Component design of high-flux nickel-based superalloy for additive manufacturing based on multi-objective optimization

Abstract

The invention provides a novel model and a novel method for component design of a high-flux nickel-based superalloy for additive manufacturing based on multi-objective optimization and a novel alloy, and relates to the technical field of component design of nickel-based superalloy and additive manufacturing. The invention aims to design a novel K438 alloy with excellent mechanical properties at 850 DEG C by taking the K438 alloy as an example, and the novel K438 alloy has lower crack sensitivity. The method is mainly characterized in that the influence of solidification cracks, liquefaction cracks and solid cracks is comprehensively considered, and a comprehensive crack sensitivity (CCS) model is established; the CCS values and the yield strength of 850 DEG C of tens of thousands of alloys are obtained through high-flux thermodynamics calculation by combining a CCS model and a high-temperature yield strength model, and the Pareto alloy is automatically optimized by utilizing a self-written Python script. According to the method, a data basis can be provided for design and production of the nickel-based high-temperature alloy for additive manufacturing, and a new theoretical basis and method are provided for development of the high-strength printable nickel-based high-temperature alloy.

Description

Technical Field

[0001] The present invention relates to the technical field of nickel-based superalloy composition design and additive manufacturing, and particularly relates to a method for designing the composition of a nickel-based superalloy for additive manufacturing. Background Art

[0002] Due to their excellent high-temperature stability and mechanical properties, nickel-based superalloys have been widely used in gas turbine engines, combustion chambers, or rocket engines. Due to the extremely complex operating environment of the engines, the geometric shapes of the components made of nickel-based superalloys are also more complex. Although investment casting, as a traditional processing method, can perform precision casting, the processing technology is relatively cumbersome, the processing efficiency is relatively low, and there are certain limitations in the production of components with complex shapes. As a type of additive manufacturing technology, additive manufacturing can process complex geometric shapes, achieve fewer processing process flows, have higher processing freedom, and more efficient material utilization rate. However, currently, traditional nickel-based superalloys are based on traditional casting methods and do not consider the process characteristics of additive manufacturing, such as high temperature gradients, high cooling rates, and cyclic heating-cooling, which leads to the problem of being difficult to balance "forming and property", that is, the problem of being unable to balance low crack sensitivity and high strength. In summary, it is necessary to design a new type of nickel-based alloy composition suitable for additive manufacturing according to the metallurgical conditions of additive manufacturing.

[0003] Existing studies have proposed several methods for designing and optimizing chemical compositions to address different cracks generated during additive manufacturing. For solidification cracks, some hot crack criteria have been proposed by considering the solidification characteristics during additive manufacturing, such as the critical solidification temperature range theory based on the Scheil-Gulliver model, the CSC criterion and the Kou criterion related to the final stage of solidification, etc. It has been found that liquation cracks are related to the local liquefaction of the sample during production, so TS can be used as a criterion. For strain-age cracks generated in the fully solidified state, considering the differences in the cracking resistance of materials caused by different compositions to thermal stress and mechanical stress, the DR criterion has been proposed. However, no study has comprehensively considered the three crack criteria and established a comprehensive model to rank the crack sensitivity of nickel-based superalloys.

[0004] The development of high-temperature alloys in China has shifted from traditional experimental research to a mode combining experiments and calculations. The material gene engineering method has been successfully applied to the research and development of new high-performance alloys. In particular, high-throughput thermodynamic calculations have added a new dimension to existing conventional research, greatly compensating for the deficiencies of the traditional "trial and error method" in the research and development of new alloys. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention establishes a new comprehensive crack sensitivity model and proposes a new method for designing the composition of high-throughput nickel-based superalloys for additive manufacturing based on multi-objective optimization, aiming to enable the nickel-based superalloy to have excellent mechanical properties at 850 °C and effectively control the cracks generated during the additive manufacturing process.

[0006] Provide a design method for additive manufacturing applicable nickel-based alloys based on multi-objective optimization design, and prepare an additive manufacturing applicable nickel-based superalloy with excellent high-temperature performance and low crack sensitivity at the same time.

[0007] To achieve the above object, the present invention mainly provides the following technical solutions:

[0008] On the one hand, a comprehensive crack sensitivity model (CCS) for the composition design of high-throughput nickel-based superalloys for additive manufacturing based on multi-objective optimization, the model is specifically as follows:

[0009] CCS = 0.45 * CSI - 0.3 * TS - 0.25 * DR

[0010] This model can better predict the cracking situation of nickel-based superalloys for additive manufacturing, and the prediction effect is as Figure 2 shown.

[0011] On the other hand, a modeling method for a comprehensive crack sensitivity model of the composition design of high-throughput nickel-based superalloys for additive manufacturing based on multi-objective optimization, characterized by including the following steps: Step P1: Collect data on the cracking situation and corresponding alloy compositions during the additive manufacturing process of existing nickel-based superalloys, and make a database; Step P2: Calculate the solidification crack sensitivity, liquefaction crack sensitivity and solid-state crack sensitivity of each alloy composition in the database, that is, calculate the CSI value, TS value and DR value; Step P3: Establish a comprehensive crack sensitivity model (CCS) according to the solidification crack sensitivity, liquefaction crack sensitivity and solid-state crack sensitivity during the additive manufacturing process of nickel-based superalloys; Step P4: According to the cracking situation of the alloys in the database, determine the weights of each crack sensitivity in the model and the CCS value for distinguishing cracking and non-cracking.

[0012] In a specific embodiment of the present invention, the model in the step P3 is as follows:

[0013] CCS = x * CSI - y * TS - z * DR

[0014] In a specific embodiment of the present invention, the CCS value for distinguishing cracking and non-cracking in the step P4 is -0.15, that is, when the CCS value is less than -0.15, the alloy is not easily cracked during the additive manufacturing process; when the CCS value is greater than -0.15, the alloy is easily cracked during the additive manufacturing process.

[0015] On the other hand, a new method for designing the composition of high-throughput nickel-based high-temperature alloy for additive manufacturing based on multi-objective optimization is characterized in that it includes the following steps: Step S1: preset N alloy elements other than nickel, and predefine the alloy element search range; Step S2: generate a series of candidate alloys with different compositions within the predetermined and alloy element search range; Step S3: obtain relevant thermodynamic information of the candidate alloys by high-throughput thermodynamic calculation; Step S4: calculate their CCS value and yield strength at 850°C based on the relevant thermodynamic information of the candidate alloys obtained in Step S3 and the CCS model and high-temperature yield strength model; Step S5: draw the Pareto frontier of the CCS value and yield strength at 850°C of the candidate alloy based on the result of Step S4, and obtain the required nickel-based high-temperature alloy for additive manufacturing.

[0016] In a specific embodiment of the present invention, the present invention is based on the currently available K438 alloy as an example to perform composition optimization, and the N described in step S1 is 11; the predefined alloy element search range is: Al 2.0-5.0wt.%, B0.01wt.%, C 0.15wt.%, Co 8.5wt.%, Cr16.0wt.%, Mo 0.5-3.0wt.%, Nb 0.9wt.%, Ta1.75wt.%, Ti 1.0-4.0wt.%, W 2.6wt.%, Zr 0.05wt.% (the content changes of three elements, Al, Mo and Ti, are specifically considered in the embodiment of the present invention).

[0017] In a specific embodiment of the present invention, the step S4 includes the following steps: step S4.1: according to the result in step S3, extract the temperature when the solid phase volume fraction is 90%, 99% and 100%; step S4.2: using the solid phase volume fraction extracted in step S4.1 and the corresponding temperature, calculate the CSI, TS and DR values ​​of the candidate alloy; step S4.3: combining the result in step S4.2 and the CCS model to calculate the CCS value of the candidate alloy; step S4.4: according to the result in step S3, extract the volume fraction of the γ matrix phase, the fraction of each solute atom in the γ matrix phase and the volume fraction of the γ' phase of the candidate alloy at 850°C; step S4.5: combining the result in step S4.4 and the yield strength model of nickel-based high-temperature alloys to calculate the yield strength of the candidate alloy at 850°C.

[0018] In a specific embodiment of the present invention, one of the alloys at the Pareto front at the end of step S5 is Al 5.0wt.%, B 0.01wt.%, C 0.15wt.%, Co 8.5wt.%, Cr16.0wt.%, Mo 3.0wt.%, Nb0.9wt.%, Ta 1.75wt.%, Ti 1.7wt.%, W2.6wt.%, and Zr 0.05wt.%.

[0019] The beneficial effects of the present invention are:

[0020] The composition design method of nickel-based high-temperature alloy for additive manufacturing provided by the present invention enables the nickel-based high-temperature alloy manufactured by additive manufacturing to achieve crack-free printing and excellent high-temperature yield strength. Compared with existing alloys, the nickel-based high-temperature alloy for additive manufacturing of the present invention can take into account both "molding-formability" and has a broader application prospect in the field of additive manufacturing. In addition, compared with the existing composition design method of nickel-based high-temperature alloy for additive manufacturing, the method of the present invention comprehensively considers the effects of solidification cracks, liquefaction cracks and solid cracks in terms of cracks, and combines literature data to calculate the weights of their effects on crack sensitivity; in terms of high-temperature mechanical properties, the relationship between alloy composition and high-temperature yield strength of 850°C is combined. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 A comprehensive crack sensitivity model (CCS) for composition design of high-throughput nickel-based high-temperature alloy for additive manufacturing based on multi-objective optimization is provided in an embodiment of the present invention.

[0023] Figure 2 The crack prediction effect of the comprehensive crack sensitivity model (CCS) established by the present invention.

[0024] Figure 3 A flow chart of a method for designing high-throughput nickel-based high-temperature alloy composition for additive manufacturing based on multi-objective optimization is provided in an embodiment of the present invention.

[0025] Figure 4 The multi-objective optimization problem and the established Pareto frontier were established to study the connection between element content and CCS and yield strength. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments described in the present invention without creative efforts fall within the protection scope of the present invention.

[0027] In the embodiments of the present invention, descriptions such as "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features.

[0028]

First Embodiment

[0029] A comprehensive crack sensitivity model (CCS) for the composition design of high-throughput nickel-based superalloys for additive manufacturing based on multi-objective optimization provided by the first embodiment of the present invention is as follows:

[0030] CCS = 0.45 * CSI - 0.3 * TS - 0.25 * DR

[0031] See Figure 1 , a modeling method for a comprehensive crack sensitivity model of the composition design of high-throughput nickel-based superalloys for additive manufacturing based on multi-objective optimization provided by the first embodiment of the present invention, characterized by including the following steps:

[0032] Step P1: Collect data on cracking conditions and corresponding alloy compositions during the additive manufacturing of existing nickel-based superalloys to create a database.

[0033] Further, step P2: Calculate the solidification crack sensitivity, liquefaction crack sensitivity, and solid-state crack sensitivity of each alloy composition in the database, that is, calculate the CSI value, TS value, and DR value.

[0034] Step P2.1: Write out the solidification crack sensitivity, liquefaction crack sensitivity, and solid-state crack sensitivity models, and the specific models are as follows respectively.

[0035]

[0036] TS = solidus temperature (2)

[0037]

[0038] where T is temperature, f s is the solid volume fraction, i is the i-th solute atom, β i is the strengthening coefficient of the i-th solute atom, are the concentrations of the i-th solute atom in the dendrite core and interdendritic space, respectively.

[0039] Step P2.2: Calculate the relevant thermodynamic information of each alloy component collected in step P1 according to relevant thermodynamic software and thermodynamic database.

[0040] Step P2.3: Extract the temperature and corresponding solid volume when the solid volume fraction is 90%, 99% and 100% according to the results in step P2.2.

[0041] Step P2.4: Combine the results in step P2.3 with formulas (1), (2) and (3) to calculate the solidification crack sensitivity, liquefaction crack sensitivity and solid state crack sensitivity of each alloy component, that is, calculate the CSI value, TS value and DR value.

[0042] Step P3: A comprehensive crack sensitivity model (CCS) is established based on the solidification crack sensitivity, liquefaction crack sensitivity and solid crack sensitivity in the additive manufacturing process of nickel-based high-temperature alloys. The model is as follows:

[0043] CCS=x*CSI-y*TS-z*DR (4)

[0044] Further, step P4: according to the cracking conditions of the alloy in the database, determine the weights of the crack sensitivities in the model and the CCS values ​​for distinguishing cracking and non-cracking. Specifically, the comprehensive crack sensitivity model (CCS) in this embodiment is:

[0045] CCS=0.45*CSI-0.3*TS-0.25*DR (5)

[0046] The CCS value that distinguishes cracking and non-cracking is -0.15, that is, when the CCS value is less than -0.15, the alloy is not easy to crack during the additive manufacturing process; when the CCS value is greater than -0.15, the alloy is easy to crack during the additive manufacturing process.

[0047] [Second embodiment]

[0048] The second embodiment of the present invention provides a new method for designing high-throughput nickel-based high-temperature alloy composition for additive manufacturing based on multi-objective optimization, such as Figure 3 As shown, the following steps are included:

[0049] Step S1: preset N alloy elements other than nickel, and predefine the alloy element search range. Specifically, the present invention is based on the currently available K438 alloy as an example to optimize the composition, and the N is 11; the predefined alloy element search range is: Al 2.0-5.0wt.%, B0.01wt.%, C 0.15wt.%, Co 8.5wt.%, Cr 16.0wt.%, Mo0.5-3.0wt.%, Nb 0.9wt.%, Ta 1.75wt.%, Ti 1.0-4.0wt.%, W 2.6wt.%, Zr 0.05wt.% (the content changes of Al, Mo and Ti3 elements are specifically considered in the embodiment of the present invention).

[0050] Further, step S2: within the composition search range predefined in step S1, candidate elements of different compositions are randomly generated by a genetic algorithm: about 25,000 alloy compositions are uniformly generated between the predefined minimum and maximum values.

[0051] Step S3: high-throughput thermodynamic calculation to obtain relevant thermodynamic information of the candidate alloy.

[0052] Furthermore, step S4: according to the relevant thermodynamic information, CCS model and high temperature yield strength model of the candidate alloys obtained in step S3, their CCS values ​​and yield strengths at 850°C are calculated.

[0053] Step S4.1: According to the result in step S3, the temperatures when the solid volume fraction is 90%, 99% and 100% are extracted.

[0054] Step S4.2: Combine equations (1), (2) and (3) with the solid phase volume fraction and corresponding temperature extracted in step S4.1 to calculate the CSI, TS and DR values ​​of the candidate alloy.

[0055] Step S4.3: Combine the results in step S4.2 and the comprehensive crack sensitivity model formula (5) to calculate the CCS value of the candidate alloy.

[0056] Step S4.4: Based on the results in step S3, extract the volume fraction of the γ matrix phase, the fraction of each solute atom in the γ matrix phase and the volume fraction of the γ' phase of the candidate alloy at 850°C.

[0057] Step S4.5: Combining the result in step S4.4 with the yield strength model of nickel-based high-temperature alloy, the yield strength of the candidate alloy at 850°C is calculated. The specific high-temperature yield strength model is shown in formula (6):

[0058]

[0059] Where T is temperature, f γand f γ′ represent the volume fraction of the γ matrix phase and the volume fraction of the γ' strengthening phase, respectively. x i is the atomic concentration of the i-th solute atom in the γ matrix phase, and β i is the solution strengthening coefficient of the i-th solute atom.

[0060] Step S5: According to the results of Step S4, plot the Pareto front of the CCS value and the yield strength at 850 °C for the candidate alloys, and obtain the required nickel-based superalloy for additive manufacturing. Finally, the specific composition of one of the alloys on the Pareto front is Al 5.0 wt.%, B 0.01 wt.%,

[0061] C 0.15 wt.%, Co 8.5 wt.%, Cr 16.0 wt.%, Mo 3.0 wt.%, Nb 0.9 wt.%, Ta

[0062] 1.75 wt.%, Ti 1.7 wt.%, W 2.6 wt.%, Zr 0.05 wt.%.

Claims

1. A comprehensive crack sensitivity model (CCS) for composition design of high-throughput nickel-based superalloys for additive manufacturing based on multi-objective optimization, as follows: CCS=0.45*CSI-0.3*TS-0.25*DR.

2. A modeling method for a comprehensive crack sensitivity model for high-throughput nickel-based high-temperature alloy composition design for additive manufacturing based on multi-objective optimization, characterized in that: The following steps are involved: Step P1: Collect the cracking data and corresponding alloy composition in the additive manufacturing process of existing nickel-based high-temperature alloys and create a database; Step P2: Calculate the solidification crack sensitivity, liquefaction crack sensitivity and solid crack sensitivity of each alloy component in the database, that is, calculate the CSI value, TS value and DR value; Step P3: Establish a comprehensive crack sensitivity model (CCS) based on the solidification crack sensitivity, liquefaction crack sensitivity and solid crack sensitivity in the additive manufacturing process of nickel-based high-temperature alloys; Step P4: According to the cracking conditions of the alloy in the database, determine the weight of each crack sensitivity in the model and the CCS value for distinguishing cracking and non-cracking.

3. The method for modeling a comprehensive crack sensitivity model for high-throughput nickel-based high-temperature alloy composition design for additive manufacturing according to claim 2, characterized in that: The model in step P3 is as follows: CCS=x*CSI-y*TS-z*DR.

4. The method for modeling a comprehensive crack sensitivity model for optimizing the composition design of a high-throughput nickel-based high-temperature alloy for additive manufacturing according to claim 2, characterized in that: The CCS value for distinguishing cracking and non-cracking in step P4 is -0.15, that is, when the CCS value is less than -0.15, the alloy is not easy to crack during the additive manufacturing process; when the CCS value is greater than -0.15, the alloy is easy to crack during the additive manufacturing process.

5. A new method for designing high-throughput nickel-based superalloy composition for additive manufacturing based on multi-objective optimization, characterized in that: The following steps are involved: Step S1: presetting N alloy elements other than nickel, and predefining a search range of the alloy elements; Step S2: generating a series of candidate alloys with different compositions within a predetermined alloy element search range; Step S3: high-throughput thermodynamic calculation to obtain relevant thermodynamic information of the candidate alloy; Step S4: according to the relevant thermodynamic information, CCS model and high temperature yield strength model of the candidate alloys obtained in step S3, the CCS value and the yield strength at 850°C are calculated; Step S5: According to the result of step S4, the Pareto frontier of the CCS value and the yield strength at 850°C of the candidate alloy is plotted, and the desired nickel-based high-temperature alloy for additive manufacturing is obtained.

6. A new method for designing high-throughput nickel-based high-temperature alloy composition for additive manufacturing based on multi-objective optimization according to claim 5, characterized in that: The present invention is based on the existing K438 alloy as an example to optimize the composition. The N in step S1 is 11; the predefined alloy element search range is: Al 2.0-5.0wt.%, B 0.01wt.%, C0.15wt.%, Co 8.5wt.%, Cr 16.0wt.%, Mo 0.5-3.0wt.%, Nb 0.9wt.%, Ta 1.75wt.%, Ti 1.0-4.0wt.%, W 2.6wt.%, Zr 0.05wt.% (the content changes of three elements, Al, Mo and Ti, are specifically considered in the embodiments of the present invention).

7. A new method for designing high-throughput nickel-based high-temperature alloy composition for additive manufacturing based on multi-objective optimization according to claim 5, characterized in that: The step S4 comprises the following steps: Step S4.1: According to the result in step S3, extract the temperature when the solid volume fraction is 90%, 99% and 100%; Step S4.2: Calculate the CSI, TS and DR values ​​of the candidate alloy using the solid phase volume fraction and corresponding temperature extracted in step S4.1; Step S4.3: Combining the result in step S4.2 with the CCS model, the CCS value of the candidate alloy is calculated; Step S4.4: according to the result in step S3, extracting the volume fraction of the γ matrix phase, the fraction of each solute atom in the γ matrix phase and the volume fraction of the γ' phase of the candidate alloy at 850°C; Step S4.5: Combining the result in step S4.4 with the yield strength model of nickel-based high-temperature alloys, calculate the yield strength of the candidate alloy at 850°C.

8. The new method for designing high-throughput nickel-based high-temperature alloy composition for additive manufacturing based on multi-objective optimization according to claim 5, characterized in that: In step S5, one of the alloys at the Pareto frontier at the end, namely a newly designed high-strength and printable new nickel-based high-temperature alloy, is Al 5.0wt.%, B 0.01wt.%, C 0.15wt.%, Co 8.5wt.%, Cr 16.0wt.%, Mo 3.0wt.%, Nb 0.9wt.%, Ta 1.75wt.%, Ti 1.7wt.%, W 2.6wt.%, Zr 0.05wt.%.

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