Methods for improving steel plate shape

Abstract

The present application relates to the technical field of cooling uniformity control for wide and thick plates, and discloses a method for improving the shape of steel plates. The method comprises: determining a steel plate sample in a quenched steel plate, and measuring the hardness values ​​of each detection point of the steel plate sample in the thickness direction; calculating the average hardness value of the detection points close to the upper surface of the steel plate sample as the hardness value of the upper part of the steel plate; calculating the average hardness value of the detection points close to the lower surface of the steel plate sample as the hardness value of the lower part of the steel plate; during the water cooling process of the steel plate, adjusting the water flow ratio between the lower water cooling device and the upper water cooling device based on the hardness value of the upper part of the steel plate and the hardness value of the lower part of the steel plate. The technical solution proposed in the present application can fundamentally optimize the cooling uniformity of the upper and lower surfaces of the steel plate, thereby improving the shape problem of the steel plate to a certain extent.

Description

Technical Field

[0001] The present application relates to the technical field of cooling uniformity control of wide and thick plates, and discloses a method for improving the shape of steel plates. Background Art

[0002] The direct quenching process after steel rolling is widely used in the production of quenched and tempered wide and thick plates. It is an environmentally friendly, short-process, and economical production process. However, during the quenching process, the steel plate is rapidly cooled from a high temperature state of nearly 760-900℃ to room temperature, generating structural stress and thermal stress. The coupling of these two stresses can easily lead to plate shape problems. Common problems include ripples, longitudinal buckling, transverse buckling, and transverse warping. Among the most difficult plate shape problems to solve are transverse buckling and transverse warping. The main reason for this type of plate shape problem is the inconsistent cooling uniformity between the upper and lower surfaces of the steel plate, resulting in asynchronous phase transformation on the upper and lower surfaces of the steel plate, thus generating large structural stress. When the critical stress of the steel plate is reached, the steel plate will deform in the width direction, which is commonly referred to as "transverse C warping" or "transverse C buckling". However, there is currently no clear direction and method for adjusting the water cooling process, and a solution to this type of plate shape problem is urgently needed. Summary of the Invention

[0003] This application relates to the technical field of cooling uniformity control for thick and wide plates, and discloses a method for improving the shape of steel plates. This method can fundamentally optimize the cooling uniformity of the upper and lower surfaces of the steel plate, thereby improving the shape of the steel plate to a certain extent.

[0004] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by practice of the present application.

[0005] According to one aspect of an embodiment of the present application, a method for improving the shape of a steel plate is provided, the method comprising: determining a steel plate specimen in a quenched steel plate, and measuring the hardness values ​​of each detection point of the steel plate specimen in a thickness direction; calculating the average hardness value of the detection points close to the upper surface of the steel plate specimen as the hardness value of the upper part of the steel plate; calculating the average hardness value of the detection points close to the lower surface of the steel plate specimen as the hardness value of the lower part of the steel plate; during the water cooling process of the steel plate, adjusting the water flow ratio between the lower water cooling device and the upper water cooling device based on the hardness value of the upper part of the steel plate and the hardness value of the lower part of the steel plate.

[0006] In one embodiment of the present application, based on the aforementioned solution, determining the steel plate sample in the quenched steel plate includes: determining the steel plate sample at the middle position in the length direction and the 1 / 4 position in the width direction of the quenched steel plate.

[0007] In one embodiment of the present application, based on the aforementioned scheme, measuring the hardness value of each detection point in the thickness direction of the steel plate sample includes: selecting multiple detection points in the steel plate sample along the thickness direction of the steel plate sample, wherein each adjacent detection point is separated by a set distance; and measuring the Vickers hardness value of each detection point.

[0008] In one embodiment of the present application, based on the aforementioned scheme, the calculation of the average hardness value of the test points close to the upper surface of the steel plate specimen includes: taking the plane where the thickness center line of the steel plate specimen is located and parallel to the upper surface of the steel plate specimen as the reference plane, determining the test points between the reference plane and the upper surface of the steel plate specimen as the upper test points; and calculating the average hardness value of each upper test point.

[0009] In one embodiment of the present application, based on the aforementioned scheme, the calculation of the average hardness value of the test points close to the lower surface of the steel plate specimen includes: taking the plane where the thickness center line of the steel plate specimen is located and parallel to the upper surface of the steel plate specimen as the reference plane, determining the test points between the reference plane and the lower surface of the steel plate specimen as the lower test points; and calculating the average hardness value of each lower test point.

[0010] In one embodiment of the present application, based on the aforementioned scheme, the water flow ratio between the lower water cooling device and the upper water cooling device is adjusted based on the hardness value of the upper part of the steel plate and the hardness value of the lower part of the steel plate, including: if the hardness value of the upper part of the steel plate is greater than the hardness value of the lower part of the steel plate, then the water flow ratio between the lower water cooling device and the upper water cooling device is increased.

[0011] In one embodiment of the present application, based on the aforementioned scheme, if the hardness value of the upper part of the steel plate is greater than the hardness value of the lower part of the steel plate, the water flow ratio between the lower water cooling device and the upper water cooling device is increased, including: if the hardness value of the upper part of the steel plate is greater than the hardness value of the lower part of the steel plate, then for every 10 hardness values ​​difference, the water flow ratio is increased by 0.1-0.4.

[0012] In one embodiment of the present application, based on the aforementioned scheme, the water flow ratio between the lower water cooling device and the upper water cooling device is adjusted based on the hardness value of the upper part of the steel plate and the hardness value of the lower part of the steel plate, including: if the hardness value of the upper part of the steel plate is less than the hardness value of the lower part of the steel plate, then reducing the water flow ratio between the lower water cooling device and the upper water cooling device.

[0013] In one embodiment of the present application, based on the aforementioned scheme, if the hardness value of the upper part of the steel plate is less than the hardness value of the lower part of the steel plate, the water flow ratio between the lower water cooling device and the upper water cooling device is reduced, including: if the hardness value of the upper part of the steel plate is less than the hardness value of the lower part of the steel plate, then for every 10 hardness values ​​difference, the water flow ratio is reduced by 0.1-0.4.

[0014] According to another aspect of the embodiments of the present application, a steel plate is provided, which is produced using the method described in any of the above embodiments.

[0015] In the technical solution proposed in this application, a steel plate sample is determined from a quenched steel plate, and the hardness values ​​of each test point of the steel plate sample in the thickness direction are measured. The average hardness value of the test points near the upper surface of the steel plate sample is calculated as the upper hardness value of the steel plate, and the average hardness value of the test points near the lower surface of the steel plate sample is calculated as the lower hardness value of the steel plate. During the water cooling process of the steel plate, the water flow ratio between the lower water cooling device and the upper water cooling device is adjusted based on the upper hardness value and the lower hardness value of the steel plate. Based on this, the present application can fundamentally optimize the cooling uniformity of the upper and lower surfaces of the steel plate, thereby improving the plate shape problem of the steel plate to a certain extent.

[0016] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are incorporated into and constitute a part of the specification, illustrating embodiments consistent with the present application and, together with the specification, explaining the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without inventive effort. In the drawings:

[0018] Figure 1 A flow chart of a method for improving the shape of a steel plate in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0019] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art.

[0020] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner.In the following description, many specific details are provided so as to provide a full understanding of the embodiments of the present application. However, it will be appreciated by those skilled in the art that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps etc. can be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0021] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0022] It should be noted that the term "plurality" used in this document refers to two or more. "And / or" describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. The character " / " generally indicates an "or" relationship between the associated objects.

[0023] The following is a detailed description of the implementation details of the technical solution of the embodiment of the present application:

[0024] Figure 1 A flow chart of a method for improving the shape of a steel plate in an embodiment of the present application is shown.

[0025] like Figure 1 As shown, the method for improving the shape of a steel plate includes at least steps 100 to 400.

[0026] The following will Figure 1 Steps 100 to 400 are described in detail:

[0027] In step 100, a steel plate sample is determined from a quenched steel plate, and hardness values ​​of various detection points of the steel plate sample in a thickness direction are measured.

[0028] In the present application, a steel plate sample is selected at an appropriate position in a quenched steel plate, and a hardness tester is used to measure the hardness value of each test point in the thickness direction of the steel plate, that is, the Vickers hardness value of each test point between the upper surface of the steel plate sample and the lower surface of the steel plate sample is measured.

[0029] Continue to refer to Figure 1 In step 200, the average hardness value of the detection points close to the upper surface of the steel plate sample is calculated as the hardness value of the upper part of the steel plate.

[0030] In the present application, the average value of the Vickers hardness values ​​of the various detection points close to the upper surface of the steel plate sample is calculated, and the average value is used as the hardness value of the upper portion of the steel plate.

[0031] Continue to refer to Figure 1 In step 300, the average hardness value of the detection points close to the lower surface of the steel plate sample is calculated as the hardness value of the lower part of the steel plate.

[0032] In the present application, the average value of the Vickers hardness values ​​of the various detection points close to the lower surface of the steel plate sample is calculated, and the average value is used as the hardness value of the lower portion of the steel plate.

[0033] Continue to refer to Figure 1 In step 400, during the water cooling process of the steel plate, the water flow ratio between the lower water cooling device and the upper water cooling device is adjusted based on the hardness value of the upper portion of the steel plate and the hardness value of the lower portion of the steel plate.

[0034] In the present application, during the water cooling process of the quenching treatment of the steel plate, according to the difference between the hardness value of the upper part of the steel plate and the hardness value of the lower part of the steel plate, different amplitudes are adopted to adjust the water flow ratio between the upper water cooling equipment and the lower water cooling equipment according to the different differences.

[0035] In one embodiment of the present application, determining the steel plate sample in the quenched steel plate includes: determining the steel plate sample at the middle position in the length direction and the 1 / 4 position in the width direction of the quenched steel plate.

[0036] In this application, steel plate samples are selected at the middle position in the length direction and 1 / 4 position in the width direction of the quenched steel plate. The steel plate at this position is selected as the steel plate sample because the various properties of the steel plate at this position are most similar to the various properties of the entire steel plate.

[0037] In one embodiment of the present application, measuring the hardness value of each detection point in the thickness direction of the steel plate sample includes: selecting multiple detection points in the steel plate sample along the thickness direction of the steel plate sample, wherein each adjacent detection point is separated by a set distance; and measuring the Vickers hardness value of each detection point.

[0038] In the present application, multiple testing points are selected in the steel plate sample along the thickness direction of the steel plate sample, and one testing point is selected every 3 mm from the upper surface to the lower surface of the steel plate sample. The Vickers hardness value of each testing point is measured to obtain the Vickers hardness value of the testing point in the full thickness direction.

[0039] In one embodiment of the present application, the calculation of the average hardness value of the test points close to the upper surface of the steel plate specimen includes: taking the plane where the thickness center line of the steel plate specimen is located and parallel to the upper surface of the steel plate specimen as a reference plane, determining the test points between the reference plane and the upper surface of the steel plate specimen as upper test points; and calculating the average hardness value of each upper test point.

[0040] In this application, the plane where the thickness center line of the steel plate sample is located and is parallel to the upper surface of the steel plate sample is used as the reference plane, and each detection point between the reference plane and the upper surface of the steel plate sample is used as the upper detection point. The average value of the Vickers hardness value of each upper detection point is calculated, and the average value is used as the upper hardness value of the steel plate.

[0041] In one embodiment of the present application, the calculation of the average hardness value of the test points close to the lower surface of the steel plate specimen includes: taking the plane where the thickness center line of the steel plate specimen is located and parallel to the upper surface of the steel plate specimen as a reference plane, determining the test points between the reference plane and the lower surface of the steel plate specimen as lower test points; and calculating the average hardness value of each lower test point.

[0042] In this application, the plane where the thickness center line of the steel plate sample is located and is parallel to the upper surface of the steel plate sample is used as the reference plane, and each detection point between the reference plane and the lower surface of the steel plate sample is used as the lower detection point. The average value of the Vickers hardness value of each lower detection point is calculated, and the average value is used as the lower hardness value of the steel plate.

[0043] In one embodiment of the present application, the water flow ratio between the lower water cooling device and the upper water cooling device is adjusted based on the hardness value of the upper part of the steel plate and the hardness value of the lower part of the steel plate, including: if the hardness value of the upper part of the steel plate is greater than the hardness value of the lower part of the steel plate, then the water flow ratio between the lower water cooling device and the upper water cooling device is increased.

[0044] In the present application, if the hardness value of the upper part of the steel plate is greater than the hardness value of the lower part of the steel plate, it means that the cooling rate of the upper surface of the steel plate is faster than the cooling rate of the lower surface of the steel plate, resulting in deformation of the steel plate in the width direction and the problem of the steel plate warping laterally. In this case, it is necessary to increase the water flow ratio between the lower water cooling equipment and the upper water cooling equipment during the water cooling process.

[0045] In one embodiment of the present application, if the hardness value of the upper part of the steel plate is greater than the hardness value of the lower part of the steel plate, the water flow ratio between the lower water cooling device and the upper water cooling device is increased, including: if the hardness value of the upper part of the steel plate is greater than the hardness value of the lower part of the steel plate, then for every 10 hardness values ​​difference, the water flow ratio is increased by 0.1-0.4.

[0046] In the present application, if the hardness value of the upper part of the steel plate is greater than the hardness value of the lower part of the steel plate, it means that the cooling rate of the upper surface of the steel plate is faster than the cooling rate of the lower surface of the steel plate, resulting in the hardness value of the upper part of the steel plate being greater than the hardness value of the lower part of the steel plate. Then, for every 10 Vickers hardness values ​​that differ, the water flow ratio is increased by 0.1-0.4. The water flow ratio will vary to a certain extent due to the influence of the thickness of the steel plate.

[0047] In one embodiment of the present application, the water flow ratio between the lower water cooling device and the upper water cooling device is adjusted based on the hardness value of the upper part of the steel plate and the hardness value of the lower part of the steel plate, including: if the hardness value of the upper part of the steel plate is less than the hardness value of the lower part of the steel plate, then reducing the water flow ratio between the lower water cooling device and the upper water cooling device.

[0048] In the present application, if the hardness value of the upper part of the steel plate is less than the hardness value of the lower part of the steel plate, it means that the cooling rate of the upper surface of the steel plate is slower than the cooling rate of the lower surface of the steel plate, resulting in deformation of the steel plate in the width direction and the problem of lateral buckling of the steel plate. In this case, the water flow ratio between the lower water cooling equipment and the upper water cooling equipment needs to be reduced during the water cooling process.

[0049] In one embodiment of the present application, if the hardness value of the upper part of the steel plate is less than the hardness value of the lower part of the steel plate, the water flow ratio between the lower water cooling device and the upper water cooling device is reduced, including: if the hardness value of the upper part of the steel plate is less than the hardness value of the lower part of the steel plate, then for every 10 hardness values ​​difference, the water flow ratio is reduced by 0.1-0.4.

[0050] In the present application, if the hardness value of the upper part of the steel plate is smaller than the hardness value of the lower part of the steel plate, it means that the cooling rate of the upper surface of the steel plate is slower than the cooling rate of the lower surface of the steel plate, resulting in the hardness value of the upper part of the steel plate being smaller than the hardness value of the lower part of the steel plate. Then, for every 10 Vickers hardness values ​​that differ, the water flow ratio is reduced by 0.1-0.4. The water flow ratio will vary to a certain extent due to the influence of the thickness of the steel plate.

[0051] According to another aspect of the embodiments of the present application, a steel plate is provided, which is produced using the method described in any of the above embodiments.

[0052] In order to make it easier for those skilled in the art to understand the present application, the present application will be described below with reference to a specific embodiment.

[0053] The specific implementation steps of this embodiment are as follows:

[0054] Step 1: A steel plate with a thickness of 25 mm, a length of 30 m, and a width of 2500 mm that has been quenched is selected, and a steel plate sample is selected at a position of 15 m in the length direction and 625 mm in the width direction of the steel plate.

[0055] Step 2, use a hardness tester to measure the hardness of the steel plate sample in the thickness direction, starting from the upper surface of the steel plate sample, set a detection point at every 3 mm interval, and measure the Vickers hardness value of each detection point, that is, the first detection point is measured 3 mm from the upper surface of the steel plate sample, the second detection point is measured 6 mm from the upper surface of the steel plate sample, the third detection point is measured 9 mm from the upper surface of the steel plate sample, the fourth detection point is measured 12 mm from the upper surface of the steel plate sample, the fifth detection point is measured 15 mm from the upper surface of the steel plate sample, the sixth detection point is measured 18 mm from the upper surface of the steel plate sample, the seventh detection point is measured 21 mm from the upper surface of the steel plate sample, and the eighth detection point is measured 24 mm from the upper surface of the steel plate sample. The distance between each detection point and the upper surface of the steel plate sample and the Vickers hardness value of each detection point are shown in Table 1.

[0056] Step 3: Take the plane where the thickness center line of the steel plate sample is located and is parallel to the upper surface of the steel plate sample as the reference plane, determine the detection points between the reference plane and the upper surface of the steel plate sample, that is, the detection points within 12.5 mm from the upper surface of the steel plate sample, as the upper detection points, calculate the average hardness value of each upper detection point, and use the average value as the hardness value of the upper part of the steel plate. As shown in Table 1, the 1st to 4th detection points are used as the upper detection points, and the calculated hardness value of the upper part of the steel plate is 336 HV.

[0057] Step 4: Take the plane where the thickness center line of the steel plate sample is located and is parallel to the upper surface of the steel plate sample as the reference plane, determine the detection points between the reference plane and the lower surface of the steel plate sample, that is, the detection points with a distance of more than 12.5 mm from the upper surface of the steel plate sample, as the lower detection points, calculate the average hardness value of each lower detection point, and use the average value as the lower hardness value of the steel plate. As shown in Table 1, the 5th to 8th detection points are used as the lower detection points, and the calculated hardness value of the lower steel plate is 295HV.

[0058] Step 5: If the hardness value of the upper portion of the steel plate is greater than the hardness value of the lower portion of the steel plate, and the hardness value of the upper portion of the steel plate differs from the hardness value of the lower portion of the steel plate by 41 HV, then the water flow ratio between the lower water cooling device and the upper water cooling device during the water cooling process is increased by 0.4.

[0059]

[0060]

[0061] Table 1

[0062] Some of the technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0063] The present application proposes a quantitative method for solving the "transverse C warping" and "transverse C buckling" plate shape problems of steel plates during online quenching, and the method is easy to operate.

[0064] This application starts from the organizational morphology and hardness value, and adjusts the manifold flow of the water cooling equipment according to the hardness value of the steel plate in the thickness direction after quenching, so as to finally achieve synchronous organizational transformation and consistent hardness of the upper and lower surfaces during the cooling process of the steel plate, fundamentally optimizing the cooling uniformity of the upper and lower surfaces of the steel plate, thereby optimizing the plate shape problem of online quenching.

[0065] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art that are not disclosed herein.

[0066] Furthermore, the above-mentioned figures are merely illustrative of the processes included in the methods according to exemplary embodiments of the present application and are not intended to be limiting. It is readily understood that the processes illustrated in the above-mentioned figures do not indicate or limit the temporal order of these processes. Furthermore, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0067] It should be understood that the present application is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes can be performed without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for improving the shape of a steel plate, characterized in that: The method comprises: Determining a steel plate sample from the quenched steel plate, and measuring the hardness value of each detection point of the steel plate sample in the thickness direction; Calculate the average hardness value of the test points close to the upper surface of the steel plate sample as the hardness value of the upper part of the steel plate; Calculate the average hardness value of the detection points close to the lower surface of the steel plate sample as the hardness value of the lower part of the steel plate; During the water cooling process of the steel plate, the water flow ratio between the lower water cooling equipment and the upper water cooling equipment is adjusted based on the hardness value of the upper part of the steel plate and the hardness value of the lower part of the steel plate. According to the difference between the hardness value of the upper part of the steel plate and the hardness value of the lower part of the steel plate, different amplitudes are adopted to adjust the water flow ratio between the upper water cooling equipment and the lower water cooling equipment according to different differences. For every difference of 10 hardness values, the adjustment amplitude of the water flow ratio is 0.1-0.

4.

2. The method according to claim 1, characterized in that The step of determining a steel plate sample from a quenched steel plate comprises: The steel plate specimens were determined at the middle position in the length direction and the 1 / 4 position in the width direction of the quenched steel plate.

3. The method according to claim 1, characterized in that The measuring of the hardness value of each detection point of the steel plate sample in the thickness direction includes: Selecting a plurality of detection points in the steel plate sample along the thickness direction of the steel plate sample, wherein a set distance is set between each adjacent detection point; Measure the Vickers hardness value of each test point.

4. The method according to claim 1, wherein The calculating the average hardness value of the detection points close to the upper surface of the steel plate sample includes: A plane on which the thickness center line of the steel plate sample is located and which is parallel to the upper surface of the steel plate sample is used as a reference plane, and a detection point between the reference plane and the upper surface of the steel plate sample is determined as an upper detection point; Calculate the average hardness value of each upper test point.

5. The method according to claim 1, characterized in that The calculating the average hardness value of the detection point close to the lower surface of the steel plate sample includes: A plane where the thickness center line of the steel plate sample is located and parallel to the upper surface of the steel plate sample is used as a reference plane, and a detection point between the reference plane and the lower surface of the steel plate sample is determined as a lower detection point; Calculate the average hardness value of each lower test point.

6. The method according to claim 1, characterized in that The adjusting the water flow ratio between the lower water cooling device and the upper water cooling device based on the upper hardness value of the steel plate and the lower hardness value of the steel plate includes: If the hardness value of the upper portion of the steel plate is greater than the hardness value of the lower portion of the steel plate, the water flow ratio between the lower water cooling device and the upper water cooling device is increased.

7. The method according to claim 6, characterized in that If the hardness value of the upper portion of the steel plate is greater than the hardness value of the lower portion of the steel plate, increasing the water flow ratio between the lower water cooling device and the upper water cooling device includes: If the hardness value of the upper portion of the steel plate is greater than the hardness value of the lower portion of the steel plate, the water flow ratio is increased by 0.1-0.4 for every 10 hardness values ​​difference.

8. The method according to claim 1, characterized in that The adjusting the water flow ratio between the lower water cooling device and the upper water cooling device based on the upper hardness value of the steel plate and the lower hardness value of the steel plate includes: If the hardness value of the upper portion of the steel plate is less than the hardness value of the lower portion of the steel plate, the water flow ratio between the lower water cooling device and the upper water cooling device is reduced.

9. The method according to claim 8, characterized in that If the hardness value of the upper portion of the steel plate is less than the hardness value of the lower portion of the steel plate, reducing the water flow ratio between the lower water cooling device and the upper water cooling device includes: If the hardness value of the upper portion of the steel plate is smaller than the hardness value of the lower portion of the steel plate, the water flow rate ratio is reduced by 0.1-0.4 for every 10 hardness values ​​difference.

10. A steel plate produced by the method according to any one of claims 1 to 9.

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