Simulation device and simulation method for continuous casting shell solidification process

Abstract

The invention relates to the technical field of ferrous metallurgy continuous casting processes, in particular to a simulation device and a simulation method for a continuous casting blank shell solidification process, the simulation device comprises a refractory material barrel, a steel grade casting blank, a cooling assembly, a movable heating assembly and a temperature sensing assembly, the steel grade casting blank is embedded in the refractory material barrel, and the temperature sensing assembly is arranged in the refractory material barrel. The cooling assembly is arranged at a barrel opening of the refractory material barrel, the cooling assembly is used for cooling the outer end of the steel grade casting blank, the cooling speed is adjustable, and the movable heating assembly is used for movably heating different positions of the steel grade casting blank. And the temperature sensing assembly is used for detecting the temperatures of different positions of the steel grade casting blank. According to the simulation device and method, for specific steel types, a method for strictly controlling the temperature and the cooling speed in the blank shell process is adopted, accurate simulation of the phase change of the solidification structure of the blank shell can be achieved, and the problems that under existing conditions, blank shell phase change simulation is poor in accuracy and the technology is complex are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of continuous casting technology for iron and steel metallurgy, and in particular to a simulation device and a simulation method for a continuous casting billet shell solidification process. Background Art

[0002] Continuous casting is to continuously pour high-temperature molten steel into one or several copper mold crystallizers with forced water cooling and ingot guides. The molten steel quickly condenses with the ingot guide rods. After the molten steel solidifies into a shell of a certain thickness, it is slowly pulled out from the lower end of the crystallizer. With the vibration demoulding of the crystallizer, under the traction of the lower ingot guide rods, the ingot with a certain shell thickness will be continuously pulled out of the water-cooled crystallizer, and continue to spray water in the second cooling zone of the casting machine, cooling and solidifying while walking. After the ingot is completely solidified, it is cut into billets of a certain size by flame cutting or shearing machines. This process of pouring high-temperature molten steel into billets is called continuous casting.

[0003] During the continuous solidification process of the ingot, the temperature of the ingot shell gradually decreases. The initial temperature of the just solidified ingot shell is 1400-1500℃. After gradual cooling, it gradually decreases to about 600-800℃ at the outlet of the casting machine. The temperature drop of the ingot shell is accompanied by the phase change of the solidification structure. With the change of the structure, the general law of the solid phase change of steel is as follows: Figure 1 For example, steel with a C content of 0.5% will experience a high temperature phase transition of L 液相 —L 液相 +δ 铁素体 —A 奥氏体 —A 奥氏体 +F 铁素体 —F 铁素体 +P 珠光体 During the phase change process, if the water distribution, pulling speed, straightening temperature and other process controls during the continuous casting process are not properly implemented, various surface defects such as transverse cracks, longitudinal cracks and corner cracks will occur. These defects will affect the yield of the ingot at the mildest level, and will cause the shell to rupture and the casting machine to shut down, resulting in huge losses. Therefore, metallurgical engineers and casting machine designers usually use the method of organizational phase change simulation to understand the phase change law of the solidification organization of a specific type of steel, formulate corresponding process measures, and prevent defects.

[0004] Simulating the continuous casting production process and analyzing the phase change of the solidification structure of steel under different process conditions have become the most direct methods for studying the continuous casting process of various steels. At present, there are two main methods for simulating the continuous casting production process: (1) using numerical simulation methods and computer simulation to study the phase change and temperature field changes of the solidification heat transfer process of the continuous casting billet. (2) using the small-scale continuous casting method, that is, according to the composition of the variety of steel, smelting is carried out, using a small-scale continuous casting machine, matching the appropriate casting process, including pulling speed, superheat, secondary cooling water, crystallizer vibration, etc., to cast into small-sized billets, and then dissecting the billets to analyze the grain structure of the billets in different areas, so as to determine the billet structure of each section of the continuous casting process, and finally obtain the organizational phase change process of the billet in the crystallizer. Problems with the existing technology:

[0005] (1) Problems in numerical simulation: ① The actual continuous casting production process is affected by various factors such as steel type, test conditions, and operating process. Its heat transfer, cooling, and solidification processes are complex and difficult to simulate accurately; ② Accurate numerical simulation requires appropriate boundary conditions, but the selection of boundary conditions is relatively empirical and requires high technical requirements;

[0006] (2) Problems with small-scale continuous casting simulation: ① A small-scale casting machine is equivalent to a large-scale casting machine with a certain reduction in size to achieve miniaturization. Its equipment is complex and the scale is still large. It can only be implemented under pilot conditions and cannot be fully realized in the laboratory. The equipment investment is high, and it requires the cooperation of multiple people when starting up, and the operation is complicated. ② The process of dissecting the ingot is labor-intensive, complex, time-consuming, and inefficient. ③ It is impossible to observe the phase change of the solidification process in a timely manner. It is difficult to use the rapid solidification method to maintain the microstructure of the ingot in this section. The authenticity of the microstructure obtained by dissection needs to be further improved. Summary of the invention

[0007] The present invention aims at the problem that the shell of a continuous casting steel sheet undergoes phase changes with temperature, which easily causes surface defects, and the existing simulation methods are complicated. A simulation device and a simulation method for simulating the phase change of a continuous casting shell sheet solidification process are proposed. The simulation device and method are targeted at specific steel grades and adopt a method of strictly controlling the temperature and cooling rate of the shell sheet process to achieve accurate simulation of the solidification structure phase change of the shell sheet, effectively solving the problems of poor accuracy and complex process of shell sheet phase change simulation under existing conditions.

[0008] The present invention provides a simulation device for the solidification process of a continuous casting billet shell, the simulation device comprises a refractory barrel, a steel billet, a cooling component, a movable heating component and a temperature sensing component, the steel billet is embedded in the refractory barrel, the cooling component is arranged at the barrel mouth of the refractory barrel, the cooling component is used to cool the outer end of the steel billet and the cooling speed is adjustable, the movable heating component is used to move and heat different positions of the steel billet, and the temperature sensing component is used to detect the temperature at different positions of the steel billet.

[0009] As a further optimization scheme of the present invention, the outer diameter of the steel ingot is the same as the inner diameter of the refractory barrel, and the outer end surface of the steel ingot is flush with the barrel mouth of the refractory barrel.

[0010] As a further optimization solution of the present invention, the steel ingot and the refractory barrel are both cylindrical in shape.

[0011] As a further optimization scheme of the present invention, the cooling assembly includes a cooling block, a water flow channel formed inside the cooling block, and a water supply assembly. The cooling block is arranged close to the barrel mouth of the refractory barrel and is in direct contact with the outer end surface of the steel ingot. The water supply assembly is used to regulate the water volume and flow rate of the cooling water inside the cooling block.

[0012] As a further optimization solution of the present invention, the cooling block is made of copper.

[0013] As a further optimization scheme of the present invention, the movable heating assembly includes an induction heating coil and a displacement mechanism, the induction heating coil is sleeved on the refractory barrel, and the displacement mechanism is used to move the induction heating coil along the length direction of the steel ingot.

[0014] As a further optimization scheme of the present invention, the height of the induction heating coil is 1 / 8-1 / 7 of the length of the steel ingot.

[0015] As a further optimization solution of the present invention, the temperature sensing component includes a plurality of temperature-sensing thermocouples, and the plurality of temperature-sensing thermocouples are disposed on the inner wall of the refractory barrel and are arranged at intervals along the length direction thereof.

[0016] The present invention also provides a method for simulating the solidification process of a continuous casting billet shell. Using the simulation system for the solidification process of a continuous casting billet shell, the simulation method comprises:

[0017] Step 1: placing the steel ingot in a refractory barrel with a temperature sensing component, closing the barrel opening of the refractory barrel with a cooling component, and moving the movable heating component to the vicinity of the barrel opening;

[0018] Step 2: The internal structure of the steel ingot inside the refractory barrel is completely austenitized by the induction heating coil of the movable heating component, the induction heating power is kept constant, and the set heating temperature of the area is ensured to be consistent with the temperature detected by the temperature sensing component, and then the induction heating coil is slowly moved to the far end of the refractory barrel at a set moving speed until the internal structure of the steel ingot is completely austenitized in the entire section;

[0019] Step 3: When the temperature of the steel ingot near the barrel mouth reaches the set heating temperature, start the cooling component to perform heat transfer cooling, so that the entire steel ingot is gradually cooled by unidirectional heat transfer until it drops to room temperature, so that the cooling conditions of the steel ingot are similar to those of the actual continuous casting shell, thereby simulating the solidification structure of the second cooling zone of the continuous casting shell.

[0020] As a further optimization scheme of the present invention, in step 1, the induction heating coil is moved to 5mm-10mm close to one side of the barrel mouth.

[0021] As a further optimization scheme of the present invention, in step 2, the set heating temperature of the movable heating component is 1400° C., and the moving speed is 10-50 mm / min.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] (1) The temperature sensing component monitors the temperature of different positions of the steel ingot in real time to ensure the temperature control accuracy during heating and cooling, and can accurately simulate the phase change process of the ingot shell at different temperatures. The cooling component can adjust the cooling speed as needed to simulate the cooling conditions in the actual continuous casting process, which is helpful to study the effect of different cooling speeds on the quality of the ingot shell.

[0024] (2) Compared with the existing small-scale continuous casting simulation method, the simulation device used in the present invention is simpler and smaller in size, does not require large equipment support, and can complete the simulation experiment in a laboratory environment, reducing the equipment investment cost. The device is easy to operate and does not require the cooperation of multiple people, which reduces labor costs, simplifies the experimental process, reduces the time and resource consumption required for the experiment, and improves the experimental efficiency.

[0025] (3) The copper cooling block is used as a forced cooling wall for contact heat exchange. The heat exchange intensity is adjusted by adjusting the water volume. The steel sample is placed in a refractory barrel so that it is in an adiabatic state in other directions. The end in contact with the copper cooling block forms a unidirectional solidification state. The cooling process of the steel sample is accurately controlled under the conditions of timely monitoring of the temperature-sensing thermocouple and water volume control of the cooling speed, which can realize the accurate simulation of the solidification structure phase change of the billet shell, effectively solving the problems of poor accuracy of the billet shell phase change simulation and complex process.

[0026] (4) By moving the induction heating coil along the length of the steel ingot through the displacement mechanism, different parts of the ingot shell can be heated in a targeted manner, which enhances the flexibility of the simulation device. The cooling speed can be adjusted according to the experimental needs to adapt to different steel grades and process conditions.

[0027] (5) The simulation device can simulate the solidification process of the billet shell in the actual continuous casting process more realistically, which helps metallurgical engineers and casting machine designers to better understand the causes of billet shell defects and thus formulate corresponding process measures to prevent these defects.

[0028] (6) By accurately simulating the solidification structure phase transformation process of the billet shell, the surface defects of the billet shell in actual production can be effectively reduced, the yield of the billet can be improved, and downtime and production losses can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a diagram of the solid-state phase transformation of steel.

[0030] Figure 2 It is a schematic structural diagram of a simulation device for the continuous casting slab shell solidification process of the present invention.

[0031] Figure 3 This is a comparison chart of the results obtained by using the solidification process simulation method of the present invention and the results obtained in actual production, where: Figure 3 In the figure, a is a result diagram obtained by simulating the solidification process using the method of the present invention, and b is a result diagram obtained by actual production.

[0032] In the figure: 1. refractory barrel, 2. steel ingot, 3. cooling assembly, 301. cooling block, 302. water flow channel, 4. movable heating assembly, 401. induction heating coil, 5. temperature sensing assembly, 501. temperature sensing thermocouple. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred implementation scheme of the present invention is described below in conjunction with specific embodiments. However, it should be understood that the drawings are only used for exemplary description and cannot be understood as a limitation on this patent. In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationship described in the drawings is only for exemplary description and cannot be understood as a limitation on this patent.

[0034] The following is combined with Figure 2-3 The present invention is further described in detail, and a simulation device and a simulation method for the continuous casting billet shell solidification process are explained.

[0035] Example 1

[0036] like Figure 2 As shown, this embodiment provides a simulation device for the continuous casting billet shell solidification process, including the following main components: a refractory material barrel 1, a steel billet 2, a cooling component 3, a movable heating component 4 and a temperature sensing component 5.

[0037] The refractory barrel 1 is used to contain the steel ingot 2 and ensure good insulation during heating and cooling. The refractory barrel 1 is preferably cylindrical, and its inner diameter should be the same as the outer diameter of the steel ingot 2 to ensure that the steel ingot 2 can be tightly embedded therein. The barrel mouth should be flush with the outer end surface of the steel ingot 2 to ensure that the cooling assembly 3 can closely contact the steel ingot 2.

[0038] The steel ingot 2 is made of a specific steel type, and its shape matches the refractory barrel 1 and is also cylindrical. The length of the steel ingot 2 can be adjusted according to experimental needs.

[0039] The cooling assembly 3 includes a cooling block 301, an internal water flow channel 302, and a water supply assembly. The cooling block 301 is arranged close to the barrel mouth of the refractory barrel 1 and is in direct contact with the outer end surface of the steel type ingot 2 to achieve efficient heat conduction. Heat conduction enters the cooling block 301, and cooling water is passed through the water channel, and the heat is continuously taken away, simulating the heat exchange process of the ingot two cold waters. The water supply assembly is used to adjust the water volume and flow rate of the cooling water inside the cooling block 301 to control the cooling speed, and different cooling conditions can be simulated. The cooling block 301 preferably uses a copper material with good thermal conductivity to ensure efficient heat transfer. The water supply assembly should have a fine adjustment function so that the cooling speed can be adjusted according to the requirements of different steel types. The water supply assembly usually includes components such as a water pump, a valve, and a flow meter. The amount of water entering the cooling block 301 is controlled by adjusting the valve opening on the water supply pipeline. The larger the valve opening, the larger the water volume and the faster the cooling speed. The speed of the water flow can be changed by adjusting the speed of the water pump. The higher the speed, the larger the water volume and the faster the cooling speed. Install a flow meter to monitor the actual water volume and ensure the accuracy of water volume regulation. The flow meter can be mechanical or electronic and can display instantaneous flow and cumulative flow.

[0040] The movable heating assembly 4 includes an induction heating coil 401 and a displacement mechanism. The induction heating coil 401 is sleeved on the refractory barrel 1, and the height of the coil is between 1 / 8 and 1 / 7 of the length of the ingot. This design can ensure that only a portion of the steel ingot 2 is heated each time. The height direction of the coil is consistent with the translation direction of the coil, that is, Figure 2 The displacement mechanism is used to translate the induction heating coil 401 along the length direction of the billet, from the barrel mouth to the barrel bottom, so as to heat different positions of the billet to simulate the change of temperature gradient from the surface to the inside of the steel billet 2 under different working conditions, which can better simulate the actual cooling process of the steel billet 2. The heating power of the induction heating coil 401 should be adjustable to meet the heating requirements of different steel grades. The displacement mechanism should have sufficient precision to ensure the accuracy of the heating position, and its specific structure can be selected conventionally in the field.

[0041] The temperature sensing assembly 5 is composed of a plurality of temperature sensing thermocouples 501, which are evenly distributed along the inner wall of the refractory barrel 1 and arranged at intervals along the length direction of the steel type ingot 2. Each thermocouple is connected to an external data acquisition system for real-time monitoring of the temperature at different positions of the steel type ingot 2. The layout of the temperature sensing thermocouples 501 should be optimized according to the length and diameter of the ingot to ensure that the temperature change of the ingot can be fully monitored.

[0042] Example 2

[0043] The steel type 2 casting billet is forced to cool from the crystallizer to the second cooling section. The liquid core continuous casting billet is moving downward, transferring heat, and solidifying until it is completely solidified out of the casting machine. Furthermore, a simulation method using the above-mentioned simulation device for the continuous casting billet shell solidification process is introduced. The method simulates the continuous casting process and adopts a method of strictly controlling the temperature and cooling rate of the billet shell process to achieve an accurate simulation of the phase change of the solidification structure of the billet shell. The specific steps are as follows:

[0044] Preparation stage: first, place the steel ingot 2 into the refractory barrel 1 and ensure that the ingot is in close contact with the barrel wall, then install the cooling block 301 at the barrel mouth of the refractory barrel 1, and move the induction heating coil 401 to 5mm-10mm on one side of the barrel mouth through the displacement mechanism.

[0045] Heating stage: Start the induction heating coil 401 to heat the steel ingot 2 in the refractory barrel 1, set the heating temperature to 1400°C, and monitor the temperature of the steel ingot 2 through the temperature-sensing thermocouple 501. Once the first section of the steel ingot 2 reaches the set temperature, the induction heating coil 401 is moved to the far end of the refractory barrel 1 (i.e., the bottom end of the barrel) at a certain moving speed through the displacement mechanism until the entire length of the steel ingot 2 is heated.

[0046] Cooling stage: When the first section of steel ingot 2 reaches the set heating temperature, it is cooled by the cooling component 3. The cooling speed is controlled by adjusting the flow rate of cooling water to simulate the cooling conditions in the actual continuous casting process. With the heat transfer effect of the cooling component 3, the steel ingot 2 is gradually cooled, simulating the solidification process of the continuous casting shell in the second cooling zone. In this way, a small ingot sample is formed with the barrel cold end as the surface layer of the ingot and the hot end as the internal structure of the ingot. After the ingot sample is cut and dissected, the structural organization of the ingot with different thicknesses from the surface to the core is obtained.

[0047] Example 3

[0048] The test simulates the solidification structure of high manganese steel, with a manganese content of 10%-15%, a carbon content of 0.8%-1.0%, and a silicon content of 0.4%-0.6%. The steel with this composition is cut into The sample with a length of 115mm is placed in a refractory barrel. The copper cooling block is moved to one end of the refractory barrel to contact the steel sample and close the refractory barrel. The induction coil is moved to 5mm-10mm close to one side of the cooling wall and powered on for heating. When the temperature of the lower temperature sensor reaches 1400℃, the induction heating power is kept unchanged and the induction coil is slowly moved to the other end at a speed of 25mm / min. It is then cooled with the metal block. During the process, water is ensured to flow through the copper cooling block until it drops to room temperature. The metal block is taken out and dissected from the middle. Figure 3 As shown, the results show that the macrostructure of the ingot obtained in actual production (equiaxed crystal ratio of 43%) is basically consistent with the macrostructure obtained by simulation of the present invention (equiaxed crystal ratio of 45%), and the equiaxed crystal ratio is 40%-45%.

[0049] In summary, the simulation device and method of the present invention can effectively solve the problems of poor accuracy and complex process of slab shell phase change simulation, which helps to improve the quality of continuous casting slab shell and reduce defects in the production process.

[0050] According to the description and drawings of the present invention, those skilled in the art can easily manufacture or use the simulation device and simulation method of the continuous casting shell solidification process of the present invention, and can produce the positive effects recorded in the present invention.

[0051] The above is only a preferred embodiment of the present invention, but the present invention is not limited to the above specific embodiments. Those skilled in the art may make some modifications, supplements or use similar methods instead without departing from the principle of the present invention, which should also be regarded as the protection scope of the present invention.

Claims

1. A simulation device for the solidification process of a continuous casting shell, characterized in that: The simulation device comprises a refractory barrel (1), a steel ingot (2), a cooling component (3), a movable heating component (4) and a temperature sensing component (5); the steel ingot (2) is embedded in the refractory barrel (1); the cooling component (3) is arranged at the barrel mouth of the refractory barrel (1); the cooling component (3) is used to cool the outer end of the steel ingot (2) and the cooling speed is adjustable; the movable heating component (4) is used to move and heat different positions of the steel ingot (2); and the temperature sensing component (5) is used to detect the temperature at different positions of the steel ingot (2).

2. The device for simulating the solidification process of the continuous casting shell according to claim 1, characterized in that: The outer diameter of the steel ingot (2) is the same as the inner diameter of the refractory barrel (1), and the outer end surface of the steel ingot (2) is flush with the barrel mouth of the refractory barrel (1).

3. The device for simulating the solidification process of the continuous casting shell according to claim 2, characterized in that: The steel ingot (2) and the refractory barrel (1) are both cylindrical in shape.

4. The device for simulating the solidification process of continuous casting shell according to claim 1, characterized in that: The cooling assembly (3) comprises a cooling block (301), a water flow channel (302) formed inside the cooling block (301), and a water supply assembly. The cooling block (301) is arranged in close contact with the barrel mouth of the refractory barrel (1) and is in direct contact with the outer end surface of the steel ingot (2). The water supply assembly is used to regulate the water volume and flow rate of the cooling water inside the cooling block (301).

5. The device for simulating the solidification process of continuous casting shell according to claim 1, characterized in that: The movable heating component (4) comprises an induction heating coil (401) and a displacement mechanism, wherein the induction heating coil (401) is sleeved on the refractory barrel (1), and the displacement mechanism is used to move the induction heating coil (401) along the length direction of the steel ingot (2).

6. The device for simulating the solidification process of the continuous casting shell according to claim 5, characterized in that: The height of the induction heating coil (401) is 1 / 8-1 / 7 of the length of the steel ingot (2).

7. The device for simulating the solidification process of the continuous casting shell according to claim 1, characterized in that: The temperature sensing component (5) comprises a plurality of temperature sensing thermocouples (501), and the plurality of temperature sensing thermocouples (501) are arranged on the inner wall of the refractory barrel (1) and are spaced apart along the length direction thereof.

8. A method for simulating the solidification process of a continuous casting shell, characterized in that: Using the simulation system for the continuous casting shell solidification process according to any one of claims 1 to 7, the simulation method comprises: Step 1: placing a steel ingot (2) in a refractory barrel (1) with a temperature sensing component (5), using a cooling component (3) to seal the barrel opening of the refractory barrel (1), and moving a movable heating component (4) to the vicinity of the barrel opening; Step 2: The induction heating coil (401) of the movable heating component (4) is used to completely austenitize the internal metal structure of the steel ingot (2) inside the refractory barrel (1), the induction heating power is kept constant, and it is ensured that the set heating temperature of the area is consistent with the temperature detected by the temperature sensing component (5), and then the induction heating coil (401) is slowly moved at a set moving speed to the far end of the refractory barrel (1) until the internal metal structure of the entire section of the steel ingot (2) is completely austenitized; Step 3: When the temperature of the steel ingot (2) near the barrel mouth reaches the set heating temperature, the cooling component (3) is started to perform heat transfer cooling, so that the entire steel ingot (2) is gradually cooled by unidirectional heat transfer until it drops to room temperature, so that the cooling conditions of the steel ingot (2) are similar to those of the actual continuous casting shell, thereby simulating the solidification structure of the second cooling zone of the continuous casting shell.

9. The method for simulating the solidification process of the continuous casting shell according to claim 8, characterized in that: In step 1, the induction heating coil (401) is moved to a position 5 mm to 10 mm close to the side of the barrel mouth.

10. The method for simulating the solidification process of the continuous casting shell according to claim 8, characterized in that: In step 2, the set heating temperature of the movable heating component (4) is 1400° C., and the moving speed is 10-50 mm / min.

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