Method, system and application for predicting stresses in wrought superalloy vacuum consumable processes

Abstract

The present application relates to the field of vacuum consumable melting, and provides a method for predicting stress in a deformed high-temperature alloy vacuum consumable process, the method comprising: S1, obtaining high-temperature mechanical properties and strength limits of a high-temperature alloy material through a high-temperature tensile test, and fitting to obtain a relationship between alloy yield strength and tensile strength and temperature; S2, establishing a melting model and a geometry model of the melting of the vacuum consumable melting, and obtaining a temperature field of the high-temperature alloy in the smelting process; S3, establishing a stress calculation model of the vacuum consumable melting, and solving to obtain a predicted thermal stress result of the vacuum consumable melting; and S4, establishing a criterion for cracking of the ingot, and judging whether the ingot cracks in the melting process according to the predicted thermal stress result of the vacuum consumable melting in step S3 and the criterion. The present application can calculate thermal stress in the ingot and whether the ingot cracks, and provides a reference for determining a demolding process, a stress relief annealing system and a homogenization process design after the self-consumable melting of a large ingot is completed.

Description

Technical Field

[0001] This invention relates to the field of vacuum arc remelting, and particularly to a method, system, and application for predicting stress during the vacuum arc remelting process of deformed high-temperature alloys. Background Technology

[0002] Vacuum arc remelting (VAR) involves melting the metal at the bottom of the consumable electrode into droplets via an electric arc. These droplets then fall into a water-cooled copper crystallizer and solidify sequentially into ingots. It is an important smelting method for producing high-temperature alloy ingots with low segregation, inclusions, and defects. However, with the increasing demand for large ingots, the ingot sizes and weights produced by vacuum arc remelting furnaces are constantly increasing. This increased ingot size and weight leads to longer arc remelting times. The bottom-to-top solidification sequence makes the internal temperature field of the ingot more complex, sometimes resulting in the temperature at the bottom of the ingot reaching the same level as the crystallizer, while the top of the ingot is still molten steel. The thermal stress caused by this temperature difference cannot be ignored, placing higher demands on the actual production control of enterprises.

[0003] With the development of computational science, simulating the actual vacuum arc remelting (VAR) production process using computer simulation technology has become an effective method for result prediction and parameter optimization. Chinese patent application CN 113987892 B proposes a model for controlling segregation and solidification in VAR, which can calculate the molten pool temperature, molten pool depth, and dendrite spacing during actual production. Chinese patent application CN 114091248 A also constructed a similar model. However, related research focuses on the solidification and segregation of large VAR ingots, such as molten pool evolution, elemental distribution, speckle formation probability, and dendrite spacing. There is limited research on stress changes during the ingot melting, solidification, and cooling process, and very little analysis of stress after VAR. Furthermore, alloys can only withstand limited thermal stress at different temperatures, and current research and control principles for thermal stress-induced cracking are scarce. Therefore, a method is urgently needed to explore and control thermal stress and cracking tendency during VAR. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method, system and application for predicting the stress in the vacuum self-consumption process of deformed high-temperature alloys. It can predict and calculate the thermal stress during the cooling process after ingot melting, and provide a reference for the demolding process, stress relief annealing regime determination and homogenization process design after the self-consumption melting of large ingots. It solves the stress control problem of ingots in the vacuum self-consumption melting process of high-temperature alloys in China and avoids the fracture damage of ingots due to excessive local stress.

[0005] The present invention adopts the following technical solution:

[0006] A method for predicting stress during the vacuum self-consumption process of deformed superalloys, comprising:

[0007] S1. By conducting high-temperature tensile tests, the high-temperature mechanical properties and strength limits of high-temperature alloy materials are obtained, and the relationship between the alloy yield strength and tensile strength and temperature is obtained by fitting.

[0008] S2. Establish a melting model for vacuum self-consumable melting and a geometric model for melting. Input the node coordinates, boundary conditions, melting parameters and physical property parameters of high-temperature alloy materials obtained from the geometric model into the melting model to obtain the temperature field of the high-temperature alloy smelting process.

[0009] S3. Establish a stress calculation model for vacuum self-consumable melting. The process temperature field obtained in step S2 is thermo-coupled with the stress calculation model. Input the physical property parameters of the high-temperature alloy material, the relationship between the yield strength and tensile strength of the alloy high-temperature mechanical properties obtained in step S1 and the nodal coordinates and process temperature field obtained in step S2 into the stress calculation model, and solve to obtain the predicted thermal stress results of vacuum self-consumable melting.

[0010] Steps S1 and S2 have no specific order.

[0011] In addition to any of the possible implementations described above, a further implementation is provided, wherein the method further includes:

[0012] S4. Establish cracking criteria for ingots. Based on the predicted thermal stress results of vacuum self-consumable melting in step S3 and the cracking criteria, determine whether the ingot cracks during the melting process.

[0013] In addition to any of the possible implementations described above, another implementation is provided in which the measurement temperature range of the high-temperature tensile test in step S1 is between 25 and 1200°C.

[0014] In addition to any of the possible implementations described above, another implementation is provided, in step S2,

[0015] The melting model of vacuum self-consuming melting includes a vacuum self-consuming electromagnetic field model, a flow field model, and a heat transfer model.

[0016] The geometric model includes dividing the electrodes and ingots into grids based on the electrode geometry, ingot size, ingot mass, and crystallizer radius.

[0017] In addition to any of the possible implementations described above, another implementation is provided, in step S2,

[0018] The boundary conditions include the thermal conductivity of the crystallizer, the thermal conductivity of the chassis, the heat transfer coefficients of the crystallizer and cooling water, the radiative heat transfer coefficient of the ingot side, the radiative heat transfer coefficient of the ingot top, the cooling water temperature, the initial temperature of the crystallizer, and the initial temperature of the electrode.

[0019] The melting parameters include current, voltage, melting time, and melting rate;

[0020] The physical properties of the high-temperature alloy material include liquid phase density, solid phase density, liquidus line, solidus line, latent heat, electrical conductivity, thermal conductivity, specific heat, viscosity, and solid fraction.

[0021] In addition to any of the possible implementations described above, another implementation is provided in which the stress calculation model for vacuum arc remelting is implemented using the finite element software Abaqus, and step S3 specifically includes:

[0022] S31. Extract the node coordinate information obtained from the geometric model in step S2, and the process temperature field and corresponding time information obtained from the smelting model;

[0023] S32. Based on the node coordinate information in step S31, establish a finite element model in Abaqus and generate finite element mesh node nodes.

[0024] S33. Assign the process temperature field and corresponding time information obtained in step S31 to the finite element mesh node obtained in step S32 as initial conditions.

[0025] S34. Input the physical property parameters of the high-temperature alloy material and the relationship between the yield strength and tensile strength of the alloy as a function of temperature in Abaqus, and assign them to finite element elements.

[0026] S35. Calculate the temperature load using the Abaqus solver in Abaqus to obtain the stress change of the ingot during the smelting process, and finally obtain the thermal stress distribution of the ingot after smelting and cooling.

[0027] In addition to any of the possible implementations described above, another implementation is provided in which, in step S4, the cracking criterion is determined by calculating whether the internal stress of the ingot at different times is simultaneously lower than the limit values ​​of the first strength theory and the fourth strength theory at that temperature, and whether the ingot cracks when it is removed from the furnace and demolded after the vacuum is broken.

[0028] First strength cracking criterion value:

[0029]

[0030] Fourth strength cracking criterion value:

[0031]

[0032] Cracking criterion value:

[0033] P = max{P1, P4};

[0034] In the formula, P1 is the cracking criterion value determined according to the first strength theory, P4 is the cracking criterion value determined according to the fourth strength theory, and σ s For yield strength, σ b For tensile strength, σ1 is the first principal stress, σ2 is the second principal stress, and σ3 is the third principal stress; yield strength and tensile strength are obtained through high-temperature tensile tests and fitted into a relationship; the principal stresses of the ingot at different times are obtained through a stress model of vacuum arc remelting.

[0035] Cracking criterion: At any moment during the ingot smelting process, if the cracking criterion value P≥1, the ingot is judged to be cracked;

[0036] Only when both P1 and P4 are less than 1, that is, when the maximum cracking criterion value P<1 among P1 and P4, sufficient strength and plasticity are built up inside the ingot, and there is no tendency to crack, the ingot will not crack.

[0037] On the other hand, the present invention also provides a prediction system for the stress during the vacuum self-consumption process of deformed superalloys. The prediction system uses the above-described prediction method and includes:

[0038] The alloy strength-temperature relationship fitting unit obtains the high-temperature mechanical properties and strength limit of high-temperature alloy materials through high-temperature tensile tests, and fits the relationship between the alloy yield strength and tensile strength as a function of temperature.

[0039] The alloy melting temperature field acquisition unit is used to establish a melting model for vacuum consumable melting and a melting geometric model. The nodal coordinates, boundary conditions, melting parameters and physical property parameters of high-temperature alloy materials obtained from the geometric model are input into the melting model to obtain the temperature field of the high-temperature alloy smelting process.

[0040] The alloy melting stress prediction unit is used to establish a stress calculation model for vacuum self-consumable melting and solve for the predicted thermal stress results of vacuum self-consumable melting.

[0041] The cracking judgment unit is used to establish cracking criteria for ingots and to determine whether the ingot cracks during the melting process based on the predicted thermal stress results of vacuum self-consumable melting and the cracking criteria.

[0042] On the other hand, the present invention also provides an application of a method for predicting stress and cracking in the vacuum self-consumption melting process of deformed high-temperature alloys. The prediction method is applied to the optimization design of subsequent high-temperature alloy ingot stress relief and homogenization processes. Specifically, based on the predicted thermal stress and cracking results of vacuum self-consumption melting obtained by the prediction method, the parameters of subsequent high-temperature alloy ingot stress relief and homogenization processes are optimized to ensure that the final thermal stress value of the ingot is less than a set threshold, thereby avoiding cracking.

[0043] On the other hand, the present invention also provides an application of a method for predicting stress and cracking in the vacuum self-consumption process of deformed high-temperature alloys. The prediction method is applied to the optimization of the melting process of vacuum self-consumption melting. Specifically, based on the predicted thermal stress results of vacuum self-consumption melting obtained by the prediction method, the melting parameters, boundary conditions and demolding time are optimized so that the cracking criterion value of the ingot during the cooling process of the melted ingot is always less than 1.

[0044] The beneficial effects of this invention are as follows:

[0045] 1. This invention constructs electromagnetic field, fluid and heat transfer models based on MeltFlow-VAR software, calculates the temperature field of vacuum consumable melting, assigns a temperature field and performs thermo-mechanical coupling by reconstructing the mesh in Abaqus, calculates the thermal stress of the vacuum consumable melting process calculated by MeltFlow-VAR, obtains the stress distribution in the vacuum consumable ingot, and constructs a cracking criterion through high-temperature tensile experiments and strength theory, which can determine the cracking tendency of the ingot.

[0046] 2. Based on different ingot size geometric models, material types and properties or smelting parameters, this invention can calculate the internal thermal stress of ingots under different working conditions, and visualize the stress distribution and cracking tendency of vacuum consumable ingots under different working conditions.

[0047] 3. By understanding and calculating the stress distribution and cracking tendency of vacuum consumable ingots, this invention is beneficial for enterprises to determine the demolding time and design the stress relief and homogenization process. Attached Figure Description

[0048] Figure 1 The diagram shown is a flowchart illustrating a method for predicting stress and cracking during the vacuum self-consumption process of deformed high-temperature alloys according to an embodiment of the present invention.

[0049] Figure 2 The figure shown is the geometric model of vacuum consumable melting of 400kg GH4169 alloy in Example 1.

[0050] Figure 3 The following are the physical properties of the GH4169 alloy in Example 1 as a function of temperature: (a) thermal conductivity, (b) specific heat, (c) viscosity, and (d) solid fraction.

[0051] Figure 4 The figure shows the temperature field calculated by MeltFlow-VAR for 40 minutes after the completion of vacuum arc remelting of 400 kg GH4169 alloy in Example 1.

[0052] Figure 5 The image shows the Abaqus reconstructed mesh of 400kg GH4169 alloy vacuum consumable melting in Example 1 and the temperature field 40 minutes after melting.

[0053] Figure 6 The figure shows the stress field calculated by Abaqus 40 minutes after the completion of the vacuum consumable melting of 400kg GH4169 alloy in Example 1.

[0054] Figure 7 The figure shows the cracking criterion value P calculated by Abaqus 40 minutes after the completion of vacuum arc remelting of 400kg GH4169 alloy in Example 1.

[0055] Figure 8 The figure shows the temperature field of 18tGH4169 alloy 120 min after vacuum arc melting calculated by MeltFlow-VAR in Example 2.

[0056] Figure 9 The image shows the Abaqus reconstructed mesh of the 18t GH4169 alloy vacuum consumable melting in Example 2 and the temperature field 120 minutes after melting.

[0057] Figure 10 The figure shows the stress field calculated by Abaqus 120 minutes after the completion of vacuum arc remelting of 18tGH4169 alloy.

[0058] Figure 11 The figure shows the cracking criterion value P calculated by Abaqus 120 minutes after the completion of vacuum arc remelting of 18tGH4169 alloy in Example 2.

[0059] Figure 12 The following are the physical properties of the GH4738 alloy in Example 3 as a function of temperature: (a) thermal conductivity, (b) specific heat, (c) viscosity, and (d) solid fraction.

[0060] Figure 13 The figure shows the temperature field calculated by MeltFlow-VAR for 40 minutes after the completion of vacuum arc remelting of 400 kg GH4738 alloy in Example 3.

[0061] Figure 14 The image shows the Abaqus reconstructed mesh of 400kg GH4738 alloy vacuum consumable melting in Example 3 and the temperature field 40 minutes after melting.

[0062] Figure 15 The figure shows the stress field calculated by Abaqus 40 minutes after the completion of the vacuum self-consumable melting of 400kg GH4738 alloy in Example 3.

[0063] Figure 16 The figure shows the cracking criterion value P calculated by Abaqus 40 minutes after the completion of vacuum arc remelting of 400kg GH4738 alloy in Example 1. Detailed Implementation

[0064] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation, but can be combined with each other to achieve better technical effects.

[0065] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for predicting stress during the vacuum self-consumption process of a deformed high-temperature alloy, comprising:

[0066] S1. By conducting high-temperature tensile tests, the high-temperature mechanical properties and strength limits of high-temperature alloy materials are obtained, and the relationship between the alloy yield strength and tensile strength and temperature is obtained by fitting.

[0067] S2. Establish a melting model for vacuum self-consumable melting and a geometric model for melting. Input the node coordinates, boundary conditions, melting parameters and physical property parameters of high-temperature alloy materials obtained from the geometric model into the melting model to obtain the temperature field of the high-temperature alloy smelting process.

[0068] S3. Establish a stress calculation model for vacuum self-consumable melting. The process temperature field obtained in step S2 is thermo-coupled with the stress calculation model. Input the physical property parameters of the high-temperature alloy material, the relationship between the yield strength and tensile strength of the alloy high-temperature mechanical properties obtained in step S1 and the nodal coordinates and process temperature field obtained in step S2 into the stress calculation model, and solve to obtain the predicted thermal stress results of vacuum self-consumable melting.

[0069] Steps S1 and S2 have no specific order.

[0070] In one specific embodiment, the method further includes:

[0071] S4. Establish cracking criteria for ingots. Based on the predicted thermal stress results of vacuum self-consumable melting in step S3 and the cracking criteria, determine whether the ingot cracks during the melting process.

[0072] In one specific embodiment, in step S1, the measurement temperature range of the high-temperature tensile test is between 25 and 1200°C.

[0073] In one specific embodiment, in step S2,

[0074] The melting model of vacuum self-consuming melting includes a vacuum self-consuming electromagnetic field model, a flow field model, and a heat transfer model.

[0075] The geometric model includes dividing the electrodes and ingots into grids based on the electrode geometry, ingot size, ingot mass, and crystallizer radius.

[0076] In one specific embodiment, in step S2,

[0077] The boundary conditions include the thermal conductivity of the crystallizer, the thermal conductivity of the chassis, the heat transfer coefficients of the crystallizer and cooling water, the radiative heat transfer coefficient of the ingot side, the radiative heat transfer coefficient of the ingot top, the cooling water temperature, the initial temperature of the crystallizer, and the initial temperature of the electrode.

[0078] The melting parameters include current, voltage, melting time, and melting rate;

[0079] The physical properties of the high-temperature alloy material include liquid phase density, solid phase density, liquidus line, solidus line, latent heat, electrical conductivity, thermal conductivity, specific heat, viscosity, and solid fraction.

[0080] In one specific embodiment, the stress calculation model of the vacuum self-consumable melting is implemented using the finite element software Abaqus, and step S3 specifically includes:

[0081] S31. Extract the node coordinate information obtained from the geometric model in step S2, and the process temperature field and corresponding time information obtained from the smelting model;

[0082] S32. Based on the node coordinate information in step S31, establish a finite element model in Abaqus and generate finite element mesh node nodes.

[0083] S33. Assign the process temperature field and corresponding time information obtained in step S31 to the finite element mesh node obtained in step S32 as initial conditions.

[0084] S34. Input the physical property parameters of the high-temperature alloy material and the relationship between the yield strength and tensile strength of the alloy as a function of temperature in Abaqus, and assign them to finite element elements.

[0085] S35. Calculate the temperature load using the Abaqus solver in Abaqus to obtain the stress change of the ingot during the smelting process, and finally obtain the thermal stress distribution of the ingot after smelting and cooling.

[0086] In one specific embodiment, in step S4, the cracking criterion is determined by calculating whether the internal stress of the ingot at different times is simultaneously lower than the limit values ​​of the first strength theory and the fourth strength theory at that temperature, and whether the ingot cracks when it is removed from the furnace and demolded after being exposed to vacuum.

[0087] First strength cracking criterion value:

[0088]

[0089] Fourth strength cracking criterion value:

[0090]

[0091] Cracking criterion value:

[0092] P = max{P1, P4};

[0093] In the formula, P1 is the cracking criterion value determined according to the first strength theory, P4 is the cracking criterion value determined according to the fourth strength theory, and σ s For yield strength, σ b For tensile strength, σ1 is the first principal stress, σ2 is the second principal stress, and σ3 is the third principal stress; yield strength and tensile strength are obtained through high-temperature tensile tests and fitted into a relationship; the principal stresses of the ingot at different times are obtained through a stress model of vacuum arc remelting.

[0094] Cracking criterion: At any moment during the ingot smelting process, if the cracking criterion value P≥1, the ingot is judged to be cracked;

[0095] Only when both P1 and P4 are less than 1, that is, when the maximum cracking criterion value P<1 among P1 and P4, sufficient strength and plasticity are built up inside the ingot, and there is no tendency to crack, the ingot will not crack.

[0096] This invention provides a system for predicting stress during the vacuum self-consumption process of deformed superalloys. Using the aforementioned prediction method, the prediction system includes:

[0097] The alloy strength-temperature relationship fitting unit obtains the high-temperature mechanical properties and strength limit of high-temperature alloy materials through high-temperature tensile tests, and fits the relationship between the alloy yield strength and tensile strength as a function of temperature.

[0098] The alloy melting temperature field acquisition unit is used to establish a melting model for vacuum consumable melting and a melting geometric model. The nodal coordinates, boundary conditions, melting parameters and physical property parameters of high-temperature alloy materials obtained from the geometric model are input into the melting model to obtain the temperature field of the high-temperature alloy smelting process.

[0099] The alloy melting stress prediction unit is used to establish a stress calculation model for vacuum self-consumable melting and solve for the predicted thermal stress results of vacuum self-consumable melting.

[0100] The cracking judgment unit is used to establish cracking criteria for ingots and to determine whether the ingot cracks during the melting process based on the predicted thermal stress results of vacuum self-consumable melting and the cracking criteria.

[0101] This invention relates to an application of a method for predicting stress and cracking during the vacuum arc melting process of deformed high-temperature alloys. The prediction method is applied to the optimization design of subsequent high-temperature alloy ingot stress relief and homogenization processes. Specifically, based on the predicted thermal stress and cracking results of vacuum arc melting obtained by the prediction method, the parameters of subsequent high-temperature alloy ingot stress relief and homogenization processes are optimized to ensure that the final thermal stress value of the ingot is less than a set threshold, thereby avoiding cracking.

[0102] This invention relates to an application of a method for predicting stress and cracking during the vacuum self-consumption process of deformed high-temperature alloys. The prediction method is applied to the optimization of the smelting process of vacuum self-consumption melting. Specifically, based on the predicted thermal stress results of vacuum self-consumption melting obtained by the prediction method, the smelting parameters, boundary conditions, and demolding time are optimized so that the cracking criterion value of the ingot is always less than 1 during the cooling process of the smelted ingot.

[0103] Example 1

[0104] Calculations were performed on the vacuum consumable melting of 400 kg GH4169 alloy, with an electrode radius of 140 mm, a crystallizer radius of 173 mm, and a consumable ingot height of 530 mm. A geometric model was constructed and meshed as follows: Figure 2 As shown in Table 1, the physical properties of GH4169 alloy are as follows: Figure 3 As shown in Table 2, the boundary conditions are as follows, and the melting rate during the steady-state melting stage is 2.5 kg / min. The relationship between the strength obtained by high-temperature tensile testing of the self-consumable GH4169 alloy and temperature is as follows:

[0105] When the temperature is below 800℃:

[0106] σ s =―0.2T+500

[0107] σ s =―0.3T+600

[0108] When the temperature is greater than 800℃

[0109] σ s =1400-38T+3×10 ―3 T 2 ―1×10 ―5 T 3

[0110] σ b =11700-30T+3×10 ―3 T 2 ―8×10 ―5 T 3

[0111] MeltFlow-VAR calculations show the temperature field after melting is completed and the crystallizer is placed for 40 minutes. Figure 4 , Figure 5 It combines the mesh reconstruction information from the MeltFlow-VAR software with the node temperature applied 40 minutes after the melting process. Figure 6 The equivalent stress distribution of the ingot at this time, calculated by Abaqus, shows a maximum stress of 120.6 MPa. Figure 7 The cracking criterion P for the ingot at this time was calculated, with a maximum value of 0.271, indicating that cracking will not occur.

[0112] Table 1 Physical properties of GH4169 alloy

[0113]

[0114] Table 2 Boundary conditions for vacuum arc melting

[0115]

[0116] Example 2

[0117] Calculations were performed on the vacuum consumable melting of 18t GH4169 alloy, with an electrode radius of 800mm, a crystallizer radius of 920mm, and a consumable ingot height of 3320mm. A geometric model was constructed and meshed. The physical properties of the GH4169 alloy are shown in Table 1. Figure 3 As shown in Table 2, the boundary conditions are the same, and the melting rate during the stable melting stage is 5.0 kg / min. The temperature field calculated by MeltFlow-VAR after melting, placed in the crystallizer for 120 min, is as follows: Figure 8 , Figure 9 It combines the mesh reconstruction information from the MeltFlow-VAR software with the node temperature applied 40 minutes after the melting process. Figure 10 The equivalent stress distribution of the ingot at this time, calculated by Abaqus, shows a maximum stress of 192.2 MPa. Figure 11 The cracking criterion P for the ingot at this time was calculated, with a maximum value of 131.5, indicating that cracking may occur.

[0118] Example 3

[0119] Calculations were performed on approximately 400 kg of GH4738 alloy vacuum consumable melting. The electrode radius was 140 mm, the crystallizer radius was 173 mm, and the consumable ingot height was 530 mm. A geometric model was constructed and meshed. The physical properties of the GH4738 alloy are shown in Table 3. Figure 12 As shown in Table 2, the boundary conditions are as follows: the melting rate during the stable smelting stage is 2.5 kg / min.

[0120] When the temperature is below 800℃:

[0121] σ s =―0.05T+500

[0122] σ s =―0.3T+976

[0123] When the temperature is greater than 800℃

[0124] σ s =1300-9T+1×10 ―2 T 2 ―6×10 ―6 T 3

[0125] σ b =11800-27T+2×10 ―2 T 2 ―5×10 ―6 T 3

[0126] MeltFlow-VAR calculations show the temperature field after melting is completed and the crystallizer is placed for 40 minutes. Figure 13 , Figure 14 It combines the mesh reconstruction information from the MeltFlow-VAR software with the node temperature applied 40 minutes after the melting process. Figure 15 The equivalent stress distribution of the ingot at this time, calculated by Abaqus, shows a maximum stress of 332.3 MPa. Figure 16 The calculated cracking criterion value P for the ingot at this time is 0.214, indicating that cracking will not occur.

[0127] Table 3 Physical properties of GH4738 alloy

[0128]

[0129] After obtaining the thermal stress distribution of the vacuum arc remelting ingot, it is compared with the alloy cracking criterion, and the melting parameters, boundary conditions, and demolding time are adjusted accordingly to ensure that the cracking criterion of vacuum arc remelting is less than 1, and cracking does not occur. This can also be used to design subsequent stress relief and homogenization processes for high-temperature alloy ingots.

[0130] While embodiments of the present invention have been provided herein, those skilled in the art should understand that modifications can be made to the embodiments without departing from the spirit of the invention. The above embodiments are merely exemplary and should not be construed as limiting the scope of the invention.

Claims

1. A method for predicting stress during the vacuum self-consumption process of deformed superalloys, characterized in that, The method includes: S1. By conducting high-temperature tensile tests, the high-temperature mechanical properties and strength limits of high-temperature alloy materials are obtained, and the relationship between the alloy yield strength and tensile strength and temperature is obtained by fitting. S2. Establish a melting model for vacuum self-consumable melting and a geometric model for melting. Input the node coordinates, boundary conditions, melting parameters and physical property parameters of high-temperature alloy materials obtained from the geometric model into the melting model to obtain the temperature field of the high-temperature alloy smelting process. S3. Establish a stress calculation model for vacuum self-consumable melting. The process temperature field obtained in step S2 is thermo-coupled with the stress calculation model. Input the physical property parameters of the high-temperature alloy material, the high-temperature mechanical properties of the alloy obtained in step S1, and the nodal coordinates and process temperature field obtained in step S2 into the stress calculation model, and solve to obtain the predicted thermal stress results of vacuum self-consumable melting. S4. Establish the cracking criterion for the ingot. Based on the predicted thermal stress results of vacuum self-consumable melting in step S3 and the cracking criterion, determine whether the ingot cracks during the melting process. Steps S1 and S2 have no specific order; The stress calculation model for vacuum self-consumable melting is implemented using the finite element software Abaqus. Step S3 specifically includes: S31. Extract the node coordinate information obtained from the geometric model in step S2, and the process temperature field and corresponding time information obtained from the smelting model; S32. Based on the node coordinate information in step S31, establish a finite element model in Abaqus and generate finite element mesh node nodes. S33. Assign the process temperature field and corresponding time information obtained in step S31 to the finite element mesh node obtained in step S32 as initial conditions. S34. Input the physical property parameters and high-temperature mechanical properties of the high-temperature alloy material into Abaqus and assign them to finite element elements. S35. Calculate the temperature load using the Abaqus solver in Abaqus to obtain the stress change of the ingot during the smelting process, and finally obtain the thermal stress distribution of the ingot after smelting and cooling. In step S4, the cracking criterion is determined by calculating whether the internal stress of the ingot at different times is simultaneously lower than the limit values ​​of the first strength theory and the fourth strength theory at that temperature, and whether the ingot cracks when it is removed from the furnace and demolded after the vacuum is broken. First strength cracking criterion value: ； Fourth strength cracking criterion value: ； Cracking criterion value: ； In the formula, P1 is the cracking criterion value determined according to the first strength theory, P4 is the cracking criterion value determined according to the fourth strength theory, and σ s For yield strength, σ b For tensile strength, σ1 is the first principal stress, σ2 is the second principal stress, and σ3 is the third principal stress; yield strength and tensile strength are obtained through high-temperature tensile tests and fitted into a relationship; the principal stresses of the ingot at different times are obtained through a stress model of vacuum arc remelting. Cracking criterion: At any moment during the ingot smelting process, if the cracking criterion value P ≥ 1, the ingot is judged to be cracked; Only when both P1 and P4 are less than 1, that is, when the maximum cracking criterion value P < 1 among P1 and P4, the ingot has sufficient strength and plasticity built up inside, has no tendency to crack, and the ingot will not crack.

2. The method for predicting stress during the vacuum self-consumption process of deformed high-temperature alloys as described in claim 1, characterized in that, In step S1, the measurement temperature range for the high-temperature tensile test is between 25 and 1200℃.

3. The method for predicting stress during the vacuum self-consumption process of deformed high-temperature alloys as described in claim 1, characterized in that, In step S2, The melting model of vacuum self-consuming melting includes a vacuum self-consuming electromagnetic field model, a flow field model, and a heat transfer model. The geometric model includes dividing the electrodes and ingots into grids based on the electrode geometry, ingot size, ingot mass, and crystallizer radius.

4. The method for predicting stress during the vacuum self-consumption process of deformed high-temperature alloys as described in claim 1, characterized in that, In step S2, The boundary conditions include the thermal conductivity of the crystallizer, the thermal conductivity of the chassis, the heat transfer coefficients of the crystallizer and cooling water, the radiative heat transfer coefficient of the ingot side, the radiative heat transfer coefficient of the ingot top, the cooling water temperature, the initial temperature of the crystallizer, and the initial temperature of the electrode. The melting parameters include current, voltage, melting time, and melting rate; The physical properties of the high-temperature alloy material include liquid phase density, solid phase density, liquidus line, solidus line, latent heat, electrical conductivity, thermal conductivity, specific heat, viscosity, and solid fraction.

5. A system for predicting stress during the vacuum self-consumption process of deformed high-temperature alloys, characterized in that, The prediction system uses the prediction method as described in any one of claims 1-4, and the prediction system comprises: The alloy strength-temperature relationship fitting unit obtains the high-temperature mechanical properties and strength limit of high-temperature alloy materials through high-temperature tensile tests, and fits the relationship between the alloy yield strength and tensile strength as a function of temperature. The alloy melting temperature field acquisition unit is used to establish a melting model for vacuum consumable melting and a melting geometric model. The nodal coordinates, boundary conditions, melting parameters and physical property parameters of high-temperature alloy materials obtained from the geometric model are input into the melting model to obtain the temperature field of the high-temperature alloy smelting process. The alloy melting stress prediction unit is used to establish a stress calculation model for vacuum self-consumable melting and solve for the predicted thermal stress results of vacuum self-consumable melting. The cracking judgment unit is used to establish cracking criteria for ingots and to determine whether the ingot cracks during the melting process based on the predicted thermal stress results of vacuum self-consumable melting and the cracking criteria.

6. An application of a method for predicting stress during the vacuum self-consumption process of deformed high-temperature alloys, characterized in that, The prediction method described in any one of claims 1-4 is applied to the design of subsequent high-temperature alloy ingot stress relief and homogenization processes, specifically: based on the predicted thermal stress results and cracking conditions obtained from the vacuum self-consumable melting method, the parameters of the subsequent high-temperature alloy ingot stress relief and homogenization processes are designed so that the final thermal stress value of the ingot is less than a set threshold, thereby avoiding cracking.

7. An application of a method for predicting stress during the vacuum self-consumption process of deformed high-temperature alloys, characterized in that, The prediction method described in any one of claims 1-4 is applied to the optimization of the smelting process of vacuum consumable melting, specifically: based on the predicted thermal stress results of vacuum consumable melting obtained by the prediction method, the smelting parameters, boundary conditions and demolding time are optimized so that the cracking criterion value of the ingot is always less than 1 during the ingot cooling process.

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