A normalizing process for high magnetic induction 25WD1300 non-oriented silicon steel

Abstract

The present application relates to the technical field of steel rolling production, and specifically to a normalizing process for high magnetic induction 25WD1300 non-oriented silicon steel, which includes: trimming hot-rolled silicon steel coils; normalizing heating in a normalizing furnace, which is divided into a preheating section, a non-oxidizing heating section, a radiant tube heating section, and a soaking section; determining the comprehensive heat transfer coefficient at each moment of the radiant tube heating section, dynamically adjusting the heating power of the radiant tube heating section, and normalizing cooling after heating, which is divided into a primary slow cooling section, a secondary slow cooling section, a tertiary slow cooling section, a quaternary slow cooling section, and a fast cooling section; using a shot blasting machine to blast the normalized steel, and then using shallow trough turbulent acid for three-stage pickling; rolling the pickled steel to obtain a chilled coil; annealing the chilled coil to obtain a non-oriented silicon steel. The present application improves the magnetic property consistency of 25WD1300 non-oriented silicon steel.

Description

Technical Field

[0001] The present application relates to the technical field of steel rolling production, and in particular to a normalizing process for high magnetic induction 25WD1300 non-oriented silicon steel. Background Art

[0002] 25WD1300 non-oriented silicon steel is a non-oriented silicon steel with an iron loss value of 13W / kg (P15 / 50) and a nominal thickness of 0.25mm. Non-oriented silicon steel is a ferrosilicon alloy, also known as non-oriented electrical steel. The manufacturing process of non-oriented silicon steel and its stable magnetic properties can ensure the output power and efficiency of the drive motor. At the same time, the low loss characteristics can also reduce the energy consumption of the drive motor. It is widely used in new energy vehicle drive motors and high-efficiency energy-saving motors.

[0003] In the production process of non-oriented silicon steel, the normalizing process can prevent ridge defects, release the rolling stress of hot-rolled plates, and improve the hot-rolled structure. Among them, the radiant tube heating can provide uniform heating, which is conducive to the uniform distribution of the temperature inside the steel and improves the consistency of the magnetic properties of non-oriented silicon steel. At present, the radiant tube heating adopts a fixed heating power parameter, and the steel temperature is affected by the radiation heat transfer performance of the normalizing furnace gas and the coupling of the interval temperature. There is a mismatch between the heating power parameter and the actual steel temperature distribution, which makes it difficult to ensure the uniform growth of the grains inside the steel, resulting in poor magnetic uniformity of the non-oriented silicon steel. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides a high magnetic induction 25WD1300 non-oriented silicon steel normalizing processing technology to solve the existing problems.

[0005] A high magnetic induction 25WD1300 non-oriented silicon steel normalizing process of the present application adopts the following technical solution:

[0006] An embodiment of the present application provides a normalizing process for high magnetic induction 25WD1300 non-oriented silicon steel, the process comprising the following steps:

[0007] (1) Trimming of hot-rolled silicon steel coils;

[0008] (2) After the treatment in step (1), normalization heating is carried out in a normalization furnace, which is divided into a preheating section, a non-oxidation heating section, a radiant tube heating section and a soaking section; the heating power of the radiant tube heating section is dynamically adjusted, specifically:

[0009] Collect thermal images of the steel on the upper surface of the steel in the normalizing furnace at each time, collect the furnace gas temperature at each time of the preset position of the non-oxidation heating section and the radiation tube heating section, and collect the steel speed at each time;

[0010] Analyze the correlation between the furnace gas temperatures of the non-oxidation heating section and the radiant tube heating section in the local time period at each moment, as well as the degree of approximation between the furnace gas temperatures of the non-oxidation heating section and the radiant tube heating section, and determine the furnace gas thermal coupling strength of the radiant tube heating section at each moment;

[0011] The average temperature level of all pixels in the steel thermal imaging image at each moment is obtained, and threshold segmentation is performed based on the deviation of the temperature of each pixel from the average level, and pixels whose deviation is greater than the segmentation threshold are obtained as significant pixels; the proportion of the significant pixels in the steel thermal imaging image at each moment, and the degree of deviation of the significant pixels from the segmentation threshold are analyzed to determine the temperature disorder of the steel at each moment in the radiant tube heating section;

[0012] Analyze the synchronization of the change of the steel temperature disorder in the local time period at each moment and the change of the furnace gas temperature of the radiant tube heating section, and determine the thermal coupling weakening strength of the radiant tube heating section at each moment in combination with the furnace gas thermal coupling strength; obtain the predicted value of the steel speed at the next moment based on the steel speed at each moment and its historical moments; analyze the difference between the predicted value of the steel speed and the preset value of the steel speed, and determine the comprehensive heat transfer coefficient of the radiant tube heating section at each moment in combination with the thermal coupling weakening strength, and adjust the heating power of the radiant tube heating section;

[0013] (3) After heating, normalization cooling is carried out, which is divided into a primary slow cooling section, a secondary slow cooling section, a tertiary slow cooling section, a quaternary slow cooling section and a fast cooling section;

[0014] (4) The steel after normalization treatment is shot blasted by a shot blasting machine, and then three-stage pickling is performed using shallow trough turbulent acid;

[0015] (5) Rolling the pickled steel to obtain a cold-hardened coil;

[0016] (6) The cold-hardened coil is annealed and coated to obtain non-oriented silicon steel.

[0017] In one of the embodiments, the chemical composition of the silicon steel hot-rolled coil includes, by mass percentage: C≤0.005%, S≤0.006%, Si: 0.8~1.4%, Mn: 0.2~0.5%, P≤0.03%, Al: 0.15%~0.60%, N≤0.004%, Sb≤0.12%, and the remainder is Fe and unavoidable impurity elements.

[0018] In one embodiment, the preheating section, the non-oxidation heating section, the radiant tube heating section and the soaking section include:

[0019] The 0-25m section of the normalizing furnace is the preheating section, which heats the steel to 330-340℃. The 25-80m section of the normalizing furnace is the non-oxidation heating section, which heats the steel to 900-1000℃. The 80-90m section of the normalizing furnace is the radiation tube heating section, which heats the steel to 1000±10℃. The 90-190m section of the normalizing furnace is the equalizing section, which maintains the temperature at 1000±10℃.

[0020] In one embodiment, the determination of the furnace gas thermal coupling strength includes:

[0021] The furnace gas temperatures at each moment of the radiant tube heating section and the non-oxidation heating section and at multiple moments before each moment are respectively formed into a first furnace gas temperature sequence and a second furnace gas temperature sequence, and the difference between the elements at the same position in the first furnace gas temperature sequence and the second furnace gas temperature sequence is calculated to form a furnace gas temperature deviation sequence;

[0022] The calculation method of the furnace gas thermal coupling strength is: ; In the formula, is the furnace gas thermal coupling intensity at the ith moment in the radiant tube heating section, is the estimated slope value of the furnace gas temperature deviation sequence at the i-th moment, is the first furnace gas temperature sequence at the i-th moment, is the second furnace gas temperature series at the i-th moment, and Pea() is the calculation function of the Pearson correlation coefficient.

[0023] In one embodiment, the calculation method of the temperature disorder of the steel is:

[0024] ; In the formula, is the temperature disorder of the steel at the moment i in the radiant tube heating section, is the deviation of the nth significant pixel in the steel thermal imaging image at the i-th moment, T is the segmentation threshold, is the number of significant pixels in the steel thermal image at the i-th moment, It is the total number of all pixels in the steel thermal image at the i-th moment.

[0025] In one embodiment, the determination of the thermal coupling weakening strength includes:

[0026] The steel temperature chaos at each moment and the previous moments is formed into a chaos sequence, and the inverse of the metric distance between the first-order difference sequence of the chaos sequence and the first-order difference sequence of the first furnace gas temperature sequence is calculated;

[0027] The thermal coupling weakening strength is the product of the furnace gas thermal coupling strength at each moment and the reciprocal.

[0028] In one embodiment, the step of adjusting the heating power of the radiant tube heating section includes:

[0029] The calculation method of the comprehensive heat transfer coefficient is: ; In the formula, is the comprehensive heat transfer coefficient of the radiant tube heating section at the i-th moment, Norm is the normalized function, is the predicted value of steel speed at the i+1th moment, V is the preset value of steel speed, is the thermal coupling weakening strength of the radiant tube heating section at the i-th moment;

[0030] If the comprehensive heat transfer coefficient at the current moment is greater than or equal to the preset threshold, the heating power of the radiant tube heating section is increased to a preset value, otherwise, the heating power of the radiant tube heating section is not adjusted.

[0031] In one embodiment, the primary slow cooling section, the secondary slow cooling section, the tertiary slow cooling section, the quaternary slow cooling section and the fast cooling section include:

[0032] The 190-225m of the normalizing furnace is the primary slow cooling section, which cools the steel to 800±10℃, the 225-235m of the normalizing furnace is the secondary slow cooling section, which cools the steel to 770±10℃, the 235-245m of the normalizing furnace is the tertiary slow cooling section, which cools the steel to 750±10℃, the 245-260m of the normalizing furnace is the quaternary slow cooling section, which cools the steel to 600±10℃, and the 260-270m of the normalizing furnace is the fast cooling section, which cools the steel to 80℃.

[0033] In one embodiment, the three-stage pickling comprises:

[0034] The acid concentration of the level 1 acid tank is 40-60g / L, the acid concentration of the level 2 acid tank is 80-100g / L, and the acid concentration of the level 3 acid tank is 130-150g / L; the acid temperatures of the level 1 acid tank, the level 2 acid tank, and the level 3 acid tank are all 75-85°C, and hydrochloric acid is used as the acid.

[0035] In one embodiment, the total cold rolling reduction rate is 75% to 80%; and the annealing temperature is 820-880°C.

[0036] This application has at least the following beneficial effects:

[0037] The present application collects thermal imaging images of the steel on the upper surface of the steel in the normalizing furnace at various times, collects the furnace gas temperatures at various times at the preset positions of the non-oxidation heating section and the radiation tube heating section, and collects the steel speed at various times; analyzes the correlation between the furnace gas temperatures of the non-oxidation heating section and the radiation tube heating section in the local time period at various times, as well as the degree of approach between the furnace gas temperatures of the non-oxidation heating section and the radiation tube heating section, and determines the furnace gas thermal coupling strength of the radiation tube heating section at various times; the furnace gas thermal coupling strength reflects the thermal coupling effect of the furnace gas of the non-oxidation heating section on the radiation tube heating section, reflects the degree of interference of the furnace gas of the radiation tube heating section by the furnace gas of the non-oxidation heating section, and improves the thermal coupling strength of the radiation tube. The accuracy of temperature analysis in the heating section is improved; further, the average level of temperature of all pixels in the steel thermal imaging image at each moment is obtained, and threshold segmentation is performed based on the deviation of the temperature of each pixel from the average level, and the pixels whose deviation is greater than the segmentation threshold are obtained as significant pixels; the proportion of the significant pixels in the steel thermal imaging image at each moment, and the degree of deviation of the significant pixels from the segmentation threshold are analyzed to determine the temperature disorder of the steel at each moment in the radiant tube heating section. The temperature disorder of the steel reflects the uneven degree of temperature distribution on the surface of the steel, embodies the necessity of regulating the heating power of the radiant tube heating section, and improves the subsequent radiant tube heating. The accuracy of heating power regulation in the hot section; finally, the synchronization of the change of the steel temperature disorder in the local time period at each moment and the change of the furnace gas temperature in the radiant tube heating section is analyzed, and the thermal coupling weakening strength of the radiant tube heating section at each moment is determined in combination with the furnace gas thermal coupling strength; based on the steel speed at each moment and its historical moments, the predicted steel speed value at the next moment is obtained; the difference between the predicted steel speed value and the preset steel speed value is analyzed, and the comprehensive heat transfer coefficient of the radiant tube heating section at each moment is determined in combination with the thermal coupling weakening strength. The determination of the comprehensive heat transfer coefficient increases the weight of the actual steel temperature distribution in the thermal coupling analysis. According to the actual steel temperature and the actual furnace gas temperature, the thermal coupling effect of the non-oxidation heating section on the radiant tube heating section is accurately weakened, which is beneficial to the dynamic adjustment of the heating power of the radiant tube heating section, promotes the uniform growth of grains inside the steel, improves the magnetic properties consistency of 25WD1300 non-oriented silicon steel, and adjusts the heating power of the radiant tube heating section. In addition, by comparing the predicted value and the preset value of the steel speed sequence, the thermal coupling weakening strength is corrected to avoid the mismatch between the heating temperature of the radiant tube heating section and the steel speed during the actual processing, resulting in the problem of excessive burning of the steel or insufficient normalization; ultimately, the uniformity of the magnetic properties of the non-oriented silicon steel is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 A flow chart of the steps of a normalization process for a high magnetic induction 25WD1300 non-oriented silicon steel provided in this application;

[0040] Figure 2 This is a schematic diagram of the physical model of the steel heating process in the radiant tube heating section;

[0041] Figure 3 This is the flow chart for adjusting the heating power of the radiant tube heating section. DETAILED DESCRIPTION

[0042] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following is a detailed description of the specific implementation method, structure, characteristics and effects of a high magnetic induction 25WD1300 non-oriented silicon steel normalization processing technology proposed in the present application in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0043] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0044] The specific scheme of the normalization processing technology of high magnetic induction 25WD1300 non-oriented silicon steel provided by the present application is described in detail below with reference to the accompanying drawings.

[0045] Example 1

[0046] Example 1 provides a normalizing process for high magnetic induction 25WD1300 non-oriented silicon steel. For the flow chart of the steps, please refer to Figure 1 , the specific process steps are as follows:

[0047] The production process of high magnetic induction 25WD1300 non-oriented silicon steel in this embodiment includes: trimming, normalizing heating, normalizing cooling, shot blasting and pickling, rolling, and annealing coating; specifically, the process is as follows:

[0048] (1) Trimming: The silicon steel hot-rolled coil is trimmed, and the cut surface ratio is more than 30%. In Example 1, the cut surface ratio is 40%, so as to improve the overall surface quality of the silicon steel hot-rolled coil. The silicon steel hot-rolled coil is coiled at a low temperature, and the coiling temperature is 450°C, so as to avoid the abnormal growth of surface grains of the silicon steel hot-rolled coil compared with the internal grains during normalization treatment, and improve the magnetic uniformity of the non-oriented silicon steel. The chemical composition of the silicon steel hot-rolled coil includes, by mass percentage: C≤0.005%, S≤0.006%, Si: 0.8-1.4%, Mn: 0.2-0.5%, P≤0.03%, Al: 0.15%-0.60%, N≤0.004%, Sb≤0.12%, and the balance is Fe and unavoidable impurity elements, wherein the addition of Sb element can improve the magnetic properties of the non-oriented silicon steel.

[0049] Among them, in Example 1 of the present application, the chemical composition of the silicon steel hot-rolled coil is C=0.0028%, S=0.0029%, Si=0.8%, Mn=0.2%, P=0.02%, Al=0.15%, N=0.002%, and Sb=0.1% in mass percentage.

[0050] (2) Normalizing heating: The normalizing heating process of the normalizing furnace has four heat treatment sections, namely the preheating section, the non-oxidation heating section, the radiant tube heating section and the soaking section. Among them, the preheating section is at 0-25m of the normalizing furnace, where the steel is heated to 330°C, the non-oxidation heating section is at 25-80m of the normalizing furnace, where the steel is heated to 900°C, the radiant tube heating section is at 80-90m of the normalizing furnace, where the steel is heated to 9990°C, and the soaking section is at 90-190m of the normalizing furnace, where the temperature is maintained at 9990°C. The steel speed is 50-60m / min.

[0051] In the normalizing process of high magnetic induction 25WD1300 non-oriented silicon steel, the normalizing heat treatment of steel is a continuous and dynamic process. The function of the non-oxidizing heating section is to further heat the steel in a non-oxidizing environment to prevent oxidation and decarburization, and provide a basis for subsequent radiant tube heating. The radiant tube heating section can provide uniform heating and achieve uniform distribution of temperature inside the steel. The soaking section focuses on maintaining the normalizing temperature, reducing the internal stress of the steel caused by temperature differences, making the grains larger and more uniform, and improving the magnetic uniformity of non-oriented silicon steel. Figure 2 This is a schematic diagram of the physical model of the steel heating process in the radiant tube heating section. Figure 2 201 is the top of the normalizing furnace, 202 is the bottom of the normalizing furnace, 203 is the radiation tube, 204 is the roller, 205 is the steel, and the direction of the arrow is the movement direction of the steel.

[0052] The heating power of the radiant tube heating section is dynamically adjusted, specifically:

[0053] Step S001, collect thermal images of the steel surface at each moment in the normalizing furnace, collect the furnace gas temperature at each moment in the preset position of the non-oxidation heating section and the radiation tube heating section, and collect the steel speed at each moment.

[0054] This embodiment uses a DCS (Distributed Control System) instrument system to collect furnace gas temperature data, steel thermal imaging images, and steel speed. A thermal imaging device with a high-temperature resistant infrared probe is installed at the center of the radiant tube heating section to collect the steel thermal imaging image on the upper surface of the steel in the normalizing furnace. A thermocouple sensor is placed next to the high-temperature resistant infrared probe to collect the furnace gas temperature data in the normalizing furnace, and a laser surface velocity meter is used at the entrance of the normalizing furnace to collect the steel speed. The data collection time interval is 1s. The collection time interval can be set by the implementer according to the actual situation, and this embodiment does not limit it. At this point, the steel thermal imaging image at each moment of the radiant tube heating section, the furnace gas temperature data at each moment of the center of the radiant tube heating section, and the steel speed at each moment can be obtained.

[0055] Step S002, analyzing the correlation between the furnace gas temperatures of the non-oxidation heating section and the radiant tube heating section in the local time period at each moment, as well as the degree of approximation between the furnace gas temperatures of the non-oxidation heating section and the radiant tube heating section, to determine the furnace gas thermal coupling strength of the radiant tube heating section at each moment.

[0056] During the heating process of the radiant tube, there is a temperature difference between the non-oxidation heating section and the radiant tube heating section. Therefore, the temperature of the radiant tube heating section is easily disturbed by the adjacent non-oxidation heating section, and there is a thermal coupling phenomenon. This thermal coupling phenomenon may greatly destroy the uniform heat transfer during the heating process of the radiant tube. The stronger the thermal coupling effect of the radiant tube heating section on the non-oxidation heating section, the closer the furnace gas temperature of the non-oxidation heating section and the radiant tube heating section.

[0057] Based on the above analysis, this embodiment uses the non-oxidizing heating section 5m before the radiant tube heating section as the front temperature section, and uses a thermocouple sensor to collect furnace gas temperature data at the center of the front temperature section. The collection time interval is 1s, which is consistent with the collection time interval of the furnace gas temperature data of the radiant tube heating section. The implementer can determine the length of the front temperature section according to actual conditions.

[0058] In this embodiment, the furnace gas temperature data of each moment of the radiant tube heating section and the previous 10 moments are used to form a first furnace gas temperature sequence at each moment in ascending time order, and the second furnace gas temperature sequence of the previous temperature interval is obtained by the same method for the previous temperature interval. At each moment, the difference between the furnace gas temperature data at the same position in the first furnace gas temperature sequence and the second furnace gas temperature sequence is calculated, and the furnace gas temperature deviation sequence at each moment is formed in order, and the furnace gas temperature deviation sequence is used as the input of the Sen's slope estimation algorithm, and the slope estimation value of the furnace gas temperature deviation sequence is output.

[0059] It should be noted that the lengths of the first furnace gas temperature sequence and the second furnace gas temperature sequence can be set by the implementer according to actual conditions, and this embodiment does not impose any restrictions thereon; the difference between the elements at the same position in the first furnace gas temperature sequence and the second furnace gas temperature sequence can be calculated by using the square of the difference, the absolute value of the difference, etc., and this embodiment uses the absolute value of the difference as the method for calculating the difference; Sen's slope estimation algorithm is an existing well-known technology, and the implementer can choose other existing feasible slope estimation algorithms at his or her discretion, and this embodiment will not be described in detail here.

[0060] The calculation method of the furnace gas thermal coupling intensity of the radiant tube heating section at each moment is:

[0061] ; In the formula, is the furnace gas thermal coupling intensity at the ith moment in the radiant tube heating section, is the estimated slope value of the furnace gas temperature deviation sequence at the i-th moment, is the first furnace gas temperature sequence at the i-th moment, is the second furnace gas temperature series at the i-th moment, and Pea() is the calculation function of the Pearson correlation coefficient.

[0062] The stronger the correlation between the temperature change of the radiant tube heating section and the previous temperature range, that is, The larger it is, the better the heat transfer effect between the radiant tube heating section and the front temperature range is. At the same time, when the furnace gas temperature of the radiant tube heating section and the front temperature range is getting closer and closer, that is, The larger it is, the stronger the thermal coupling effect of the furnace gas from the non-oxidation heating section on the radiant tube heating section is. The greater the thermal coupling intensity of the furnace gas is, the greater the degree of interference of the furnace gas from the non-oxidation heating section on the radiant tube heating section is.

[0063] Step S003, obtaining the average level of the temperatures of all pixels in the thermal imaging image of steel at each moment, performing threshold segmentation based on the deviation of the temperature of each pixel from the average level, and obtaining the pixels whose deviation is greater than the segmentation threshold as significant pixels; analyzing the proportion of the significant pixels in the thermal imaging image of steel at each moment, and the degree of deviation of the significant pixels from the segmentation threshold, to determine the temperature chaos of the steel at each moment in the radiant tube heating section.

[0064] Since there is a temperature difference between the furnace gas in the non-oxidation heating section and the furnace gas in the radiant tube heating section, the furnace gas, as the medium for radiant tube radiation heating, is the basis for uniform heating of all parts of the steel. Therefore, in the normal processing technology, the furnace gas temperature in the radiant tube heating section is prone to heat loss, transferring a large amount of heat to the non-oxidation heating section, and ultimately affecting the temperature distribution on the steel surface. At the same time, during the radiant tube heating process, the temperature of the steel will have a small difference due to the material of the radiant tube, the furnace gas structure and the composition of the steel.

[0065] This embodiment calculates the temperature mean of all pixels in the steel thermal imaging image at each moment of the radiant tube heating section, and uses the difference between each pixel temperature value and the temperature mean as the input of the OTSU algorithm, outputs the segmentation threshold, and uses the pixels with a difference greater than the segmentation threshold as significant pixels. The difference between each pixel temperature value and the temperature mean is recorded as the deviation of each pixel. The OTSU algorithm is an existing well-known technology, and the implementer can choose other existing feasible threshold segmentation algorithms. The calculation method of the steel temperature chaos at each moment of the radiant tube heating section is:

[0066] ; In the formula, is the temperature disorder of the steel at the moment i in the radiant tube heating section, is the deviation of the nth significant pixel in the steel thermal imaging image at the i-th moment, T is the segmentation threshold, is the number of significant pixels in the steel thermal image at the i-th moment, It is the total number of all pixels in the steel thermal image at the i-th moment.

[0067] when The larger the value, the more the temperature of a certain part of the steel deviates from the allowable temperature difference. The larger it is, the more uneven the temperature distribution of the steel is and the greater the temperature chaos of the steel is.

[0068] Step S004, analyzing the synchronization between the change of the steel temperature disorder in the local time period at each moment and the change of the furnace gas temperature of the radiant tube heating section, and determining the thermal coupling weakening strength of the radiant tube heating section at each moment in combination with the furnace gas thermal coupling strength; obtaining the predicted steel speed value at the next moment based on the steel speed at each moment and its historical moments; analyzing the difference between the predicted steel speed value and the preset steel speed value, and determining the comprehensive heat transfer coefficient of the radiant tube heating section at each moment in combination with the thermal coupling weakening strength, and adjusting the heating power of the radiant tube heating section.

[0069] In the normal processing technology, the furnace gas in the radiant tube heating section is thermally coupled with the non-oxidizing heating section, which easily forms complex and changeable furnace gas radiation and convection heat transfer, destroying the uniform heating characteristics of the radiant tube heating section, causing unstable heating of the steel, and the uneven degree of steel temperature is affected by the furnace gas temperature.

[0070] In this embodiment, the steel temperature chaos at each moment of the radiant tube heating section and the previous 10 moments are combined into a chaos sequence at each moment in ascending time order. The influence weight of the furnace gas temperature at each moment of the radiant tube heating section is calculated as follows:

[0071] ; In the formula, is the influence weight of the furnace gas temperature at the ith moment in the radiant tube heating section, is the first-order difference sequence of the disorder sequence of the radiant tube heating section at the i-th moment, is the first-order difference sequence of the first furnace gas temperature sequence at the ith moment in the radiant tube heating section, It is the calculation function of DTW (Dynamic Time Warping) distance.

[0072] It should be understood that the calculation of DTW distance is an existing well-known technology. This embodiment only provides a calculation method for measuring the metric distance between sequences. The implementer can choose other existing feasible metric distance calculation methods according to actual conditions, such as Euclidean distance, Manhattan distance, etc.

[0073] When the temperature change of furnace gas in the heating section of the radiant tube is more synchronous with the uneven temperature change of steel, The larger it is, the more likely it is that the change in furnace gas temperature caused by thermal coupling will cause uneven temperature of steel. The greater the weight of furnace gas temperature, the more easily the steel temperature will be affected by furnace gas temperature, and the more likely it will cause uneven temperature of steel.

[0074] In order to make the steel temperature uniform, the steel grains grow uniformly, and improve the magnetic consistency of non-oriented silicon steel, the thermal coupling phenomenon in the radiation area should be weakened as much as possible. Therefore, the thermal coupling weakening strength at each moment in the heating section of the radiation tube is calculated. The specific calculation method is:

[0075] ; In the formula, is the thermal coupling weakening strength of the radiant tube heating section at the i-th moment, is the influence weight of the furnace gas temperature at the ith moment in the radiant tube heating section, is the furnace gas thermal coupling intensity at the i-th moment in the radiant tube heating section.

[0076] The stronger the thermal coupling effect of the radiant tube heating section on the furnace gas of the non-oxidizing heating section, that is, The larger the value, the more complex the change of furnace gas temperature in the radiant tube heating section, and the more serious the damage to the uniform heating characteristics of the radiant tube heating section. At the same time, the steel temperature is more easily affected by the furnace gas temperature. The larger it is, the greater the weight should be given to ensure the uniformity of steel temperature heating, and the temperature change of furnace gas in the radiant tube heating section should be minimized. The thermal coupling phenomenon in the radiant tube heating section should be eliminated. The greater the thermal coupling weakening strength, the more heat transfer between the radiant tube heating section and the non-oxidation heating section, resulting in a decrease in the furnace gas heat in the radiant tube heating section. The more it is necessary to increase the heating power, speed up the heating speed of the radiant tube to the steel, provide sufficient heat for the radiant tube heating section, weaken the interference of thermal coupling phenomenon on the steel temperature, and ensure the stability of the furnace gas temperature in the radiant tube heating section.

[0077] In the normalizing process, the heating power of the normalizing furnace is closely related to the steel speed. When the steel speed increases, in order to fully normalize the steel and fully grow the grains, the heating power should be appropriately increased. When the steel speed decreases, in order to prevent the steel from over-burning, the heating power should be appropriately reduced.

[0078] In this embodiment, the steel speed at each moment and the 10 moments before it are combined into a steel speed sequence at each moment in ascending order of time. The steel speed sequence is used as the input of the EMA (Exponential Moving Average) algorithm, where the smoothing factor is 0.5 in this embodiment, and the implementer can set it according to the actual situation. This embodiment does not limit it here. The output of the EMA algorithm is the predicted value of the steel speed at the next moment of each moment. The comprehensive heat transfer coefficient of the radiant tube heating section at each moment is calculated, specifically:

[0079] ; In the formula, is the comprehensive heat transfer coefficient of the radiant tube heating section at the i-th moment, Norm is the normalized function, is the predicted value of steel speed at the i+1th moment, V is the preset value of steel speed, is the thermal coupling weakening strength of the radiant tube heating section at the i-th moment. m / min.

[0080] It should be noted that the length of the steel velocity sequence can be set by the implementer according to the actual situation, and this embodiment does not impose any restrictions on this. The EMA algorithm is an existing well-known technology, and the implementer can choose other existing feasible time series prediction algorithms according to the actual situation, and no special restrictions are imposed on this.

[0081] When the predicted steel speed value of the next moment at each moment is greater than the preset steel speed value, in order to fully normalize the steel, the thermal coupling weakening force should be amplified, the heating power should be increased, and more heat should be added to the radiant tube heating section, and the comprehensive heat transfer coefficient will be greater; when the predicted steel speed value of the next moment at each moment is less than the preset steel speed value, in order to prevent the steel from over-burning, the thermal coupling weakening force should be reduced, the heating power should be reduced, and the heat of the radiant tube heating section should be reduced, and the comprehensive heat transfer coefficient will be smaller.

[0082] The comprehensive heat transfer coefficient of the radiant tube heating section at the current moment is obtained, and a threshold is preset. The threshold value in this embodiment is 0.7. The implementer can set it according to the actual situation. This embodiment does not make any restrictions here. The temperature control system is used to dynamically adjust the heating power of the radiant tube heating section.

[0083] If the comprehensive heat transfer coefficient at the current moment is greater than or equal to 0.7, it means that the thermal coupling phenomenon of the radiant tube heating section by the non-oxidation heating section is obvious, which is easy to affect the uniform heating of the steel. It is urgent to amplify the thermal coupling weakening strength and increase the heating power of the radiant tube heating section. The adjusted heating power in this embodiment can be specifically , is the heating power of the radiant tube heating section before adjustment; the implementer can determine the increase range of the heating power according to the actual situation, and this embodiment does not limit it here.

[0084] If the comprehensive heat transfer coefficient at the current moment is less than 0.7, it means that the heat of the radiant tube heating section is sufficient, and the radiation heat transfer to the steel is uniform, and there is no need to adjust the heating power of the radiant tube heating section. The heating power adjustment flow chart of the radiant tube heating section is as follows: Figure 3 shown.

[0085] (3) Normalizing cooling: The normalizing cooling process of the normalizing furnace is divided into the primary slow cooling section, the secondary slow cooling section, the tertiary slow cooling section, the quaternary slow cooling section and the rapid cooling section. Among them, the normalizing furnace 190-225m is the primary slow cooling section, which cools the steel to 790℃, the normalizing furnace 225-235m is the secondary slow cooling section, which cools the steel to 760℃, the normalizing furnace 235-245m is the tertiary slow cooling section, which cools the steel to 740℃, the normalizing furnace 245-260m is the quaternary slow cooling section, which cools the steel to 590℃, and the normalizing furnace 260-270m is the rapid cooling section, which cools the steel to 80℃.

[0086] (4) Shot blasting and pickling: The steel after normalizing treatment is shot blasted by a shot blasting machine to remove the iron oxide scale on the surface of the strip, and then a shallow turbulent acid is used for three-stage pickling, wherein the acid concentration of the first-level acid tank is 40g / L and the acid temperature is 75°C; the acid concentration of the second-level acid tank is 80g / L and the acid temperature is 75°C; the acid concentration of the third-level acid tank is 130g / L and the acid temperature is 75°C. The acid is hydrochloric acid, which can quickly dissolve the iron oxide scale and rarely corrode the parent material. The pickling control data are shown in Table 1. The first-level acid tank is represented by 1# acid tank, the second-level acid tank is represented by 2# acid tank, and the third-level acid tank is represented by 3# acid tank.

[0087] Table 1 Pickling control data

[0088]

[0089] (5) Rolling: The pickled steel is rolled using a single stand, wherein the coil core temperature of the steel is raised to above 40°C by a heater before rolling. The rolling process is repeated for 5 times, and the total cold rolling reduction is 75%, thereby obtaining a cold-hardened coil.

[0090] (6) Annealing coating: The obtained cold hardened coil is annealed at a constant speed in a continuous annealing furnace at a temperature of 820°C, and then the annealed steel strip is cooled by three-stage cooling; the cooled steel strip is coated and finished to obtain a 0.25 mm non-oriented silicon steel product.

[0091] Example 2

[0092] Example 2 provides a normalizing process for high magnetic induction 25WD1300 non-oriented silicon steel. For the flow chart of the steps, please refer to Figure 1 , the specific process is as follows:

[0093] In Example 2 of the present application, during the slicing process of step (1), the cut surface ratio is 45%, the coiling temperature is 480°C, and the chemical composition of the silicon steel hot coil is as follows in mass percentage: C=0.003%, S=0.003%, Si=1.1%, Mn=0.4%, P=0.015%, Al=0.35%, N=0.0025%, and Sb=0.08%.

[0094] In step (2), the 0-25m section of the normalizing furnace is the preheating section, in which the temperature of the steel is raised to 335°C; the 25-80m section of the normalizing furnace is the non-oxidation heating section, in which the temperature of the steel is raised to 950°C; the 80-90m section of the normalizing furnace is the radiation tube heating section, in which the temperature of the steel is raised to 1000°C; and the 90-190m section of the normalizing furnace is the soaking section, in which the temperature is maintained at 1000°C.

[0095] In step (3), the normalizing furnace 190-225m is the primary slow cooling section, cooling the steel to 800°C, the normalizing furnace 225-235m is the secondary slow cooling section, cooling the steel to 770°C, the normalizing furnace 235-245m is the tertiary slow cooling section, cooling the steel to 750°C, the normalizing furnace 245-260m is the quaternary slow cooling section, cooling the steel to 600°C, and the normalizing furnace 260-270m is the rapid cooling section, cooling the steel to 80°C.

[0096] In step (4), the acid concentration of the acid tank #1 is 50 g / L and the acid temperature is 80°C; the acid concentration of the acid tank #2 is 80 g / L and the acid temperature is 80°C; the acid concentration of the acid tank #3 is 130 g / L and the acid temperature is 80°C.

[0097] In step (5), the total cold rolling reduction is 78%.

[0098] In step (6), the annealing temperature is 850°C.

[0099] The remaining steps are exactly the same as those in Example 1 of the present application to prepare non-oriented silicon steel.

[0100] Example 3

[0101] Example 3 provides a normalizing process for high magnetic induction 25WD1300 non-oriented silicon steel. For the flow chart of the steps, please refer to Figure 1 , the specific process is as follows:

[0102] In Example 3 of the present application, during the slicing process of step (1), the cut surface ratio is 50%, the coiling temperature is 520°C, and the chemical composition of the silicon steel hot coil is as follows in mass percentage: C=0.0032%, S=0.0035%, Si=1.4%, Mn=0.5%, P=0.01%, Al=0.60%, N=0.003%, and Sb=0.09%.

[0103] In step (2), the 0-25m section of the normalizing furnace is the preheating section, in which the temperature of the steel is raised to 340°C; the 25-80m section of the normalizing furnace is the non-oxidation heating section, in which the temperature of the steel is raised to 1000°C; the 80-90m section of the normalizing furnace is the radiation tube heating section, in which the temperature of the steel is raised to 1010°C; and the 90-190m section of the normalizing furnace is the soaking section, in which the temperature is maintained at 1010°C.

[0104] In step (3), the normalizing furnace 190-225m is the primary slow cooling section, cooling the steel to 810°C, the normalizing furnace 225-235m is the secondary slow cooling section, cooling the steel to 780°C, the normalizing furnace 235-245m is the tertiary slow cooling section, cooling the steel to 760°C, the normalizing furnace 245-260m is the quaternary slow cooling section, cooling the steel to 610°C, and the normalizing furnace 260-270m is the rapid cooling section, cooling the steel to 80°C.

[0105] In step (4), the acid concentration of the acid tank #1 is 60 g / L and the acid temperature is 85°C; the acid concentration of the acid tank #2 is 100 g / L and the acid temperature is 85°C; the acid concentration of the acid tank #3 is 150 g / L and the acid temperature is 85°C.

[0106] In step (5), the total cold rolling reduction is 80%.

[0107] In step (6), the annealing temperature is 880°C.

[0108] The remaining steps are exactly the same as those in Example 1 of the present application to prepare non-oriented silicon steel.

[0109] The non-oriented silicon steel prepared in the embodiment was tested:

[0110] In Example 1, the maximum iron loss value of the non-oriented silicon steel is 12.3W / kg when the frequency is 50 Hz and the waveform is sinusoidal and the magnetic induction peak is 1.5 Tesla, the yield strength is 408Mpa, the magnetic induction intensity is 1.672T when the magnetic field strength is 5000A / m, and the head, middle and tail magnetic induction B 5000 The fluctuation is 0.003T.

[0111] In Example 2, the maximum iron loss value of the non-oriented silicon steel is 12.1 W / kg when the frequency is 50 Hz and the waveform is sinusoidal and the magnetic induction peak is 1.5 Tesla, the yield strength is 413 MPa, the magnetic induction intensity is 1.675 T when the magnetic field strength is 5000 A / m, and the head, middle and tail magnetic induction B 5000 The fluctuation is 0.002T.

[0112] In Example 3, the maximum iron loss value of the non-oriented silicon steel is 12.4 W / kg when the frequency is 50 Hz and the waveform is sinusoidal and the magnetic induction peak is 1.5 Tesla, the yield strength is 410 MPa, the magnetic induction intensity is 1.669 T when the magnetic field strength is 5000 A / m, and the head, middle and tail magnetic induction B 5000 The fluctuation is 0.003T.

[0113] It should be understood that the head-mid-tail magnetic induction B 5000Fluctuation refers to the extreme difference of magnetic induction intensity at the head, middle and tail of non-oriented silicon steel measured under the condition of magnetic field strength of 5000A / m.

[0114] During the normalization heating process, the heating power of the radiant tube heating section is not adjusted, and the rest of the process steps and parameters are exactly the same as those in Example 1, as Comparative Example 1;

[0115] During the normalization heating process, the heating power of the radiant tube heating section is not adjusted, and the rest of the process steps and parameters are exactly the same as those of Example 2, as Comparative Example 2;

[0116] During the normalization heating process, the heating power of the radiant tube heating section is not adjusted, and the rest of the process steps and parameters are exactly the same as those of Example 3, which is used as Comparative Example 3.

[0117] The non-oriented silicon steel prepared in the comparative example was tested:

[0118] In Comparative Example 1, the maximum iron loss value of non-oriented silicon steel is 12.7W / kg when the frequency is 50 Hz and the waveform is sinusoidal and the magnetic induction peak is 1.5 Tesla, the yield strength is 384Mpa, the magnetic induction intensity is 1.659T when the magnetic field strength is 5000A / m, and the head, middle and tail magnetic induction B 5000 The fluctuation is 0.008T.

[0119] In Comparative Example 2, the maximum iron loss value of non-oriented silicon steel is 12.7W / kg when the frequency is 50 Hz and the waveform is sinusoidal and the magnetic induction peak is 1.5 Tesla, the yield strength is 391Mpa, the magnetic induction intensity is 1.661T when the magnetic field strength is 5000A / m, and the head, middle and tail magnetic induction B 5000 The fluctuation is 0.010T.

[0120] In Comparative Example 3, the maximum iron loss value of non-oriented silicon steel is 12.9W / kg when the frequency is 50 Hz and the waveform is sinusoidal and the magnetic induction peak is 1.5 Tesla, the yield strength is 385Mpa, the magnetic induction intensity is 1.655T when the magnetic field strength is 5000A / m, and the head, middle and tail magnetic induction B 5000 The fluctuation is 0.012T.

[0121] It can be seen from the embodiments and comparative examples that the non-oriented silicon steel in the embodiments of the present application has lower magnetic induction fluctuation. Therefore, the present application improves the uniformity of the magnetic properties of the non-oriented silicon steel.

[0122] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0123] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0124] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Modifications to the technical solutions recorded in the aforementioned embodiments, or equivalent replacement of some of the technical features therein, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A normalizing process for high magnetic induction 25WD1300 non-oriented silicon steel, characterized in that: The process includes the following steps: (1) Trimming of hot-rolled silicon steel coils; (2) After the treatment in step (1), normalization heating is carried out in a normalization furnace, which is divided into a preheating section, a non-oxidation heating section, a radiant tube heating section and a soaking section; the heating power of the radiant tube heating section is dynamically adjusted, specifically: Collect thermal images of the steel on the upper surface of the steel in the normalizing furnace at each time, collect the furnace gas temperature at each time of the preset position of the non-oxidation heating section and the radiation tube heating section, and collect the steel speed at each time; Analyze the correlation between the furnace gas temperatures of the non-oxidation heating section and the radiant tube heating section in the local time period formed by each moment and the moments before it, as well as the degree of approximation between the furnace gas temperatures of the non-oxidation heating section and the radiant tube heating section, and determine the furnace gas thermal coupling strength of the radiant tube heating section at each moment; The average level of the temperature of all pixels in the steel thermal imaging image at each moment is obtained, threshold segmentation is performed based on the deviation of the temperature of each pixel from the average level, the segmentation threshold is obtained, and the pixels whose deviation is greater than the segmentation threshold are regarded as significant pixels; the proportion of the significant pixels in the steel thermal imaging image at each moment, and the degree of deviation of the significant pixels from the segmentation threshold are analyzed to determine the temperature disorder of the steel at each moment in the radiant tube heating section; Analyze the synchronization of the change of the steel temperature disorder in the local time period formed by each moment and the moment before it and the change of the furnace gas temperature of the radiant tube heating section, and determine the thermal coupling weakening strength of the radiant tube heating section at each moment in combination with the furnace gas thermal coupling strength; obtain the predicted value of the steel speed at the next moment based on the steel speed at each moment and its historical moments; analyze the difference between the predicted value of the steel speed and the preset value of the steel speed, and determine the comprehensive heat transfer coefficient of the radiant tube heating section at each moment in combination with the thermal coupling weakening strength, and adjust the heating power of the radiant tube heating section; (3) After heating, normalization cooling is carried out, which is divided into a primary slow cooling section, a secondary slow cooling section, a tertiary slow cooling section, a quaternary slow cooling section and a fast cooling section; (4) The steel after normalization treatment is shot blasted by a shot blasting machine, and then three-stage pickling is performed using shallow trough turbulent acid; (5) Rolling the pickled steel to obtain a cold-hardened coil; (6) Annealing and coating the cold-hardened coil to obtain non-oriented silicon steel; The determination of the furnace gas thermal coupling strength includes: The furnace gas temperatures at each moment of the radiant tube heating section and at a plurality of moments before that are combined into a first furnace gas temperature sequence; The furnace gas temperatures at each moment of the non-oxidizing heating section and at multiple moments before that are combined into a second furnace gas temperature sequence, and the difference between the furnace gas temperature data at the same position in the first furnace gas temperature sequence and the second furnace gas temperature sequence is calculated to form a furnace gas temperature deviation sequence; The calculation method of the furnace gas thermal coupling strength is: ; In the formula, is the furnace gas thermal coupling intensity at the ith moment in the radiant tube heating section, is the estimated slope value of the furnace gas temperature deviation sequence at the i-th moment, is the first furnace gas temperature sequence at the i-th moment, is the second furnace gas temperature sequence at the i-th moment, Pea() is the calculation function of the Pearson correlation coefficient; The calculation method of the steel temperature disorder is: ; In the formula, is the temperature disorder of the steel at the moment i in the radiant tube heating section, is the deviation of the nth significant pixel in the steel thermal imaging image at the i-th moment, T is the segmentation threshold, is the number of significant pixels in the steel thermal image at the i-th moment, is the total number of all pixels in the steel thermal image at the i-th moment; The determination of the thermal coupling weakening strength includes: The steel temperature chaos at each moment and the previous moments is formed into a chaos sequence, and the inverse of the metric distance between the first-order difference sequence of the chaos sequence and the first-order difference sequence of the first furnace gas temperature sequence is calculated; The thermal coupling weakening strength is the product of the furnace gas thermal coupling strength at each moment and the reciprocal; The step of adjusting the heating power of the radiant tube heating section comprises: The calculation method of the comprehensive heat transfer coefficient is: ; In the formula, is the comprehensive heat transfer coefficient of the radiant tube heating section at the i-th moment, Norm is the normalized function, is the predicted value of steel speed at the i+1th moment, V is the preset value of steel speed, is the thermal coupling weakening strength of the radiant tube heating section at the i-th moment; If the comprehensive heat transfer coefficient at the current moment is greater than or equal to the preset threshold, the heating power of the radiant tube heating section is increased to a preset value, otherwise, the heating power of the radiant tube heating section is not adjusted.

2. A high magnetic induction 25WD1300 non-oriented silicon steel normalizing process as claimed in claim 1, characterized in that: The chemical composition of the silicon steel hot-rolled coil is as follows in mass percentage: C≤0.005%, S≤0.006%, Si: 0.8-1.4%, Mn: 0.2-0.5%, P≤0.03%, Al: 0.15%-0.60%, N≤0.004%, Sb≤0.12%, and the remainder is Fe and unavoidable impurity elements.

3. The normalizing process of high magnetic induction 25WD1300 non-oriented silicon steel according to claim 1, characterized in that: The preheating section, non-oxidation heating section, radiant tube heating section and soaking section include: The 0-25m section of the normalizing furnace is the preheating section, which heats the steel to 330-340℃. The 25-80m section of the normalizing furnace is the non-oxidation heating section, which heats the steel to 900-1000℃. The 80-90m section of the normalizing furnace is the radiation tube heating section, which heats the steel to 1000±10℃. The 90-190m section of the normalizing furnace is the equalizing section, which maintains the temperature at 1000±10℃.

4. The normalizing process of high magnetic induction 25WD1300 non-oriented silicon steel according to claim 1, characterized in that: The primary slow cooling section, the secondary slow cooling section, the tertiary slow cooling section, the quaternary slow cooling section and the fast cooling section include: The 190-225m of the normalizing furnace is the primary slow cooling section, which cools the steel to 800±10℃, the 225-235m of the normalizing furnace is the secondary slow cooling section, which cools the steel to 770±10℃, the 235-245m of the normalizing furnace is the tertiary slow cooling section, which cools the steel to 750±10℃, the 245-260m of the normalizing furnace is the quaternary slow cooling section, which cools the steel to 600±10℃, and the 260-270m of the normalizing furnace is the fast cooling section, which cools the steel to 80℃.

5. The normalizing process of high magnetic induction 25WD1300 non-oriented silicon steel according to claim 1, characterized in that: The three-stage pickling comprises: The acid concentration of the level 1 acid tank is 40-60g / L, the acid concentration of the level 2 acid tank is 80-100g / L, and the acid concentration of the level 3 acid tank is 130-150g / L; the acid temperatures of the level 1 acid tank, the level 2 acid tank, and the level 3 acid tank are all 75-85°C, and hydrochloric acid is used as the acid.

6. A normalizing process for high magnetic induction 25WD1300 non-oriented silicon steel as claimed in claim 1, characterized in that: The total cold rolling reduction rate of the rolling is 75% to 80%; the annealing temperature is 820-880°C.

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