A method of evaluating the formability of an aluminum alloy additively manufactured and applications

Abstract

The application discloses a method for evaluating the forming performance of aluminum alloy additive manufacturing, and first proposes using the DSC cooling curve of the aluminum alloy as a criterion, combining the surface additive manufacturing processing result of the aluminum alloy, evaluating the additive manufacturing forming performance of the aluminum alloy, and quickly screening and designing the aluminum alloy for additive manufacturing with excellent additive manufacturing forming performance. Through the DSC cooling curve preliminary judgment, the laser additive manufacturing scanning verification and iteration of the surface of the casting blank, the powder additive manufacturing verification and iteration, whether the designed aluminum alloy cracks in the additive manufacturing is observed, and finally the aluminum alloy which can be directly applied to the additive manufacturing and has excellent forming performance is designed. The application can be used for the rapid iteration design of the special alloy system for additive manufacturing, reduces the development cost, improves the research and development efficiency, and can be popularized to the development and design of other additive manufacturing alloy systems. Meanwhile, the application can be used for quickly obtaining the parameter range of the alloy additive manufacturing process.

Description

Technical Field

[0001] This invention relates to a method for evaluating the additive manufacturing performance of aluminum alloys, belonging to the field of aluminum alloys and additive manufacturing. Background Technology

[0002] Additive manufacturing technology has unique advantages in the fabrication of complex-shaped components. The extremely high temperature gradients and solidification rates during additive manufacturing processes easily induce cracking. Aluminum alloys possess excellent mechanical properties and high specific strength, making them widely used in aerospace structural components. However, aluminum alloys are highly prone to cracking during additive manufacturing, making forming difficult and hindering the achievement of ideal microstructure and mechanical properties.

[0003] Therefore, it is necessary to evaluate the additive manufacturing performance of aluminum alloys and analyze and screen suitable alloy compositions for additive manufacturing. Currently, the main method for evaluating the additive manufacturing performance of aluminum alloys is to directly additively manufacture the powder to obtain printed parts and observe whether the printed parts crack to assess the additive manufacturing performance. XU et al. [XU H, et al. Laser-directed energy deposition of ZrH2 particles reinforced Al7075 alloy: Crackselimination and strength enhancement[J]. Additive Manufacturing,2023,78:103877] used a three-dimensional planetary mixer to prepare 7075 aluminum alloy powders with different ZrH2 contents, and then used additive manufacturing to prepare printed parts, observing whether the printed parts cracked to evaluate the additive manufacturing performance of the designed aluminum alloy. This method has a long process flow, low efficiency, and high cost.

[0004] To address the aforementioned problems, this invention provides a method for evaluating the additive manufacturing forming performance of aluminum alloys. First, the DSC cooling curve of the designed aluminum alloy is tested to assess its solidification behavior. If two exothermic peaks appear in the DSC cooling curve, the designed aluminum alloy is considered to have potentially good additive manufacturing forming performance. The designed aluminum alloy block is then subjected to laser surface treatment to simulate the additive manufacturing process. If no cracks appear in the laser-scanned area, the designed aluminum alloy is deemed to have good additive manufacturing forming performance. Then, the alloy powder is prepared and additive manufacturing is performed to obtain a printed part, verifying the accuracy and practicality of the evaluation method, resulting in an aluminum alloy that can be directly used for additive manufacturing. The method provided by this invention can quickly, accurately, and efficiently evaluate and verify the crack sensitivity and additive manufacturing forming performance of aluminum alloys, offering a novel solution for the composition design and evaluation of additive manufacturing forming performance of aluminum alloys. Summary of the Invention

[0005] This invention provides, for the first time, a method for evaluating the additive manufacturing forming performance of aluminum alloys. First, the DSC cooling curve of the designed aluminum alloy is tested. If two exothermic peaks appear in the DSC cooling curve, the designed aluminum alloy is considered to have potentially good additive manufacturing forming performance. The designed aluminum alloy block is then subjected to laser additive manufacturing surface treatment to simulate the additive manufacturing process. If no cracks appear in the laser-treated area, the designed aluminum alloy is determined to have good additive manufacturing forming performance. Then, the alloy powder is prepared and additive manufacturing is performed to obtain a printed part, verifying the accuracy and practicality of the above evaluation method, thus obtaining an aluminum alloy that can be directly used for additive manufacturing.

[0006] The basic principle of this invention is illustrated by taking 2A14 and Y-modified 2A14 (2A14Y) aluminum alloy as an example:

[0007] During the solidification process of 2A14 aluminum alloy, the liquid phase L solidifies according to formula (1) to form α-Al phase + a small amount of Al2Cu phase. Its DSC cooling curve only shows one exothermic peak, and the α-Al dendrites are fully grown. In the later stage of solidification, the liquid phase is insufficient to fill the gaps between the α-Al dendrites, forming solidification cracks, which shows poor additive manufacturing forming performance.

[0008] Y alters the phase composition of 2A14Y aluminum alloy, thereby changing its solidification behavior. The DSC cooling curve of 2A14Y aluminum alloy shows two exothermic peaks. The solidification process of the aluminum alloy proceeds according to equations (2) and (3). First, solidification occurs according to equation (2), forming the primary phase α-Al. Pri +eutectic melt L E Then, L E According to formula (3), solidification forms a eutectic structure. In the aluminum alloy melt L (2A14Y) During the solidification process, the primary phase α-Al forms first. Pri With L E Coexistence, with a well-flowing eutectic liquid phase L E It can fill the primary α-Al phase Pri Interval. During LPBF, primary α-Al Pri The dendritic interstitial phase L was obtained from the eutectic liquid phase. E The filling helps to eliminate solidification cracks.

[0009] L (2A14) →α-Al+Al2Cu (1)

[0010] L (2A14Y) →α-Al Pri +L E (2)

[0011] L E →(α-Al+Y-rich phase) E (3)

[0012] The solidification behavior of the aluminum alloy was characterized by differential scanning calorimetry (DSC). The DSC cooling curve showed two exothermic peaks, indicating that the designed aluminum alloy solidified according to equations (2) and (3). In the later stage of solidification, the liquid phase L... E Filling the dendrite interstices helps eliminate additive manufacturing cracking, resulting in good additive manufacturing forming performance. The intensity and temperature difference of the two exothermic peaks in the DSC cooling curve are closely related to the additive manufacturing forming performance of aluminum alloys. When the intensity of the low-temperature peak is greater or the temperature difference between the two exothermic peaks is smaller, there is sufficient liquid phase to fill the dendrite interstices in the later stage of solidification, and the alloy has low cracking sensitivity.

[0013] The surface treatment simulation of the laser additive manufacturing process for alloy bulk materials can further evaluate the laser additive manufacturing forming performance of the designed aluminum alloy based on the DSC cooling curve criterion, making the selection results of aluminum alloy composition more accurate.

[0014] When the DSC cooling curve of the designed aluminum alloy does not show two exothermic peaks, the aluminum alloy composition is optimized. For alloy blocks with two exothermic peaks in the DSC cooling curve, laser additive manufacturing surface treatment is performed. When cracks appear in the laser-treated area, the aluminum alloy composition is optimized and iterated until a crack-free aluminum alloy composition is obtained. When no cracks appear in the laser-treated area, it indicates that the designed aluminum alloy has good additive manufacturing forming performance, and further verification can be performed using alloy powder additive manufacturing to obtain a crack-free aluminum alloy composition. This invention, through iteration, can quickly screen aluminum alloys suitable for additive manufacturing.

[0015] This invention discloses a method for evaluating the additive manufacturing forming performance of aluminum alloys, comprising the following steps:

[0016] (1) Design the aluminum alloy composition, configure the raw materials according to the designed aluminum alloy, make the alloy billet, homogenize the billet, and use differential scanning calorimetry (DSC) to test the cooling curve of the designed aluminum alloy. When the obtained DSC cooling curve shows two exothermic peaks, it is preliminarily determined that the designed aluminum alloy has good additive manufacturing forming performance.

[0017] (2) When two exothermic peaks appear in the DSC cooling curve of the designed aluminum alloy, the aluminum alloy block is subjected to additive manufacturing surface treatment, and the aluminum alloy is observed to see if cracking occurs; if no cracking occurs, it is determined that the designed aluminum alloy has low cracking sensitivity and good additive manufacturing forming performance.

[0018] (3) Evaluate the additive manufacturing performance of the designed aluminum alloy according to steps (1) and (2). If the DSC cooling curve of the designed aluminum alloy shows two exothermic peaks and the aluminum alloy block does not crack after additive manufacturing surface treatment, then prepare the designed aluminum alloy powder and perform additive manufacturing to verify the additive manufacturing performance of the designed aluminum alloy.

[0019] The present invention provides a method for evaluating the additive manufacturing forming performance of aluminum alloys. In step (1), during the DSC cooling curve test, the temperature is first heated to 700-750°C and held for 5-10 minutes, and then cooled at a rate of 5-10°C / min. The test is conducted in a protective atmosphere, wherein the protective atmosphere is an inert gas such as nitrogen, helium, argon, or a mixture of nitrogen, helium, and argon.

[0020] The present invention provides a method for evaluating the forming performance of aluminum alloy additive manufacturing. In steps (1) and (2), raw materials are prepared according to the designed aluminum alloy composition, melted, and cast into a billet, which is then homogenized. The billet is machined to form a block with a thickness greater than 5 mm. The surface of the alloy block to be laser additive manufacturing is ground to a roughness of less than 1.6 μm and then sandblasted to obtain a clean alloy block for laser additive manufacturing.

[0021] This invention discloses a method for evaluating the additive manufacturing forming performance of aluminum alloys. The method involves performing laser additive manufacturing surface treatment on the alloy block. The laser additive manufacturing parameters are as follows: laser power of 300-400W, laser scanning speed of 200-1000mm / s, and overlap spacing of 80-120μm. The protective atmosphere is an inert gas such as nitrogen, argon, or helium, or a mixture of nitrogen, argon, and helium, with an oxygen content of less than 0.0001wt%.

[0022] This invention provides a method for evaluating the additive manufacturing performance of aluminum alloys. The method involves observing whether cracking occurs in the alloy block after laser additive manufacturing surface treatment. If cracking occurs in the laser-treated area, it indicates that the additive manufacturing performance of the designed aluminum alloy is poor and additive manufacturing cracking will occur. If no cracking occurs in the laser-treated area, it indicates that the additive manufacturing performance of the designed aluminum alloy is good and additive manufacturing cracking will not occur.

[0023] This invention provides a method for evaluating the additive manufacturing forming performance of aluminum alloys. The method involves observing whether the surface-treated alloy block undergoes laser additive manufacturing and cracking. If the alloy block does not crack, 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 aluminum alloy produced by additive manufacturing. This verifies the accuracy of the evaluation method and yields an aluminum alloy that can be directly used for additive manufacturing.

[0024] This invention provides a method for evaluating the additive manufacturing forming performance of aluminum alloys. When the DSC cooling curve of the designed aluminum alloy shows two exothermic peaks, the alloy block is subjected to laser additive manufacturing surface treatment to obtain an additive manufacturing process parameter range that does not cause cracking, which serves as a reference range for additive manufacturing parameters suitable for the alloy.

[0025] This invention provides a method for evaluating the additive manufacturing forming performance of aluminum alloys. The method involves preparing blocks with different alloy compositions but the same thickness, arranging the blocks closely together, and performing laser additive manufacturing surface treatment on multiple alloy composition blocks in a single experiment. This achieves high-throughput evaluation and screening of alloy compositions and high-throughput screening of additive manufacturing process parameters, resulting in aluminum alloys that can be directly used for additive manufacturing. Alternatively, alloy blocks with the same composition can be used for high-throughput screening of additive manufacturing process parameters to obtain a reference range for the alloy's additive manufacturing process parameters.

[0026] The present invention provides a method for evaluating the additive manufacturing forming performance of aluminum alloys. When the DSC cooling curve of the designed aluminum alloy does not show two exothermic peaks, the composition of the aluminum alloy is optimized and the DSC cooling curve is retested until the DSC curve of the designed aluminum alloy shows two exothermic peaks.

[0027] Laser additive manufacturing surface treatment was performed on the alloy block with two exothermic peaks in the DSC cooling curve. When cracks appeared in the laser treatment area, steps (1) and (2) were repeated to optimize the aluminum alloy composition until the alloy block after laser additive manufacturing surface treatment did not crack. The alloy that did not crack was taken as the optimized alloy. Alloy powder was prepared according to the optimized alloy composition and additive manufacturing was performed. The crack-free aluminum alloy prepared by additive manufacturing was observed to obtain the aluminum alloy prepared by additive manufacturing. The accuracy of the evaluation method was further verified and the aluminum alloy that can be directly used for additive manufacturing was obtained.

[0028] Advantages and positive effects of the present invention:

[0029] (1) This invention is the first to design a judgment path of "preliminary judgment of DSC cooling curve - laser additive manufacturing scanning evaluation and verification and iteration of billet surface", which provides a brand-new approach for rapidly evaluating the additive manufacturing forming performance of aluminum alloys. The judgment path designed in this invention, combined with powder additive manufacturing verification, can simultaneously optimize the composition of the target product. This not only provides the necessary conditions for accurate and rapid judgment, but also provides a strong guarantee for the exponential growth of the composition optimization speed.

[0030] (2) This invention proposes to use DSC cooling curve as a preliminary evaluation standard for the forming performance of aluminum alloy additive manufacturing, which can be used for rapid screening of aluminum alloy composition for additive manufacturing. This can quickly optimize alloy composition, improve the accuracy of the criteria, and greatly reduce the number of experiments and the workload.

[0031] (3) The aluminum alloy block designed in this invention is homogenized before DSC cooling curve testing and laser surface treatment. This can effectively eliminate the deviation between the sampled composition and the designed composition caused by element segregation during the casting process. At the same time, it can prevent the phenomenon of uneven composition on the surface of the alloy during laser scanning, thereby improving the accuracy of the additive manufacturing forming performance evaluation of the designed aluminum alloy composition.

[0032] (4) The present invention ingeniously designed the process of “preliminary judgment of DSC cooling curve - laser additive manufacturing scanning verification and iteration on the surface of billet - powder additive manufacturing verification and iteration”, and combined multiple iterative design and verification when necessary to achieve rapid screening and optimization design of selected aluminum alloy components.

[0033] (5) The present invention uses an optimized alloy block 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 aluminum alloys and other alloy systems used for additive manufacturing. Attached Figure Description

[0034] Figure 1 This is a flowchart of the aluminum alloy additive manufacturing formability evaluation method of the present invention;

[0035] Figure 2 This is the DSC cooling curve of the 2A14 aluminum alloy in Example 1;

[0036] Figure 3 This is an OM image of the longitudinal section (XZ) of 2A14 aluminum alloy prepared by LPBF in Example 1;

[0037] Figure 4 This is the DSC cooling curve of the 1.3Y-2A14 aluminum alloy in Example 2;

[0038] Figure 5 This is an OM image of the longitudinal section (XZ) of 1.3Y-2A14 aluminum alloy prepared by LPBF in Example 2;

[0039] Figure 6 This is the DSC cooling curve of the 2Y-2A14 aluminum alloy in Example 3;

[0040] Figure 7 This is a metallographic image of the 2Y-2A14 aluminum alloy sample prepared by LPBF in Example 3;

[0041] Figure 8 This is the DSC cooling curve of the YZr-2A14 aluminum alloy in Example 4;

[0042] Figure 9 This is a metallographic image of the YZr-2A14 aluminum alloy sample prepared by LPBF in Example 4;

[0043] Figure 10 These are the DSC cooling curves of the Al-Cu-Mg and Al-Cu-Mg-Y alloys cited in the literature cited in Example 5;

[0044] Figure 11 This is an OM image of the Al-Cu-Mg alloy prepared by LPBF in the literature cited in Example 5;

[0045] Figure 12 This is an OM image of the Al-Cu-Mg-Y alloy prepared by LPBF in the literature cited in Example 5. Detailed Implementation

[0046] The flowchart for evaluating the additive manufacturing performance of aluminum alloys in this invention is as follows: Figure 1 As shown in the figure. The present invention will be further described below through specific embodiments.

[0047] Example 1:

[0048] To practically evaluate the accuracy and practicality of the method proposed in this invention, the method was used to evaluate the additive manufacturing forming performance of 2A14 aluminum alloy, including the following steps:

[0049] (1) Test the DSC cooling curve for preliminary evaluation: Based on the composition of 2A14 aluminum alloy, prepare raw materials, melt and cast them into billets, homogenize the billets, and test their DSC cooling curves, such as... Figure 2 As shown, the initial solidification temperature of 2A14 aluminum alloy is 634.0℃, the solidification point temperature is 548.8℃, and the solidification temperature range is 85.2℃. Only one exothermic peak is observed, indicating that the laser additive manufacturing forming performance of 2A14 aluminum alloy is poor.

[0050] (2) Surface treatment using laser additive manufacturing was evaluated again: The homogenized billet was machined to form a block with a thickness of 6 mm; then, the surface of the block to be additively manufactured was ground to a roughness of less than 1.6 μm; finally, the surface to be laser-scanned was sandblasted. Laser powder bed melting (LPBF) technology was used for surface treatment of the alloy block: a high-energy laser beam with a power of 300–400 W was applied to the surface of the 2A14 aluminum alloy block, with a laser scanning speed of 200–1000 mm / s and a laser scanning spacing of 80–120 μm. The protective atmosphere was inert argon gas with an oxygen content of less than 0.0001 wt%. Observation of the laser-scanned area revealed obvious cracking, indicating that the additive manufacturing forming performance of the 2A14 aluminum alloy is low and additive manufacturing cracking will occur.

[0051] (3) The additive manufacturing performance of 2A14 aluminum alloy powder was further verified by additive manufacturing: 2A14 aluminum alloy ingots were prepared by argon atomization to form alloy powder, and laser powder bed melting (LPBF) technology was used for forming. The parameters were set as follows: laser power 200~360W, laser scanning speed 500~1300mm / s, overlap spacing 80μm, and layer thickness 30μm. Figure 3 The image shown is an OM image of the longitudinal section (XZ) of 2A14 aluminum alloy prepared by LPBF. Cracks and porosity are visible in all samples. Process parameters have no significant effect on the crack morphology, number, and distribution. The cracks are almost straight, parallel to the fabrication direction, and some cracks penetrate the entire field of view. The additive manufacturing results indicate that the 2A14 aluminum alloy suffers from severe cracking and has poor additive manufacturing formability.

[0052] The DSC cooling curve of 2A14 aluminum alloy showed only one exothermic peak. The melt solidified to form α-Al dendrites. In the later stage of solidification, the α-Al dendrites could not be fully filled by the melt, resulting in solidification cracks.

[0053] The evaluation results of laser surface treatment and the verification results of powder additive manufacturing show that 2A14 aluminum alloy has high cracking sensitivity and poor additive manufacturing forming performance, indicating that the evaluation method of the present invention is reliable.

[0054] Using DSC cooling profiles, the additive manufacturing forming performance of aluminum alloys can be preliminarily evaluated, and the composition of aluminum alloys can be quickly screened. Simultaneously, the surface treatment results of laser additive manufacturing can further determine the additive manufacturing forming performance of aluminum alloys and verify the accuracy of the preliminary judgment.

[0055] Example 2:

[0056] Based on the results of Example 1, an attempt was made to design aluminum alloys with bimodal DSC cooling curves. For example, using Y-modified 2A14 aluminum alloy, a 1.3Y-2A14 aluminum alloy was designed. The method of this invention was used to evaluate the laser additive manufacturing forming performance of the 1.3Y-2A14 aluminum alloy, including the following steps:

[0057] (1) DSC cooling curve testing for preliminary evaluation: The design composition of 1.3Y-2A14 aluminum alloy is Al-4.2Cu-1.3Y-0.6Mg-1.0Si-0.7Mn. Based on the composition information, raw materials are prepared, melted, and cast into a billet. The billet is homogenized, and its DSC cooling curve is tested, such as... Figure 4 As shown, the initial solidification temperature of 1.3Y-2A14 aluminum alloy is 633.5℃, the solidification point temperature is 564.8℃, and the solidification temperature range is 68.7℃. Two obvious exothermic peaks are observed, suggesting that the 1.3Y-2A14 aluminum alloy may have good laser additive manufacturing forming performance.

[0058] (2) Surface treatment using laser additive manufacturing was evaluated again: The homogenized billet was machined to form a block with a thickness of 6 mm; then, the surface of the block to be additively manufactured was ground to achieve a roughness of less than 1.6 μm; finally, the surface to be laser-scanned was sandblasted. LPBF technology was used for surface treatment of the alloy block: a high-energy laser beam with a power of 300–400 W was applied to the surface of the 1.3Y-2A14 aluminum alloy block, with a laser scanning speed of 200–1000 mm / s and a laser scanning spacing of 80–120 μm. The protective atmosphere was inert argon gas with an oxygen content of less than 0.0001 wt%. Microcracks were observed in the laser-scanned area, indicating that the additive manufacturing forming performance of the 1.3Y-2A14 aluminum alloy was low and additive manufacturing cracking was likely to occur.

[0059] (3) 1.3Y-2A14 aluminum alloy powder was used for additive manufacturing to further verify its additive manufacturing forming performance: 1.3Y-2A14 aluminum alloy ingot was prepared into alloy powder by argon atomization and formed by LPBF technology. The parameters were set as follows: laser power 200~360W, laser scanning speed 500~1300mm / s, overlap spacing 80μm, and layer thickness 30μm. Figure 5 The image shown is an OM image of the longitudinal section (XZ) of 1.3Y-2A14 aluminum alloy. Cracks and porosity are visible in all samples. The cracks are almost straight and parallel to the construction direction, with some cracks penetrating the entire field of view. The crack density can be reduced by adjusting the process parameters, but it is impossible to prepare crack-free samples.

[0060] Experimental results show that compared with 2A14 aluminum alloy, 1.3Y-2A14 aluminum alloy has reduced cracking sensitivity and improved additive manufacturing forming performance to some extent, but the additive manufacturing forming performance of 1.3Y-2A14 aluminum alloy cannot meet the requirements.

[0061] Y modification alters the solidification behavior of aluminum alloys. The solidification process of 1.3Y-2A14 aluminum alloy is completed in two steps. First, the primary phase α-Al is formed according to equation (2). Pri +eutectic melt L E Then L E (α-Al+Y-rich phase) is formed according to formula (3). E Therefore, its DSC cooling curve shows two exothermic peaks. The first formed primary phase α-Al Pri With L E Coexistence, with a well-flowing eutectic liquid phase L E It can fill the primary α-Al phase Pri Dendritic intergranulation effectively reduces the susceptibility to solidification cracking. Furthermore, during the solidification of the eutectic melt, α-Al preferentially selects its crystals within the α-Al crystal structure.Pri Surface growth improves the grain boundary bonding state, thereby enhancing crack resistance.

[0062] Example 3:

[0063] Based on the results of Example 2, Y modification can improve the additive manufacturing forming performance of 2A14 aluminum alloy. Therefore, this example is further iterated: the amount of Y added is increased, and a 2Y-2A14 aluminum alloy is designed. The method of this invention is used to evaluate the additive manufacturing forming performance of the 2Y-2A14 aluminum alloy, including the following steps:

[0064] (1) DSC cooling curve testing for preliminary evaluation: The design composition of 2Y-2A14 aluminum alloy is Al-4.2Cu-2Y-0.6Mg-1.0Si-0.7Mn. Based on the composition information, raw materials were prepared, smelted, and cast into a billet. The billet underwent homogenization treatment, and its DSC cooling curve was tested. Figure 6 As shown, the initial solidification temperature of 2Y-2A14 aluminum alloy is 629.2℃, the solidification point temperature is 575.3℃, and the solidification temperature range is 53.9℃. Two obvious exothermic peaks are observed, indicating that 2Y-2A14 aluminum alloy may have good laser additive manufacturing forming performance.

[0065] (2) Surface treatment using laser additive manufacturing was evaluated again: The homogenized billet was machined to form a block with a thickness of 6 mm; then, the surface of the block to be additively manufactured was ground to achieve a roughness of less than 1.6 μm; finally, the surface to be laser-scanned was sandblasted. LPBF technology was used for surface treatment of the alloy block: a high-energy laser beam with a power of 300–400 W was applied to the surface of the 2Y-2A14 aluminum alloy block, with a laser scanning speed of 200–1000 mm / s and a laser scanning spacing of 80–120 μm. The protective atmosphere was inert argon gas with an oxygen content of less than 0.0001 wt%. No cracking was observed in the laser-scanned area under different process parameters, indicating that the 2Y-2A14 aluminum alloy has good additive manufacturing forming performance and will not experience additive manufacturing cracking.

[0066] (3) Additive manufacturing of 2Y-2A14 aluminum alloy powder was used to further verify the additive manufacturing forming performance of 2Y-2A14 aluminum alloy: 2Y-2A14 aluminum alloy ingot was prepared into alloy powder by argon atomization and formed by LPBF technology. The parameters were set as follows: laser power 320~360W, laser scanning speed 500~900mm / s, overlap spacing 80μm, and layer thickness 30μm. Figure 7The image shown is an OM image of the longitudinal section (XZ) of 2Y-2A14 aluminum alloy. No cracks were found in any of the samples. Only the sample with a laser power of 360W and a scanning speed of 500mm / s had a large keyhole.

[0067] Experimental results show that compared with 1.3Y-2A14 aluminum alloy, 2Y-2A14 aluminum alloy has reduced cracking sensitivity and significantly improved additive manufacturing forming performance. The laser additive manufacturing forming performance of 2Y-2A14 aluminum alloy meets the requirements. Laser additive manufacturing surface treatment of 2Y-2A14 aluminum alloy blocks yields a range of additive manufacturing process parameters that do not cause cracking, which can be used as a reference range for the process parameters of laser powder bed melting technology suitable for this alloy.

[0068] Compared to 1.3Y-2A14 aluminum alloy, the 2Y-2A14 aluminum alloy exhibits a stronger low-temperature exothermic peak in its DSC cooling curve, indicating that the eutectic melt L E There are many, which can fully fill the primary α-Al phase. Pri Dendritic interstitial space. Simultaneously, the eutectic melt L... E In α-Al Pri Dendritic surface nucleation and growth improves intergranular bonding strength, enhances crack resistance, and eliminates solidification cracks.

[0069] The 2Y-2A14 aluminum alloy iteratively designed in this embodiment has low cracking sensitivity and good formability in additive manufacturing, and can be directly used in additive manufacturing.

[0070] This result further demonstrates that the evaluation method of the present invention is reliable and the application method is reasonable.

[0071] Example 4:

[0072] Based on the results of Examples 2 and 3, Y modification can improve the additive manufacturing forming performance of 2A14 aluminum alloy. This example further iterates: Zr element is further added to design YZr-2A14 aluminum alloy. The method of the present invention is used to evaluate the laser additive manufacturing forming performance of YZr-2A14 aluminum alloy, including the following steps:

[0073] (1) Testing the DSC cooling curve for preliminary evaluation: The design composition of YZr-2A14 aluminum alloy is Al-4.2Cu-1.3Y-0.6Mg-1.0Si-0.7Mn-0.7Zr. Based on the composition information, raw materials are prepared, smelted, and cast into a billet. The billet is homogenized, and its DSC cooling curve is tested, such as... Figure 8As shown, the initial solidification temperature of YZr-2A14 aluminum alloy is 635.4℃, the solidification point temperature is 566.7℃, and the solidification temperature range is 68.7℃, exhibiting two distinct exothermic peaks. Compared to 1.3Y-2A14 aluminum alloy, the temperature difference between the two exothermic peaks in YZr-2A14 aluminum alloy is smaller, which is more conducive to the liquid phase fully filling the dendrite interstices in the later stage of solidification, indicating that YZr-2A14 aluminum alloy may have better laser additive manufacturing forming performance.

[0074] (2) Surface treatment using laser additive manufacturing was evaluated again: The homogenized billet was machined into a circular block with a thickness of 5 mm. The surface of the block was then ground to a roughness of less than 1.6 μm. Finally, the surface to be laser-scanned was sandblasted. LPBF technology was used for surface treatment of the alloy block: A high-energy laser beam with a power of 300–400 W was applied to the surface of the YZr-2A14 aluminum alloy block. The laser scanning speed was 200–1000 mm / s, and the laser scanning spacing was 80–120 μm. The protective atmosphere was inert argon gas with an oxygen content of less than 0.0001 wt%. No cracking was observed in the laser-scanned areas under different process parameters, indicating that the YZr-2A14 aluminum alloy has good additive manufacturing forming performance and will not crack during additive manufacturing.

[0075] (3) Additive manufacturing of YZr-2A14 aluminum alloy powder was used to further verify the additive manufacturing forming performance of YZr-2A14 aluminum alloy: YZr-2A14 aluminum alloy ingot was prepared into alloy powder by argon atomization and formed by LPBF technology. The parameters were set as follows: laser power 320~360W, laser scanning speed 500~900mm / s, overlap spacing 80μm, and layer thickness 30μm. Figure 9 The image shown is an OM image of the longitudinal section (XZ) of YZr-2A14 aluminum alloy. No cracks were found in any of the samples. Only the sample with a laser power of 360W and a scanning speed of 500mm / s had a large keyhole.

[0076] Experimental results show that the laser additive manufacturing forming performance of YZr-2A14 aluminum alloy meets the requirements; laser additive manufacturing surface treatment of YZr-2A14 aluminum alloy blocks yields a range of additive manufacturing process parameters that do not cause cracking, which can be used as a reference range for the process parameters of laser powder bed melting technology suitable for this alloy.

[0077] Compared to 1.3Y-2A14 aluminum alloy, the YZr-2A14 aluminum alloy exhibits a smaller temperature difference between the two exothermic peaks in its DSC cooling curve, indicating a stronger primary α-Al phase. Pri Growth is restricted, and the eutectic melt can fully fill the primary α-Al phase. Pri Dendritic interstitial spaces. Simultaneously, the eutectic melt in α-Al...Pri Dendritic surface nucleation and growth improves intergranular bonding strength, enhances crack resistance, and eliminates solidification cracks.

[0078] The YZr-2A14 aluminum alloy iteratively designed in this embodiment has low cracking sensitivity and good formability in additive manufacturing, and can be directly used for additive manufacturing.

[0079] This result further demonstrates that the evaluation method of the present invention is reliable and the application method is reasonable.

[0080] Example 5:

[0081] Al-Cu-Mg and Al-Cu-Mg-Y alloys

[0082] [1]CHEN et al,Microstructure characterization and mechanicalproperties of crack-free Al-Cu-Mg-Y alloy fabricated by laser powder bedfusion,Additive Manufacturing,58(2022)103006

[0083] CHEN et al. [1] disclosed the DSC cooling curves of Al-Cu-Mg alloys as follows: Figure 10 As shown, only one exothermic peak appears. Therefore, according to Figure 10 The DSC cooling curve of the Al-Cu-Mg alloy shown is based on the preliminary evaluation of this invention. The results indicate that the Al-Cu-Mg alloy has poor additive manufacturing forming performance and will exhibit additive manufacturing cracking.

[0084] CHEN et al. [1] used LPBF technology to prepare Al-Cu-Mg alloys, and additive manufacturing cracks appeared in the printed parts, such as Figure 11 As shown, the additive manufacturing forming performance of Al-Cu-Mg alloy is poor. The preliminary evaluation results of this invention are consistent with the LPBF preparation results of CHEN et al. [1], indicating that the method of this invention is reliable.

[0085] CHEN et al. [1] used Y to modify Al-Cu-Mg alloy. The DSC cooling curve of Al-Cu-Mg-Y alloy showed two exothermic peaks, such as Figure 10 As shown in the figure. Based on the DSC cooling curve, the Al-Cu-Mg-Y alloy has a lower cracking sensitivity than the Al-Cu-Mg alloy, and it is preliminarily determined that it has better printability.

[0086] according to Figure 10The DSC cooling curves of the Al-Cu-Mg alloy shown are based on the preliminary evaluation of this invention. The results indicate that the Al-Cu-Mg alloy has good additive manufacturing forming performance and a low probability of additive manufacturing cracking.

[0087] CHEN et al. [1] prepared Al-Cu-Mg-Y alloy samples using the LPBF process with a laser power of 250W, a scanning speed of 1200mm / s, a layer thickness of 0.03mm, and an overlap spacing of 0.08mm. Figure 12 As shown, no cracking occurs. Experiments verify that Al-Cu-Mg-Y alloy has low cracking sensitivity in additive manufacturing, does not experience additive manufacturing cracking, and has good additive manufacturing forming performance.

[0088] The preliminary evaluation results of this invention are consistent with the LPBF preparation results of CHEN et al. [1], which further demonstrates that the method of this invention is reliable.

[0089] The results of CHEN et al. [1] show that:

[0090] (1) The method for evaluating the additive manufacturing forming performance of aluminum alloys proposed in this invention is reliable, the evaluation results are forward-looking, and the composition design method involved can be used for the composition design of Al-Cu-Mg alloy systems. By using Y to improve Al-Cu-Mg alloys, the additive manufacturing forming performance of Al-Cu-Mg alloys can be significantly improved, and crack-free additive manufacturing Al-Cu-Mg-Y alloys can be directly obtained;

[0091] (2) The work of CHEN et al. [1] verified that the method for evaluating the additive manufacturing performance of aluminum alloys proposed in this invention and the composition design method involved are feasible and can quickly screen alloy components.

Claims

1. A method for evaluating the additive manufacturing forming performance of aluminum alloys, characterized in that, Includes the following steps: (1) Design the aluminum alloy composition, configure the raw materials according to the designed aluminum alloy, make the alloy billet, homogenize the billet, and use differential scanning calorimetry (DSC) to test the cooling curve of the designed aluminum alloy. When the obtained DSC cooling curve shows two exothermic peaks, it is preliminarily determined that the designed aluminum alloy has good additive manufacturing forming performance. (2) When two exothermic peaks appear in the DSC cooling curve of the designed aluminum alloy, the aluminum alloy block is subjected to additive manufacturing surface treatment, and the aluminum alloy is observed to see if cracking occurs. If no cracking occurs, the designed aluminum alloy is deemed to have low cracking sensitivity and good additive manufacturing forming performance. The alloy block undergoes laser additive manufacturing surface treatment, with the following laser additive manufacturing parameters: laser power of 300-400 W, laser scanning speed of 200-1000 mm / s, and overlap spacing of 80-120 μm. The protective atmosphere is an inert gas, nitrogen, argon, helium, or a mixture of nitrogen, argon, and helium, with an oxygen content of less than 0.0001 wt%. (3) Evaluate the additive manufacturing performance of the designed aluminum alloy according to steps (1) and (2). If the DSC cooling curve of the designed aluminum alloy shows two exothermic peaks and the aluminum alloy block does not crack after additive manufacturing surface treatment, prepare the designed aluminum alloy powder and perform additive manufacturing to verify the additive manufacturing performance of the designed aluminum alloy. When the DSC cooling curve of the designed aluminum alloy does not show two exothermic peaks, the composition of the aluminum alloy is optimized and the DSC cooling curve is retested until the DSC curve of the designed aluminum alloy shows two exothermic peaks. Laser additive manufacturing surface treatment was performed on the alloy block with two exothermic peaks in the DSC cooling curve. When cracks appeared in the laser treatment area, steps (1) and (2) were repeated to optimize the aluminum alloy composition until the alloy block after laser additive manufacturing surface treatment did not crack. The alloy that does not crack is used as the optimized alloy. Alloy powder is prepared according to the optimized alloy composition and then additively manufactured. The presence or absence of cracks in the alloy block prepared by additive manufacturing is observed to obtain the crack-free aluminum alloy prepared by additive manufacturing, which further verifies the accuracy of the evaluation method.

2. The method for evaluating the additive manufacturing forming performance of aluminum alloys according to claim 1, characterized in that: In step (1) of the DSC cooling curve test, the temperature is first heated to 700~750℃ and held for 5~10 min, and then cooled at a rate of 5~10℃ / min. The test is conducted in a protective atmosphere, wherein the protective atmosphere is an inert gas such as nitrogen, helium, argon, or a mixture of nitrogen, helium, and argon.

3. The method for evaluating the additive manufacturing forming performance of aluminum alloys according to claim 1, characterized in that: In steps (1) and (2), raw materials are prepared according to the designed aluminum alloy composition, melted, and cast into billets, which are then homogenized. The homogenized billets are machined to form blocks with a thickness greater than 5 mm. The surface of the alloy block to be laser additive manufacturing is ground to a roughness of less than 1.6 μm and then sandblasted to obtain a clean alloy block for laser additive manufacturing.

4. The method for evaluating the additive manufacturing performance of aluminum alloys according to claim 1, characterized in that: Observe whether there is cracking in the alloy block after laser additive manufacturing surface treatment; if cracking occurs in the laser-treated area, it indicates that the additive manufacturing forming performance of the designed aluminum alloy is poor and additive manufacturing cracking will occur; if no cracking occurs in the laser-treated area, it indicates that the additive manufacturing forming performance of the designed aluminum alloy is good and additive manufacturing cracking will not occur.

5. The method for evaluating the additive manufacturing performance of aluminum alloys according to claim 1, characterized in that: Observe whether the alloy block after laser additive manufacturing surface treatment 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; By observing the surface condition of the additively manufactured alloy block, we can obtain the crack-free aluminum alloy prepared by additive manufacturing and verify the accuracy of the evaluation method.

6. The method for evaluating the additive manufacturing performance of aluminum alloys according to claim 1, characterized in that: When the DSC cooling curve of the designed aluminum alloy shows two exothermic peaks, the alloy block is subjected to laser additive manufacturing surface treatment to obtain an additive manufacturing process parameter range that does not cause cracking, which serves as a reference range for additive manufacturing parameters suitable for the alloy.

7. The method for evaluating the additive manufacturing forming performance of aluminum alloys according to claim 1, characterized in that: Prepare blocks with different alloy compositions but the same thickness, arrange the blocks closely, and complete the laser additive manufacturing surface treatment of multiple alloy composition blocks in a single experiment to achieve high-throughput screening of alloy composition.

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