A combined cooling method and control system for heat treatment of stainless steel plates

Abstract

This invention discloses a combined cooling method and control system for heat treatment of stainless steel plates. After solution heating and heat preservation, the stainless steel plate is conveyed to a spray zone for spray quenching. After spray quenching, the stainless steel plate is moved to a material frame and quenched in a water tank. This combination of spray quenching and water tank quenching effectively cools the stainless steel plate, improving the control of plate flatness after quenching. During processing, the stainless steel plate material number is input, and corresponding dimensional data is generated by identifying the material number. Based on the dimensional data, corresponding control information is generated and sent to a timing module. The timing module then starts timing according to the control information. When the time reaches a threshold, a prompt is issued to remind the operator, at which point the material frame is lifted out of the water tank. This method controls the quenching time in the water tank, resulting in simple operation and high control precision.

Description

Technical Field

[0001] This invention relates to the field of stainless steel processing, and more specifically to a combined cooling method and control system for heat treatment of stainless steel plates. Background Technology

[0002] Austenitic stainless steel refers to stainless steel that has an austenitic structure at room temperature. The pressure processing flow for ordinary austenitic stainless steel plates involves the following steps: slab heating, rolling, solution heat treatment, straightening, shot blasting, pickling, manual grinding, and packaging. The main purpose of solution heat treatment is to obtain good performance characteristics. For ordinary austenitic stainless steel, the austenitic stainless steel is heated to 1000–1150℃ to dissolve all carbides into the austenite, followed by water cooling or rapid cooling to obtain a single-phase austenitic structure. The solution heat treatment process for stainless steel plates, including the quenching and cooling process, primarily determines the internal properties of ordinary austenitic stainless steel plates and also significantly affects the plate's flatness. Currently, commonly used quenching and cooling equipment for solution heat treatment of ordinary austenitic stainless steel plates includes medium-thick plate roller quenching machines and unconstrained quenching controlled cooling equipment. Therefore, the current quenching and cooling processes are divided into two types:

[0003] 1. Roller quenching involves conveying steel plates via roller conveyors into a water spray zone for quenching. The steel plates are quenched while in motion. Roller quenching machines offer a high cooling rate, but the process is complex, controlling the cooling process is difficult, and the cost of roller quenching machines for medium and heavy plates is high. Strong cooling requires high water consumption, and the quenching machine must have approximately 7000m³ of water. 3 A water supply capacity of over / h is required to meet the quenching requirements of stainless steel, resulting in high water consumption. As the thickness of the stainless steel plate increases, the cost of the quenching equipment also increases significantly.

[0004] 2. Unconstrained quenching and controlled cooling equipment transports steel plates via roller conveyors into a water spray zone for quenching. The steel plates undergo quenching while in motion. Its advantages include a high cooling rate, simple process, and low difficulty in controlling the cooling process. Due to its unconstrained nature, the equipment is less expensive, requiring a water supply capacity of 900m³. 3 The water supply is less than that of a roller quenching machine, but the flatness of the plate after quenching reaches 20-40mm / m. The thickness of the stainless steel plate is limited by the quenching equipment and process, and the pass rate of the primary internal material performance of the stainless steel plate is low.

[0005] Therefore, there is a need for a heat treatment cooling method for stainless steel plates with a thickness of 6-116mm, a width of 1000-3800mm, and a length of 2000-12800mm, which can significantly reduce the water supply during the solution heat treatment quenching process (saving water), improve the control of plate flatness after quenching, and increase the pass rate of primary internal material properties of stable stainless steel plates. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a combined cooling method for heat treatment of stainless steel plates, comprising:

[0007] S1: The stainless steel plate after solution treatment, heating and heat preservation is transported to the spraying area, where the stainless steel plate is sprayed and quenched with water.

[0008] S2: The stainless steel plate, after being sprayed and quenched, is moved into the material frame;

[0009] S3: Move the material frame into the water tank, and quench the stainless steel plate in the water tank.

[0010] S4: The material frame is lifted out of the water tank, the stainless steel plate is conveyed to the roller conveyor, and the material frame is reset.

[0011] Preferably, the water supply capacity of the spray zone water supply system in step S1 is 800m³. 3 / h, working water pressure is 0.1-0.15MPa.

[0012] Preferably, the stainless steel plate moves forward at a speed of 0.8-6 m / min in the spray zone.

[0013] Preferably, the stainless steel plate temperature at the start of the spray zone in S1 is 980-1150℃. In S2, at the end of the spray zone: when the stainless steel plate thickness H ≤ 10mm, the stainless steel plate temperature at the end of the spray zone is 600-720℃; when the stainless steel plate thickness 10mm < H ≤ 25mm, the stainless steel plate temperature at the end of the spray zone is 605-736℃; when the stainless steel plate thickness 25mm < H ≤ 35mm, the stainless steel plate temperature at the end of the spray zone is 610-750℃; and when the stainless steel plate thickness 35mm < H ≤ 116mm, the stainless steel plate temperature at the end of the spray zone is 615-800℃.

[0014] Preferably, in step S3, the cooling time of the stainless steel plate in the water tank is h, where h ≥ (1~2,3)×H seconds (the thickness H of the steel plate is in mm), and the temperature of the water outlet is ≤100℃.

[0015] Preferably: when the stainless steel plate thickness H≤10mm, the time coefficient is 1, and the temperature of the stainless steel plate in the water tank is 600-720℃; when the stainless steel plate thickness 10mm<H≤25mm, the time coefficient is 1.5, and the temperature of the stainless steel plate in the water tank is 605-736℃; when the stainless steel plate thickness 25mm<H≤35mm, the time coefficient is 2, and the temperature of the stainless steel plate in the water tank is 610-750℃; when the stainless steel plate thickness 35mm<H≤116mm, the time coefficient is 3, and the temperature of the stainless steel plate in the water tank is 615-800℃.

[0016] Preferably, when the stainless steel plate is lifted out of the water tank in step S4, the material frame is tilted at a certain angle in the width direction, specifically 6-15°.

[0017] A control system is provided, comprising:

[0018] The input module is used to input the material number of the stainless steel plate. After the material number is input, the corresponding size data is generated, and control information is generated based on the size data and sent to the corresponding module.

[0019] The timing module performs timing based on the control information.

[0020] Preferably, after the stainless steel plate material number is input into the input module, the corresponding size data is generated by recognizing the material number, and corresponding control information is generated based on the size data. The control information is then sent to the timing module. At this time, the timing module starts timing according to the control information. When the time reaches the threshold, a prompt is issued to remind the staff.

[0021] The technical effects and advantages of this invention are as follows:

[0022] 1. By combining spray quenching and water bath quenching methods to cool the stainless steel plate, the water supply during the solution heat treatment quenching process is significantly reduced, with the actual water supply being around 800m³. 3 / h. When the lifting frame exits the water tank, after leaving the water surface: the frame tilts at a 6-15° angle in the width direction, allowing water on the upper surface of the steel plate to naturally flow into the water tank, eliminating the need for a wind-blowing device. Improved control over plate flatness after quenching: 1) Over 85% of the plate flatness is >5-18 mm / m; 2) the remainder is >18-28 mm / m; meeting the requirements of subsequent straightening processes, with the flatness of the straightened stainless steel plate ≤5 mm / m, satisfying the high standards of the market and users. Improved and stabilized the primary internal material performance qualification rate of stainless steel, maintaining it above 99.9%.

[0023] 2. The control system is set up so that when processing stainless steel plates, the stainless steel plate material number is input, the corresponding size data is generated by recognizing the material number, and the corresponding control information is generated based on the size data. The control information is then sent to the timing module. At this time, the timing module starts timing according to the control information. When the time reaches the threshold, it issues a prompt to remind the staff. At this time, the material frame is lifted out of the water tank, thereby controlling the water quenching time in the water tank. The operation is simple. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a combined cooling method for heat treatment of stainless steel plates provided in an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of a control system provided in an embodiment of this application;

[0026] Figure 3 This is a schematic diagram illustrating a specific implementation of the first embodiment provided in this application;

[0027] Figure 4 This is a schematic diagram illustrating a specific implementation of the second embodiment provided in this application.

[0028] In the picture:

[0029] 10. Input module; 11. Timing module. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

[0031] Depend on Figure 1 As shown, this embodiment provides a combined cooling method for heat treatment of stainless steel plates. S1: The stainless steel plate after solution heating and heat preservation is transported to the spray zone, and the stainless steel plate is sprayed and quenched through the spray zone.

[0032] S2: The stainless steel plate after spraying and quenching is moved to the material frame;

[0033] S3: Move the material frame into the water tank and quench the stainless steel plate in the water tank.

[0034] S4: Lift the material frame out of the water tank, convey the stainless steel plate to the roller conveyor, and reset the material frame.

[0035] In step S1, the water supply system for the sprinkler area supplies 800m³ of water. 3 / h, working water pressure is 0.1-0.15MPa.

[0036] The stainless steel plate moves at a speed of 0.8-6 m / min in the spray zone;

[0037] First, the hot-rolled stainless steel sheet is solution-treated and heated to a specific temperature according to the process. After exiting the solution heat treatment furnace, the stainless steel sheet runs on a roller conveyor to the spray zone roller conveyor. At this point, cooling begins, and the stainless steel sheet temperature reaches 980–1150℃. After passing through the spray zone roller conveyor, the stainless steel sheet advances to the roller conveyor before the water tank, marking the end of the spray zone. The temperatures of stainless steel sheets of different thicknesses after the spray zone are shown in the table below.

[0038]

[0039]

[0040] After the spraying zone ends, the stainless steel plate temperature is also the inlet water tank temperature. The stainless steel plate is then lifted into the water tank using a lifting frame. The cooling time of the stainless steel plate in the water tank is h, where h ≥ (1~2,3)×H seconds (the plate thickness H is in mm). For stainless steel plates with a thickness H ≤ 10mm, the time coefficient is 1; for plates with a thickness of 10mm < H ≤ 25mm, the time coefficient is 1.5; for plates with a thickness of 25mm < H ≤ 35mm, the time coefficient is 2; and for plates with a thickness of 35mm < H ≤ 116mm, the time coefficient is 3. The temperature changes of stainless steel plates of different thicknesses in the water tank are shown in the table below:

[0041]

[0042] When lifting the material frame out of the water tank, after it leaves the water surface, tilt the frame 6-15° in the width direction to allow water from the upper surface of the stainless steel plate to flow into the water tank. Then, lift the frame horizontally and return it to the track in front of the water tank. Subsequent processes include shot blasting, straightening, pickling, manual inspection (grinding), and packaging. The surface (internal) quality of the steel plate meets the standards and user requirements.

[0043] The stainless steel plate is cooled by combining spray quenching and water bath quenching, which significantly reduces the water supply during the solution heat treatment quenching process. The actual water supply is 800m³. 3 / h. When the lifting frame exits the water tank, after leaving the water surface: the frame tilts at a 6-15° angle in the width direction, allowing water on the upper surface of the steel plate to naturally flow into the water tank, eliminating the need for a wind-blowing device. Improved control over plate flatness after quenching: 1) Over 85% of the plate flatness is >5-18 mm / m; 2) the remainder is >18-28 mm / m; meeting the requirements of subsequent straightening processes, with the flatness of the straightened stainless steel plate ≤5 mm / m, satisfying the high standards of the market and users. Improved and stabilized the primary internal material performance qualification rate of stainless steel, maintaining it above 99.9%.

[0044] Depend on Figure 2 As shown, this embodiment provides a control system, an input module for inputting the material number of a stainless steel plate, generating corresponding size data after inputting the material number, and generating control information based on the size data and sending it to the corresponding module;

[0045] The timing module performs timing based on the control information.

[0046] The control system is set up so that when processing stainless steel plates, the material number of the stainless steel plate is input, the corresponding dimensional data is generated by identifying the material number, and corresponding control information is generated based on the dimensional data. The control information is then sent to the timing module, which starts timing according to the control information. When the time reaches a threshold, it issues a prompt to remind the operator. It should be noted that the timing device of the timing module 11 can be determined according to actual needs. In this embodiment, a timer is used for timing. When the timer issues a prompt, the material frame is lifted out of the water tank, thereby controlling the quenching time in the water tank. The operation is simple and the control accuracy is high.

[0047] Example 1

[0048] Depend on Figure 3 As shown in this embodiment, a specific implementation method for a hot-rolled S32168 austenitic stainless steel plate is provided. The stainless steel plate has a thickness of 28mm, a width of 1820mm, and a length of 5940mm. First, the hot-rolled S32168 austenitic stainless steel plate is subjected to solution heating and heat preservation according to the process. Then, it exits the solution heat treatment furnace. The stainless steel plate runs on the roller conveyor to the spray zone roller conveyor area. The initial cooling temperature of the stainless steel plate is 980℃. After passing through the spray zone roller conveyor, the stainless steel plate advances to the roller conveyor in front of the water tank. The spray zone ends, and at this time, the temperature of the stainless steel plate is 650℃.

[0049] The spray zone's ending temperature is also the inlet water tank temperature. A lifting frame is used to hoist the stainless steel plate into the water tank. It should be noted that before processing the stainless steel plate, the material number of the stainless steel plate is input into the control system using the required equipment. The system automatically identifies its size data based on the material number and uses the timing module 11 to time the process, thereby controlling the cooling time of the stainless steel plate in the water tank. In this embodiment, the stainless steel plate cools for 56 seconds in the water tank. When the lifting frame exits the water tank, it tilts 6-15° in the width direction after leaving the water surface, allowing water from the upper surface of the stainless steel plate to flow into the water tank. Then, the lifting frame is laid flat and returned to the front track of the water tank. At this point, the steel plate temperature is 65°C. Subsequent processes include shot blasting, straightening, pickling, manual inspection (grinding), and packaging. The surface (internal) quality of the steel plate meets the standards and user requirements.

[0050] Using the above method, the flatness of the plate after quenching is 12mm / m, which meets the requirements of the subsequent straightening process. The flatness of the stainless steel plate after straightening is ≤5mm / m, satisfying the high standards of the market and users.

[0051] Example 2

[0052] Depend on Figure 4As shown in this embodiment, a specific implementation method for a hot-rolled S31603 austenitic stainless steel plate is provided. The stainless steel plate has a thickness of 58mm, a width of 2300mm, and a length of 6000mm. First, the hot-rolled S31603 austenitic stainless steel plate is subjected to solution heating and heat preservation according to the process. After that, it exits the solution heat treatment furnace. The stainless steel plate runs on the roller conveyor to the spray zone roller conveyor area. The initial cooling temperature of the stainless steel plate is 1020℃. After passing through the spray zone roller conveyor, the stainless steel plate advances to the roller conveyor in front of the water tank. The spray zone ends, and at this time, the temperature of the stainless steel plate is 765℃.

[0053] The spray zone's ending temperature is also the inlet water tank temperature. A lifting frame is used to hoist the stainless steel plate into the water tank. It should be noted that before processing the stainless steel plate, the material number of the stainless steel plate is input into the control system using the required equipment. The system automatically identifies its size data based on the material number and uses the timing module 11 to time the process, thereby controlling the cooling time of the stainless steel plate in the water tank. In this embodiment, the cooling time of the stainless steel plate in the water tank is 190 seconds. When the lifting frame exits the water tank, it tilts 6-15° in the width direction after leaving the water surface, allowing water from the upper surface of the stainless steel plate to flow into the water tank. Then, the lifting frame is laid flat and returned to the front track of the water tank. At this time, the steel plate temperature is 86℃. Subsequent processes include shot blasting, straightening, pickling, manual inspection (grinding), and packaging. The surface (internal) quality of the steel plate meets the standards and user requirements.

[0054] Using the above method, the flatness of the plate after quenching is 8mm / m, which meets the requirements of the subsequent straightening process. The flatness of the stainless steel plate after straightening is ≤5mm / m, satisfying the high standards of the market and users.

[0055] The working principle of this invention is:

[0056] The first step involves conveying the stainless steel sheet after solution heating and heat preservation to the spraying area for spray quenching. The second step involves moving the spray-quenched stainless steel sheet to a material frame. The third step involves moving the material frame to a water tank for water quenching. The fourth step involves lifting the material frame out of the water tank, conveying the stainless steel sheet to a roller conveyor, and resetting the material frame. This combination of spray quenching and water tank quenching significantly reduces the water supply required during the solution heat treatment quenching process, improves the control of plate flatness after quenching, and increases and stabilizes the first-pass yield of stainless steel. The cooling time of the stainless steel sheet in the water tank is controlled by adjusting the lifting of the material frame. Specifically, the control system automatically controls the water quenching time by controlling the time the lifting frame is in the water tank. The operation is simple and the control precision is high.

[0057] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art and related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A combined cooling method for heat treatment of an austenitic stainless steel sheet, characterized by, include: S1: The stainless steel plate after solution treatment, heating and heat preservation is transported to the spraying area, where the stainless steel plate is sprayed and quenched with water. S2: The stainless steel plate, after being sprayed and quenched, is moved into the material frame; S3: Move the material frame into the water tank, and quench the stainless steel plate in the water tank. S4: The material frame is lifted out of the water tank, the stainless steel plate is conveyed to the roller conveyor, and the material frame is reset; At the start of the spray zone in S1, the temperature of the stainless steel plate is 980-1150℃; at the end of the spray zone in S2: when the thickness H of the stainless steel plate is ≤10mm, the temperature of the stainless steel plate at the end of the spray zone is 600-720℃; when the thickness H is ≤25mm, the temperature of the stainless steel plate at the end of the spray zone is 605-736℃; when the thickness H is ≤35mm, the temperature of the stainless steel plate at the end of the spray zone is 610-750℃; when the thickness H is ≤116mm, the temperature of the stainless steel plate at the end of the spray zone is 615-800℃.

2. The combined cooling method of heat treatment of an austenitic stainless steel sheet according to claim 1, characterized in that, The water supply amount of the water supply system of the spraying area in the S1 is 800 m 3 / h, and the working water pressure is 0.1-0.15 MPa.

3. The combined cooling method for heat treatment of austenitic stainless steel plate according to claim 2, characterized in that, The stainless steel plate moves forward at a speed of 0.8-6 m / min in the spray zone.

4. The combined cooling method for heat treatment of austenitic stainless steel plate according to claim 1, characterized in that, The cooling time of the stainless steel plate in the water tank in S3 is h, where h ≥ time coefficient * H seconds, the thickness H of the steel plate is in mm, and the temperature of the water outlet is ≤100℃. When the thickness of the stainless steel plate H ≤ 10mm, the time coefficient is 1, and the temperature of the stainless steel plate in the water tank is 600-720℃. When the thickness of the stainless steel plate 10mm < H ≤ 25mm, the time coefficient is 1.5, and the temperature of the stainless steel plate in the water tank is 605-736℃. When the thickness of the stainless steel plate 25mm < H ≤ 35mm, the time coefficient is 2, and the temperature of the stainless steel plate in the water tank is 610-750℃. When the thickness of the stainless steel plate 35mm < H ≤ 116mm, the time coefficient is 3, and the temperature of the stainless steel plate in the water tank is 615-800℃.

5. The combined cooling method for heat treatment of austenitic stainless steel plate according to claim 4, characterized in that, When the stainless steel plate in step S4 is lifted out of the water tank, the material frame is tilted at a certain angle in the width direction, specifically 6-15°.

6. A control system for a combined cooling method for heat treatment of austenitic stainless steel plates as described in any one of claims 1-5, characterized in that, include: The input module (10) is used to input the material number of the stainless steel plate. After inputting the material number, the corresponding size data is generated, and a control information is generated based on the above size data and sent to the corresponding module. The timing module (11) performs timing according to the control information; After the stainless steel plate material number is input into the input module (10), the corresponding size data is generated by recognizing the material number, and corresponding control information is generated according to the size data. The control information is then sent to the timing module (11). At this time, the timing module (11) starts timing according to the control information. When the time reaches the threshold, a prompt is issued to remind the staff.

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