A method for preparing rare earth alloy steel material

Abstract

The present invention relates to the technical field of material preparation, and in particular to a method for preparing a rare earth alloy steel material, comprising: S1, sampling a molten rare earth alloy steel liquid after high-temperature melting and mixing, and performing fluidity detection; S2, classifying the splitting tendency of the molten rare earth alloy steel liquid; S3, controlling the operation of a vacuum pump connected to a vacuum tank and various ventilation nozzles uniformly arranged at the bottom of the vacuum tank; S4, obtaining the refined molten rare earth alloy steel liquid, and improving the removal efficiency of bubbles included in the molten rare earth alloy steel liquid.

Description

Technical Field

[0001] The invention relates to the technical field of material preparation, and in particular to a method for preparing a rare earth alloy steel material. Background Art

[0002] Rare earth elements have high chemical activity and are easy to react with gas residues in molten alloy steel. Gas residues will reduce the mechanical properties of the material, such as strength, toughness, and fatigue life. Removing gas can reduce these defects and improve the corrosion resistance and oxidation resistance of the material. Therefore, it is very important to remove gas from molten rare earth alloy steel during the preparation of rare earth alloy steel materials.

[0003] Chinese patent publication number: CN111411372A, discloses a method for preparing a rare earth iron alloy, comprising: preparing a rare earth iron intermediate alloy by non-consumable cathode electrolysis; loading an electrolyte into an electrolytic cell, using a graphite carbon plate as an anode, a tungsten or molybdenum material as a cathode, and a crucible below the tungsten-molybdenum cathode as a receiver; in a rare earth fluoride and lithium fluoride molten salt electrolyte system, using rare earth oxide and iron as raw materials, passing direct current electrolysis, and collecting a rare earth iron intermediate alloy in the receiver; putting the rare earth iron intermediate alloy and iron as raw materials into a crucible, and further smelting the rare earth iron intermediate alloy by a melting method in a medium frequency induction furnace to obtain a rare earth iron alloy;

[0004] However, the prior art still has the following problems:

[0005] In the prior art, a vacuum degassing process is often used to release bubbles by reducing the ambient pressure, but gas residue is likely to occur. No consideration has been given to combining the bubble flotation process to introduce an inert gas that is not easy to react to float smaller bubbles through bubble flotation. In addition, in a vacuum environment, bubbles are easily precipitated, and due to the nature of the inert gas, it is not suitable to stay in the molten alloy steel liquid, and it is not easy to introduce new impurities.

[0006] Furthermore, in the prior art, it is not considered to determine the specific degassing process according to the specific conditions of the molten rare earth alloy steel liquid during the degassing process, which affects the removal efficiency of the bubbles included in the molten rare earth alloy steel liquid. Summary of the invention

[0007] To this end, the present invention provides a method for preparing a rare earth alloy steel material, which is used to overcome the problem that the prior art does not consider determining a specific degassing process according to the specific conditions of the molten rare earth alloy steel liquid during the degassing process, thereby affecting the removal efficiency of the bubbles included in the molten rare earth alloy steel liquid.

[0008] To achieve the above object, the present invention provides a method for preparing a rare earth alloy steel material, comprising:

[0009] S1, sampling the molten rare earth alloy steel liquid after high-temperature melting and mixing, and performing fluidity detection, including placing the molten rare earth alloy steel liquid in a container, tilting the container at a predetermined angle, and collecting the poured molten rare earth alloy steel liquid to analyze flow characteristic parameters;

[0010] S2, placing the molten rare earth alloy steel liquid into a vacuum tank, controlling the operation of each stirring mechanism in the vacuum tank, obtaining the viscous resistance of the molten rare earth alloy steel liquid through a resistance monitoring device arranged on the stirring mechanism, calculating the resistance characteristic characterization parameter for the molten rare earth alloy steel liquid in combination with the flow characteristic parameter, and classifying the splitting tendency category of the molten rare earth alloy steel liquid;

[0011] S3, according to the splitting tendency category of the molten rare earth alloy steel liquid, controlling the operation of a vacuum pump connected to the vacuum tank and each ventilation nozzle evenly arranged at the bottom of the vacuum tank, including:

[0012] According to the resistance characteristic characterization parameter, the ventilation time of the gas input by each ventilation nozzle is adjusted, and the operation of the vacuum pump is controlled to obtain the pressure value in the vacuum tank, determine the pressure fluctuation characterization parameter, and determine whether there is an abnormal fluctuation tendency, so as to adjust the vacuum pumping rate according to the pressure fluctuation characterization parameter;

[0013] Or, maintain the predetermined ventilation time to uniformly input gas into the vacuum tank;

[0014] S4, controlling the vacuum pump to evacuate the vacuum tank to obtain the refined molten rare earth alloy steel liquid.

[0015] Furthermore, in S1, the process of obtaining flow characteristic parameters is:

[0016] The weight of the molten rare earth alloy steel liquid poured out within a predetermined pouring time is obtained to obtain flow characteristic parameters.

[0017] Furthermore, in S2, the resistance characteristic parameter is calculated by formula (1):

[0018] (1)

[0019] Where Z is the resistance characteristic parameter, N is the flow characteristic parameter, Y is the viscous resistance, N0 is the average value of the flow characteristic parameters of each molten rare earth alloy steel liquid in history, Y0 is the average value of the viscous resistance of each molten rare earth alloy steel liquid in history, α is the flow weight coefficient, and β is the viscosity weight coefficient.

[0020] Furthermore, in said S2, the splitting tendency categories of said molten rare earth alloy steel liquid are classified, including:

[0021] If the resistance characteristic characterization parameter is less than or equal to the preset resistance characteristic characterization parameter, the molten rare earth alloy steel liquid is determined to be a strong splitting tendency category;

[0022] If the resistance characteristic characterization parameter is greater than the preset resistance characteristic characterization parameter, the molten rare earth alloy steel liquid is determined to be a weak splitting tendency category.

[0023] Further, in S3, according to the splitting tendency category of the molten rare earth alloy steel liquid, the vacuum pump connected to the vacuum tank and the ventilation nozzles evenly arranged at the bottom of the vacuum tank are controlled to operate, including:

[0024] If the molten rare earth alloy steel liquid is of a type with a strong tendency to split, the gas is uniformly input into the vacuum tank for a predetermined ventilation time;

[0025] If the molten rare earth alloy steel liquid is of the weak splitting tendency category, the ventilation duration of the gas input into each ventilation nozzle is adjusted according to the resistance characteristic characterization parameter, and the operation of the vacuum pump is controlled. The pressure fluctuation characterization parameter is determined by a vacuum gauge arranged in the vacuum tank to determine whether there is an abnormal fluctuation tendency, so as to adjust the vacuum pump suction rate according to the pressure fluctuation characterization parameter.

[0026] Furthermore, the ventilation duration of the gas input by each ventilation nozzle is adjusted according to the resistance characteristic parameter, wherein:

[0027] The resistance characteristic parameters are positively correlated with ventilation duration.

[0028] Further, in S3, the process of determining the pressure fluctuation characterization parameter by a vacuum gauge disposed in the vacuum tank includes:

[0029] Draw a pressure time domain curve based on the pressure obtained by the vacuum gauge;

[0030] Draw a slope time domain curve based on the slope of the pressure time domain curve segment corresponding to the specific time interval;

[0031] The interval duration between each inflection point in the slope time domain curve is obtained to calculate the variance of each interval duration and obtain the pressure fluctuation characterization parameter.

[0032] Furthermore, the process of obtaining the specific time interval includes:

[0033] Obtaining a time node in the pressure time domain curve where the slope is less than or equal to a preset slope;

[0034] A predetermined time interval after the time node is determined as a specific time interval.

[0035] Furthermore, judging whether there is an abnormal fluctuation tendency based on the pressure fluctuation characterization parameter includes:

[0036] If the pressure fluctuation characterization parameter is less than or equal to the preset pressure fluctuation characterization parameter, the vacuum pump is controlled to continuously use the predetermined pumping rate to complete the vacuum treatment of the molten rare earth alloy steel liquid;

[0037] If the pressure fluctuation characterization parameter is greater than the preset pressure fluctuation characterization parameter, the pumping rate of the vacuum pump is adjusted according to the pressure fluctuation characterization parameter.

[0038] Furthermore, in S3, the pumping rate of the vacuum pump is adjusted according to the pressure fluctuation characterization parameter, wherein:

[0039] The pressure fluctuation characterization parameter is negatively correlated with the vacuum pump's pumping rate.

[0040] Compared with the prior art, the beneficial effect of the present invention lies in that the present invention analyzes the sampled molten rare earth alloy steel liquid to determine the specific flow characteristic parameters and viscous resistance of the molten rare earth alloy steel liquid, and determines the method of removing the included bubbles according to the determined specific parameters. In actual situations, the molten rare earth alloy steel liquid has tiny included bubbles that cannot be discharged only by vacuum treatment; by setting a plurality of nozzles, large bubbles are blown into the molten rare earth alloy steel liquid to push out the included tiny bubbles, so as to fully remove the included bubbles; the splitting tendency category of the molten rare earth alloy steel liquid is divided according to the calculated resistance characteristic characterization parameters to determine the specific degassing method. When it is determined to be a weak splitting tendency category, the molten rare earth alloy steel liquid is more viscous and has worse fluidity because of its The cohesive force between molecules is strong, and the resistance inside the molten rare earth alloy steel liquid affects the movement and deformation of bubbles, and is more likely to restrict tiny bubbles. In this case, the ventilation volume of each nozzle is determined in a targeted manner so that the large bubbles blown out by the nozzle can evenly push out the small bubbles included in the molten rare earth alloy steel liquid. During the bubble precipitation process, the vacuum gauge continuously monitors the pressure fluctuation in the vacuum tank to determine whether the bubbles are precipitated evenly, and adjusts the operating speed of the vacuum pump when the bubble precipitation fluctuation is large. The pressure shock inside the molten rare earth alloy steel liquid is reduced by slow pressure changes to reduce the rupture of bubbles during the precipitation process, so that the bubbles are precipitated stably, effectively improving the strength of the material, and further improving the removal efficiency of bubbles included in the molten rare earth alloy steel liquid.

[0041] Furthermore, the present invention calculates resistance characteristic characterization parameters based on flow characteristic parameters and viscous resistance. In actual situations, the difficulty of bubble precipitation is affected by the specific properties of the molten rare earth alloy steel liquid. When the viscous resistance of the liquid is high, the difficulty of bubble precipitation increases. The higher viscous resistance increases the friction between the bubble surface and the liquid, making it difficult for the bubbles to separate from the liquid. The fluidity of the molten rare earth alloy steel liquid will also affect the precipitation of bubbles. The fluidity characterizes the viscosity of the liquid. The more viscous the liquid, the more difficult it is for bubbles to precipitate. The viscosity of the molten rare earth alloy steel liquid is characterized by calculating the resistance characteristic characterization parameters, which provides data support for the subsequent classification of splitting tendency categories, facilitates the subsequent adaptive selection of corresponding bubble precipitation parameters to precipitate bubbles, and then timely adjusts the control parameters to reduce the influence of the viscosity of the molten rare earth alloy steel liquid on bubble precipitation, thereby improving the strength of the rare earth alloy steel material.

[0042] Furthermore, during the bubble precipitation process, the vacuum gauge continuously monitors the pressure fluctuation in the vacuum tank to determine whether the bubbles are uniformly precipitated, and the slope of the pressure-time domain curve segment corresponding to the specific time interval is obtained to draw a slope-time domain curve. In the specific time interval, a large number of bubbles are completely precipitated, and only a small number of bubbles are mixed in the molten rare earth alloy steel liquid. During the operation of the vacuum pump, the vacuum gauge in the vacuum tank measures a gentle decrease in pressure. When bubbles are precipitated, the pressure in the vacuum tank will rise or reduce the pressure reduction rate. After the bubble precipitation is completed, the pressure in the vacuum tank recovers to the reduction rate of the bubbles that have not been precipitated. The concentrated bubble precipitation time is determined by obtaining the inflection point of the slope-time domain curve, and the variance of the interval time between each inflection point is determined to determine the fluctuation of the bubble precipitation. When the bubble precipitation fluctuation is large, the operating rate of the vacuum pump is adjusted, and the pressure shock inside the molten rare earth alloy steel liquid is reduced by slow pressure changes, so as to reduce the rupture of bubbles during the precipitation process, so that the bubbles are stably precipitated, and the removal efficiency of the bubbles mixed in the molten rare earth alloy steel liquid is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a flow chart of the steps of the method for preparing the rare earth alloy steel material according to an embodiment of the present invention;

[0044] Figure 2 A logic decision diagram for classifying the splitting tendency categories of molten rare earth alloy steel according to an embodiment of the present invention;

[0045] Figure 3 A logic decision diagram for controlling the operation of a vacuum pump and each ventilation nozzle according to an embodiment of the present invention;

[0046] Figure 4 This is a logical decision diagram for determining whether there is an abnormal fluctuation tendency in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0049] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0050] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] See also Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, they are respectively a flow chart of the steps of the method for preparing a rare earth alloy steel material according to an embodiment of the present invention, a logic determination diagram for classifying the splitting tendency of the molten rare earth alloy steel liquid, a logic determination diagram for controlling the operation of the vacuum pump and each ventilation nozzle, and a logic determination diagram for determining whether there is an abnormal fluctuation tendency; a method for preparing a rare earth alloy steel material according to an embodiment of the present invention comprises:

[0052] S1, sampling the molten rare earth alloy steel liquid after high-temperature melting and mixing, and performing fluidity detection, including placing the molten rare earth alloy steel liquid in a container, tilting the container at a predetermined angle, and collecting the poured molten rare earth alloy steel liquid to analyze flow characteristic parameters;

[0053] S2, placing the molten rare earth alloy steel liquid into a vacuum tank, controlling the operation of each stirring mechanism in the vacuum tank, obtaining the viscous resistance of the molten rare earth alloy steel liquid through a resistance monitoring device arranged on the stirring mechanism, calculating the resistance characteristic characterization parameter for the molten rare earth alloy steel liquid in combination with the flow characteristic parameter, and classifying the splitting tendency category of the molten rare earth alloy steel liquid;

[0054] S3, according to the splitting tendency category of the molten rare earth alloy steel liquid, controlling the operation of a vacuum pump connected to the vacuum tank and each ventilation nozzle evenly arranged at the bottom of the vacuum tank, including:

[0055] According to the resistance characteristic characterization parameter, the ventilation time of the gas input by each ventilation nozzle is adjusted, and the operation of the vacuum pump is controlled to obtain the pressure value in the vacuum tank, determine the pressure fluctuation characterization parameter, and determine whether there is an abnormal fluctuation tendency, so as to adjust the vacuum pumping rate according to the pressure fluctuation characterization parameter;

[0056] Or, maintain the predetermined ventilation time to uniformly input gas into the vacuum tank;

[0057] S4, controlling the vacuum pump to evacuate the vacuum tank to obtain the refined molten rare earth alloy steel liquid.

[0058] Specifically, there is no limitation on the specific structure of the vacuum tank. The vacuum tank only needs to provide a storage space for molten rare earth alloy steel liquid. Commonly, the vacuum tank can be evacuated by a vacuum pump to achieve a vacuum effect in the storage space. This is a prior art and will not be elaborated herein.

[0059] Specifically, the process of determining the viscous resistance of the molten rare earth alloy steel liquid is not limited. A torque sensor can be set in the stirring mechanism to measure the torque borne by the stirring shaft during the stirring process. By measuring the torque, the stirring resistance can be indirectly calculated. It can be understood that the stirring resistance is the viscous resistance.

[0060] Set, Fr = / r Where Fr is the stirring resistance, is the torque, r is the radius of the stirring shaft, and will not be repeated here.

[0061] Specifically, the specific structure of the nozzle is not limited, and each nozzle is evenly arranged at the bottom of the vacuum tank. It can be understood that each nozzle can evenly introduce gas into the vacuum tank, and no further details are given.

[0062] It is understandable that the gas output from the nozzle should not react with the molten rare earth alloy steel liquid to avoid contaminating the molten rare earth alloy steel liquid.

[0063] Specifically, the present invention analyzes the sampled molten rare earth alloy steel liquid to determine the specific flow characteristic parameters and viscous resistance of the molten rare earth alloy steel liquid, and determines the method of removing the included bubbles according to the determined specific parameters. In actual situations, the molten rare earth alloy steel liquid has tiny included bubbles that cannot be discharged only by vacuum treatment; by setting a plurality of nozzles, large bubbles are blown into the molten rare earth alloy steel liquid to push out the included tiny bubbles, so as to fully remove the included bubbles; the splitting tendency category of the molten rare earth alloy steel liquid is divided according to the calculated resistance characteristic characterization parameters to determine the specific degassing method. When it is determined to be a weak splitting tendency category, the molten rare earth alloy steel liquid is more viscous and has worse fluidity because the cohesive force between its molecules The resistance inside the molten rare earth alloy steel liquid is relatively strong, which affects the movement and deformation of the bubbles and is more likely to restrict the tiny bubbles. In this case, the ventilation volume of each nozzle is determined in a targeted manner so that the large bubbles blown out by the nozzle can evenly push out the small bubbles mixed in the molten rare earth alloy steel liquid. During the bubble precipitation process, the vacuum gauge continuously monitors the pressure fluctuation in the vacuum tank to determine whether the bubbles are evenly precipitated. When the bubble precipitation fluctuation is large, the operating speed of the vacuum pump is adjusted to reduce the pressure shock inside the molten rare earth alloy steel liquid through slow pressure changes, so as to reduce the rupture of bubbles during the precipitation process, so that the bubbles can be precipitated stably, which effectively improves the strength of the material and further improves the removal efficiency of the bubbles mixed in the molten rare earth alloy steel liquid.

[0064] Specifically, in S1, the process of obtaining flow characteristic parameters is:

[0065] The weight of the molten rare earth alloy steel liquid poured out within a predetermined pouring time is obtained to obtain flow characteristic parameters.

[0066] Specifically, it can be understood that the weight of the collected and poured molten rare earth alloy steel liquid can be obtained by a weighing device, which will not be elaborated.

[0067] Specifically, the process of determining the predetermined pouring time is to obtain the time taken for the mass of the molten rare earth alloy steel liquid poured out from each historical sample to reach 0.5 times the total mass of the sample, solve the average of each time taken, and obtain the predetermined pouring time.

[0068] Specifically, in S2, the resistance characteristic parameter is calculated by formula (1):

[0069] (1)

[0070] Where Z is the resistance characteristic parameter, N is the flow characteristic parameter, Y is the viscous resistance, N0 is the average value of the flow characteristic parameters of each molten rare earth alloy steel liquid in history, Y0 is the average value of the viscous resistance of each molten rare earth alloy steel liquid in history, α is the flow weight coefficient, and β is the viscosity weight coefficient.

[0071] Specifically, α is set to 0.7 and β is set to 0.3.

[0072] Specifically, there is no limit on the number of historical molten rare earth alloy steel liquids selected. It is understandable that the sample size needs to be sufficient. Optionally, in order to have data representativeness, the number of historical molten rare earth alloy steel liquids selected is not less than 100. This will not be repeated.

[0073] Specifically, the present invention calculates resistance characteristic characterization parameters based on flow characteristic parameters and viscous resistance. In actual situations, the difficulty of bubble precipitation is affected by the specific properties of the molten rare earth alloy steel liquid. When the viscous resistance of the liquid is high, the difficulty of bubble precipitation increases. The higher viscous resistance increases the friction between the bubble surface and the liquid, making it difficult for the bubbles to separate from the liquid. The fluidity of the molten rare earth alloy steel liquid will also affect the precipitation of bubbles. The fluidity characterizes the viscosity of the liquid. The more viscous the liquid, the more difficult it is for bubbles to precipitate. The viscosity of the molten rare earth alloy steel liquid is characterized by calculating the resistance characteristic characterization parameters, which provides data support for the subsequent classification of splitting tendency categories, facilitates the subsequent adaptive selection of corresponding bubble precipitation parameters to precipitate bubbles, and then timely adjusts the control parameters to reduce the influence of the viscosity of the molten rare earth alloy steel liquid on bubble precipitation, and improves the strength of the rare earth alloy steel material.

[0074] Specifically, the splitting tendency categories of the molten rare earth alloy steel liquid are classified in S2, including:

[0075] If the resistance characteristic characterization parameter is less than or equal to the preset resistance characteristic characterization parameter, the molten rare earth alloy steel liquid is determined to be a strong splitting tendency category;

[0076] If the resistance characteristic characterization parameter is greater than the preset resistance characteristic characterization parameter, the molten rare earth alloy steel liquid is determined to be a weak splitting tendency category.

[0077] Specifically, the preset resistance characteristic parameter Z0 is selected within the interval [1.25, 1.3].

[0078] Specifically, in S3, according to the splitting tendency category of the molten rare earth alloy steel liquid, the vacuum pump connected to the vacuum tank and the ventilation nozzles evenly arranged at the bottom of the vacuum tank are controlled to operate, including:

[0079] If the molten rare earth alloy steel liquid is of a type with a strong tendency to split, the gas is uniformly input into the vacuum tank for a predetermined ventilation time;

[0080] If the molten rare earth alloy steel liquid is of the weak splitting tendency category, the ventilation duration of the gas input into each ventilation nozzle is adjusted according to the resistance characteristic characterization parameter, and the operation of the vacuum pump is controlled. The pressure fluctuation characterization parameter is determined by a vacuum gauge arranged in the vacuum tank to determine whether there is an abnormal fluctuation tendency, so as to adjust the vacuum pump suction rate according to the pressure fluctuation characterization parameter.

[0081] Specifically, the ventilation duration of the gas input by each ventilation nozzle is adjusted according to the resistance characteristic parameter, wherein:

[0082] The resistance characteristic parameters are positively correlated with ventilation duration.

[0083] In this embodiment, optionally, the resistance characteristic parameter Z is compared with a first preset parameter comparison threshold Z1 and a second preset parameter comparison threshold Z2:

[0084] If Z≤Z1, the ventilation duration is determined as the first ventilation duration t1, and t1=1.11t0 is set;

[0085] If Z1<Z≤Z2, the ventilation duration is determined as the second ventilation duration t2, and t2=1.22t0 is set;

[0086] If Z>Z2, the ventilation duration is determined as the third ventilation duration t3, and t3=1.33t0 is set;

[0087] Among them, t0 is the initial ventilation duration, Z1=1.3Z0, Z2=1.5Z0.

[0088] Specifically, in S3, the process of determining the pressure fluctuation characterization parameter by using a vacuum gauge disposed in the vacuum tank includes:

[0089] Draw a pressure time domain curve based on the pressure obtained by the vacuum gauge;

[0090] Draw a slope time domain curve based on the slope of the pressure time domain curve segment corresponding to the specific time interval;

[0091] The interval duration between each inflection point in the slope time domain curve is obtained to calculate the variance of each interval duration and obtain the pressure fluctuation characterization parameter.

[0092] Specifically, during the bubble precipitation process, the vacuum gauge continuously monitors the pressure fluctuation in the vacuum tank to determine whether the bubbles are precipitated evenly, obtains the slope of the pressure-time domain curve segment corresponding to the specific time interval, and draws the slope-time domain curve. In the specific time interval, a large number of bubbles are precipitated, and only a small number of bubbles are mixed in the molten rare earth alloy steel liquid. During the operation of the vacuum pump, the vacuum gauge in the vacuum tank measures a gentle decrease in pressure. When bubbles are precipitated, the pressure in the vacuum tank will rise or reduce the pressure reduction rate. After the bubble precipitation is completed, the pressure in the vacuum tank recovers to the reduction rate of the unprecipitated bubbles. The concentrated bubble precipitation time is determined by obtaining the inflection point of the slope-time domain curve, and the fluctuation of the bubble precipitation is determined by determining the variance of the interval time between each inflection point. When the bubble precipitation fluctuation is large, the operating speed of the vacuum pump is adjusted, and the pressure shock inside the molten rare earth alloy steel liquid is reduced by slow pressure changes, so as to reduce the rupture of bubbles during the precipitation process, so that the bubbles are precipitated stably, and the removal efficiency of the bubbles mixed in the molten rare earth alloy steel liquid is further improved.

[0093] Specifically, the process of acquiring the specific time interval is to acquire a time node in the pressure time domain curve whose slope is less than or equal to a preset slope, take the time node as the initial node, and determine the time interval after the initial node in the pressure time domain curve as the specific time interval.

[0094] Specifically, the preset slope K0 is selected within the interval [0.25X0, 0.35X0], and X0 is the average value of the slope means of each pressure-time domain curve corresponding to each historical molten rare earth alloy steel liquid.

[0095] Specifically, whether there is an abnormal fluctuation tendency is determined based on the pressure fluctuation characterization parameters, including:

[0096] If the pressure fluctuation characterization parameter is less than or equal to the preset pressure fluctuation characterization parameter, the vacuum pump is controlled to continuously use the predetermined pumping rate to complete the vacuum treatment of the molten rare earth alloy steel liquid;

[0097] If the pressure fluctuation characterization parameter is greater than the preset pressure fluctuation characterization parameter, the pumping rate of the vacuum pump is adjusted according to the pressure fluctuation characterization parameter.

[0098] Specifically, the preset pressure fluctuation characterization parameter P0 is selected within the interval [1.15U0, 1.23U0], and U0 is the average value of the pressure fluctuation characterization parameter corresponding to each historical molten rare earth alloy steel liquid.

[0099] Specifically, in S3, the pumping rate of the vacuum pump is adjusted according to the pressure fluctuation characterization parameter, wherein:

[0100] The pressure fluctuation characterization parameter is negatively correlated with the vacuum pump's pumping rate.

[0101] In this embodiment, optionally, the pressure fluctuation characterization parameter P is compared with a first preset fluctuation comparison threshold value P1 and a second preset fluctuation comparison threshold value P2:

[0102] If P≤P1, the vacuum pump's pumping rate is determined as the first pumping rate v1, and v1=0.9v0;

[0103] If P1<P≤P2, the vacuum pump's pumping rate is determined as the second pumping rate v2, and v2=0.8v0 is set;

[0104] If P>P2, the vacuum pump's pumping rate is determined as the third pumping rate v3, and v3=0.7v0 is set;

[0105] Among them, v0 is the initial pumping rate of the vacuum pump, P1=1.2P0, P2=1.4P0.

[0106] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a rare earth alloy steel material, characterized in that: include: S1, sampling the molten rare earth alloy steel liquid after high-temperature melting and mixing, and performing fluidity detection, including placing the molten rare earth alloy steel liquid in a container, tilting the container at a predetermined angle, and collecting the poured molten rare earth alloy steel liquid to analyze flow characteristic parameters; S2, placing the molten rare earth alloy steel liquid into a vacuum tank, controlling the operation of each stirring mechanism in the vacuum tank, obtaining the viscous resistance of the molten rare earth alloy steel liquid through a resistance monitoring device arranged on the stirring mechanism, calculating the resistance characteristic characterization parameter for the molten rare earth alloy steel liquid in combination with the flow characteristic parameter, and classifying the splitting tendency category of the molten rare earth alloy steel liquid; S3, according to the splitting tendency category of the molten rare earth alloy steel liquid, controlling the operation of a vacuum pump connected to the vacuum tank and each ventilation nozzle evenly arranged at the bottom of the vacuum tank, including: According to the resistance characteristic characterization parameter, the ventilation time of the gas input by each ventilation nozzle is adjusted, and the operation of the vacuum pump is controlled to obtain the pressure value in the vacuum tank, determine the pressure fluctuation characterization parameter, and determine whether there is an abnormal fluctuation tendency, so as to adjust the vacuum pumping rate according to the pressure fluctuation characterization parameter; Or, maintain the predetermined ventilation time to uniformly input gas into the vacuum tank; S4, controlling the vacuum pump to evacuate the vacuum tank to obtain the refined molten rare earth alloy steel liquid.

2. The method for preparing rare earth alloy steel material according to claim 1, characterized in that: In the above S1, the process of obtaining the flow characteristic parameters is to obtain the weight of the molten rare earth alloy steel liquid poured out within a predetermined pouring time to obtain the flow characteristic parameters.

3. The method for preparing a rare earth alloy steel material according to claim 2, characterized in that: In S2, the resistance characteristic parameter is calculated by formula (1): （1） Where Z is the resistance characteristic parameter, N is the flow characteristic parameter, Y is the viscous resistance, N0 is the average value of the flow characteristic parameters of each molten rare earth alloy steel liquid in history, Y0 is the average value of the viscous resistance of each molten rare earth alloy steel liquid in history, α is the flow weight coefficient, and β is the viscosity weight coefficient.

4. The method for preparing rare earth alloy steel material according to claim 3, characterized in that: The splitting tendency categories of the molten rare earth alloy steel liquid are classified in S2, including: If the resistance characteristic characterization parameter is less than or equal to the preset resistance characteristic characterization parameter, the molten rare earth alloy steel liquid is determined to be a strong splitting tendency category; If the resistance characteristic characterization parameter is greater than the preset resistance characteristic characterization parameter, the molten rare earth alloy steel liquid is determined to be a weak splitting tendency category.

5. The method for preparing rare earth alloy steel material according to claim 4, characterized in that: In S3, according to the splitting tendency category of the molten rare earth alloy steel liquid, the vacuum pump connected to the vacuum tank and the ventilation nozzles evenly arranged at the bottom of the vacuum tank are controlled to operate, including: If the molten rare earth alloy steel liquid is of a type with a strong tendency to split, the gas is uniformly input into the vacuum tank for a predetermined ventilation time; If the molten rare earth alloy steel liquid is of the weak splitting tendency category, the ventilation duration of the gas input into each ventilation nozzle is adjusted according to the resistance characteristic characterization parameter, and the operation of the vacuum pump is controlled. The pressure fluctuation characterization parameter is determined by a vacuum gauge arranged in the vacuum tank to determine whether there is an abnormal fluctuation tendency, so as to adjust the vacuum pump suction rate according to the pressure fluctuation characterization parameter.

6. The method for preparing rare earth alloy steel material according to claim 5, characterized in that: The ventilation duration of the gas input by each ventilation nozzle is adjusted according to the resistance characteristic parameter, wherein: The resistance characteristic parameters are positively correlated with ventilation duration.

7. The method for preparing rare earth alloy steel material according to claim 6, characterized in that: In S3, the process of determining the pressure fluctuation characterization parameter by a vacuum gauge disposed in the vacuum tank includes: Draw a pressure time domain curve based on the pressure obtained by the vacuum gauge; Draw a slope time domain curve based on the slope of the pressure time domain curve segment corresponding to the specific time interval; The interval duration between each inflection point in the slope time domain curve is obtained to calculate the variance of each interval duration and obtain the pressure fluctuation characterization parameter.

8. The method for preparing rare earth alloy steel material according to claim 7, characterized in that: The process of obtaining the specific time interval includes: Obtaining a time node in the pressure time domain curve where the slope is less than or equal to a preset slope; A predetermined time interval after the time node is determined as a specific time interval.

9. The method for preparing rare earth alloy steel material according to claim 8, characterized in that: Determine whether there is an abnormal fluctuation tendency based on the pressure fluctuation characterization parameters, including: If the pressure fluctuation characterization parameter is less than or equal to the preset pressure fluctuation characterization parameter, the vacuum pump is controlled to continuously use the predetermined pumping rate to complete the vacuum treatment of the molten rare earth alloy steel liquid; If the pressure fluctuation characterization parameter is greater than the preset pressure fluctuation characterization parameter, the exhaust rate of the vacuum pump is adjusted according to the pressure fluctuation characterization parameter.

10. The method for preparing rare earth alloy steel material according to claim 9, characterized in that: In S3, the pumping rate of the vacuum pump is adjusted according to the pressure fluctuation characterizing parameter, wherein: The pressure fluctuation characterization parameter is negatively correlated with the vacuum pump's pumping rate.

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