at 100mm from the working side edge of the strip. edge_DS The thickness is located 100mm from the drive side of the strip.

6. The method for manufacturing electrical steel according to claim 5, characterized in that, The quality assessment step also includes: A rejection signal is generated and sent to the coiler or slitting shear downstream of the finishing mill. Based on the position coordinates of the defective product along the length of the strip, the coiler is controlled to not coil or the segment shear is controlled to physically cut the defective product, thus separating it from the production line.

7. The method for manufacturing electrical steel according to claim 6, characterized in that, In the slab heating process, the heating temperature of the slab is controlled at 1130℃~1170℃, and the furnace exit temperature of the slab is controlled at 1100℃~1140℃.

8. The method for manufacturing electrical steel according to any one of claims 1-7, characterized in that, After the hot-rolled strip steel that has passed the inspection enters the cold rolling process, it undergoes pickling and continuous rolling treatment. During the pickling and continuous rolling process, the single-sided edge trimming amount is controlled to be 20mm to 40mm to remove areas with abnormal edge thickness.

9. An electrical steel, characterized in that, The hot-rolled strip steel produced by the manufacturing method of electrical steel according to any one of claims 1-8 is obtained by cold rolling, wherein the chemical composition of the electrical steel, by weight percentage, is: C≤0.0055%, 0.20%≤Si≤3.50%, 0.10%≤Mn≤0.90%, P≤0.15%, S≤0.006%, 0.15%≤Als≤1.50%, and the balance is iron and unavoidable trace elements.

10. The electrical steel according to claim 9, characterized in that, The thickness of the electrical steel is 0.20mm to 0.50mm, and the rate of grade reduction of the rib defects of the electrical steel is ≤0.05%.

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