A method for additive manufacturing of high crack sensitive alloys

Abstract

The application provides a method suitable for additive manufacturing of high crack sensitivity alloy, and belongs to the technical field of 3D printing. The application utilizes the characteristics of a uniform laser spot diameter, high laser power and uniform energy distribution to pre-sinter metal powder, so that the preheating of a substrate can be realized, and the preheating of the formed material can be realized in the middle and later stages of additive manufacturing. Then, a Gaussian laser is used for processing, so that the temperature difference between the molten pool and the substrate (or the formed material) is reduced, the temperature gradient is reduced, the thermal stress in the cooling process is reduced, the stress concentration is reduced, and thus the formation and expansion of cracks are reduced. The characteristics of a small Gaussian laser spot diameter and energy concentration are used for secondary scanning sintering of the pre-sintered alloy, so that the material is more fine, the problems of uneven material distribution, surface defects and the like that may exist are eliminated, the risk of cracks is further reduced, and the additive manufacturing of high crack sensitivity alloy is suitable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of 3D printing, and specifically relates to a method for additive manufacturing using high crack-sensitive alloy. BACKGROUND

[0002] Additive manufacturing is a technology that manufactures three-dimensional products through layer-by-layer material addition, melting by heat source, and solidification by cooling. Unlike traditional subtractive manufacturing methods, additive manufacturing can achieve highly complex structural design, reduce material waste, and shorten product development cycle. In recent years, additive manufacturing technology has received widespread attention in the fields of aerospace, medical, automotive, and electronics.

[0003] Current additive manufacturing technologies include laser powder bed fusion (L-PBF), laser directed energy deposition (L-DED), electron beam melting (EBM), stereolithography (SLA), etc. Each technology has its own characteristics in material type, manufacturing speed and precision, and application field. Laser powder bed fusion (L-PBF) uniformly spreads metal powder on the substrate, then scans specific areas by laser, and the laser beam irradiates the powder bed, making the selected area of powder rapidly melt into liquid state. With the movement of the laser, the liquid metal gradually cools and solidifies to form the first layer structure. The automatic powder spreading device covers a new layer of metal powder on the surface of the formed structure, and scans again by laser. Repeat this process until the entire part is completed. The characteristics of L-PBF are that it can achieve micron-level printing precision, is suitable for manufacturing complex and fine parts, and provides greater design freedom.

[0004] However, high crack-sensitive alloys cannot be used with L-PBF. High crack-sensitive alloys are prone to defects such as porosity and cracks during forming, which can reduce the overall mechanical properties of the product and thus fail to meet application requirements. This is because high crack-sensitive alloys are prone to thermal stress and residual stress during melting and cooling, which leads to the generation and propagation of cracks, especially in the case of rapid cooling, where the temperature gradient is large and local stress is concentrated. Certain high crack-sensitive alloys may also undergo phase transformation or element segregation during melting, resulting in uneven material properties, and the volume change caused by phase transformation and the interaction between different phases can further exacerbate crack formation.

[0005] In order to solve the problem that high crack sensitivity alloy is prone to cracks in the additive manufacturing process, generally, the method of preheating the substrate is adopted, by increasing the temperature of the substrate, especially in the early stage of printing, the temperature gradient of the molten pool can be reduced, the thermal stress concentration is reduced, thereby reducing the risk of alloy cracks. However, the substrate preheating needs a higher temperature, sometimes reaching 1000℃ or even higher, the high temperature environment causes a greater burden on the equipment, accelerates the wear and aging of the equipment, and increases the manufacturing cost; moreover, the substrate preheating has a good effect only in the early stage of printing, and the improvement effect is limited in the middle and later stages. SUMMARY

[0006] The purpose of the present application is to provide a method suitable for additive manufacturing of high crack sensitivity alloy. The method provided by the present application can reduce the crack risk of high crack sensitivity alloy in the whole additive manufacturing process, and does not need high temperature preheating, thereby reducing the manufacturing cost.

[0007] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0008] The present application provides a method suitable for additive manufacturing of high crack sensitivity alloy, which adopts laser powder bed melting technology for additive manufacturing, and adopts double laser treatment for each layer of metal powder, including: first using a homogenization laser to pre-sinter the metal powder to obtain a pre-sintered body, and then using a Gaussian laser to scan and sinter the pre-sintered body; the spot diameter of the homogenization laser is 100-500μm, and the power is 800-2000W; the spot diameter of the Gaussian laser is 40-100μm, and the power is 80-500W.

[0009] Preferably, the high crack sensitivity alloy includes aluminum alloy, nickel-based superalloy, stainless steel, TiAl alloy or NiAl alloy.

[0010] Preferably, when the solidification interval of the high crack sensitivity alloy is higher than 350K, the double laser treatment of each layer of metal powder includes: first using a homogenization laser to pre-sinter the whole metal powder to obtain a pre-sintered body, dividing the pre-sintered body into a solid area and a frame area surrounding the periphery of the solid area according to the target area, the width of the frame area is 0.1-0.5mm, and then using a Gaussian laser to scan and sinter the solid area.

[0011] Preferably, when the solidification interval of the high crack sensitivity alloy is between 265K and 350K, the double laser treatment of each layer of metal powder includes: dividing the metal powder into a solid area and a frame area surrounding the periphery of the solid area according to the target area, the width of the frame area is 0.1-0.5mm, first using a homogenization laser to pre-sinter the solid area to obtain a pre-sintered body, and then using a Gaussian laser to scan and sinter the frame area.

[0012] Preferably, the scanning speed of the homogenization laser is 100-7000 mm / s.

[0013] Preferably, the scanning speed of the Gaussian laser is 100-3000 mm / s.

[0014] Preferably, the printing substrate and the metal powder are of the same material during the additive manufacturing.

[0015] Preferably, the metal powder is dried before use, the drying temperature is 70-90℃, and the drying time is 4-6h.

[0016] Preferably, the additive manufacturing is carried out in an inert atmosphere.

[0017] Preferably, the powder laying thickness of each layer of metal powder is independently 30-200 μm.

[0018] The present application provides a method for additive manufacturing of high crack sensitivity alloy, which uses laser powder bed fusion technology for additive manufacturing, and uses double laser treatment for each layer of metal powder, including: first using a homogenization laser to pre-sinter the metal powder to obtain a pre-sintered body, and then using a Gaussian laser to scan and sinter the pre-sintered body; the spot diameter of the homogenization laser is 100-500 μm, and the power is 800-2000 W; the spot diameter of the Gaussian laser is 40-100 μm, and the power is 80-500 W. The present application uses the characteristics of large spot diameter, high laser power and uniform energy distribution of the homogenization laser to pre-sinter the metal powder, which can realize the preheating of the substrate, and in the middle and later stages of additive manufacturing, it can realize the preheating of the formed material; then using the Gaussian laser for treatment, which reduces the temperature difference between the molten pool and the substrate (or the formed material), reduces the temperature gradient, reduces the thermal stress in the cooling process, reduces stress concentration, thereby reducing the formation and expansion of cracks; using the characteristics of small spot diameter and energy concentration of the Gaussian laser to perform secondary scanning and sintering on the pre-sintered alloy, which can make the material more fine, eliminate possible problems such as uneven material distribution and surface defects, further reduce the risk of cracks, and is suitable for additive manufacturing of high crack sensitivity alloy. The results of the embodiments show that the method provided by the present application can effectively inhibit the cracks of high crack sensitivity alloy in additive manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The flowchart of the method for additive manufacturing of high crack sensitivity alloy provided by the present application is shown;

[0020] Figure 2 The structure diagram of the double laser system used in the additive manufacturing of the present application is shown;

[0021] Figure 3 A schematic diagram for zoning processing of the high crack sensitivity alloy of the present application;

[0022] Figure 4 A schematic diagram for spot shape and energy distribution of the homogenization laser used in the embodiment of the present application;

[0023] Figure 5 A schematic diagram for spot shape and energy distribution of the Gaussian laser used in the embodiment of the present application;

[0024] Figure 6 A metallographic optical microscope graph of the TiAl alloy processed and shaped in the embodiment 1 of the present application;

[0025] Figure 7 A metallographic optical microscope graph of the IN939 alloy processed and shaped in the embodiment 2 of the present application;

[0026] Figure 8 A metallographic optical microscope graph of the TiAl alloy processed and shaped in the comparative example 1 of the present application;

[0027] Figure 9 A metallographic optical microscope graph of the IN939 alloy processed and shaped in the comparative example 2 of the present application. DETAILED DESCRIPTION

[0028] The present application provides a method suitable for additive manufacturing of high crack sensitivity alloy, which adopts laser powder bed fusion technology for additive manufacturing, and adopts double laser processing for each layer of metal powder, including: using a homogenization laser to pre-sinter the metal powder to obtain a pre-sintered body, and then using a Gaussian laser to scan and sinter the pre-sintered body; the spot diameter of the homogenization laser is 100-500 μm, and the power is 800-2000 W; the spot diameter of the Gaussian laser is 40-100 μm, and the power is 80-500 W.

[0029] In the present application, the high crack sensitivity alloy preferably includes an aluminum alloy, a nickel-based superalloy, stainless steel, a TiAl alloy or a NiAl alloy.

[0030] The present application does not have special requirements for the type of the high crack sensitivity alloy, and all high crack sensitivity alloys can be subjected to additive manufacturing by the method of the present application.

[0031] The present application adopts laser powder bed fusion technology for additive manufacturing.

[0032] In the present application, the printing substrate for additive manufacturing is preferably of the same material as the metal powder. The printing substrate and the metal powder are of the same material, which can make the printing substrate and the shaped material have similar heat transfer performance, which is conducive to the stable shaping of the material on the printing substrate.

[0033] In the present application, the additive manufacturing is preferably carried out in an inert atmosphere, and the present application does not have a particular requirement for the specific type of the inert atmosphere, and an inert atmosphere commonly used in the art can be adopted; in the embodiments of the present application, argon or helium is adopted to reduce the oxygen content to below 800 ppm. The additive manufacturing in an inert atmosphere can prevent the metal from being oxidized, and is conducive to improving the material quality.

[0034] In the present application, the printing substrate is preferably subjected to surface treatment before the additive manufacturing, and the surface treatment is preferably sand blasting. By subjecting the printing substrate to surface treatment, dirt, oxide layers and other impurities on the surface of the printing substrate are removed, which is conducive to the bonding of the forming material and the printing substrate.

[0035] In the additive manufacturing, the present application adopts double laser treatment for each layer of metal powder.

[0036] In the present application, the metal powder is preferably dried before use, and the drying temperature is preferably 70-90°C, and more preferably 75-85°C; the drying time is preferably 4-6h, and more preferably 4.5-5.5h. Drying the metal powder can reduce the moisture content of the metal powder, prevent agglomeration, improve the flowability of the powder, and is conducive to uniform powder spreading.

[0037] In the present application, the powder spreading thickness of each layer of metal powder is independently preferably 30-200μm, and more preferably 30-100μm; as an embodiment of the present application, the powder spreading thickness can be 35μm, 40μm, 45μm, 55μm, 65μm, 75μm, 85μm, 110μm, 150μm or 180μm. The powder spreading thickness of each layer of metal powder in the above range is conducive to improving the uniformity of the material.

[0038] As an embodiment of the present application, when the solidification range of the high crack sensitivity alloy is higher than 350K, the double laser treatment of each layer of metal powder preferably comprises: first using a homogenization laser to pre-sinter the whole metal powder to obtain a pre-sintered body, dividing the pre-sintered body into a solid region and a frame region surrounding the periphery of the solid region according to the target region, the width of the frame region being 0.1-0.5mm, and then using a Gaussian laser to scan and sinter the solid region. When the solidification range of the alloy is higher than 350K, the crack sensitivity of the alloy is very high, and the present application uses a homogenization laser for pre-sintering, uses a Gaussian laser for secondary sintering of the solid region, and does not use a Gaussian laser for scanning and sintering of the frame region, which can further reduce the risk of cracks.

[0039] As another embodiment of the present application, the double laser processing of each layer of metal powder when the solidification range of the high crack sensitive alloy is between 265K and 350K preferably includes: dividing the metal powder into a solid area and a frame area surrounding the periphery of the solid area according to the target area, the width of the frame area is 0.1-0.5mm, using a homogenizing laser to pre-sinter the solid area to obtain a pre-sintered body, and then using a Gaussian laser to scan and sinter the frame area. When the solidification range of the alloy is between 265K and 350K, the crack sensitivity of the alloy is relatively high, the present application uses a homogenizing laser to pre-sinter the solid area, which can increase the temperature of the substrate (or the formed material), and uses a Gaussian laser to sinter the frame area, which can reduce the temperature gradient, is conducive to reducing the risk of cracks, and can also improve the surface quality of the frame area.

[0040] In the present application, the spot diameter of the homogenizing laser is 100-500μm, preferably 200-400μm, and more preferably 250-350μm. As an embodiment of the present application, the spot diameter of the homogenizing laser can be 220μm, 280μm, 330μm, 360μm, 390μm, 420μm or 450μm. The spot diameter of the homogenizing laser has a larger molten pool area in the above range, which can provide uniform energy distribution, reduce stress concentration and reduce the occurrence of cracks.

[0041] In the present application, the power of the homogenizing laser is 800-2000W, preferably 1200-1600W, and more preferably 1400-1500W. As an embodiment of the present application, the power of the homogenizing laser can be 850W, 950W, 1100W, 1250W, 1300W, 1450W, 1700W, 1800W or 1900W. The power of the homogenizing laser affects the temperature of the scan sintering, and the power of the homogenizing laser in the above range can melt the metal powder and effectively preheat the printed substrate or the formed material, reduce the temperature gradient, reduce the occurrence of cracks, and also avoid burn-through caused by excessive power.

[0042] In the present application, the spot diameter of the Gaussian laser is 40-100 μm, preferably 50-80 μm, and more preferably 60-70 μm. As an embodiment of the present application, the spot diameter of the Gaussian laser can be 45 μm, 55 μm, 65 μm, 75 μm, 85 μm, 90 μm or 95 μm. In the present application, the power of the Gaussian laser is 80-500 W, preferably 200-400 W, and more preferably 250-350 W. As an embodiment of the present application, the power of the Gaussian laser can be 100 W, 150 W, 220 W, 280 W, 300 W, 330 W, 370 W, 420 W or 450 W. The spot diameter and power of the Gaussian laser in the above range can perform more fine scanning sintering on the material, eliminate possible material unevenness, surface defects and the like, and reduce the occurrence of cracks.

[0043] In the present application, the scanning speed of the homogenization laser is preferably 100-7000 mm / s, and more preferably 500-2000 mm / s. As an embodiment of the present application, the scanning speed of the homogenization laser can be 600 mm / s, 900 mm / s, 1200 mm / s, 1500 mm / s, 3000 mm / s, 4000 mm / s or 6000 mm / s. The scanning speed of the homogenization laser in the above range can take into account the product quality and processing speed.

[0044] In the present application, the scanning speed of the Gaussian laser is preferably 100-3000 mm / s, and more preferably 500-1000 mm / s. As an embodiment of the present application, the scanning speed of the Gaussian laser can be 400 mm / s, 600 mm / s, 700 mm / s, 1100 mm / s, 1300 mm / s, 1800 mm / s, 2000 mm / s or 2500 mm / s. The scanning speed of the Gaussian laser in the above range can take into account the product quality and processing speed.

[0045] The present application does not have special requirements for other operations of the additive manufacturing, and the additive manufacturing process according to the conventional additive manufacturing process in the art. As an embodiment of the present application, the process of the additive manufacturing can be: sandblasting treatment of the printing substrate; drying of the metal powder; mounting the sandblasted printing substrate to the object table, lowering the printing substrate below the printing level using the lifting platform; using the air extraction system to replace the inert gas; manually finding zero to keep the printing substrate at the same height as the printing level; rotating the powder shaft to lower the metal powder, and using the scraper to spread the powder; after the model is established, the corresponding process parameters are input into the control system after the slicing treatment, and the double laser is used for sintering; starting the automatic printing, repeating the powder spreading-sintering process for each layer until the final layer, and obtaining the additive manufacturing part.

[0046] The flowchart of the additive manufacturing process of the application using laser powder bed melting technology is shown in the figure: Figure 1 As shown in the figure: according to the three-dimensional model information of the metal part, slicing is carried out; according to the slicing information, a double laser system is selected for printing; for high crack-sensitive alloys with a solidification interval greater than 350K, first, a homogenization laser is used for pre-sintering to preheat the powder bed, and then a Gaussian laser is used for reprocessing; for high crack-sensitive alloys with a solidification interval between 260K and 350K, first, a homogenization laser is used to sinter the solid area, and then a Gaussian laser is used to sinter the frame area; after the double laser printing process of all layers is completed, the part of the high crack-sensitive alloy is obtained.

[0047] The application utilizes the characteristics of large homogenization laser spot diameter, high laser power and uniform energy distribution to pre-sinter the metal powder, which can realize the preheating of the substrate, and in the middle and later stages of additive manufacturing, it can realize the preheating of the formed material. When a Gaussian laser is used for processing, the temperature difference between the molten pool and the substrate (or the formed material) is reduced, the temperature gradient is reduced, the thermal stress in the cooling process is reduced, the stress concentration is reduced, and thus the formation and expansion of cracks are reduced. By utilizing the characteristics of small Gaussian laser spot diameter and energy concentration, the pre-sintered alloy is scanned and sintered again, which can make the material more fine, eliminate possible problems such as uneven material distribution and surface defects, and further reduce the risk of cracks.

[0048] The technical solutions in the application will be clearly and completely described below in combination with the embodiments in the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0049] Embodiment 1

[0050] A method suitable for additive manufacturing of high crack-sensitive alloy, the high crack-sensitive alloy is Ti-48Al-2Cr-2Nb alloy, abbreviated as TiAl alloy, and the solidification interval is 417K. The schematic diagram of the additive manufacturing device is shown in the figure: Figure 2 In the figure, 1 and 2 are galvanometer mirrors, 3 is the formed material, 4 is metal powder, 5 is a printing substrate, 6 is a stage, 7 is a lifting platform, 8 is a Gaussian laser, 9 is a homogenization laser, 10 is a computer, 11 is a Gaussian laser, 12 is a homogenization laser, and 13 is a printing direction.

[0051] The schematic diagram of the partition processing of the TiAl alloy in this embodiment is shown in the figure: Figure 3 In the figure, 14 is the frame area with a width of 0.1mm, and 15 is the solid area.

[0052] The schematic diagram of the spot shape and energy distribution of the homogenized laser in this embodiment is shown in FIG. 1, and the spot diameter is 400 pm. Figure 4

[0053] The schematic diagram of the spot shape and energy distribution of the Gaussian laser in this embodiment is shown in FIG. 2, and the spot diameter is 80 pm. Figure 5

[0054] The specific steps of additive manufacturing are as follows:

[0055] Step 1: Put the printing substrate 5 into the sand blasting machine to perform sand blasting treatment on each surface of the substrate. After sand blasting, remove the sand attached to the substrate by the compressed air gun in the sand blasting machine. Dip the high-grade wiping paper in alcohol and wipe the surface in one direction. Dry the surface using the drying machine for 5 min, and prepare for use. The printing substrate 5 is a TiAl alloy substrate with a size of 248 mm*248 mm*30 mm.

[0056] Step 2: Put the TiAl alloy metal powder 4 into the oven for drying. The drying temperature is 80°C, and the drying time is 5 h.

[0057] Step 3: Place the sand-blasted printing substrate 5 on the object table 6 and fix it using screws. Lower the printing substrate 5 to 4 cm below the printing level using the mechanical lifting table 7.

[0058] Step 4: Turn on the air extraction system and introduce argon gas until the oxygen content is less than 800 ppm.

[0059] Step 5: Perform manual zero-finding to keep the printing substrate 5 at the same height as the printing level.

[0060] Step 6: Rotate the powder shaft by 0.3 turns, lower the appropriate amount of powder, and use the scraper to spread the powder. The forward speed of the scraper is 80 mm / s, the forward distance is 500 mm, and the powder thickness is 30 pm.

[0061] Step 7: Perform slicing processing on the established model and input the corresponding process parameters. First, turn on the homogenized laser 9 and use the homogenized laser 12 to scan in the printing direction 13 for pre-sintering. The laser power is 800 W, the scanning speed is 550 mm / s, and the scanning interval is 250 pm. Then, turn on the Gaussian laser 8 and use the Gaussian laser 11 to scan the solid region 15. The laser power is 100 W, the scanning speed is 450 mm / s, and the scanning interval is 50 pm. Complete the sintering of one layer.

[0062] Step 8: Turn on the automatic printing. Repeat steps 6 to 7 for each layer until the final layer, and obtain the additive manufacturing part.

[0063] Example 2

[0064] ​​A method for additive manufacturing of a high crack sensitive alloy, the high crack sensitive alloy being IN939 alloy, the solidification interval being 343 K. The specific steps of the additive manufacturing are:

[0065] Step 1: Put the printing substrate 5 into the sand blasting machine to sand blast each face of the substrate, after sand blasting, remove the sand attached to the substrate by compressed air gun in the sand blasting machine, use advanced wiping paper dipped in alcohol to wipe the surface in one direction, use the drying machine to dry for 5 min, and standby; the printing substrate 5 is IN939 alloy substrate, the size is 248mm*248mm*30mm;

[0066] Step 2: Put the IN939 alloy metal powder 4 into the oven for drying; the drying temperature is 80℃, and the drying time is 6h;

[0067] Step 3: Place the sand blasted printing substrate 5 on the object table 6 and fix it with screws, and use the mechanical lifting platform 7 to lower the printing substrate 5 to 4cm below the printing level;

[0068] Step 4: Turn on the air extraction system and pass in argon gas to make the oxygen content less than 800ppm;

[0069] Step 5: Perform manual zero finding to keep the printing substrate 5 at the same height as the printing level;

[0070] Step 6: Rotate the powder shaft 0.3 turns, lower the appropriate amount of powder, and use the scraper to spread the powder, the forward speed of the scraper is 80mm / s, the forward distance is 500mm, and the powder spreading thickness is 30μm;

[0071] Step 7: Slice the established model and input the corresponding process parameters, first turn on the homogenization laser 9, use the homogenization laser 12 to pre-sinter the solid area 15 in the printing direction 13, the laser power is 850W, the scanning speed is 1000mm / s, the scanning interval is 300μm, then turn on the Gaussian laser 8, use the Gaussian laser 11 to scan the frame area 14 (width is 0.1mm), the laser power is 270W, the scanning speed is 1800mm / s, the scanning interval is 50μm, and the sintering of one layer is completed;

[0072] Step 8: Turn on the automatic printing, repeat steps 6 to 7 for each layer until the final layer, and obtain the additive manufacturing part.

[0073] Comparative Example 1

[0074] A method for additive manufacturing, the raw material and preparation method are the same as those of Example 1, except that only Gaussian laser is used for one-time scanning sintering.

[0075] Comparative Example 2

[0076] A method of additive manufacturing, raw materials and preparation method are the same as those of Example 2, except that only one scanning sintering is performed using a Gaussian laser.

[0077] The alloy parts obtained by processing Example 1, 2 and Comparative Examples 1, 2 are observed by metallographic optical microscope, respectively, to obtain metallographic pictures, as shown in Figures 6 to 9

[0078] By comparing Figure 6 and Figure 8 It can be seen that the alloy part obtained by processing Example 1 controls the macroscopic cracks into micro-cracks, and the crack inhibition effect is very significant.

[0079] By comparing Figure 7 and Figure 9 It can be seen that the alloy part obtained by processing Example 2 effectively eliminates the cracks generated by Gaussian laser scanning.

[0080] From the above examples and comparative examples, it can be seen that the method provided by the present application can effectively inhibit the generation and development of cracks of high crack sensitive alloy during additive manufacturing.

[0081] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.​

Claims

1. A method for additive manufacturing of high crack sensitive alloys, using laser powder bed fusion technology, characterized in that, The double laser processing of each layer of metal powder comprises: firstly, using a homogenization laser to pre-sinter the metal powder to obtain a pre-sintered body, and then using a Gaussian laser to scan and sinter the pre-sintered body; the spot diameter of the homogenization laser is 100-500 μm, and the power is 800-2000 W; the spot diameter of the Gaussian laser is 40-100 μm, and the power is 80-500 W; The high crack sensitivity alloy comprises an aluminum alloy, a nickel-based high-temperature alloy, a stainless steel, a TiAl alloy or a NiAl alloy; When the solidification range of the high crack sensitivity alloy is higher than 350 K, the double laser processing of each layer of metal powder comprises: firstly, using a homogenization laser to integrally pre-sinter the metal powder to obtain a pre-sintered body, dividing the pre-sintered body into a solid region and a frame region surrounding the periphery of the solid region according to a target region, the width of the frame region being 0.1-0.5 mm, and then using a Gaussian laser to scan and sinter the solid region; When the solidification range of the high crack sensitivity alloy is between 265 K and 350 K, the double laser processing of each layer of metal powder comprises: dividing the metal powder into a solid region and a frame region surrounding the periphery of the solid region according to a target region, the width of the frame region being 0.1-0.5 mm, firstly using a homogenization laser to pre-sinter the solid region to obtain a pre-sintered body, and then using a Gaussian laser to scan and sinter the frame region.

2. The method of claim 1, wherein, The scanning speed of the homogenization laser is 100-7000 mm / s.

3. The method of claim 1, wherein, The scanning speed of the Gaussian laser is 100-3000 mm / s.

4. The method of claim 1, wherein, The printing substrate in the additive manufacturing is of the same material as the metal powder.

5. The method of claim 1, wherein, The metal powder is dried before use, the drying temperature is 70-90 ℃, and the drying time is 4-6 h.

6. The method of claim 1, wherein, The additive manufacturing is carried out in an inert atmosphere.

7. The method of claim 1, wherein, The powder laying thickness of each layer of metal powder is independently 30-200 μm. The powder laying thickness of each layer of metal powder is independently 30-200 μm.

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