A method for evaluating the additive manufacturing cracking sensitivity of a nickel-based superalloy and applications thereof

Abstract

The application discloses a kind of nickel-based superalloy additive manufacturing cracking sensitivity evaluation methods, first propose using alloy solidification temperature interval ΔT S As a criterion, in combination with the additive manufacturing processing result of alloy surface, the additive manufacturing cracking sensitivity of nickel-based superalloy is evaluated, and the composition of low cracking sensitivity of nickel-based superalloy for additive manufacturing is quickly screened and designed. Through criterion preliminary judgment-laser additive manufacturing scanning of casting blank surface-surface topography observation-powder additive manufacturing, whether the alloy of design composition will crack in the process of additive manufacturing is observed, and according to whether cracking condition, solidification temperature range criterion (ΔT S ) Critical Is corrected, and finally the low cracking sensitivity nickel-based superalloy that can be directly applied to additive manufacturing is designed. The application can be used for the rapid iterative design of special alloy system for additive manufacturing, reduce development cost, improve research and development efficiency, and can be popularized to the development and design of other additive manufacturing alloy system. At the same time, it can be used for the rapid acquisition of alloy additive manufacturing process parameter range.

Description

Technical Field

[0001] This invention relates to a method and application for assessing the cracking sensitivity of nickel-based superalloy additive manufacturing, belonging to the field of superalloys and additive manufacturing. Background Technology

[0002] Additive manufacturing, with its extremely high energy input and temperature gradients and rapid solidification rate, is a crucial technology for fabricating high-performance, complex structural components. Nickel-based superalloys, with their complex compositions and excellent high-temperature mechanical properties, have wide applications in aerospace and shipbuilding. However, nickel-based superalloys are highly susceptible to cracking during additive manufacturing, which limits their application in complex structural components.

[0003] Currently, the main method for assessing the crack susceptibility of nickel-based superalloy additive manufacturing is to directly use powder to create printed parts and then observe whether the printed parts crack. This method is lengthy, inefficient, and costly. There is currently no efficient method for evaluating the crack susceptibility of nickel-based superalloy additive manufacturing.

[0004] To address the aforementioned problems, this invention provides a method for assessing the crack sensitivity of nickel-based superalloys in additive manufacturing. This method can quickly and efficiently assess and verify the crack sensitivity of nickel-based superalloys in additive manufacturing, providing a novel solution for the composition design and evaluation of nickel-based superalloys used in additive manufacturing. Summary of the Invention

[0005] To address the lack of effective assessment methods and theoretical guidance for the crack sensitivity of nickel-based superalloys in additive manufacturing, this invention provides a method for assessing the crack sensitivity of nickel-based superalloys in additive manufacturing. For the first time, it proposes using the solidification temperature range ΔT of the alloy. S As a criterion, combined with the additive manufacturing process of alloy surfaces, the additive manufacturing crack sensitivity of nickel-based superalloys is evaluated, and nickel-based superalloy compositions with low crack sensitivity for additive manufacturing are quickly screened and designed.

[0006] This invention discloses a method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing, comprising the following steps:

[0007] (1) Based on the composition of the nickel-based superalloy to be evaluated, select the corresponding nickel-based superalloy as the reference alloy and obtain the solidification temperature range ΔT of the reference alloy. 参S (=T) 参L –T 参S ), as the critical solidification temperature range (ΔT) S ) Critical ;

[0008] (2) Based on the composition of the nickel-based superalloy to be evaluated, obtain the liquidus point temperature T of the nickel-based superalloy to be evaluated. 参L and solid point temperature T 参S Calculate the solidification temperature range ΔT of the nickel-based superalloy to be evaluated. 待S ; where ΔT 待S The smaller the value, the lower the cracking sensitivity of the nickel-based superalloy to be evaluated;

[0009] (3) When the ΔT of the nickel-based superalloy to be evaluated 待S Satisfy ΔT 待S ≤(ΔT S ) Critical At that time, raw materials were prepared according to the composition of the alloy to be evaluated, alloy billets were made, homogenized and heat-treated to obtain the nickel-based high-temperature alloy bulk material to be evaluated;

[0010] (4) According to the additive manufacturing process, the nickel-based superalloy block to be evaluated is subjected to additive manufacturing surface treatment, and the presence of cracks is observed. If there are no cracks, it is determined that the additive manufacturing crack sensitivity of the nickel-based superalloy to be evaluated is low.

[0011] In step (1), the reference alloy is preferably René 104, Inconel 738 or CM247LC, as well as other known nickel-based high-temperature alloys.

[0012] This invention discloses a method for assessing the crack sensitivity of nickel-based superalloys in additive manufacturing, wherein the liquidus point temperature T of the nickel-based superalloy is... L and solid point temperature T S The methods for obtaining it include:

[0013] Obtained from the DSC curve of the alloy;

[0014] The liquidus point and solidus point of the alloy can be calculated using the following formulas:

[0015] T L = A + a1·X1+ a2·X2+ a3·X3+ a4·X4+ ········ (1)

[0016] T S = B + b1·X1+ b2·X2+ b3·X3+ b4·X4+ ········ (2)

[0017] The liquid point temperature T is calculated using formulas (1) and (2). L and solid point temperature T S Where A and B are characteristic constants, which are related to the material, and a i and b i These are the liquidus point temperatures T of component i in the alloy, respectively.L and solid point temperature T S Correlation coefficient, X i It is the molar percentage of alloy component i;

[0018] Alternatively, you can obtain the information by consulting relevant literature.

[0019] This invention discloses a method for assessing the crack sensitivity of nickel-based superalloys in additive manufacturing. The calculation formulas for the liquidus point and solidus point of the nickel-based superalloy are as follows:

[0020] T S = -120 + 17.7· X Ni +16.0· X Co + 15.2· X Al + 2.1· X Ti + 13.4· X Ta + 19.2· X Cr +5.0· X Mo + 20.4· X W + 34.3· X RE + 23.1· X Ru + 15.4· X Fe + 6.4·( X Nb + X Hf (3)

[0021] T L = 956.9 + 8.2 X Ni + 7.6· X Co + 2.2· X Al + 3.4· X Ti – 3.7· X Ta + 3.9· X Cr + 7.2· X Mo +11.5· X W + 21.1· XRE + 12.1· X Ru + 7.4· X Fe – 3.3·( X Nb + X Hf (4)

[0022] Then, the solidification temperature range ΔT of the nickel-based superalloy is calculated. S =T L –T S .

[0023] This invention discloses a method for assessing the crack sensitivity of nickel-based superalloys in additive manufacturing. When the nickel-based superalloy to be assessed satisfies ΔT... 待S ≤(ΔT S ) Critical At that time, the raw materials were prepared according to the composition of the nickel-based high-temperature alloy to be evaluated, melted, and cast into a billet. The billet was homogenized. The billet was machined to make a block material with a thickness greater than 5 mm. The obtained block was surface-processed to make a surface with a roughness of less than 1.6 μm for additive manufacturing and sandblasted to obtain a clean surface-treated alloy block for additive manufacturing.

[0024] In this invention, the thickness of the block is selected to be more than 5 mm in order to avoid the internal stress generated during the additive manufacturing process causing the block to warp and deform, which would lead to misjudgment.

[0025] In this invention, the surface roughness of the block is selected to be below 1.6 μm in order to improve the accuracy of laser processing and prevent local overheating, which could lead to misjudgment.

[0026] This invention discloses a method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing. The method involves laser additive manufacturing of the alloy block surface. The laser additive manufacturing parameters are: laser power of 250-380 W, laser scanning speed of 400-1100 mm / s, overlap spacing of 70-110 μm, preheating temperature of 100-200 ℃, and scanning method of serpentine or checkerboard scanning. The protective atmosphere is an inert gas, helium, argon, or a mixture of argon and helium, wherein the oxygen content is less than 0.0001 wt.%.

[0027] This invention provides a method for assessing the cracking sensitivity of nickel-based superalloy additive manufacturing, by observing the surface condition of alloy blocks processed by laser additive manufacturing;

[0028] When the alloy block does not crack after laser additive manufacturing surface treatment, it indicates that the alloy has low additive manufacturing crack sensitivity and will not crack during additive manufacturing, and can be used for additive manufacturing.

[0029] When cracks appear in the alloy block after laser additive manufacturing surface treatment, it indicates that the alloy has a high sensitivity to additive manufacturing cracking and will experience additive manufacturing cracking.

[0030] Application of the present invention: A method for assessing the crack susceptibility of nickel-based superalloy additive manufacturing:

[0031] When the alloy block does not crack after laser additive manufacturing surface treatment, (ΔT) S ) Critical It can be used as a criterion for the cracking susceptibility of the nickel-based superalloy system to be evaluated, and can be used to assess the cracking susceptibility of the nickel-based superalloy system in this system.

[0032] When cracks appear in the alloy block after laser additive manufacturing surface treatment, the crack sensitivity criterion (ΔT) needs to be adjusted. S ) Critical Decrease (ΔT) S ) Critical The value of ΔT is used as the new criterion. S ) Critical Repeat steps (1) to (4) to observe whether the alloy block after laser additive manufacturing surface treatment cracks; take the uncracking alloy as the optimized alloy and take the solidification temperature range of the optimized alloy as the new criterion.

[0033] This invention relates to an application of a method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing. When cracks appear in the alloy block after laser additive manufacturing surface treatment, the crack sensitivity criterion (ΔT) is adjusted. S ) Critical Decrease (ΔT) S ) Critical The value of ΔT is used as the new criterion. S ) Critical The composition of the nickel-based high-temperature alloy to be evaluated is optimized. Steps (1) to (4) are repeated until the alloy block after laser additive manufacturing surface treatment does not crack. The alloy that does not crack is taken as the optimized alloy. Alloy powder is prepared according to the optimized alloy composition. Alloy powder is prepared into alloy block by additive manufacturing technology. The rationality of the new criterion is further verified by observing whether the alloy cracks.

[0034] If no cracks occur, the optimized alloy has low cracking sensitivity in additive manufacturing and can be used for additive manufacturing. The solidification temperature range of the optimized alloy is used as a new criterion (∆T). S ) Critical This is used as a criterion for evaluating the alloy system;

[0035] If cracking occurs, repeat the above steps until no cracking occurs, obtaining an alloy that does not crack. The solidification temperature range of the crack-free alloy is used as a new criterion (∆T).S ) Critical .

[0036] This invention relates to an application of a method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing. The method involves observing whether the alloy block, after laser additive manufacturing surface treatment, cracks. If no cracks appear in the alloy block, alloy powder is prepared, and additive manufacturing technology is used to prepare the alloy powder into a block. The surface condition of the additively manufactured alloy block is observed to obtain a crack-free nickel-based superalloy prepared by additive manufacturing, thus verifying the accuracy of the assessment method.

[0037] This invention relates to an application of a method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing, wherein the nickel-based superalloy to be assessed satisfies ΔT 待S ≤(ΔT S ) Critical According to the designed alloy configuration, the raw materials are used to make an alloy billet. After the alloy block is subjected to laser additive manufacturing surface treatment with certain parameters, the state of the laser additive manufacturing surface is observed to obtain the range of additive manufacturing process parameters that do not crack, which is used as the range of laser additive manufacturing parameters suitable for the alloy.

[0038] This invention relates to an application of a method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing, wherein the nickel-based superalloy to be assessed satisfies ΔT 待S ≤(ΔT S ) Critical At that time, according to ΔT 待S The smaller the size, the better the composition of nickel-based high-temperature materials.

[0039] In summary, the advantages and positive effects of this invention are:

[0040] (1) This invention is the first to design a method for "obtaining the solidification range ΔT of the alloy". S The "preliminary judgment based on criteria—laser scanning of the billet surface—observation and re-judgment of surface morphology" judgment path provides a novel approach for rapidly determining the cracking susceptibility of nickel-based superalloy additive manufacturing. This invention's judgment path, combined with powder additive manufacturing verification, allows for simultaneous iteration of criteria and optimization of the target product composition. This not only provides the necessary conditions for accurate and rapid judgment but also strongly guarantees the exponential growth of composition optimization speed.

[0041] (2) This invention is the first to propose using the solidification range ΔT of the alloy. S As the critical solidification criterion (ΔT) S ) Critical This critical solidification criterion is used as an evaluation criterion for the crack sensitivity of nickel-based superalloy additive manufacturing. It can be used for rapid screening of nickel-based superalloy components for laser additive manufacturing, which can quickly optimize alloy composition, improve the accuracy of the criterion, and greatly reduce the number of experiments and workload.

[0042] (3) The present invention ingeniously designed the "obtaining alloy solidification range ΔT" S The process of "preliminary judgment based on criteria, laser scanning of the billet surface, observation and re-judgment of surface morphology, and verification and optimization through powder additive manufacturing" combines multiple cyclic verifications when necessary to achieve rapid iteration of the selected nickel-based superalloy composition and the corresponding crack sensitivity criterion (ΔT). S ) Critical Optimization.

[0043] (4) The present invention uses optimized alloy powder to perform additive manufacturing under multiple parameters to obtain additive manufacturing process parameters that do not crack. It can quickly determine and / or broaden the range of additive manufacturing process parameters for alloys and can be used for all high-temperature alloys, as well as other alloy systems used for additive manufacturing. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the overall design concept of the present invention;

[0045] Figure 2 The image shows the metallographic structure of the René 104 alloy in Example 1.

[0046] Figure 3 The image shows the metallographic structure of the René 104 LAT alloy in Example 1.

[0047] Figure 4 Metallographic image of René104 HfY alloy in Example 2;

[0048] Figure 5 Metallographic image of René104ScY alloy in Example 3;

[0049] Figure 6 Metallographic image of René104ScY alloy in Example 2;

[0050] Figure 7 The metallographic image of the Inconel 738 alloy cited in Example 5;

[0051] Figure 8 The metallographic image of the Inconel 738 Hf alloy cited in Example 5;

[0052] Figure 9 The metallographic image of the CM247LC alloy cited in Example 6;

[0053] Figure 10 The image shows the metallographic diagram of the CM247LC Hf alloy cited in Example 6. Detailed Implementation

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0055] Example 1:

[0056] To practically evaluate the scientific validity and practicality of the method proposed in this invention, René 104 nickel-based superalloy was first selected as the reference alloy system, the composition of which is shown in Table 1 below.

[0057]

[0058] This alloy is known to be highly susceptible to cracking during additive manufacturing. The metallographic image of the printed part is shown below. Figure 2 As shown. The theoretical liquidus point temperature and solidus point temperature of René 104 alloy are calculated using formulas (3) and (4), respectively:

[0059] T S = -120 + 17.7· X Ni +16.0· X Co + 15.2· X Al + 2.1· X Ti + 13.4· X Ta + 19.2· X Cr +5.0· X Mo + 20.4· X W + 34.3· X RE + 23.1· X Ru + 15.4· X Fe + 6.4·( X Nb + X Hf (3)

[0060] T L = 956.9 + 8.2 X Ni + 7.6· X Co + 2.2·X Al + 3.4· X Ti – 3.7· X Ta + 3.9· X Cr +7.2· X Mo +11.5· X W + 21.1· X RE + 12.1· X Ru + 7.4· X Fe – 3.3·( X Nb + X Hf (4)

[0061] Calculate the solidus temperature T of René 104 alloy S =1507.55 K and the liquidus point temperature are respectively T L =1621.09 K, further calculate ΔT S =113.54K, therefore let (ΔT) S ) Critical = ΔT S =113.54K.

[0062] The composition of René104 nickel-based superalloy was improved by reducing the content of Al and Ti elements to obtain René104LAT nickel-based superalloy. The specific composition is shown in Table 2. Its cracking sensitivity was evaluated and verified.

[0063] Step 1: Select René 104LAT nickel-based superalloy, the composition of which is shown in the table below.

[0064]

[0065] Step 2: Calculate the theoretical liquidus point temperature and solidus point temperature of René 104 LAT alloy using formulas (3) and (4), respectively:

[0066] T S = -120 + 17.7· X Ni +16.0· X Co + 15.2· X Al + 2.1· XTi + 13.4· X Ta + 19.2· X Cr +5.0· X Mo + 20.4· X W + 34.3· X RE + 23.1· X Ru + 15.4· X Fe + 6.4·( X Nb + X Hf (3)

[0067] T L = 956.9 + 8.2 X Ni + 7.6· X Co + 2.2· X Al + 3.4· X Ti – 3.7· X Ta + 3.9· X Cr +7.2· X Mo +11.5· X W + 21.1· X RE + 12.1· X Ru + 7.4· X Fe – 3.3·( X Nb + X Hf (4)

[0068] The calculated solidus temperature T of René 104LAT alloy S =1534.34 K and the liquidus point temperature are respectively T L =1641.62 K, further calculate ΔT S =107.27K.

[0069] Step 3: Determine the printing cracking tendency of René 104LAT alloy: due to ΔT S <(ΔT)S ) Critical Therefore, it is judged that René104LAT has a relatively low tendency to crack.

[0070] Step 4: Prepare raw materials according to the composition of René 104LAT alloy, melt the pure metal and intermediate alloy, cast them into a billet, and homogenize the billet; machine the homogenized billet to make a cylindrical block with a thickness of 6 mm and a diameter of 40 mm, and then grind and sandblast the surface to be laser scanned.

[0071] Step 5: A high-energy laser beam with a power of 320 W is applied to the surface of the cast René 104LAT alloy block. The laser scanning speed is 500 mm / s, and the laser scanning interval is 80 μm. The protective atmosphere is an inert gas: helium, argon, or a mixture of argon and helium, wherein the oxygen content is less than 0.0001 wt.%.

[0072] Step 6: Observe whether there is cracking in the laser scanning area. The results show that René104LAT alloy does not crack during the actual printing process.

[0073] Step 7: Laser powder bed fusion (LPBF) was performed using René104LAT alloy atomized powder. The forming parameters were: laser power 320 W, scanning speed 500 mm / s, and scanning spacing 80 μm, resulting in a completely crack-free René104 LAT nickel-based superalloy printed part, such as... Figure 3 As shown, the feasibility of the proposed solution in this invention is further verified.

[0074] Therefore, the ΔT of René 104 alloy S This can be used as the current (ΔT) of the alloy in this system. S ) Critical It is used as a criterion for the susceptibility of additive manufacturing cracking of nickel-based superalloys in the René 104 system, and is used to evaluate the susceptibility of additive manufacturing cracking of nickel-based superalloys in this system.

[0075] To further increase the reliability of the criterion, ΔT of René 104 LAT can be used. S It can be used as a further optimized criterion for the development of new nickel-based superalloys.

[0076] Example 2:

[0077] Based on the results of Example 1, in order to further verify the effect of rare earth microalloying on the crack susceptibility of René104 alloy, this example uses Hf and Y microalloying to improve René104 alloy, obtaining René104HfY alloy, the specific composition of which is shown in Table 3. Its crack susceptibility is then evaluated:

[0078]

[0079] Using the ΔT of the René 104 alloy from Example 1 S =113.54K, as (ΔT) S ) Critical .

[0080] The solidus temperature T of René104 HfY alloy was calculated using formulas (3) and (4). S =1507.75 K and the liquidus point temperature are respectively T L = 1621.33 K, further calculate ΔT S =113.42 K.

[0081] Because of ΔT S <(ΔT) S ) Critical Therefore, it was determined that René104 HfY has a low tendency to crack, and it was initially concluded that the René104 HfY alloy has high printability. Therefore, the billet preparation and surface observation processes in steps 4 to 6 of Example 1 were omitted, and step 7 was directly performed to verify the crack sensitivity of additive manufacturing using René104 HfY alloy powder.

[0082] René104 HfY alloy powder was prepared according to the composition of René104 HfY alloy, and then formed using laser powder bed melting technology. The forming parameters were: laser power 320 W, scanning speed 400 mm / s, and overlap spacing 80 μm. The metallographic image of the printed part is shown below. Figure 4 As shown, no cracking occurred. The verification results indicate that the René104HfY alloy has low cracking susceptibility.

[0083] Finally, René104 HfY alloy powder was shaped using laser powder bed melting process parameters of 200-360 W laser power and 600-1100 mm / s scanning speed. The metallographic images of a batch of samples prepared are shown below. Figure 5 As shown, no additive manufacturing cracking occurred in any of the samples. This verification result further demonstrates that the René104HfY alloy has low cracking susceptibility.

[0084] The above experimental results show that:

[0085] (1) By using Hf and Y microalloying to improve René104 alloy, the cracking sensitivity of René104 alloy can be significantly reduced, and crack-free additive manufacturing René104HfY alloy can be directly obtained.

[0086] (2) The nickel-based superalloy additive manufacturing sensitivity assessment method proposed in this invention is reliable, the assessment results are forward-looking, the composition design method involved is practical and feasible, and it can quickly screen alloy compositions. The additive manufacturing cracking sensitivity criterion (ΔT) S ) Critical Accurate and reliable;

[0087] (3) This invention can explore parameters suitable for additive manufacturing, thus broadening the range of additive manufacturing process parameters.

[0088] Example 3:

[0089] The René104 alloy was improved by microalloying with Sc and Y to obtain the René104ScY alloy. The specific composition is shown in Table 4. Its cracking sensitivity was evaluated.

[0090]

[0091] Using the ΔT of the René 104 alloy from Example 1 S =113.54K, as (ΔT) S ) Critical .

[0092] The solidus temperature T of René 104ScY alloy was calculated according to formulas (3) and (4). S =1510.72 K and the liquidus point temperature are respectively T L =1623.14 K, further calculate ΔT S =112.42K.

[0093] Because of ΔT S <(ΔT) S ) Critical Therefore, René104ScY was judged to have a low tendency to crack and high printability, and was preliminarily identified as having high printability. Therefore, the billet preparation and surface observation processes in steps 4 to 6 of Example 1 were omitted, and step 7 was directly performed to verify the crack sensitivity of additive manufacturing using René104ScY alloy powder.

[0094] René 104ScY alloy powder was prepared according to the composition of René 104ScY alloy, and then formed using laser powder bed melting technology. The forming parameters were: laser power 320 W, scanning speed 400 mm / s, and overlap spacing 80 μm. The crack sensitivity of René 104ScY alloy was verified, and the metallographic image of the printed part is shown below. Figure 6 As shown, no cracking occurred. The verification results indicate that the René104ScY alloy has low cracking susceptibility.

[0095] The above experimental results show that:

[0096] (1) By using Sc and Y microalloying to improve René104 alloy, the cracking sensitivity of René104ScY alloy can be significantly reduced, and crack-free additive manufacturing René104ScY alloy can be obtained directly.

[0097] (2) The nickel-based superalloy additive manufacturing sensitivity assessment method proposed in this invention is reliable, the assessment results are forward-looking, the composition design method involved is practical and feasible, and it can quickly screen alloy compositions. The additive manufacturing cracking sensitivity criterion (ΔT) S ) Critical Accurate and reliable.

[0098] Example 4:

[0099] Based on Example 1, the composition of René104 nickel-based superalloy was improved by increasing the content of Al and Ti elements to obtain René104 HAT. The specific composition is shown in Table 5. Its cracking sensitivity was evaluated and verified.

[0100]

[0101] Using the ΔT of the René 104 alloy from Example 1 S =113.54K, as (ΔT) S ) Critical .

[0102] The solidus temperature T of René 104HAT alloy was calculated according to formulas (3) and (4). S =1542.31 K and the liquidus point temperature are respectively T L = 1659.63 K, further calculate ΔT S =117.32K, because ΔT S >(ΔT) S ) Critical Therefore, it is judged that René104HAT has a high tendency to crack, poor printability, and is prone to additive manufacturing cracks.

[0103] Following steps 4-5 of Example 1, laser additive manufacturing scanning was performed on the surface of the block, resulting in cracking.

[0104] Therefore, step 7 in Example 1 is not performed.

[0105] Based on the results and optimized design approach of this embodiment, the alloy composition design approach of this embodiment is abandoned. This saves a significant number of experiments and workload, and provides a clear direction for alloy composition design.

[0106] Example 5:

[0107] Inconel 738 nickel-based superalloy

[0108] [1] Yu et. al, The effect of Hf on solidification cracking inhibition of IN738LC processed by Selective Laser Melting, Materials Science &Engineering A, 804 (2021) 140733;

[0109] To further evaluate the scientific validity and practicality of the method proposed in this invention, Inconel 738 nickel-based superalloy was selected as the reference alloy system.

[0110] Yu et al. [1] prepared Inconel 738 nickel-based superalloy using selective laser melting. The composition of Inconel 738 alloy is shown in Table 6. Additive manufacturing cracks appeared in the Inconel 738 alloy printed parts (printing parameters: power 250w, scanning speed 900mms, overlap spacing 80μm). Figure 7 As shown, Inconel 738 exhibits high susceptibility to cracking in additive manufacturing.

[0111]

[0112] The solidus temperature T of Inconel 738 alloy was calculated using formulas (3) and (4) respectively. S =1554.78 K and the liquidus point temperature are respectively T L = 1639.13 K, further calculate the solidification interval ΔT S =84.35K, Inconel 738 is known to have a high tendency to crack and poor printability, let (ΔT) S ) Critical =ΔT S =84.35 K.

[0113] Yu et al. [1] used Hf element to improve the composition of Inconel 738 nickel-based superalloy, and its composition is shown in Table 7.

[0114]

[0115] The solidus temperature T of Inconel 738 Hf alloy was calculated using formulas (3) and (4). S =1561.18 K and the liquidus point temperature are respectively T L = 1635.83 K, further calculate the solidification interval ΔTS =74.65K, ΔT S =74.65K<(ΔT S ) Critical =84.35 K, cracking tendency is reduced, and it is preliminarily determined that the printability is high.

[0116] Yu et al. [1] prepared a batch of Inconel 738 Hf alloy samples using laser powder bed melting process parameters of laser power 150-300 W, scanning speed 550-2000 mm / s, and overlap spacing 90-130 μm. Among them, the metallographic image of the product obtained with laser power of 230 W, scanning speed of 750 mm / s, and overlap spacing of 100 μm is shown in the figure. Figure 8 As shown, no cracking occurred. Experiments verify that Inconel Hf 738 alloy has low cracking sensitivity in additive manufacturing and no additive manufacturing cracking occurred.

[0117] The experimental results of Yu et al. [1] show that:

[0118] (1) The method for assessing the sensitivity of nickel-based superalloy additive manufacturing proposed in this invention is reliable and the assessment results are forward-looking. The composition design method involved can be used for the composition design of Inconel 738 nickel-based superalloy system. By using Hf to improve Inconel 738 alloy, the cracking sensitivity of Inconel 738 alloy can be significantly reduced, and crack-free additive manufacturing Inconel 738 alloy can be obtained directly.

[0119] (2) The work of Yu et al. [1] verified that the nickel-based superalloy additive manufacturing sensitivity assessment method and the composition design method involved in this invention are feasible and can quickly screen alloy composition. The additive manufacturing cracking sensitivity criterion (ΔT) S ) Critical Accurate and reliable.

[0120] Example 6:

[0121] CM247LC Nickel-Based High Temperature Alloy

[0122] [2] Griffiths et. al, Influence of Hf on the heat treatment response of additively manufactured Ni-base superalloy CM247LC, MaterialsCharacterization, 171 (2021) 110815;

[0123] CM247LC nickel-based superalloy was selected as the reference alloy system.

[0124] Griffiths et al.[2] prepared CM247LC nickel-based superalloy using laser powder bed melting technology. Its composition is shown in Table 8. Additive manufacturing cracks appeared in the CM247LC alloy printed parts, such as... Figure 9 As shown, CM247LC exhibits high susceptibility to cracking during additive manufacturing.

[0125]

[0126] The solidus temperature T of CM247LC alloy was calculated using formulas (3) and (4) respectively. S =1614.21 K and the liquidus point temperature are respectively T L = 1682.29 K, further calculate ΔT S =68.08K, given that CM247LC has a high tendency to crack and poor printability, let (ΔT) S ) Critical =ΔT S =68.08 K.

[0127] Griffiths et al. [2] used Hf element to improve the composition of CM247LC nickel-based superalloy, and its composition is shown in Table 9.

[0128]

[0129] The solidus temperature T of Hf-CM247LC alloy was calculated using formulas (3) and (4) respectively. S =1621.98 K and the liquidus point temperature are respectively T L = 1677.77K, further calculate ΔT S =55.79K, the solidification range is smaller compared to CM247LC alloy, ΔT S =55.79K<(ΔT S ) Critical =68.08K, cracking tendency is reduced, and it is preliminarily determined that the printability is high.

[0130] Griffiths et al. [2] used laser powder bed melting technology to prepare Hf-CM247LC alloy. The forming parameters were: laser power 175 W, scanning speed 750 mm / s, and overlap spacing 75 μm. The metallographic image of the prepared Hf-CM247LC alloy is shown below. Figure 10 As shown, no cracking occurred. Experiments verify that the Hf-CM247LC alloy has low cracking sensitivity in additive manufacturing and no additive manufacturing cracking occurred.

[0131] The experimental results of Griffiths et al. [2] show that:

[0132] (1) The method for assessing the sensitivity of nickel-based superalloy additive manufacturing proposed in this invention is reliable and the assessment results are forward-looking. The composition design method involved can be used for the composition design of the CM247LC nickel-based superalloy system. By using Hf to improve the CM247LC alloy, the cracking sensitivity of the Hf-CM247LC alloy can be significantly reduced, and crack-free additive manufacturing Hf-CM247LC alloy can be directly obtained.

[0133] (2) The work of Griffiths et al. [2] verified that the nickel-based superalloy additive manufacturing sensitivity assessment method and the composition design method involved in this invention are feasible and can quickly screen alloy compositions. The additive manufacturing cracking sensitivity criterion (ΔT) S ) Critical Accurate and reliable.

Claims

1. A method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing, characterized in that: Includes the following steps: (1) Based on the composition of the nickel-based superalloy to be evaluated, select the corresponding nickel-based superalloy as the reference alloy and obtain the solidification temperature range ΔT of the reference alloy. 参S As the critical solidification temperature range (ΔT) S ) Critical The ΔT 参S =T 参L –T 参S ; (2) Based on the composition of the nickel-based superalloy to be evaluated, obtain the liquidus point temperature T of the nickel-based superalloy to be evaluated. 待L and solid point temperature T 待S Calculate the solidification temperature range ΔT of the nickel-based superalloy to be evaluated. 待S ; where ΔT 待S The smaller the value, the lower the cracking sensitivity of the nickel-based superalloy to be evaluated; (3) When the ΔT of the nickel-based superalloy to be evaluated 待S Satisfy ΔT 待S ≤(ΔT S ) Critical At that time, raw materials were prepared according to the composition of the alloy to be evaluated, alloy billets were made, homogenized and heat-treated to obtain the nickel-based high-temperature alloy bulk material to be evaluated; (4) According to the additive manufacturing process, the nickel-based superalloy block to be evaluated is subjected to additive manufacturing surface treatment, and the presence of cracks is observed. If there are no cracks, it is determined that the additive manufacturing crack sensitivity of the nickel-based superalloy to be evaluated is low.

2. The method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing according to claim 1, characterized in that: Liquidation point temperature T of nickel-based superalloys L and solid point temperature T S The methods for obtaining it include: Obtained from the DSC curve of the alloy; The liquidus point and solidus point of the alloy can be calculated using the following formulas: T L = A + a1·X1+ a2·X2+ a3·X3+ a4·X4+ ······· (1) T S = B + b1·X1+ b2·X2+ b3·X3+ b4·X4+ ······· (2) The liquid point temperature T is calculated using formulas (1) and (2). L and solid point temperature T S Where A and B are characteristic constants, which are related to the material, and a i and b i These are the liquidus point temperatures T of component i in the alloy, respectively. L and solid point temperature T S Correlation coefficient, X i It is the molar percentage of alloy component i; Alternatively, you can obtain the information by consulting relevant literature.

3. The method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing according to claim 2, characterized in that: The formulas for calculating the liquidus point and solidus point of nickel-based superalloys are as follows: T S = -120 + 17.7· X Ni + 16.0· X Co + 15.2· X Al + 2.1· X Ti + 13.4· X Ta + 19.2· X Cr +5.0· X Mo + 20.4· X W + 34.3· X RE + 23.1· X Ru + 15.4· X Fe + 6.4·( X Nb + X Hf ) （3） T L = 956.9 + 8.2· X Ni + 7.6· X Co + 2.2· X Al + 3.4· X Ti – 3.7· X Ta + 3.9· X Cr +7.2· X Mo + 11.5· X W + 21.1· X RE + 12.1· X Ru + 7.4· X Fe – 3.3·( X Nb + X Hf ) （4） Then, the solidification temperature range ΔT of the nickel-based superalloy is calculated. S =T L –T S .

4. The method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing according to claim 1, characterized in that: When the nickel-based superalloy to be evaluated satisfies ΔT 待S ≤(ΔT S ) Critical According to the composition of the nickel-based high-temperature alloy to be evaluated, the raw materials are prepared, melted, and cast to obtain a billet. The billet is homogenized. The billet is machined to form a block material with a thickness greater than 5 mm. The obtained block is surface-processed to obtain a surface roughness of less than 1.6 μm for additive manufacturing and is then sandblasted to obtain a clean alloy block for additive manufacturing surface treatment.

5. The method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing according to claim 1, characterized in that: The surface of the alloy block is subjected to laser additive manufacturing. The laser additive manufacturing parameters are as follows: laser power of 250~380 W, laser scanning speed of 400~1100 mm / s, overlap distance of 70-110 μm, preheating temperature of 100-200 ℃, and scanning method of serpentine scanning or checkerboard scanning. The protective atmosphere is inert gas helium, argon, or a mixture of argon and helium, wherein the oxygen content is less than 0.0001 wt.%.

6. The method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing according to claim 5, characterized in that: Observe the surface condition of the alloy block processed by laser additive manufacturing; When the alloy block does not crack after laser additive manufacturing surface treatment, it indicates that the alloy has low additive manufacturing crack sensitivity and will not crack during additive manufacturing, and can be used for additive manufacturing. When cracks appear in the alloy block after laser additive manufacturing surface treatment, it indicates that the alloy has a high sensitivity to additive manufacturing cracking and will experience additive manufacturing cracking.

7. An application of the method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing as described in any one of claims 1 to 6, characterized in that: When the alloy block does not crack after laser additive manufacturing surface treatment, (ΔT) S ) Critical It can be used as a criterion for the cracking susceptibility of the nickel-based superalloy system to be evaluated, and can be used to assess the cracking susceptibility of the nickel-based superalloy system in this system. When cracks appear in the alloy block after laser additive manufacturing surface treatment, the crack sensitivity criterion (ΔT) needs to be adjusted. S ) Critical Decrease (ΔT) S ) Critical The value of ΔT is used as the new criterion. S ) Critical Repeat steps (1) to (4) to observe whether the alloy block after laser additive manufacturing surface treatment cracks; take the non-cracked alloy as the optimized alloy, and use the solidification temperature range of this optimized alloy as a new criterion to evaluate the alloy system.

8. The application of the method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing according to claim 7, characterized in that: When cracks appear in the alloy block after laser additive manufacturing surface treatment, the crack sensitivity criterion (ΔT) is adjusted. S ) Critical Decrease (ΔT) S ) Critical The value of ΔT is used as the new criterion. S ) Critical The composition of the nickel-based high-temperature alloy to be evaluated is optimized, and steps (1) to (4) are repeated until the alloy block after laser additive manufacturing surface treatment does not crack. The alloy that does not crack is taken as the optimized alloy. Alloy powder is prepared according to the optimized alloy composition. The alloy powder is then prepared into an alloy block using additive manufacturing technology. The rationality of the new criterion is further verified by observing whether the alloy cracks. If no cracks occur, the optimized alloy has low cracking sensitivity in additive manufacturing and can be used for additive manufacturing. The solidification temperature range of the optimized alloy is used as a new criterion (∆T). S ) Critical This is used as a criterion for evaluating the alloy system; If cracking occurs, repeat the above steps until no cracking occurs, obtaining an alloy that does not crack. The solidification temperature range of the crack-free alloy is used as a new criterion (∆T). S ) Critical .

9. The application of the method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing according to claim 7, characterized in that: Observe whether the surface-treated alloy block of laser additive manufacturing cracks; if the alloy block does not crack, prepare the alloy powder and use additive manufacturing technology to prepare the alloy powder into a block; observe the surface state of the additive-manufactured alloy block to obtain the crack-free nickel-based high-temperature alloy prepared by additive manufacturing, and verify the accuracy of the evaluation method.

10. The application of the method for assessing the crack sensitivity of nickel-based superalloy additive manufacturing according to claim 7, characterized in that: When the nickel-based high temperature to be evaluated satisfies ΔT 待S ≤(ΔT S ) Critical According to the designed alloy configuration, the raw materials are used to make an alloy billet. After the alloy block is subjected to laser additive manufacturing surface treatment with certain parameters, the state of the laser additive manufacturing surface is observed to obtain the range of additive manufacturing process parameters that do not crack, which is used as the range of laser additive manufacturing parameters suitable for the alloy.

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