Medium-thickness plate salt bath quenching partition heat treatment test system and test method

Abstract

The invention relates to a medium-thickness plate salt bath quenching partition heat treatment test system and method, and the medium-thickness plate salt bath quenching partition heat treatment test system comprises a low-temperature molten salt furnace, a medium-temperature molten salt furnace, a heating water tank, a spraying bin, a high-temperature and high-pressure air supply system, a sample clamping and moving device, a cantilever crane and a control system; the method is used for realizing salt bath Qamp of the medium-thickness plate; p, carrying out a spray quenching and soaking partition heat treatment experiment, and obtaining related experiment parameters and temperature curves; isothermal quenching cooling of the high-temperature steel plate is realized by spraying low-temperature molten salt (150-300 DEG C), isothermal partition heat treatment is performed on the steel plate by adopting medium-temperature molten salt (300-500 DEG C), the steel plate is cooled by adopting hot water, and residual molten salt on the surface of the steel plate is cleaned; through cooperation of component design and a production process, the consistency of structure transformation paths in the steel plate core and surface layer cooling process is guaranteed, and the overall performance of the steel plate is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of salt bath quenching and partitioning heat treatment of medium and thick plates, and in particular to a salt bath quenching and partitioning heat treatment test system and a test method for medium and thick plates. Background Art

[0002] In recent years, with the rapid development of my country's economy, the design and manufacturing level of large components such as high-rise buildings, large-span heavy-load bridges, oil and gas pipelines, offshore platforms, large ships, and engineering machinery has been continuously improved, and the requirements for the strength, yield strength ratio, low-temperature toughness, welding performance, corrosion resistance, fatigue resistance, and fracture resistance of structural steel have become increasingly higher. Among them, the demand for high-strength and ultra-high-strength high-performance steel with a yield strength of 690-1300MPa is increasing. If only the strength of steel is considered, the existing technical equipment level of the metallurgical industry is fully able to meet production needs. However, with the increase in the strength level of steel, the risk of brittle fracture of engineering structural steel is greater. Therefore, the ductility indicators such as toughness, plasticity, and yield strength ratio of high-strength steel must be strictly restricted, which greatly increases the difficulty of producing high-strength and ultra-high-strength high-performance steel, and also greatly limits the market application of products.

[0003] The quenching and partitioning (Q&P) process was proposed by Professor SPEER of the United States in 2003. It is a heat treatment method that controls the cooling rate, heating temperature and time and other parameters according to the properties and application requirements of the metal material during the quenching process to obtain the best quenching effect. The process of the quenching and partitioning process is as follows: first, heating is performed above the complete austenitization temperature and kept at this temperature for a period of time to make the structure completely austenitized, and then the temperature is rapidly cooled down to below the martensite transformation temperature and kept at this temperature for a certain period of time to complete the quenching process and produce martensite and residual austenite. Then the temperature is raised to the partitioning temperature and kept at this temperature for a period of time to complete the partitioning process and finally cooled to room temperature. The Q&P steel prepared by the quenching and partitioning process is a new type of partitioned martensitic steel with TRIP effect. Without adding alloying elements, the strength of the steel can reach up to 1400MPa, and the corresponding plasticity can reach 15%.

[0004] High-strength steel adopts the salt bath Q&P heat treatment process with different quenching temperatures and partitioning temperatures, which can achieve efficient matching characteristics of high strength, low yield ratio and good toughness and plasticity under different composition designs. Traditional salt bath Q&P heat treatment experiments mostly achieve isothermal quenching and partitioning effects by immersing in molten salt, but this method is only effective for thinner automotive plates, thinner diameter wires and small-sized castings and forgings. For medium and thick plates, due to their thick thickness and slow cooling speed after immersion in the salt bath, the cooling curves of the surface and the core are quite different. The difference in the organizational transformation path leads to a large difference in the performance of the core and the surface, making it difficult to meet the index requirements. Summary of the invention

[0005] The invention provides a salt bath quenching and partitioning heat treatment test system and test method for medium and thick plates, which are used to realize salt bath Q&P spray quenching + immersion partitioning heat treatment experiments of medium and thick plates, and obtain relevant experimental parameters and temperature curves; spraying low-temperature molten salt (150-300°C) is used to realize isothermal quenching cooling of high-temperature steel plates, spraying low-temperature molten salt (150-300°C) is used to realize isothermal quenching cooling of high-temperature steel plates, medium-temperature molten salt (300-500°C) is used to perform isothermal partitioning heat treatment on steel plates, and hot water is used to cool the steel plates and clean the residual molten salt on the surface of the steel plates; by coordinating component design with production technology, the consistency of the organizational transformation path during the cooling process of the core and surface of the steel plate is ensured, thereby improving the overall performance of the steel plate.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A salt bath quenching and distribution heat treatment test system for medium and thick plates, comprising a low-temperature molten salt furnace, a medium-temperature molten salt furnace, a heating water tank, a spray chamber, a high-temperature and high-pressure air supply system, a sample clamping and moving device, a cantilever crane and a control system; the low-temperature molten salt furnace is provided with a molten salt low-temperature heater and a molten salt pump; the medium-temperature molten salt furnace is provided with a molten salt medium-temperature heater; the heating water tank is provided with a water heater; the spray chamber is provided with a spray device, and the spray device is composed of an upper spray assembly and a lower spray assembly arranged oppositely; a gas-liquid mixer is provided at the spray medium inlet end of the spray device, the liquid inlet of the gas-liquid mixer is connected to the molten salt liquid outlet of the molten salt pump, and the gas inlet of the gas-liquid mixer is connected to the high-temperature and high-pressure air outlet of the high-temperature and high-pressure air supply system; the sample clamping and moving device comprises a translation mechanism, a flip mechanism and The sample clamping mechanism consists of a clamping frame and a connecting shaft, one end of the connecting shaft is connected to the clamping frame located in the spray chamber, and the other end of the connecting shaft extends out of the spray chamber and is connected to the translation mechanism through a flipping mechanism; the steel plate sample is fixed on the clamping frame, and under the action of the translation mechanism, the steel plate sample can move longitudinally along the spray chamber and can flip in the space between the upper spray assembly and the lower spray assembly; the low-temperature molten salt furnace, medium-temperature molten salt furnace, heating water tank, spray chamber, high-temperature and high-pressure air supply system and sample clamping moving device are all arranged within the lifting range of the cantilever crane; the molten salt low-temperature heater, molten salt pump, molten salt medium-temperature heater, water heater, spray device, high-temperature and high-pressure air supply system, sample clamping moving device and control ends of the cantilever crane are respectively connected to the control system.

[0008] The high-temperature and high-pressure air supply system consists of an air compressor, an air storage tank, a refrigerated dryer and an air heating furnace which are connected in sequence through pipelines. The high-temperature and high-pressure air outlet of the air heating furnace is connected to the gas inlet of the gas-liquid mixer through a high-temperature and high-pressure air pipeline.

[0009] The translation mechanism includes a translation motor and a linear guide; the flip mechanism includes a rotation motor and a gearbox; the gearbox is slidably connected to the linear guide through a slider; a translation motor is arranged at one end of the linear guide, and the gearbox can move along the linear guide under the drive of the translation motor; a rotation motor is arranged at one end of the gearbox, and the rotation motor is connected to a connecting shaft in the sample clamping mechanism through a speed change mechanism in the gearbox.

[0010] The low-temperature molten salt furnace comprises a low-temperature molten salt furnace body and a low-temperature molten salt furnace inner chamber. The low-temperature molten salt furnace inner chamber is arranged in the low-temperature molten salt furnace body and is used to place molten salt. The inlet of the molten salt pump is arranged below the molten salt material surface. The fixed end of the molten salt low-temperature heater is fixedly connected to the low-temperature molten salt furnace body through a flange, and the heating end extends into the low-temperature molten salt furnace inner chamber.

[0011] The medium-temperature molten salt furnace comprises a medium-temperature molten salt furnace body and a medium-temperature molten salt furnace inner chamber, the medium-temperature molten salt furnace inner chamber is placed in the medium-temperature molten salt furnace body, and the medium-temperature molten salt furnace inner chamber is used to place molten salt; the fixed end of the molten salt medium-temperature heater is fixedly connected to the medium-temperature molten salt furnace body through a flange, and the heating end extends into the medium-temperature molten salt furnace inner chamber; the top of the medium-temperature molten salt furnace body is closed by an upper cover plate of the medium-temperature molten salt furnace, and the upper cover plate of the medium-temperature molten salt furnace is a flap structure, which is rotatably connected to the medium-temperature molten salt furnace body through an upper cover plate flipping mechanism, and is flipped under the action of an upper cover plate hydraulic drive device.

[0012] The heating water tank includes a heating water tank body and a heating water tank inner chamber, which is placed in the heating water tank body and is used to hold water; the fixed end of the water heater is fixedly connected to the heating water tank body through a flange, and the heating end extends into the heating water tank inner chamber; the top of the heating water tank body is closed by an upper cover plate of the heating water tank, and the upper cover plate of the heating water tank is a flap structure, which is rotatably connected to the heating water tank body through an upper cover plate flipping mechanism 2, and is flipped under the action of an upper cover plate hydraulic drive device 2.

[0013] The control system has the functions of temperature monitoring, time monitoring, molten salt liquid state monitoring and temperature curve drawing.

[0014] A test method for salt bath quenching and partitioning heat treatment of medium and thick plates, the specific process is as follows:

[0015] 1) In the low-temperature molten salt furnace, the molten salt for spraying is heated to 150-300°C, and then the heated molten salt liquid is pumped out by the molten salt pump and sent to the spray chamber; at the same time, the air compressed by the air compressor and stored in the air tank is dried by the refrigerated dryer and heated by the air heater to form high-temperature and high-pressure air, which is also sent to the spray chamber;

[0016] 2) In the spray chamber, the steel plate sample with an initial temperature of 800-1000°C is sent to the spray device through the sample clamping and moving device, and is located between the upper spray assembly and the lower spray assembly; the high-temperature and high-pressure air and the molten salt liquid are fully mixed by the gas-liquid mixing device as the spray medium, and the spray medium is sprayed from the multiple nozzles of the upper spray assembly and the multiple nozzles of the lower spray assembly at the same time to spray and cool the steel plate sample; during the spraying process, the uniformity of the spray cooling is ensured by the translation and flipping of the steel plate sample; the spraying is stopped after the steel plate sample drops to 200-300°C;

[0017] 3) The steel plate sample is removed from the spray chamber and taken out from the sample clamping and moving device, and then the steel plate sample is placed in a medium-temperature molten salt furnace through a cantilever crane; the molten salt in the medium-temperature molten salt furnace has been preheated to 300-500°C, and the steel plate sample is medium-temperature distributed using the medium-temperature molten salt in the medium-temperature molten salt furnace;

[0018] 4) After the medium-temperature distribution is completed, the steel plate sample is taken out from the medium-temperature molten salt furnace by a cantilever crane and placed in a heating water tank. The molten salt is cleaned by 70-100°C hot water, and the temperature of the steel plate sample is further reduced.

[0019] During the test, the control system realizes full process control and full cycle monitoring. The main controller of the control system is an industrial computer, and a control cabinet and an operating cabinet are set up. The control cabinet is used to monitor the low-temperature molten salt furnace, the medium-temperature molten salt furnace, the heating water tank and the spray chamber, including molten salt temperature monitoring, steel plate sample temperature monitoring, each process time monitoring, molten salt status monitoring and drawing temperature curves. The operating cabinet is used to control the operation of the sample clamping and moving device, the high-temperature and high-pressure air supply system and the cantilever crane. The spray chamber recovers the molten salt liquid and returns it to the low-temperature molten salt furnace to realize the recycling of molten salt. The control system also has over-temperature alarm and safety protection functions. When the molten salt temperature, equipment current and voltage are abnormal, the control system will alarm and automatically shut down the power supply when the process parameters exceed the set values. At the same time as the sound and light alarm, the alarm information and equipment failure status will be displayed on the computer display.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) Able to efficiently complete the salt bath Q&P spray quenching + immersion partitioning heat treatment experiment of medium and thick plates, and obtain relevant experimental parameters and temperature curves;

[0022] The high-temperature steel plate is cooled by isothermal quenching by spraying low-temperature molten salt (150-300℃), the steel plate is isothermal heat treated by medium-temperature molten salt (300-500℃), and the steel plate is cooled by hot water and the residual molten salt on the surface of the steel plate is cleaned. The consistency of the structural transformation path of the core and surface of the steel plate during the cooling process is ensured by coordinating the composition design with the production process, thereby improving the overall performance of the steel plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the composition of a salt bath quenching and partitioning heat treatment test system for medium and thick plates according to the present invention.

[0024] Figure 2a It is a three-dimensional perspective view of the low-temperature molten salt furnace of the present invention.

[0025] Figure 2b It is a three-dimensional exploded view of the low-temperature molten salt furnace described in the present invention.

[0026] Figure 3a It is a three-dimensional perspective view of the medium-temperature molten salt furnace of the present invention.

[0027] Figure 3b It is a three-dimensional exploded view of the medium-temperature molten salt furnace described in the present invention.

[0028] Figure 4a It is a three-dimensional perspective view of the heating water tank of the present invention.

[0029] Figure 4b It is a three-dimensional exploded view of the heating water tank of the present invention.

[0030] Figure 5a It is a three-dimensional perspective view of the spray chamber and the sample clamping and moving device of the present invention.

[0031] Figure 5b It is a three-dimensional exploded view of the spray chamber and the sample clamping and moving device of the present invention.

[0032] Figure 5c It is a schematic diagram of the three-dimensional structure of the spray device of the present invention.

[0033] Figure 5d It is a schematic diagram of the three-dimensional structure of the sample clamping and moving device of the present invention.

[0034] Figure 6a It is a schematic diagram of the three-dimensional structure of the cantilever crane of the present invention.

[0035] Figure 6b It is a schematic diagram of the hoisting range of the cantilever crane of the present invention.

[0036] In the figure: 1. Low temperature molten salt furnace 101. Molten salt pump 102. Upper cover of low temperature molten salt furnace 103. Flange 104. Inner chamber of low temperature molten salt furnace 105. Molten salt low temperature heater 106. Side door of low temperature molten salt furnace 107. Base of low temperature molten salt furnace 2. Medium temperature molten salt furnace 201. Molten salt medium temperature heater 202. Inner chamber of medium temperature molten salt furnace 203. Upper cover hydraulic drive device 1 204. Base of medium temperature molten salt furnace 205. Upper cover of medium temperature molten salt furnace 206. Upper cover flipping mechanism 1 207. Side door of medium temperature molten salt furnace 3. Heating water tank 301. Water heater 302. Inner chamber of heating water tank 303. Side door of heating water tank 304. Hot water tank base 305. Heating water tank upper cover 306. Upper cover flip mechanism 2 307. Upper cover hydraulic drive device 2 4. Sample clamping and moving device 401. Translation motor 402. Rotation motor 403. Gearbox 404. Linear track 405. Connecting shaft 406. Clamping frame 5. Spraying chamber 501. Chamber body translation door 502. Spraying chamber body 503. Spraying chamber base 504. Base enclosure 505. Spraying chamber side door 506. Molten salt liquid collection tank 507. Spraying device 6. Cantilever crane 7. Control cabinet 8. Operation cabinet 9. Refrigerated dryer 10. Gas storage tank 11. Air compressor 12. Air heating furnace DETAILED DESCRIPTION

[0037] The salt bath quenching and partitioning heat treatment test system for medium and thick plates described in the present invention uses spraying low-temperature (150-300°C) molten salt to achieve isothermal quenching and cooling of high-temperature steel plates. Compared with the traditional salt bath immersion test method, it avoids the problem of obvious difference in cooling curves between the surface and the core due to the slow cooling rate of the steel plate, and accelerates the overall cooling rate of the surface and the core of the steel plate. The quenched steel plate is immersed in medium-temperature (300-500°C) molten salt for isothermal partitioning heat treatment, and finally the steel plate enters a hot water pool to cool and clean the residual molten salt on the surface. The salt bath quenching and partitioning heat treatment experiment is carried out using the device described in the present invention, and the chemical composition design can ensure the consistency of the structural transformation path during the cooling process of the core and surface of the steel, thereby providing reliable test data for improving the overall performance of the steel plate.

[0038] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0039] like Figure 1 As shown, the salt bath quenching and partitioning heat treatment test system of medium and thick plates described in the present invention comprises a low-temperature molten salt furnace 1, a medium-temperature molten salt furnace 2, a heating water tank 3, a spray chamber 5, a high-temperature and high-pressure air supply system, a sample clamping and moving device 4, a cantilever crane 6 and a control system; the low-temperature molten salt furnace 1 is provided with a molten salt low-temperature heater 105 and a molten salt pump 101; the medium-temperature molten salt furnace 2 is provided with a molten salt medium-temperature heater 201; the heating water tank 3 is provided with a water heater; Figure 5a , Figure 5b As shown, the spray bin 5 is provided with a spray device 507 (such as Figure 5c As shown), the spray device 507 is composed of an upper spray assembly and a lower spray assembly arranged relatively to each other; a gas-liquid mixer is provided at the spray medium inlet end of the spray device 507, the liquid inlet of the gas-liquid mixer is connected to the molten salt liquid outlet of the molten salt pump 101, and the gas inlet of the gas-liquid mixer is connected to the high-temperature and high-pressure air outlet of the high-temperature and high-pressure air supply system; the sample clamping moving device 4 includes a translation mechanism, a flipping mechanism and a sample clamping mechanism, and the sample clamping mechanism is composed of a clamping frame 406 and a connecting shaft 405, and the connecting shaft 405 One end is connected to the clamping frame 406 located in the spray chamber 5, and the other end of the connecting shaft 405 extends out of the spray chamber 5 and is connected to the translation mechanism through the flip mechanism; the steel plate sample is fixed on the clamping frame 406, and under the action of the translation mechanism, the steel plate sample can move longitudinally along the spray chamber 5 and can flip in the space between the upper spray assembly and the lower spray assembly; the low-temperature molten salt furnace 1, the medium-temperature molten salt furnace 2, the heating water tank 3, the spray chamber 5, the high-temperature and high-pressure air supply system and the sample clamping and moving device 4 are all arranged on a cantilever crane 6 (such as Figure 6a Within the lifting range (as shown) Figure 6bThe control ends of the molten salt low-temperature heater 105, the molten salt pump 101, the molten salt medium-temperature heater 201, the water heater, the spray device 507, the high-temperature and high-pressure air supply system, the sample clamping and moving device 4 and the cantilever crane 6 are respectively connected to the control system.

[0040] The high-temperature and high-pressure air supply system is composed of an air compressor 11, an air storage tank 10, a refrigerated dryer 9 and an air heating furnace 12 which are connected in sequence through pipelines. The high-temperature and high-pressure air outlet of the air heating furnace 12 is connected to the gas inlet of the gas-liquid mixer through a high-temperature and high-pressure air pipeline.

[0041] like Figure 5b , Figure 5d As shown, the translation mechanism includes a translation motor 401 and a linear guide 404; the flip mechanism includes a rotation motor 402 and a gearbox 403; the gearbox 403 is slidably connected to the linear guide 404 through a slider; a translation motor 401 is arranged at one end of the linear guide, and the gearbox 403 can move along the linear guide 404 under the drive of the translation motor 401; a rotation motor 402 is arranged at one end of the gearbox 403, and the rotation motor 402 is connected to the connecting shaft 405 in the sample clamping mechanism through a speed change mechanism in the gearbox 403.

[0042] like Figure 2a , Figure 2b As shown, the low-temperature molten salt furnace 1 includes a low-temperature molten salt furnace body and a low-temperature molten salt furnace inner chamber 104. The low-temperature molten salt furnace inner chamber 104 is placed in the low-temperature molten salt furnace body. The low-temperature molten salt furnace inner chamber 104 is used to place molten salt, and the inlet of the molten salt pump 101 is placed below the molten salt material surface; the fixed end of the molten salt low-temperature heater 105 is fixedly connected to the low-temperature molten salt furnace body through a flange, and the heating end extends into the low-temperature molten salt furnace inner chamber.

[0043] like Figure 3a , Figure 3b As shown, the medium-temperature molten salt furnace 2 includes a medium-temperature molten salt furnace body and a medium-temperature molten salt furnace inner chamber 202. The medium-temperature molten salt furnace inner chamber 202 is placed in the medium-temperature molten salt furnace body, and the medium-temperature molten salt furnace inner chamber 202 is used to place molten salt; the fixed end of the molten salt medium-temperature heater 201 is fixedly connected to the medium-temperature molten salt furnace body through a flange, and the heating end extends into the medium-temperature molten salt furnace inner chamber 202; the top of the medium-temperature molten salt furnace body is closed by a medium-temperature molten salt furnace upper cover 205, and the medium-temperature molten salt furnace upper cover 205 is a flap structure, which is rotatably connected to the medium-temperature molten salt furnace body through an upper cover flipping mechanism 206, and is flipped under the action of an upper cover hydraulic drive device 203.

[0044] like Figure 4a , Figure 4bAs shown, the heating water tank 3 includes a heating water tank body and a heating water tank inner chamber 302. The heating water tank inner chamber 302 is placed in the heating water tank body, and the heating water tank inner chamber 302 is used to hold water; the fixed end of the water heater 301 is fixedly connected to the heating water tank body through a flange, and the heating end extends into the heating water tank inner chamber 302; the top of the heating water tank body is closed by a heating water tank upper cover plate 305, and the heating water tank upper cover plate 305 is a flap structure, which is rotatably connected to the heating water tank body through an upper cover plate flipping mechanism 2 306, and is flipped under the action of an upper cover plate hydraulic drive device 2 307.

[0045] The control system has the functions of temperature monitoring, time monitoring, molten salt liquid state monitoring and temperature curve drawing.

[0046] The present invention discloses a method for testing the salt bath quenching and partitioning heat treatment of medium and thick plates, and the specific process is as follows:

[0047] 1) In the low-temperature molten salt furnace 1, the molten salt for spraying is heated to 150-300°C, and then the heated molten salt liquid is pumped out by the molten salt pump 101 and sent to the spray chamber 5; at the same time, the air compressed by the air compressor 11 and stored in the air storage tank 10 is dried by the refrigerated dryer 9 and heated by the air heater 12 to form high-temperature and high-pressure air, which is also sent to the spray chamber 5;

[0048] 2) In the spray chamber 5, the steel plate sample with an initial temperature of 800-1000°C is sent to the spray device 507 through the sample clamping and moving device 4, and is located between the upper spray assembly and the lower spray assembly; the high-temperature and high-pressure air and the molten salt liquid are fully mixed by the gas-liquid mixing device and used as the spray medium, and the spray medium is sprayed from the multiple nozzles of the upper spray assembly and the multiple nozzles of the lower spray assembly at the same time to spray and cool the steel plate sample; during the spraying process, the uniformity of the spray cooling is ensured by the translation and flipping of the steel plate sample; the spraying is stopped after the steel plate sample drops to 200-300°C;

[0049] 3) The steel plate sample is removed from the spray chamber 5 and taken out from the sample clamping and moving device 4, and then the steel plate sample is placed in the medium-temperature molten salt furnace 2 through the cantilever crane 6; the molten salt in the medium-temperature molten salt furnace 2 has been preheated to 300-500° C., and the steel plate sample is medium-temperature distributed in the medium-temperature molten salt furnace 2 using the medium-temperature molten salt;

[0050] 4) After the medium-temperature distribution is completed, the steel plate sample is taken out from the medium-temperature molten salt furnace 2 by using a cantilever crane 6 and placed in a heating water tank 3. The molten salt is cleaned by hot water at 70 to 100° C., and the temperature of the steel plate sample is further reduced.

[0051] During the test, the whole process control and full cycle monitoring are realized through the control system; the main controller of the control system is an industrial computer, and a control cabinet 7 and an operating cabinet 8 are set; the control cabinet 7 is used to monitor the low-temperature molten salt furnace 1, the medium-temperature molten salt furnace 2, the heating water tank 3 and the spray chamber 5, including molten salt temperature monitoring, steel plate sample temperature monitoring, each process time monitoring, molten salt state monitoring and drawing temperature curves; the operating cabinet 8 is used to control the operation of the sample clamping and moving device 4, the high-temperature and high-pressure air supply system and the cantilever crane 6; the spray chamber 5 recovers the molten salt liquid and returns it to the low-temperature molten salt furnace 1 to realize the recycling of the molten salt; the control system also has over-temperature alarm and safety protection functions. When the molten salt temperature, equipment current and voltage are abnormal, the control system will alarm and automatically shut down the power supply when the process parameters exceed the set values. At the same time as the sound and light alarm, the alarm information and equipment failure status are displayed on the computer display.

[0052] In order to more intuitively embody the present invention, the embodiments of the present invention are further described in conjunction with examples. The following examples are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technical solution that can be obviously obtained by a person skilled in the art within the technical scope disclosed in the present invention, including simple changes or equivalent replacements, is within the protection scope of the present invention.

[0053] [Example]

[0054] In this embodiment, the dimensions of the steel plate specimen are 40 mm (thickness) × 200 mm (width) × 400 mm (length).

[0055] In this embodiment, the salt bath quenching and partitioning heat treatment test system for medium and thick plates includes a low-temperature molten salt furnace 1, a medium-temperature molten salt furnace 2, a heating water tank 3, a spray chamber 5, a high-temperature and high-pressure air supply system, a sample clamping and moving device 4, a cantilever crane 6 and a control system; the specific structures of each part are as follows:

[0056] The low-temperature molten salt furnace 1 is mainly used to provide high-pressure molten salt liquid to the spray chamber 5. The volume of the molten salt liquid provided for each spraying is not less than 1m 3, the dimensions of the low-temperature molten salt furnace 1 are 1158×1100×1700mm. In this embodiment, the low-temperature molten salt furnace 1 includes a low-temperature molten salt furnace body, a low-temperature molten salt furnace base 107, a low-temperature molten salt furnace side door 106, a low-temperature molten salt furnace upper cover 102 and a low-temperature molten salt furnace inner chamber 104, a molten salt low-temperature heater 105, a molten salt pump 101 and a temperature measuring device. The target heating temperature of the molten salt is 150-300°C. The molten salt low-temperature heater 105 adopts an electric heater installed by a flange 103, with a total power of 10kW (two electric heaters are installed in this embodiment), a three-phase 380V power supply, and a material of SUS310S stainless steel. The molten salt low temperature heater 105 directly extends into the inner chamber 104 of the low temperature molten salt furnace to directly heat the molten salt inside it. It is required that the time for the molten salt to reach the target heating temperature shall not exceed 6 hours, the heating temperature shall be continuously adjustable, and the control accuracy of the heating temperature shall be within the range of ±10°C, so as to ensure the stable, continuous and smooth supply of molten salt liquid to the spraying device 507, and ensure the continuous and effective operation of the spraying device 507. A low temperature molten salt furnace upper cover 102 is provided on the top of the low temperature molten salt furnace body, and a molten salt pump 101 is installed. A low temperature molten salt furnace side door 106 is provided on one side of the low temperature molten salt furnace body, which is used to put in or take out the inner chamber 104 of the low temperature molten salt furnace. The low temperature molten salt furnace body is supported by a low temperature molten salt furnace base 107, and the main structure of the low temperature molten salt furnace is made of high temperature resistant and corrosion resistant steel (SUS304 stainless steel is used in this embodiment), so as to ensure that the low temperature molten salt furnace 1 does not leak or damage components during the entire test cycle. The inner chamber 104 of the low-temperature molten salt furnace is provided with a reflux molten salt inlet for receiving the molten salt liquid after spraying collected by the spray chamber 5 .

[0057] In order to ensure the molten salt spraying effect, the present invention is provided with a high-temperature and high-pressure air supply system, which is composed of an air compressor 11, an air storage tank 10, a refrigerated dryer 9 and an air heating furnace 12. After the air enters the air compressor 11, it enters the air storage tank 10 after compression and filtration. The compressed air in the air storage tank 10 enters the refrigerated dryer 9 under pressure, and is dried in the refrigerated dryer. After filtering and removing impurities therein, it is used as the air source for spraying in the spray bin. The heating furnace 12 is used to heat the steel plate sample before spraying, and the heating temperature does not exceed 1600°C, and the heating rate is 1°C / min. In order to ensure that the temperature of the molten salt liquid always meets the spraying requirements, the low-temperature molten salt pipeline connecting the low-temperature molten salt furnace 1 and the spray bin 5 has a heating and heat preservation function; the material of the low-temperature molten salt pipeline is 304 stainless steel, and a DN50 pipeline with a design temperature below 200°C is used to meet the corrosion resistance and pressure resistance requirements.

[0058] In this embodiment, the medium-temperature molten salt furnace 2 is used to achieve isothermal distribution heat treatment of medium-temperature molten salt. The target heating temperature of the molten salt is 300-500°C, and the volume of the molten salt melted each time is not less than 0.2m 3The outer dimensions of the medium-temperature molten salt furnace 2 are 1250mm×700mm×1450mm. The medium-temperature molten salt furnace 2 includes a medium-temperature molten salt furnace body, a medium-temperature molten salt furnace base 204, a medium-temperature molten salt furnace side door 207, a medium-temperature molten salt furnace upper cover 205, a medium-temperature molten salt furnace inner chamber 202, a molten salt medium-temperature heater 201, etc. The molten salt medium-temperature heater 201 adopts a flange-mounted electric heater with a total power of 8kW (two electric heaters are installed in this embodiment), a three-phase 380V power supply, and a material of SUS310S stainless steel. The molten salt medium-temperature heater 201 directly extends into the inner chamber 202 of the medium-temperature molten salt furnace to directly heat the molten salt inside it. It is required that the time for the molten salt to reach the target heating temperature does not exceed 6h, and the molten salt temperature is continuously adjustable, and the temperature control accuracy is within the range of ±10°C. The main structure of the medium-temperature molten salt furnace 2 is made of high-temperature resistant and corrosion-resistant steel (304 steel stainless steel is used in this embodiment) to ensure that the medium-temperature molten salt furnace 2 does not leak, damage to components and other problems during the entire test period. A medium-temperature molten salt furnace upper cover 205 is provided on the top of the medium-temperature molten salt furnace body, which is closed during heating and opened when the steel plate sample is in and out. The medium-temperature molten salt furnace upper cover 205 adopts a flap structure. Considering its sealing effect and flexibility of use, an upper cover hydraulic drive device 203 is used as the auxiliary power for the switch. A medium-temperature molten salt furnace side door 207 is provided on one side of the medium-temperature molten salt furnace body for placing in or taking out the inner chamber 202 of the medium-temperature molten salt furnace.

[0059] In this embodiment, the heating water tank 3 is mainly used for cooling and cleaning the steel plate sample. The target heating temperature of the water in the tank is 70-100°C, and the temperature control accuracy is within the range of ±10°C. The volume of the inner chamber 302 of the heating water tank is greater than 1m 3 . The heating water tank 3 includes a heating water tank body, a heating water tank upper cover 305, a heating water tank side door 303, a heating water tank base 304, a heating water tank inner chamber 302, a water heater 301 and a water pump. The water heater 301 also adopts a flange-mounted electric heater with a power of 15kW (2 installed), a three-phase 380V power supply, and a material of SUS304 stainless steel. The overall dimensions of the heating water tank 3 are 1300mm×960mm×1450mm. Considering the corrosive characteristics of molten salt, the main material of the heating water tank 3 is corrosion-resistant stainless steel. A heating water tank upper cover 305 is provided on the top of the heating water tank 3, which is closed during heating and opened when the steel plate sample is in and out. The heating water tank upper cover 305 adopts a flap structure. Considering its sealing effect and flexibility of use, the upper cover hydraulic drive device 2 307 is used as the auxiliary power for the switch. A heating water tank side door 303 is provided on one side of the heating water tank 3 for placing in or taking out the inner chamber 302 of the heating water tank.

[0060] In this embodiment, the sample clamping and moving device 4 is used to transport the steel plate sample for salt bath heat treatment test and to realize the flipping action of the steel plate sample in the spray chamber 5. The sample clamping and moving device 4 includes a translation mechanism, a flipping mechanism and a sample clamping mechanism. The sample clamping mechanism is composed of a clamping frame 406 and a connecting shaft 405. The translation mechanism includes a translation motor 401 and a linear guide rail, and the flipping mechanism includes a rotary motor 402 and a gearbox 403; the size of the steel plate sample that can be clamped by the clamping frame 406 is limited to 40mm×200mm×400mm. The actions that can be realized by the sample clamping and moving device 4 include horizontal movement and rotation around the axis of the connecting shaft 405. The translation mechanism is used to accurately deliver the steel plate sample to the spraying station and the hoisting station, and the movement stroke is 1m. The flipping mechanism is used to realize the flipping operation of the steel plate sample at the spraying station to ensure that the spraying process is heated evenly. The rotation angle of the clamping frame 406 is 0~360℃. The sample clamping moving device 4 moves smoothly and is accurately positioned. The strength of the connecting shaft 405 can meet the strength requirements of the torque and bending moment when the steel plate sample rotates at a uniform speed. The model of the rotating motor 402 is ECMA-JA1010SS, the input voltage is 220V, the input current is 4A, the output speed is 3000r / min, the output torque is 3.18Nm, and the output power is 10kW. The model of the translation motor 401 is ECMA-JA0807SS, the input voltage is 200V, the input current is 3A, the output speed is 3000r / min, the output torque is 2.39Nm, and the output voltage is 0.75W. The material of the connecting shaft 405 is 45 steel, the cantilever length is 1m, and the bending deformation angle of the connecting shaft 405 is less than 0.1° after the maximum size of the steel plate sample is clamped.

[0061] In this embodiment, the spray bin 5 is used to provide a relatively sealed space for low-temperature molten salt spraying, ensuring that the steel plate sample is free of impurities during the spraying process, and at the same time ensuring that there is no molten salt liquid splashing during the spraying process, thereby improving the safety of the device. The spray bin 5 includes a spray bin base 503 (including a base enclosure 504), a spray bin body 502, a spray bin sliding door 501, a spray device 507, a spray bin side door 505, a perspective window, a lighting lamp, a molten salt liquid collection tank 506, etc. The design focus of the spray bin 5 is the structural design of the spray device 507 and the optimization of the jet characteristics, ensuring that the molten salt liquid can be effectively atomized during the spraying process, and the atomized particles are small and dense. In this embodiment, the spray device 507 is composed of 16 nozzles, of which 8 nozzles are grouped as an upper spray assembly, and another 8 nozzles are grouped as a lower spray assembly, and two groups of spray assemblies are arranged on both sides of the steel plate sample. The melted molten salt liquid is pressurized by the molten salt pump 101, and after being mixed with high-temperature and high-pressure air, it quickly passes through the nozzle to form an atomization effect; spraying both sides of the steel plate sample at the same time can ensure that the surfaces on both sides complete the salt bath spray treatment at the same time, and ensure that the surfaces on both sides of the steel plate sample have the same effect after the salt bath heat treatment. The molten salt liquid used for spraying is always under temperature monitoring, and the temperature in the spray bin body 502 and the surface temperature of the steel plate sample are also under real-time monitoring. Considering the corrosiveness of the molten salt, the material of the main body of the spray bin 5 is selected from high-temperature and corrosion-resistant 304 stainless steel to ensure its service life and safety during use. The spray bin 5 has the function of recycling the molten salt liquid. The molten salt liquid after spraying is collected by the molten salt liquid collection tank 506 and introduced into the inner chamber 104 of the low-temperature molten salt furnace, so as to realize the reuse of the molten salt.

[0062] In this embodiment, the cantilever crane 6 is an important transfer equipment in the medium and thick plate salt bath quenching and distribution heat treatment test system, and its main function is to hoist and transport the steel plate samples. The cantilever crane 6 can realize the multi-station movement of the steel plate samples. In this embodiment, the cantilever crane 6 is provided with 4 stations, namely, the air heating furnace station, the spraying bin station, the medium temperature molten salt furnace station and the heating water tank station. The cantilever crane 6 is used to realize non-contact movement. During the entire test process, the high-temperature steel plate sample does not directly contact the operator to ensure the safety of operation. The cantilever beam of the cantilever crane 6 is made of 45 steel to ensure that the stiffness, strength and bending performance of the cantilever beam meet the safety requirements of hoisting. The driving motor of the cantilever crane 6 during horizontal rotation adopts a motor of model BMS0.125-01M, with a safe working load of 0.125T, a lifting height of 3m, and a three-phase 380V power supply.

[0063] In this embodiment, the test process of salt bath quenching and partitioning heat treatment of medium and thick plates is as follows:

[0064] 1) In the low-temperature molten salt furnace 1, the molten salt for spraying is heated to 200°C, and then the heated molten salt liquid is pumped out by the molten salt pump 101 and sent to the spray chamber 5; at the same time, the air compressed by the air compressor 11 and stored in the air storage tank 10 is dried by the refrigerated dryer 9 and heated by the air heater 12 to form high-temperature and high-pressure air, which is also sent to the spray chamber 5;

[0065] 2) In the spray chamber 5, the steel plate sample with an initial temperature of 900°C is sent to the spray device 507 through the sample clamping and moving device 4, and is located between the upper spray assembly and the lower spray assembly; the high-temperature and high-pressure air and the molten salt liquid are fully mixed by the gas-liquid mixing device and used as the spray medium, and the spray medium is sprayed from the multiple nozzles of the upper spray assembly and the multiple nozzles of the lower spray assembly at the same time to spray and cool the steel plate sample; during the spraying process, the uniformity of the spray cooling is ensured by translating and flipping the steel plate sample; the spraying is stopped after the steel plate sample drops to 200°C;

[0066] 3) The steel plate sample is removed from the spray chamber 5 and taken out from the sample clamping and moving device 4, and then the steel plate sample is placed into the medium-temperature molten salt furnace 2 through the cantilever crane 6; the molten salt in the medium-temperature molten salt furnace 2 has been preheated to 450° C., and the steel plate sample is medium-temperature distributed in the medium-temperature molten salt furnace 2 using the medium-temperature molten salt;

[0067] 4) After the medium-temperature distribution is completed, the steel plate sample is taken out from the medium-temperature molten salt furnace 2 by using a cantilever crane 6, and is placed in a heating water tank 3, and the molten salt is cleaned by 80° C. hot water, and the temperature of the steel plate sample is further reduced.

[0068] During the test, the whole process control and full cycle monitoring are realized through the control system; the main controller of the control system is an industrial computer, and a control cabinet 7 and an operation cabinet 8 are set; the control cabinet 7 is used to monitor the low-temperature molten salt furnace 1, the medium-temperature molten salt furnace 2, the heating water tank 3 and the spray chamber 5, including molten salt temperature monitoring, steel plate sample temperature monitoring, each process time monitoring, molten salt state monitoring and drawing temperature curves; the operation cabinet 8 is used to control the operation of the sample clamping and moving device 4, the high-temperature and high-pressure air supply system and the cantilever crane 6; the spray chamber 5 recovers the molten salt liquid and returns it to the low-temperature molten salt furnace 1 to realize the recycling of the molten salt; the control system also has over-temperature alarm and safety protection functions. When the molten salt temperature, equipment current and voltage are abnormal, the control system will alarm and automatically shut down the power supply when the process parameters exceed the set values. At the same time as the sound and light alarm, the alarm information and equipment failure status are displayed on the computer display.

[0069] This embodiment obtains various experimental parameters and temperature curves through salt bath quenching and partitioning heat treatment tests on medium and thick plates, and successfully and efficiently completes the salt bath Q&P spray quenching + immersion partitioning heat treatment test, providing reliable test data for achieving high performance of steel.

[0070] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A salt bath quenching and partitioning heat treatment test system for medium and thick plates, characterized in that: It includes a low-temperature molten salt furnace, a medium-temperature molten salt furnace, a heating water tank, a spray chamber, a high-temperature and high-pressure air supply system, a sample clamping and moving device, a cantilever crane and a control system; the low-temperature molten salt furnace is provided with a molten salt low-temperature heater and a molten salt pump; the medium-temperature molten salt furnace is provided with a molten salt medium-temperature heater; the heating water tank is provided with a water heater; the spray chamber is provided with a spray device, and the spray device consists of an upper spray assembly and a lower spray assembly arranged relatively; a gas-liquid mixer is provided at the spray medium inlet end of the spray device, the liquid inlet of the gas-liquid mixer is connected to the molten salt liquid outlet of the molten salt pump, and the gas inlet of the gas-liquid mixer is connected to the high-temperature and high-pressure air outlet of the high-temperature and high-pressure air supply system; the sample clamping and moving device includes a translation mechanism, a flipping mechanism and a sample clamping mechanism, the sample clamping mechanism consists of a clamping frame and a connecting shaft, one end of the connecting shaft is connected to the clamping frame located in the spray chamber, and the other end of the connecting shaft extends out of the spray chamber and is connected to the translation mechanism through the flipping mechanism; The steel plate sample is fixed on the clamping frame. Under the action of the translation mechanism, the steel plate sample can move longitudinally along the spray chamber and can be turned over in the space between the upper spray assembly and the lower spray assembly; the low-temperature molten salt furnace, medium-temperature molten salt furnace, heating water tank, spray chamber, high-temperature and high-pressure air supply system and sample clamping moving device are all arranged within the lifting range of the cantilever crane; the molten salt low-temperature heater, molten salt pump, molten salt medium-temperature heater, water heater, spray device, high-temperature and high-pressure air supply system, sample clamping moving device and the control end of the cantilever crane are respectively connected to the control system.

2. A medium and thick plate salt bath quenching partition heat treatment test system according to claim 1, characterized in that: The high-temperature and high-pressure air supply system consists of an air compressor, an air storage tank, a refrigerated dryer and an air heating furnace which are connected in sequence through pipelines. The high-temperature and high-pressure air outlet of the air heating furnace is connected to the gas inlet of the gas-liquid mixer through a high-temperature and high-pressure air pipeline.

3. The medium and thick plate salt bath quenching partition heat treatment test system according to claim 1, characterized in that: The translation mechanism includes a translation motor and a linear guide; the flip mechanism includes a rotation motor and a gearbox; the gearbox is slidably connected to the linear guide through a slider; a translation motor is arranged at one end of the linear guide, and the gearbox can move along the linear guide under the drive of the translation motor; a rotation motor is arranged at one end of the gearbox, and the rotation motor is connected to a connecting shaft in the sample clamping mechanism through a speed change mechanism in the gearbox.

4. The medium and thick plate salt bath quenching partition heat treatment test system according to claim 1, characterized in that: The low-temperature molten salt furnace comprises a low-temperature molten salt furnace body and a low-temperature molten salt furnace inner chamber. The low-temperature molten salt furnace inner chamber is arranged in the low-temperature molten salt furnace body and is used to place molten salt. The inlet of the molten salt pump is arranged below the molten salt material surface. The fixed end of the molten salt low-temperature heater is fixedly connected to the low-temperature molten salt furnace body through a flange, and the heating end extends into the low-temperature molten salt furnace inner chamber.

5. The medium and thick plate salt bath quenching partition heat treatment test system according to claim 1, characterized in that: The medium-temperature molten salt furnace comprises a medium-temperature molten salt furnace body and a medium-temperature molten salt furnace inner chamber, the medium-temperature molten salt furnace inner chamber is placed in the medium-temperature molten salt furnace body, and the medium-temperature molten salt furnace inner chamber is used to place molten salt; the fixed end of the molten salt medium-temperature heater is fixedly connected to the medium-temperature molten salt furnace body through a flange, and the heating end extends into the medium-temperature molten salt furnace inner chamber; the top of the medium-temperature molten salt furnace body is closed by an upper cover plate of the medium-temperature molten salt furnace, and the upper cover plate of the medium-temperature molten salt furnace is a flap structure, which is rotatably connected to the medium-temperature molten salt furnace body through an upper cover plate flipping mechanism, and is flipped under the action of an upper cover plate hydraulic drive device.

6. The medium and thick plate salt bath quenching partition heat treatment test system according to claim 1, characterized in that: The heating water tank includes a heating water tank body and a heating water tank inner chamber, which is placed in the heating water tank body and is used to hold water; the fixed end of the water heater is fixedly connected to the heating water tank body through a flange, and the heating end extends into the heating water tank inner chamber; the top of the heating water tank body is closed by an upper cover plate of the heating water tank, and the upper cover plate of the heating water tank is a flap structure, which is rotatably connected to the heating water tank body through an upper cover plate flipping mechanism 2, and is flipped under the action of an upper cover plate hydraulic drive device 2.

7. The medium and thick plate salt bath quenching partition heat treatment test system according to claim 1, characterized in that: The control system has the functions of temperature monitoring, time monitoring, molten salt liquid state monitoring and temperature curve drawing.

8. A test method for salt bath quenching and partitioning heat treatment of medium and thick plates, characterized in that: Based on the medium and thick plate salt bath quenching and partitioning heat treatment test system as described in any one of claims 1 to 7; the specific process is as follows: 1) In the low-temperature molten salt furnace, the molten salt for spraying is heated to 150-300°C, and then the heated molten salt liquid is pumped out by the molten salt pump and sent to the spray chamber; at the same time, the air compressed by the air compressor and stored in the air tank is dried by the refrigerated dryer and heated by the air heater to form high-temperature and high-pressure air, which is also sent to the spray chamber; 2) In the spray chamber, the steel plate sample with an initial temperature of 800-1000°C is sent to the spray device through the sample clamping and moving device, and is located between the upper spray assembly and the lower spray assembly; the high-temperature and high-pressure air and the molten salt liquid are fully mixed by the gas-liquid mixing device as the spray medium, and the spray medium is sprayed from the multiple nozzles of the upper spray assembly and the multiple nozzles of the lower spray assembly at the same time to spray and cool the steel plate sample; during the spraying process, the uniformity of the spray cooling is ensured by the translation and flipping of the steel plate sample; the spraying is stopped after the steel plate sample drops to 200-300°C; 3) The steel plate sample is removed from the spray chamber and taken out from the sample clamping and moving device, and then the steel plate sample is placed in a medium-temperature molten salt furnace through a cantilever crane; the molten salt in the medium-temperature molten salt furnace has been preheated to 300-500°C, and the steel plate sample is medium-temperature distributed using the medium-temperature molten salt in the medium-temperature molten salt furnace; 4) After the medium-temperature distribution is completed, the steel plate sample is taken out from the medium-temperature molten salt furnace by a cantilever crane and placed in a heating water tank. The molten salt is cleaned by 70-100°C hot water, and the temperature of the steel plate sample is further reduced.

9. A salt bath quenching partitioning heat treatment test method for medium and thick plates according to claim 8, characterized in that: During the test, the control system realizes full process control and full cycle monitoring. The main controller of the control system is an industrial computer, and a control cabinet and an operating cabinet are set up. The control cabinet is used to monitor the low-temperature molten salt furnace, the medium-temperature molten salt furnace, the heating water tank and the spray chamber, including molten salt temperature monitoring, steel plate sample temperature monitoring, each process time monitoring, molten salt status monitoring and drawing temperature curves. The operating cabinet is used to control the operation of the sample clamping and moving device, the high-temperature and high-pressure air supply system and the cantilever crane. The spray chamber recovers the molten salt liquid and returns it to the low-temperature molten salt furnace to realize the recycling of molten salt. The control system also has over-temperature alarm and safety protection functions. When the molten salt temperature, equipment current and voltage are abnormal, the control system will alarm and automatically shut down the power supply when the process parameters exceed the set values. At the same time as the sound and light alarm, the alarm information and equipment failure status will be displayed on the computer display.

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