Aluminum oxide inclusion control process for SPHC continuous casting sheet billet

Abstract

The invention relates to the technical field of SPHC continuous casting sheet preparation, in particular to an SPHC continuous casting sheet billet aluminum oxide inclusion control technology which comprises the steps that all component raw materials of an SPHC continuous casting sheet billet are smelted, and the instantaneous interference degree is obtained according to the temperature difference distribution and the temperature difference trend of the molten steel temperature and the tapping temperature in the smelting process; analyzing the correlation between the temperature difference between the molten steel temperature and the tapping temperature and the modal characteristics of the instantaneous interference degree, and obtaining the tapping interference enhancement degree in combination with the average level of the instantaneous interference degree; the method comprises the following steps of: obtaining interference continuity by combining the variation trend characteristic of tapping interference enhancement degree, setting a compensation factor by utilizing the interference continuity to obtain an expected error between an actual tapping temperature and a preset expected tapping temperature in a smelting process, controlling the tapping temperature of molten steel, continuously casting a steel ladle, roughly rolling and finely rolling to obtain a forging stock, and further obtaining the SPHC continuous casting sheet billet. According to the method, the preparation quality of the SPHC continuous casting plate can be improved.

Description

Technical Field

[0001] This application relates to the field of SPHC continuous casting plate preparation technology, specifically to a process for controlling alumina inclusions in SPHC continuous casting slabs. Background Technology

[0002] SPHC continuously cast steel is an important low-carbon, low-silicon steel grade. During the rolling process, SPHC continuously cast steel is prone to problems such as slag inclusions, scale formation, and the incorporation of iron oxide scale. The inclusions in SPHC continuously cast steel are mainly Al2O3 (alumina), thus affecting the quality of the steel. Therefore, to improve the quality of SPHC continuously cast steel products, it is necessary to control the alumina inclusions during the SPHC continuously cast steel billet process to reduce the alumina inclusion content in the billet.

[0003] Since the oxygen content in molten steel after smelting is one of the important factors in the formation of alumina inclusions in SPHC continuously cast slabs, existing technologies use fuzzy adaptive PID control to regulate the tapping temperature of molten steel. This effectively suppresses oxygen absorption in the molten steel and ensures stability during the subsequent casting process, thus preventing excessive alumina inclusions from being generated due to increased oxidizability of the molten steel. However, the tapping temperature of molten steel is affected by environmental factors, resulting in random variations between the tapping temperature and the furnace temperature. Existing fuzzy adaptive PID control methods do not fully consider these random variations, leading to poor accuracy in controlling the tapping temperature and consequently affecting the control of alumina inclusion content in SPHC continuously cast slabs. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a process for controlling alumina inclusions in SPHC continuously cast slabs, thereby resolving the existing issues.

[0005] The technical solution for controlling alumina inclusions in SPHC continuously cast slabs according to this application is as follows: One embodiment of this application provides a process for controlling alumina inclusions in SPHC continuously cast slabs, including the following steps: Weigh the raw materials of each component of the SPHC continuous casting slab and smelt them to obtain the temperature of molten steel in the converter and the tapping temperature during the smelting process. Based on the temperature difference distribution and temperature difference trend between molten steel and tapping temperature during the smelting process, the instantaneous interference degree is obtained. The correlation between the temperature difference between molten steel and tapping temperature and the modal characteristics of instantaneous interference degree is analyzed. Combined with the average level of instantaneous interference degree, the tapping interference enhancement degree at each acquisition time is obtained. By combining the changing trend characteristics of the steel tapping interference enhancement, the duration of interference at each acquisition time is obtained. The compensation factor is set using the duration of interference to obtain the expected error between the actual tapping temperature and the preset expected tapping temperature during the smelting process. The tapping temperature of molten steel is controlled by a PID controller. Then, the steel is continuously cast in a ladle and rough and finish rolled to obtain a forging billet, which in turn yields an SPHC continuously cast slab.

[0006] Preferably, the raw materials for each component of the SPHC continuous casting slab include: carbon, silicon, manganese, phosphorus, sulfur, acid-soluble aluminum, and calcium.

[0007] Preferably, the process of obtaining the instantaneous interference degree is as follows: In the formula, Let be the instantaneous disturbance degree of the j-th element in the temperature difference sequence. Let be the mean of the absolute values ​​of all elements within the sliding temperature difference sequence of the j-th element. The number of elements in the sliding temperature difference sequence. It is an exponential function with the natural constant as its base. and These are the k-th and (k-1)-th elements in the sliding temperature difference sequence of the j-th element, respectively.

[0008] Preferably, the molten steel temperature and tapping temperature at each acquisition time and the preset time before that time are arranged in chronological order to form the molten steel temperature sequence and the tapping temperature sequence at each acquisition time. The difference sequence between the molten steel temperature sequence and the tapping temperature sequence at each acquisition time is recorded as the temperature difference sequence. A window is set with each element in the temperature difference sequence as the center, and all elements in the window are used to form the sliding temperature difference sequence of each element in the temperature difference sequence.

[0009] Preferably, the process for obtaining the steel tapping interference enhancement is as follows: In the formula, Let be the steel extraction interference enhancement at the t-th acquisition time. Let be the mean of all elements in the instantaneous interference sequence at the t-th acquisition time. It is the sum of the absolute values ​​of the correlation between the absolute temperature difference sequence at the t-th acquisition time and all modal sequences corresponding to the t-th acquisition time.

[0010] Preferably, the instantaneous interference degree of all elements in the temperature difference sequence at each acquisition time is arranged in chronological order and normalized to obtain the instantaneous interference sequence at each acquisition time; the absolute value of each element in the temperature difference sequence at each acquisition time is taken and normalized to obtain the absolute temperature difference sequence at each acquisition time.

[0011] Preferably, the instantaneous interference sequence at each acquisition time is subjected to mode decomposition to obtain the mode sequence corresponding to the instantaneous interference sequence at each acquisition time.

[0012] Preferably, the process for obtaining the interference duration is as follows: In the formula, Let be the duration of the interference at the t-th acquisition time. For normalization function, Let be the fitting slope of the steel tapping interference enhancement degree in the local time before the t-th acquisition time, where the fitting slope is obtained by fitting the steel tapping interference enhancement degree within a preset time period before each acquisition time.

[0013] Preferably, the process of obtaining the compensation factor is as follows: In the formula, Let be the compensation factor at the t-th acquisition time, and exp() be an exponential function with the natural constant as the base. Let be the duration of interference at the t-th acquisition time.

[0014] Preferably, the process for obtaining the expected error between the actual tapping temperature and the preset expected tapping temperature during the smelting process is as follows: ;in, Let be the expected error at the t-th acquisition time. Let be the tapping temperature at the t-th sampling time. To preset the desired value of the tapping temperature, is the compensation factor at the t-th acquisition time.

[0015] This application has at least the following beneficial effects: This application extracts the instantaneous difference between molten steel temperature and tapping temperature to accurately measure the degree of instantaneous interference of environmental factors on the tapping temperature of molten steel. This more accurately reflects the instantaneous interference characteristics of environmental factors on the tapping temperature, which is beneficial for more accurate measurement of the continuous characteristics of severe external interference. This allows for more accurate compensation and adjustment of the temperature error between the actual tapping temperature and the preset tapping temperature. Furthermore, this application extracts the modal characteristics of instantaneous disturbance changes in steel temperature caused by environmental factors through modal decomposition, and accurately measures the degree of enhancement of the influence of external factors on the process of molten steel flowing from the tap into the ladle. This more clearly reflects the severity of the temperature difference between the tapping temperature and the molten steel temperature in the converter being affected by external factors, and reduces the control error generated in the subsequent control of the tapping temperature. This application measures the persistence of severe interference with tapping temperature by combining the trend of the increase in tapping interference within a local time period. A compensation factor is set based on the persistence of severe interference with tapping temperature by external factors to accurately compensate for the temperature error between the actual tapping temperature and the preset tapping temperature. This eliminates the adverse interference of external factors on tapping temperature control, improves the accuracy of controlling the tapping temperature of molten steel, effectively suppresses the oxygen absorption of molten steel and ensures the stability of the subsequent billet casting process, and avoids the formation of excessive alumina inclusions in the billet casting process due to the increased oxidizability of molten steel. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating the steps of a process for controlling alumina inclusions in SPHC continuously cast slabs provided in this application. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a process for controlling alumina inclusions in SPHC continuously cast slabs according to this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, terms such as “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. 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 pertains.

[0020] The following description, in conjunction with the accompanying drawings, details a specific scheme for controlling alumina inclusions in SPHC continuously cast slabs provided in this application.

[0021] This application provides an embodiment of a process for controlling alumina inclusions in SPHC continuously cast slabs. For details, please refer to [link to specific documentation]. Figure 1 This includes the following steps: Step 1: Weigh the raw materials of each component of the SPHC continuous casting slab and smelt them to obtain the temperature of the molten steel in the converter and the tapping temperature during the smelting process.

[0022] To more accurately control and adjust the tapping temperature of molten steel, it is necessary to fully consider the random differences between the tapping temperature and the molten steel temperature in the furnace under the influence of environmental factors, and to more effectively avoid the increased oxidizability of molten steel and the generation of excessive alumina inclusions, thereby improving the control effect of alumina inclusion content in SPHC continuous casting slabs.

[0023] In the preparation process of SPHC continuously cast slabs, the alumina inclusions are controlled to reduce their content. The raw materials of the SPHC continuously cast slab, by mass percentage, are as follows: C (carbon): ≤0.05%, Si (silicon): ≤0.02%, Mn (manganese): 0.10–0.18%, P (phosphorus): ≤0.02%, S (sulfur): ≤0.02%, Als (acid-soluble aluminum): 0.030–0.040%, Ca (calcium): 0.0012–0.0020%. Preferably, in this embodiment, the raw materials are weighed according to the above chemical composition ratio of the SPHC continuously cast slab. In the example, the formula ratio of each component raw material is C: 0.04%, Si: 0.02%, Mn: 0.12%, P: 0.015%, S: 0.015%, Als: 0.035%, Ca: 0.0015%. All the weighed component raw materials are placed in a converter for smelting. The molten steel in the converter flows into a ladle through the tapping port and is continuously cast into a billet. The billet is then heated and held at 1150-1250°C. After holding, the billet is rough rolled and finish rolled, and then cooled to room temperature.

[0024] In order to more accurately control and regulate the tapping temperature of molten steel, a thermocouple temperature measuring device is used to collect the temperature of molten steel in the converter and the tapping temperature of molten steel flowing into the ladle through the tapping port. The collected molten steel temperature and tapping temperature are timestamped to obtain the molten steel temperature and tapping temperature at each collection time. The sampling frequency of the thermocouple temperature measuring device is 10Hz.

[0025] Furthermore, to facilitate subsequent analysis of the random differences between the tapping temperature and the molten steel temperature in the furnace under the influence of environmental factors, in this embodiment, the molten steel temperature and tapping temperature collected at each acquisition time and within a preset time period prior to that time are normalized and arranged in chronological order. The arranged sequences are recorded as the molten steel temperature sequence and the tapping temperature sequence for each acquisition time. In this embodiment, the preset time period is 1 minute.

[0026] Step 2: Based on the temperature difference distribution and temperature change trend between molten steel and tapping temperature during the smelting process, the instantaneous interference degree is obtained. The correlation between the temperature difference between molten steel and tapping temperature and the modal characteristics of instantaneous interference degree is analyzed. Combined with the average level of instantaneous interference degree, the tapping interference enhancement degree at each acquisition time is obtained.

[0027] Because the tapping temperature of molten steel is affected by environmental factors, there is a random difference between the tapping temperature and the temperature of molten steel in the furnace. In order to improve the accuracy of the control and adjustment of the tapping temperature, it is necessary to fully consider the random difference between the tapping temperature and the temperature of molten steel in the furnace under the influence of environmental factors, so as to avoid affecting the control effect of alumina inclusion content in SPHC continuous casting slabs.

[0028] To analyze the random differences between the tapping temperature and the temperature of molten steel in the converter, the difference between the molten steel temperature sequence and the tapping temperature sequence at each acquisition time is recorded as the temperature difference sequence. A sliding window of size 1×11 is set with each element in the temperature difference sequence as the center. The sequence of all elements in the sliding window is recorded as the sliding temperature difference sequence of each element in the temperature difference sequence. If there are missing values ​​in the sliding window, the missing values ​​are filled by the mean value.

[0029] The sliding temperature difference sequence reflects the instantaneous difference between the molten steel temperature and the tapping temperature under the influence of environmental factors. The greater the difference in the trend of temperature difference growth within the sliding temperature difference sequence, and the greater the average level of temperature difference within the sliding temperature difference sequence, the higher the degree of instantaneous interference of environmental factors on the tapping temperature of the molten steel. This makes it more difficult to accurately control the tapping temperature of the molten steel, and it is impossible to effectively suppress the oxygen absorption of the molten steel and ensure the stability of the subsequent billet casting process.

[0030] Based on the above analysis, the instantaneous disturbance degree of each element in the temperature difference sequence is calculated: In the formula, Let be the instantaneous disturbance degree of the j-th element in the temperature difference sequence. Let be the mean of the absolute values ​​of all elements within the sliding temperature difference sequence of the j-th element. The number of elements in the sliding temperature difference sequence. It is an exponential function with the natural constant as its base. and These are the k-th and (k-1)-th elements in the sliding temperature difference sequence of the j-th element, respectively.

[0031] Based on the above process, it can be understood that the instantaneous interference degree reflects the degree of instantaneous interference of environmental factors on the tapping temperature of molten steel. The greater the instantaneous interference degree, the higher the degree of instantaneous interference of environmental factors on the tapping temperature, which is less conducive to the precise control of the tapping temperature of molten steel. It is easy to cause the oxidative properties of molten steel to increase and the content of alumina inclusions to increase in the subsequent casting process, thereby affecting the control effect of alumina inclusion content in SPHC continuous casting slabs.

[0032] Furthermore, the instantaneous disturbance degree of all elements in the temperature difference sequence at each acquisition time is arranged in chronological order, and the maximum value of the arranged sequence is normalized. The sequence after maximum value normalization is recorded as the instantaneous disturbance sequence at each acquisition time. The instantaneous disturbance sequence reflects the instantaneous disturbance changes caused by environmental factors during the process of molten steel flowing from the tap into the ladle in the converter.

[0033] To analyze the modal characteristics of the instantaneous disturbance changes in tapping temperature caused by environmental factors, the instantaneous disturbance sequence at each acquisition time is used as the input of Empirical Mode Decomposition (EMD). EMD uses an adaptive iterative method to obtain the modal sequences of the instantaneous disturbance sequence, reflecting the different modal characteristics of the instantaneous disturbance changes in tapping temperature caused by environmental factors. EMD is a well-known technique, and the specific process will not be described in detail.

[0034] Generally, the higher the correlation between the temperature difference between the tapping temperature and the molten steel temperature in the converter and the various modal sequences of the instantaneous disturbance changes, and the higher the average level of all elements in the instantaneous disturbance sequence, the more severe the influence of external factors on the random difference between the tapping temperature and the molten steel temperature in the converter. This makes it easier to generate control errors during the process of controlling the tapping temperature, thereby affecting the suppression effect on the oxygen absorption of molten steel.

[0035] Therefore, the absolute values ​​of all elements in the temperature difference sequence at each acquisition time are calculated, and the absolute value sequence is normalized to the maximum value. The normalized maximum value is recorded as the absolute temperature difference sequence at each acquisition time, which reflects the temperature difference change between the tapping temperature and the molten steel temperature in the converter.

[0036] Based on the above analysis, the steel tapping interference enhancement degree at each acquisition time is calculated: In the formula, Let be the steel extraction interference enhancement at the t-th acquisition time. Let be the mean of all elements in the instantaneous interference sequence at the t-th acquisition time. It is the sum of the absolute values ​​of the correlation between the absolute temperature difference sequence at the t-th acquisition time and all modal sequences corresponding to the t-th acquisition time.

[0037] The correlation can be measured by methods such as Pearson correlation coefficient and Spearman correlation coefficient. In this embodiment, Spearman correlation coefficient is used to measure the correlation.

[0038] Understandably, the degree of interference during tapping reflects the extent to which molten steel is affected by external factors during its flow from the tapping spout into the ladle. The greater the degree of interference, the more severe the random difference between the tapping temperature and the molten steel temperature in the converter is affected by external factors. In this case, it is easier to generate control errors during the tapping temperature control process, which affects the suppression effect on oxygen absorption in the molten steel.

[0039] Step 3: Combine the changing trend characteristics of the steel tapping interference enhancement to obtain the interference duration at each acquisition time, and use the interference duration to set a compensation factor to obtain the expected error between the actual tapping temperature and the preset expected tapping temperature during the smelting process. Use a PID controller to control the tapping temperature of the molten steel, and then continuously cast the steel in the ladle and rough and finish roll it to obtain a forging billet, and then obtain the SPHC continuously cast slab.

[0040] Generally, if the degree of influence of external factors on the molten steel during its flow from the tapping spout into the ladle remains high for a long period, and the smaller the decreasing trend of this influence, the more significant the impact of environmental factors on the tapping temperature. In this case, it becomes more difficult to control the tapping temperature using fuzzy adaptive PID control, and the greater the effort should be put into controlling the tapping temperature to avoid affecting the control of alumina inclusions in the subsequent SPHC continuous casting slab.

[0041] Therefore, in order to effectively strengthen the control of the tapping temperature, the tapping interference enhancement degree within a preset time period before each acquisition time is fitted to obtain the fitting slope of the tapping interference enhancement degree in the local time before each acquisition time. Preferably, in this embodiment, the tapping interference enhancement degree calculated within 1 minute before each acquisition time is arranged in chronological order, and the arranged sequence is used as the input of the least squares linear fitting algorithm. The least squares linear fitting algorithm is used to obtain the fitting slope of the tapping interference enhancement degree in the local time before each acquisition time. The STL time series decomposition algorithm is a well-known technology, and the specific process will not be described in detail.

[0042] Furthermore, the duration of interference at each acquisition time is calculated: In the formula, Let be the duration of the interference at the t-th acquisition time. For the normalization function, maximum value normalization is used in this embodiment. is the fitting slope of the steel-extraction interference enhancement degree in the local time before the t-th acquisition time.

[0043] Among them, the duration of disturbance reflects the persistence of severe external interference during the control of tapping temperature. The greater the duration of disturbance, the more clearly it indicates that the control of tapping temperature is continuously and severely affected by external interference, resulting in a larger error in the control of tapping temperature, and requiring more effective efforts to strengthen the control of tapping temperature.

[0044] Therefore, by compensating for the error through the duration of interference at each acquisition moment, the adverse interference of external factors on the control of tapping temperature is eliminated, the accuracy of controlling the tapping temperature of molten steel is improved, thereby effectively suppressing the oxygen absorption of molten steel and ensuring the stability of the subsequent billet casting process, and avoiding the enhancement of the oxidizing properties of molten steel, which would lead to the generation of excessive alumina inclusions during the billet casting process.

[0045] Based on the above analysis, the expected error at each acquisition time is calculated: ;in, In the formula, Let be the expected error at the t-th acquisition time. Let be the tapping temperature at the t-th sampling time. The desired tapping temperature is preset, and the desired value is taken within the range of 1640 to 1655℃. In this embodiment, the value is taken as 1450℃. Let be the compensation factor at the t-th acquisition time, and exp() be an exponential function with the natural constant as the base.

[0046] In this embodiment, a compensation factor is set by the duration of interference at each acquisition time to compensate and adjust the temperature error between the actual tapping temperature and the preset tapping temperature, thereby obtaining the expected error at each acquisition time. The greater the duration of interference, the greater the error compensation factor, which can effectively strengthen the control of the tapping temperature, eliminate the adverse interference of external factors on the control of the tapping temperature, and thus more accurately control and adjust the tapping temperature of the molten steel.

[0047] To control and regulate the tapping temperature using fuzzy adaptive PID control, the error change rate is calculated based on the expected error. The real-time calculated expected error and error change rate are used as inputs to the fuzzy controller. The fuzzy controller adjusts the proportional parameter Kp, integral parameter Ki, and derivative parameter Kd of the PID controller according to fuzzy control rules. The PID controller uses the adjusted control parameters to control the tapping temperature of the molten steel, thereby controlling the alumina inclusion content in the SPHC continuous casting slab. The calculation of the error change rate is a well-known technique, and the specific process will not be elaborated here.

[0048] Therefore, by controlling the tapping temperature of molten steel in the converter in real time as it flows into the ladle through the tapping port, the problem of increased oxidizability of molten steel and increased alumina inclusion content can be avoided, thereby improving the control effect of alumina inclusion content in SPHC continuous casting slabs.

[0049] Furthermore, a slab is formed by continuous casting in a ladle, and then heated and held at 1150-1250℃. Preferably, in this embodiment, the heating temperature is 1200℃. In actual application, the implementer can set the temperature as needed, and this embodiment does not impose any special restrictions on this. After holding, the slab is rough rolled and then finish rolled, and then cooled to room temperature to obtain a finish-rolled forged slab. Further, in this embodiment, the finish-rolled forged slab undergoes the following process to control alumina inclusions in the SPHC continuous casting slab: The precision-rolled forging billet is placed in a heating furnace. Modified bamboo charcoal is added to the furnace, and a mixture of methane and air is introduced into the furnace. The volume ratio of methane to air is 0.9-1.0:30. Preferably, in this embodiment, the volume ratio of methane to air is 0.95:30. After the heating temperature reaches 730-750℃, it is held for 20-25 hours. In this embodiment, after the heating temperature reaches 740℃, it is held for 24 hours. After the holding period, the introduction of the mixture into the heating furnace is stopped. A mixture of methane and air is introduced into the furnace to cool the slab to 475-500℃ (490℃ in this embodiment). The volume ratio of oxygen to air is then 1.5-1.6:5. The slab is held at 475-490℃ for 1-2 hours. Preferably, the volume ratio is 1.5:5, and the slab is held at 480℃ for 1.5 hours. After holding, the slab is air-cooled to room temperature to obtain the SPHC continuously cast slab. It should be noted that the volume ratios of methane to air, oxygen to air, heating temperature after the two gas introductions, holding time, and slab cooling temperature are determined by the implementer in the actual application scenario. Furthermore, the implementer can use existing preparation processes to operate on the specific steps of obtaining the SPHC continuously cast slab from the finished rolled forging; this embodiment does not impose any restrictions on this.

[0050] It is understood that references to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include the specific features, structures, or characteristics described in connection with that embodiment. Therefore, the appearance of phrases such as "in one embodiment," "in some embodiments," "in other embodiments," or "in still other embodiments" in different parts of this specification does not necessarily refer to the same embodiment, but rather means "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0051] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous. Moreover, the sequence numbers of the steps in the embodiments do not imply a specific order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments in this specification.

[0052] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A process for controlling alumina inclusions in SPHC continuously cast slabs, characterized in that, Includes the following steps: Weigh the raw materials of each component of the SPHC continuous casting slab and smelt them to obtain the temperature of molten steel in the converter and the tapping temperature during the smelting process. Based on the temperature difference distribution and temperature difference trend between molten steel and tapping temperature during the smelting process, the instantaneous interference degree is obtained. The correlation between the temperature difference between molten steel and tapping temperature and the modal characteristics of instantaneous interference degree is analyzed. Combined with the average level of instantaneous interference degree, the tapping interference enhancement degree at each acquisition time is obtained. By combining the changing trend characteristics of the steel tapping interference enhancement, the duration of interference at each acquisition time is obtained. The compensation factor is set using the duration of interference to obtain the expected error between the actual tapping temperature and the preset expected tapping temperature during the smelting process. The tapping temperature of molten steel is controlled by a PID controller. Then, the steel is continuously cast in a ladle and rough and finish rolled to obtain a forging billet, which in turn yields an SPHC continuously cast slab.

2. The process for controlling alumina inclusions in SPHC continuously cast slabs as described in claim 1, characterized in that, The raw materials for each component of the SPHC continuously cast slab include: carbon, silicon, manganese, phosphorus, sulfur, acid-soluble aluminum, and calcium.

3. The process for controlling alumina inclusions in SPHC continuously cast slabs as described in claim 1, characterized in that, The process of obtaining the instantaneous interference level is as follows: In the formula, Let be the instantaneous disturbance degree of the j-th element in the temperature difference sequence. Let be the mean of the absolute values ​​of all elements within the sliding temperature difference sequence of the j-th element. The number of elements in the sliding temperature difference sequence. It is an exponential function with the natural constant as its base. and These are the k-th and (k-1)-th elements in the sliding temperature difference sequence of the j-th element, respectively.

4. The process for controlling alumina inclusions in SPHC continuously cast slabs as described in claim 3, characterized in that, Arrange the molten steel temperature and tapping temperature at each acquisition time and the preset time before it in chronological order to form the molten steel temperature sequence and tapping temperature sequence at each acquisition time. Calculate the difference sequence between the molten steel temperature sequence and the tapping temperature sequence at each acquisition time and record it as the temperature difference sequence. Set a window with each element in the temperature difference sequence as the center and form the sliding temperature difference sequence of each element in the temperature difference sequence with all elements in the window.

5. The process for controlling alumina inclusions in SPHC continuously cast slabs as described in claim 4, characterized in that, The process for obtaining the steel tapping interference enhancement is as follows: In the formula, Let be the steel extraction interference enhancement at the t-th acquisition time. Let be the mean of all elements in the instantaneous interference sequence at the t-th acquisition time. It is the sum of the absolute values ​​of the correlation between the absolute temperature difference sequence at the t-th acquisition time and all modal sequences corresponding to the t-th acquisition time.

6. The process for controlling alumina inclusions in SPHC continuously cast slabs as described in claim 5, characterized in that, The instantaneous interference degree of all elements in the temperature difference sequence at each acquisition time is arranged in chronological order and normalized to obtain the instantaneous interference sequence at each acquisition time; the absolute value of each element in the temperature difference sequence at each acquisition time is taken and normalized to obtain the absolute temperature difference sequence at each acquisition time.

7. The process for controlling alumina inclusions in SPHC continuously cast slabs as described in claim 5, characterized in that, Modal decomposition is performed on the instantaneous interference sequence at each acquisition time to obtain the modal sequences corresponding to the instantaneous interference sequence at each acquisition time.

8. The process for controlling alumina inclusions in SPHC continuously cast slabs as described in claim 1, characterized in that, The process for obtaining the duration of the interference is as follows: In the formula, Let be the duration of the interference at the t-th acquisition time. For normalization function, Let be the fitting slope of the steel tapping interference enhancement degree in the local time before the t-th acquisition time, where the fitting slope is obtained by fitting the steel tapping interference enhancement degree within a preset time period before each acquisition time.

9. The process for controlling alumina inclusions in SPHC continuously cast slabs as described in claim 1, characterized in that, The process of obtaining the compensation factor is as follows: In the formula, Let be the compensation factor at the t-th acquisition time, and exp() be an exponential function with the natural constant as the base. Let be the duration of interference at the t-th acquisition time.

10. The process for controlling alumina inclusions in SPHC continuously cast slabs as described in claim 1, characterized in that, The process for obtaining the expected error between the actual tapping temperature and the preset expected tapping temperature during the smelting process is as follows: ;in, Let be the expected error at the t-th acquisition time. Let be the tapping temperature at the t-th sampling time. To preset the desired value of the tapping temperature, Let be the compensation factor at the t-th acquisition time.

Images