High efficiency low cost selective laser melting forming method

Abstract

The application discloses a high-efficiency and low-cost selective laser melting forming method, relates to the technical field of metal additive manufacturing, and aims at solving the problems of high manufacturing cost and slow efficiency of the selective laser melting technology for aviation titanium alloy components. The method comprises the following steps: obtaining titanium alloy powder, the particle size of the titanium alloy powder is 53-105 mu m, the particle size distribution D10 is 55-62 mu m, the particle size distribution D50 is 65-75 mu m, and the particle size distribution D90 is 85-95 mu m; the titanium alloy powder is placed on a laser powder bed, the layer thickness of the titanium alloy powder is 90-110 mu m, a first melting scan and a second remelting scan are sequentially performed on each forming layer by using a selective laser melting method, and thus a titanium alloy component is obtained; the starting angle of the first melting scan is 0-10 degrees, the starting angle of the second remelting scan is 55-65 degrees, and the included angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 55-65 degrees.

Description

Technical Field

[0001] This application relates to the field of metal additive manufacturing technology, specifically to a high-efficiency, low-cost selective laser melting forming method. Background Technology

[0002] Currently, my country's manufacturing of large titanium alloy components for aero-engines is facing severe technological gaps and industrialization challenges. With the fourth-generation engine entering mass production, the demand for large integral components such as the 1.8-meter diameter combustion chamber casing and the 80-millimeter thick turbine disk has surged. However, the material utilization rate of traditional forging and machining processes is less than 12%, resulting in titanium alloys accounting for as much as 43% of the cost of a single engine. This predicament is even more pronounced in the field of additive manufacturing: GE, a leading international company, has achieved the manufacturing of 150μm thick Inconel 718 components through the EAFA project, with a forming efficiency of 550g / h. Meanwhile, my country's mainstream equipment is still limited to 40-80μm thick processes, with a deposition rate of only 21% of the international level per unit time. This directly results in a 58% higher cost of titanium powder per engine compared to foreign counterparts, and the cost of the mainstream fine powder reaches 1100 yuan / kg, 3.7 times that of coarse powder.

[0003] The technological gap in manufacturing thick-layer components has jeopardized equipment reliability. When the layer thickness increases to 150μm, the aspect ratio of the molten pool exceeds the critical value of 3:1, the porosity increases sharply to 2.1%, the fatigue life of the components only reaches 65% of the forging standard, and the excessive surface waviness causes a 0.3% decrease in the engine's thrust-to-weight ratio. Furthermore, conventional large-particle titanium alloy powder suffers from problems such as surface adsorption of moisture and oil, and poor flowability, affecting the uniformity of powder spreading for thick layers. Laser absorption rate also needs further improvement, thus requiring powder pretreatment. Facing the proposed strategic goal of "increasing the efficiency of aerospace titanium alloy components by 300% and reducing costs by 50% by 2025," the current technological state still presents significant gaps: the efficiency gap between a deposition rate of 120g / h and the target value of 400g / h, the cost gap between 28,000 yuan / kg and 12,000 yuan / kg, and the quality bottleneck of a 73% UT flaw detection pass rate for large-size components compared to the aerospace standard requirement of 99.5%, collectively constitute key barriers restricting the upgrading of the aero-engine manufacturing system. With the surge in demand for large integral components for aero-engine projects (such as 1.8m diameter turbine disks and 3m-class combustion chamber shells), there is an urgent need to break through the collaborative manufacturing technology of large particles (53-105μm) and large layer thickness (80-150μm) to achieve the core goal of reducing manufacturing costs by 50% and increasing forming efficiency by 3 times.

[0004] In conclusion, research on selective laser melting manufacturing of large-particle, thick-layer Ti6Al4V alloy is of great strategic significance for solving the problems of high cost and slow efficiency in current aerospace components. It is also one of the important ways to achieve the strategic goal of "increasing the efficiency of aerospace titanium alloy components by 300% and reducing the cost by 50% by 2025". Summary of the Invention

[0005] This application discloses a high-efficiency, low-cost selective laser melting forming method to solve the problems of high manufacturing cost and slow efficiency of current selective laser melting technology for aerospace titanium alloy components.

[0006] In a first aspect, this application provides a high-efficiency, low-cost selective laser melting forming method, comprising: obtaining titanium alloy powder, wherein the particle size of the titanium alloy powder is 53μm to 105μm, and the particle size distribution D10 is 55μm to 62μm, D50 is 65μm to 75μm, and D90 is 85μm to 95μm; placing the titanium alloy powder in a laser powder bed, wherein the layer thickness of the titanium alloy powder is 90μm to 110μm; and performing a first melting scan and a second remelting scan on each forming layer sequentially using a selective laser melting method to obtain a titanium alloy component; wherein the starting angle of the first melting scan is 0° to 10°, the starting angle of the second remelting scan is 55° to 65°, and the angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 55° to 65°.

[0007] The forming method of this application, by using large-particle titanium alloy powder, has a lower raw material cost compared to conventional fine powder (particle diameter is usually less than 53μm), with a particle size of 53-105μm. At the same time, the large layer thickness process can significantly increase the deposition rate per unit time, achieving efficiency improvement and cost reduction while ensuring density and mechanical properties.

[0008] Furthermore, selective secondary remelting layer by layer significantly improves the forming quality and mechanical properties of the component. The second remelting preferentially acts on the overlapping area of ​​the adjacent first scanning trajectory, which can remelt and heal the unfused voids left by the first forming; at the same time, repeated heating and rapid solidification cycles are beneficial to grain refinement and improve the material strength according to the Hall-Petch strengthening mechanism.

[0009] Furthermore, by staggering the starting angle of the second remelting scan from that of the first melting scan, and controlling the angle between the remelting scan vector direction and the protective gas flow direction to 55°–65°, the interaction between the molten pool spreading direction and the protective gas flow can be changed, thereby suppressing the redeposition of splash particles.

[0010] In some possible embodiments, the titanium alloy powder contains, by mass fraction, 5.5wt% to 6.5wt% Al, 3.5wt% to 4.5wt% V, 0.05wt% to 0.15wt% Fe, 0.005wt% to 0.015wt% C, with the balance being Ti and unavoidable trace impurities.

[0011] In some possible implementations, the second remelting scan selectively scans only the overlapping area of ​​adjacent first melting scan trajectories.

[0012] In some possible implementations, the remelting width of the second remelting scan is 30% to 50% of the spacing of the first melting scan.

[0013] In some possible implementations, the ratio of the scanning speed of the second remelting scan to the flow rate of the protective gas is in the range of 0.8 to 1.2.

[0014] In some possible implementations, the laser spot diameter of the first melting scan is 85μm to 110μm, the laser power is 280W to 320W, the scanning speed is 600mm / s to 1200mm / s, and the scanning spacing is 75μm to 125μm.

[0015] In some possible implementations, the laser spot diameter of the second remelting scan is 90μm to 100μm, the laser power is 160W to 300W, and the scanning speed is 600mm / s to 1600mm / s.

[0016] In some possible implementations, the steps following obtaining the titanium alloy powder further include: placing the titanium alloy powder in a protective atmosphere and heat-treating the titanium alloy powder.

[0017] In some possible embodiments, the step of heat-treating the titanium alloy powder specifically includes: heat-treating the titanium alloy powder at 200℃ to 400℃ for 1h to 3h, wherein the oxygen content of the heat-treated titanium alloy powder increases by no more than 0.05wt%, and the thickness of the surface oxide layer is 5nm to 20nm.

[0018] In some possible implementations, the step of obtaining titanium alloy powder specifically includes: processing the titanium alloy powder using a gas atomization process to obtain titanium alloy powder. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of the high-efficiency, low-cost selective laser melting forming method proposed in the embodiments of this application; Figure 2The image shows the morphology and surface scan of the alloy powder after pretreatment. Figure 3 Print a schematic diagram showing the relationship between vector angles and wind field; Figure 4 Metallographic analysis image of the printed sample; Figure 5 Figures showing the mechanical properties of remelted and unremelted printed samples. Figure 6 This is a test diagram of the mechanical properties of a printed sample with a scanning vector-airflow angle. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] In embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0023] In the following embodiments of this application, the terms "first," "second," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0024] In the embodiments of this application, the terms "in some embodiments," "in some examples," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "in some embodiments," "in some examples," or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "in some embodiments," "in some examples," or "for example" is intended to present the relevant concepts in a specific manner.

[0025] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0026] Currently, my country's manufacturing of large titanium alloy components for aero-engines is facing severe technological gaps and industrialization challenges. With the fourth-generation engine entering mass production, the demand for large integral components such as the 1.8-meter diameter combustion chamber casing and the 80-millimeter thick turbine disk has surged. However, the material utilization rate of traditional forging and machining processes is less than 12%, resulting in titanium alloys accounting for as much as 43% of the cost of a single engine. This predicament is even more pronounced in the field of additive manufacturing: GE, a leading international company, has achieved the manufacturing of 150μm thick Inconel 718 components through the EAFA project, with a forming efficiency of 550g / h. Meanwhile, my country's mainstream equipment is still limited to 40-80μm thick processes, with a deposition rate of only 21% of the international level per unit time. This directly results in a 58% higher cost of titanium powder per engine compared to foreign counterparts, and the cost of the mainstream fine powder reaches 1100 yuan / kg, 3.7 times that of coarse powder.

[0027] The technological gap in manufacturing thick-layer components has jeopardized equipment reliability. When the layer thickness increases to 150μm, the aspect ratio of the molten pool exceeds the critical value of 3:1, the porosity increases sharply to 2.1%, the fatigue life of the components only reaches 65% of the forging standard, and the excessive surface waviness causes a 0.3% decrease in the engine's thrust-to-weight ratio. Furthermore, conventional large-particle titanium alloy powder suffers from problems such as surface adsorption of moisture and oil, and poor flowability, affecting the uniformity of powder spreading for thick layers. Laser absorption rate also needs further improvement, thus requiring powder pretreatment. Facing the proposed strategic goal of "increasing the efficiency of aerospace titanium alloy components by 300% and reducing costs by 50% by 2025," the current technological state still presents significant gaps: the efficiency gap between a deposition rate of 120g / h and the target value of 400g / h, the cost gap between 28,000 yuan / kg and 12,000 yuan / kg, and the quality bottleneck of a 73% UT flaw detection pass rate for large-size components compared to the aerospace standard requirement of 99.5%, collectively constitute key barriers restricting the upgrading of the aero-engine manufacturing system. With the surge in demand for large integral components for aero-engine projects (such as 1.8m diameter turbine disks and 3m-class combustion chamber shells), there is an urgent need to break through the collaborative manufacturing technology of large particles (53-105μm) and large layer thickness (80-150μm) to achieve the core goal of reducing manufacturing costs by 50% and increasing forming efficiency by 3 times.

[0028] In summary, research on selective laser melting manufacturing of large-particle, thick-layer Ti6Al4V alloy is of great strategic significance for solving the problems of high cost and slow efficiency in current aerospace components. It is also one of the important ways to achieve the strategic goal of "increasing the efficiency of aerospace titanium alloy components by 300% and reducing the cost by 50% by 2025".

[0029] To address the issues of high cost and low efficiency in current selective laser melting technology for aerospace titanium alloy components, please refer to... Figure 1 This application provides a high-efficiency, low-cost selective laser melting forming method, comprising: S10, obtain titanium alloy powder, wherein the particle size of the titanium alloy powder is 53μm~105μm, and the particle size distribution D10 is 55μm~62μm, D50 is 65μm~75μm, and D90 is 85μm~95μm.

[0030] In some examples, the titanium alloy powder has a sphericity of 0.85–1.00, a tap density of 2.70–2.85 g / cm³, a flowability of 20–26 s / 50 g, and a loose density of 2.35–2.55 g / cm³.

[0031] S20, titanium alloy powder is placed in a laser powder bed with a layer thickness of 90μm to 110μm. Selective laser melting is used to sequentially perform a first melting scan and a second remelting scan on each forming layer to obtain a titanium alloy component. The starting angle of the first melting scan is 0° to 10°, the starting angle of the second remelting scan is 55° to 65°, and the angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 55° to 65°.

[0032] The forming method of this application, by using large-particle titanium alloy powder, has a lower raw material cost compared to conventional fine powder (particle diameter is usually less than 53μm), with a particle size of 53-105μm. At the same time, the large layer thickness process can significantly increase the deposition rate per unit time, achieving efficiency improvement and cost reduction while ensuring density and mechanical properties.

[0033] Furthermore, selective secondary remelting layer by layer significantly improves the forming quality and mechanical properties of the component. The second remelting preferentially acts on the overlapping area of ​​the adjacent first scanning trajectory, which can remelt and heal the unfused voids left by the first forming; at the same time, repeated heating and rapid solidification cycles are beneficial to grain refinement and improve the material strength according to the Hall-Petch strengthening mechanism.

[0034] Furthermore, by staggering the starting angle of the second remelting scan from that of the first melting scan, and controlling the angle between the remelting scan vector direction and the protective gas flow direction to 55°–65°, the interaction between the molten pool spreading direction and the protective gas flow can be changed, thereby suppressing the redeposition of splash particles.

[0035] In some possible implementations, the titanium alloy powder contains, by mass fraction, 5.5wt% to 6.5wt% Al, 3.5wt% to 4.5wt% V, 0.05wt% to 0.15wt% Fe, 0.005wt% to 0.015wt% C, with the balance being Ti and unavoidable trace impurities.

[0036] In some embodiments, the second remelting scan selectively scans only the overlapping area of ​​the adjacent first melting scan trajectory.

[0037] In some embodiments, the remelting width of the second remelting scan is 30% to 50% of the spacing of the first melting scan. This allows for precise healing of defects.

[0038] In some embodiments, the ratio of the scanning speed to the shielding gas flow rate of the second remelting scan ranges from 0.8 to 1.2. This allows the spatter to be carried away from the melting zone by the shielding gas flow, thereby suppressing interlayer incomplete fusion defects caused by spatter redeposition under high-energy input and large-layer thickness.

[0039] In some embodiments, the laser spot diameter of the first melting scan is 85μm to 110μm, the laser power is 280W to 320W, the scanning speed is 600mm / s to 1200mm / s, and the scanning spacing is 75μm to 125μm.

[0040] In some examples, the scanning strategy for the first melting scan is a global scan with an interlayer rotation angle of 55° to 65°.

[0041] In some embodiments, the laser spot diameter of the second remelting scan is 90μm to 100μm, the laser power is 160W to 300W, and the scanning speed is 600mm / s to 1600mm / s.

[0042] In some examples, the interlayer rotation angle of the second remelting scan is 55° to 65°.

[0043] In some embodiments, the steps following obtaining the titanium alloy powder further include: Titanium alloy powder is placed in a protective atmosphere and then heat-treated.

[0044] In this way, by subjecting large-particle titanium alloy powder to heat treatment under a protective atmosphere, adsorbates on the surface of the titanium alloy powder can be removed and a uniform thin oxide layer that is conducive to laser absorption can be formed, thereby improving the spreading stability and energy coupling efficiency of the titanium alloy powder.

[0045] In some embodiments, the step of heat-treating titanium alloy powder specifically includes: Titanium alloy powder was heat-treated at 200℃~400℃ for 1h~3h, wherein the oxygen content of the heat-treated titanium alloy powder increased by no more than 0.05wt%, and the thickness of the surface oxide layer was 5nm~20nm.

[0046] In this way, on the one hand, water vapor and organic pollutants adsorbed on the powder surface can be removed, reducing porosity defects caused by gas release during the forming process; on the other hand, a uniform thin oxide layer of 5nm to 20nm can be formed on the surface of titanium alloy powder, improving the absorption efficiency of titanium alloy powder for infrared lasers and improving the uniformity of large-layer powder spreading on the order of 100μm.

[0047] In some embodiments, the step of obtaining titanium alloy powder specifically includes: Titanium alloy powder was processed using a gas atomization process to obtain titanium alloy powder powder.

[0048] The technical solutions of this application are not limited to the specific embodiments exemplified below, but also include any combination of the specific embodiments.

[0049] Example 1 This embodiment proposes a high-efficiency, low-cost selective laser melting forming method, including the following steps: Step 1: Obtain titanium alloy powder, specifically Ti6Al4V titanium alloy. The Ti6Al4V titanium alloy powder was purchased from Jirek Metal Materials (Shandong) Co., Ltd. The selective laser melting equipment was a Demetal-150 laser 3D printing equipment manufactured by Leijia Company. The substrate used was Ti6Al4V titanium alloy with dimensions of 250 mm × 250 mm × 15 mm. The surface of the substrate was polished with an angle grinder until no oxides were found. The oil and dirt on the surface of the substrate were cleaned with acetone and alcohol, respectively. The titanium alloy powder contained 5.99 wt% Al, 4.0 wt% V, 0.1 wt% Fe, and 0.01 wt% C by mass fraction, with the balance being Ti and unavoidable trace impurities. The titanium alloy powder has a particle size of 53μm to 105μm, a particle size distribution of D10 of 58.2μm, D50 of 70.1μm, and D90 of 88.9μm, a particle size distribution of D10: 58.2μm, D50: 70.1μm, and D90: 88.9μm, a sphericity of >0.85, a tap density of 2.78g / cm3, a flowability of 23.3s / 50g, and a loose density of 2.46g / cm3.

[0050] Step 2: Place the titanium alloy powder in the laser powder bed of the printer hopper. Set the sample size to 7x7x7mm. The laser spot diameter for the first melting scan is 95μm, the laser power is 280W, the scanning speed is 600mm / s, the scanning interval is 100μm, the layer thickness is 100μm, the scanning strategy is overall scanning, the interlayer rotation angle is 60°, and the starting angle is 0°. The laser spot diameter for the second remelting scan is 95μm, the laser power is 280W, the scanning speed is 1200mm / s, the scanning interval is 100μm, the scanning strategy is selective scanning, the interlayer rotation angle is 60°, the starting angle is 60°, the protective gas flow rate is 1.2m / s, and the angle between the scanning vector direction of the second remelting scan and the protective gas flow direction is 60°.

[0051] Argon gas was introduced before printing to reduce the oxygen content to below 500 ppm. Printing was carried out under the protection of argon atmosphere and cooled in the chamber for 2 hours to obtain the printed Ti6Al4V alloy.

[0052] Comparative Example 1 Step 1: Obtain titanium alloy powder, specifically Ti6Al4V titanium alloy. The Ti6Al4V titanium alloy powder was purchased from Jirek Metal Materials (Shandong) Co., Ltd. The selective laser melting equipment was a Demetal-150 laser 3D printing equipment manufactured by Leijia Company. The substrate used was Ti6Al4V titanium alloy with dimensions of 250 mm × 250 mm × 15 mm. The surface of the substrate was polished with an angle grinder until no oxides were found. The oil and dirt on the surface of the substrate were cleaned with acetone and alcohol, respectively. The titanium alloy powder contained 5.99 wt% Al, 4.0 wt% V, 0.1 wt% Fe, and 0.01 wt% C by mass fraction, with the balance being Ti and unavoidable trace impurities. The titanium alloy powder has a particle size of 53μm to 105μm, a particle size distribution of D10 of 58.2μm, D50 of 70.1μm, and D90 of 88.9μm, a particle size distribution of D10: 58.2μm, D50: 70.1μm, and D90: 88.9μm, a sphericity of >0.85, a tap density of 2.78g / cm3, a flowability of 23.3s / 50g, and a loose density of 2.46g / cm3.

[0053] Step 2: Place the titanium alloy powder into the laser powder bed of the printer hopper. Set the sample size to 7x7x7mm, the laser spot diameter for melting and scanning to 95μm, the laser power to 280W, the scanning speed to 600mm / s, the scanning interval to 100μm, the layer thickness to 100μm, the scanning strategy to be overall scanning, the interlayer rotation angle to 60°, the starting angle to 0°, and the protective gas flow rate to 1.2m / s.

[0054] Argon gas was introduced before printing to reduce the oxygen content to below 500 ppm. Printing was carried out under the protection of argon atmosphere and cooled in the chamber for 2 hours to obtain the printed Ti6Al4V alloy.

[0055] Example 2 This embodiment proposes a high-efficiency, low-cost selective laser melting forming method, including the following steps: Step 1: Obtain titanium alloy powder, specifically Ti6Al4V titanium alloy. The Ti6Al4V titanium alloy powder was purchased from Jirek Metal Materials (Shandong) Co., Ltd. The selective laser melting equipment was a Demetal-150 laser 3D printing equipment manufactured by Leijia Company. The substrate used was Ti6Al4V titanium alloy with dimensions of 250 mm × 250 mm × 15 mm. The surface of the substrate was polished with an angle grinder until no oxides were found. The oil and dirt on the surface of the substrate were cleaned with acetone and alcohol, respectively. The titanium alloy powder contained 5.99 wt% Al, 4.0 wt% V, 0.1 wt% Fe, and 0.01 wt% C by mass fraction, with the balance being Ti and unavoidable trace impurities. The titanium alloy powder has a particle size of 53μm to 105μm, a particle size distribution of D10 of 58.2μm, D50 of 70.1μm, and D90 of 88.9μm, a particle size distribution of D10: 58.2μm, D50: 70.1μm, and D90: 88.9μm, a sphericity of >0.85, a tap density of 2.78g / cm3, a flowability of 23.3s / 50g, and a loose density of 2.46g / cm3.

[0056] Step 2: Place the titanium alloy powder in the laser powder bed of the printer hopper. Set the sample size to 7x7x7mm. The laser spot diameter for the first melting scan is 95μm, the laser power is 300W, the scanning speed is 800mm / s, the scanning interval is 100μm, the layer thickness is 100μm, the scanning strategy is overall scanning, the interlayer rotation angle is 60°, and the starting angle is 0°. The laser spot diameter for the second remelting scan is 95μm, the laser power is 300W, the scanning speed is 1600mm / s, the scanning interval is 100μm, the scanning strategy is selective scanning, the interlayer rotation angle is 60°, the starting angle is 60°, the protective gas flow rate is 1.67m / s, and the angle between the scanning vector direction of the second remelting scan and the protective gas flow direction is 60°.

[0057] Argon gas was introduced before printing to reduce the oxygen content to below 500 ppm. Printing was carried out under the protection of argon atmosphere and cooled in the chamber for 2 hours to obtain the printed Ti6Al4V alloy.

[0058] Comparative Example 2 This embodiment proposes a high-efficiency, low-cost selective laser melting forming method, including the following steps: Step 1: Obtain titanium alloy powder, specifically Ti6Al4V titanium alloy. The Ti6Al4V titanium alloy powder was purchased from Jirek Metal Materials (Shandong) Co., Ltd. The selective laser melting equipment was a Demetal-150 laser 3D printing equipment manufactured by Leijia Company. The substrate used was Ti6Al4V titanium alloy with dimensions of 250 mm × 250 mm × 15 mm. The surface of the substrate was polished with an angle grinder until no oxides were found. The oil and dirt on the surface of the substrate were cleaned with acetone and alcohol, respectively. The titanium alloy powder contained 5.99 wt% Al, 4.0 wt% V, 0.1 wt% Fe, and 0.01 wt% C by mass fraction, with the balance being Ti and unavoidable trace impurities. The titanium alloy powder has a particle size of 53μm to 105μm, a particle size distribution of D10 of 58.2μm, D50 of 70.1μm, and D90 of 88.9μm, a particle size distribution of D10: 58.2μm, D50: 70.1μm, and D90: 88.9μm, a sphericity of >0.85, a tap density of 2.78g / cm3, a flowability of 23.3s / 50g, and a loose density of 2.46g / cm3.

[0059] Step 2: Place the titanium alloy powder in the laser powder bed of the printer hopper. Set the sample size to 7x7x7mm, the laser spot diameter for melting scanning to 95μm, the laser power to 300W, the scanning speed to 800mm / s, the scanning interval to 100μm, the layer thickness to 100μm, the scanning strategy to be overall scanning, the interlayer rotation angle to 60°, the starting angle to 0°, the protective gas flow rate to 1.67m / s, and the angle between the scanning vector direction of the second remelting scan and the protective gas flow direction to 60°.

[0060] Argon gas was introduced before printing to reduce the oxygen content to below 500 ppm. Printing was carried out under the protection of argon atmosphere and cooled in the chamber for 2 hours to obtain the printed Ti6Al4V alloy.

[0061] Example 3 This embodiment proposes a high-efficiency, low-cost selective laser melting forming method, including the following steps: Step 1: Obtain titanium alloy powder, specifically Ti6Al4V titanium alloy. The Ti6Al4V titanium alloy powder was purchased from Jirek Metal Materials (Shandong) Co., Ltd. The selective laser melting equipment was a Demetal-150 laser 3D printing equipment manufactured by Leijia Company. The substrate used was Ti6Al4V titanium alloy with dimensions of 250 mm × 250 mm × 15 mm. The surface of the substrate was polished with an angle grinder until no oxides were found. The oil and dirt on the surface of the substrate were cleaned with acetone and alcohol, respectively. The titanium alloy powder contained 5.99 wt% Al, 4.0 wt% V, 0.1 wt% Fe, and 0.01 wt% C by mass fraction, with the balance being Ti and unavoidable trace impurities. The titanium alloy powder has a particle size of 53μm to 105μm, a particle size distribution of D10 of 58.2μm, D50 of 70.1μm, and D90 of 88.9μm, a particle size distribution of D10: 58.2μm, D50: 70.1μm, and D90: 88.9μm, a sphericity of >0.85, a tap density of 2.78g / cm3, a flowability of 23.3s / 50g, and a loose density of 2.46g / cm3.

[0062] Step 2: Place the titanium alloy powder into the laser powder bed of the printer hopper. Set the sample size to 7x7x7mm. The laser spot diameter for the first melting scan is 95μm, the laser power is 320W, the scanning speed is 1200mm / s, the scanning interval is 100μm, the layer thickness is 100μm, the scanning strategy is overall scanning, the interlayer rotation angle is 60°, and the starting angle is 0°. The laser spot diameter for the second remelting scan is 95μm, the laser power is 160W, the scanning speed is 1200mm / s, the scanning interval is 100μm, the scanning strategy is selective scanning, the interlayer rotation angle is 60°, the starting angle is 60°, the protective gas flow rate is 1.34m / s, and the angle between the scanning vector direction of the second remelting scan and the protective gas flow direction is 60°.

[0063] Argon gas was introduced before printing to reduce the oxygen content to below 500 ppm. Printing was carried out under the protection of argon atmosphere and cooled in the chamber for 2 hours to obtain the printed Ti6Al4V alloy.

[0064] Comparative Example 3 This embodiment proposes a high-efficiency, low-cost selective laser melting forming method, including the following steps: Step 1: Obtain titanium alloy powder, specifically Ti6Al4V titanium alloy. The Ti6Al4V titanium alloy powder was purchased from Jirek Metal Materials (Shandong) Co., Ltd. The selective laser melting equipment was a Demetal-150 laser 3D printing equipment manufactured by Leijia Company. The substrate used was Ti6Al4V titanium alloy with dimensions of 250 mm × 250 mm × 15 mm. The surface of the substrate was polished with an angle grinder until no oxides were found. The oil and dirt on the surface of the substrate were cleaned with acetone and alcohol, respectively. The titanium alloy powder contained 5.99 wt% Al, 4.0 wt% V, 0.1 wt% Fe, and 0.01 wt% C by mass fraction, with the balance being Ti and unavoidable trace impurities. The titanium alloy powder has a particle size of 53μm to 105μm, a particle size distribution of D10 of 58.2μm, D50 of 70.1μm, and D90 of 88.9μm, a particle size distribution of D10: 58.2μm, D50: 70.1μm, and D90: 88.9μm, a sphericity of >0.85, a tap density of 2.78g / cm3, a flowability of 23.3s / 50g, and a loose density of 2.46g / cm3.

[0065] Step 2: Place the titanium alloy powder into the laser powder bed of the printer hopper. Set the sample size to 7x7x7mm, the laser spot diameter for melting and scanning to 95μm, the laser power to 320W, the scanning speed to 1200mm / s, the scanning interval to 100μm, the layer thickness to 100μm, the scanning strategy to overall scanning, the interlayer rotation angle to 60°, the starting angle to 0°, and the protective gas flow rate to 1.34m / s.

[0066] Argon gas was introduced before printing to reduce the oxygen content to below 500 ppm. Printing was carried out under the protection of argon atmosphere and cooled in the chamber for 2 hours to obtain the printed Ti6Al4V alloy.

[0067] Comparative Example 4 This embodiment proposes a high-efficiency, low-cost selective laser melting forming method, including the following steps: Step 1: Obtain titanium alloy powder, specifically Ti6Al4V titanium alloy. The Ti6Al4V titanium alloy powder was purchased from Jirek Metal Materials (Shandong) Co., Ltd. The selective laser melting equipment was a Demetal-150 laser 3D printing equipment manufactured by Leijia Company. The substrate used was Ti6Al4V titanium alloy with dimensions of 250 mm × 250 mm × 15 mm. The surface of the substrate was polished with an angle grinder until no oxides were found. The oil and dirt on the surface of the substrate were cleaned with acetone and alcohol, respectively. The titanium alloy powder contained 5.99 wt% Al, 4.0 wt% V, 0.1 wt% Fe, and 0.01 wt% C by mass fraction, with the balance being Ti and unavoidable trace impurities. The titanium alloy powder has a particle size of 53μm to 105μm, a particle size distribution of D10 of 58.2μm, D50 of 70.1μm, and D90 of 88.9μm, a particle size distribution of D10: 58.2μm, D50: 70.1μm, and D90: 88.9μm, a sphericity of >0.85, a tap density of 2.78g / cm3, a flowability of 23.3s / 50g, and a loose density of 2.46g / cm3.

[0068] Step 2: Place Ti6Al4V powder into a vacuum tube furnace for heat treatment. After evacuating to 10⁻²Pa, fill with high-purity argon to atmospheric pressure, heat to 300℃ at 8℃ / min and hold for 2 hours. Then cool to room temperature with the furnace, remove and sieve for later use.

[0069] Step 3: Place the heat-treated titanium alloy powder into the laser powder bed of the printer hopper. The sample size is set to 7x7x7mm. The laser spot diameter for the first melting scan is 95μm, the laser power is 280W, the scanning speed is 600mm / s, the scanning interval is 100μm, the layer thickness is 100μm, the scanning strategy is overall scanning, the interlayer rotation angle is 60°, and the starting angle is 0°. The laser spot diameter for the second remelting scan is 95μm, the laser power is 280W, the scanning speed is 1200mm / s, the scanning interval is 100μm, the scanning strategy is selective scanning, the interlayer rotation angle is 60°, the starting angle is 60°, the protective gas flow rate is 1.2m / s, and the angle between the scanning vector direction of the second remelting scan and the protective gas flow direction is 60°.

[0070] Argon gas was introduced before printing to reduce the oxygen content to below 500 ppm. Printing was carried out under the protection of argon atmosphere and cooled in the chamber for 2 hours to obtain the printed Ti6Al4V alloy.

[0071] Comparative Example 5 The method in this embodiment is roughly the same as that in embodiment 2, except that the angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 30°.

[0072] Comparative Example 6 The method in this embodiment is roughly the same as that in embodiment 2, except that the angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 67°.

[0073] Comparative Example 7 The method in this embodiment is roughly the same as that in embodiment 2, except that the angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 40°.

[0074] Comparative Example 8 The method in this embodiment is roughly the same as that in embodiment 2, except that the angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 0°.

[0075] Comparative Example 9 The method in this embodiment is roughly the same as that in embodiment 2, except that the angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 20°.

[0076] Comparative Example 10 The method in this embodiment is roughly the same as that in embodiment 2, except that the angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 80°.

[0077] After metallographic polishing, the molded parts obtained in each embodiment and comparative example were observed under a microscope. The density and forming efficiency are shown in Table 1, the tensile strength and elongation after fracture are shown in Table 2, and the influence of the scanning vector-airflow angle on the forming quality and mechanical properties are shown in Table 3.

[0078] Table 1 Table 2 Table 3 Please also refer to Figures 2-6The results showed that, under the condition that the first melting scanning parameters, interlayer rotation angle, starting angle, and protective gas flow rate remained consistent, the powders used in Examples 1-3 and Comparative Examples 1-3 did not undergo high-temperature pretreatment. Among them, Examples 1-3, due to the use of a second selective remelting, achieved densities of 99.45%, 99.72%, and 99.91%, respectively, all higher than the corresponding unremelted comparative examples. Comparative Example 4, compared to Example 1, only added high-temperature powder pretreatment, and its density, tensile strength, elongation after fracture, and forming efficiency reached 99.95%, 1158 MPa, 13.0%, and 4 mm³ / s, respectively, all the best data among the groups. This indicates that high-temperature powder pretreatment can improve the spreading and melting stability of large powder particles, and further improve forming quality, mechanical properties, and forming efficiency. Comparing the printing efficiency of this application with previous studies, the printing rate of this application is more than twice that of most studies on the market, achieving the goal of more than doubling the manufacturing efficiency.

[0079] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within this application.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application.

Claims

1. A high-efficiency, low-cost selective laser melting forming method, characterized in that, include: Titanium alloy powder is obtained, wherein the particle size of the titanium alloy powder is 53μm to 105μm, and the particle size distribution is D10 of 55μm to 62μm, D50 of 65μm to 75μm, and D90 of 85μm to 95μm; The titanium alloy powder is placed in a laser powder bed, and the layer thickness of the titanium alloy powder is 90μm to 110μm. Selective laser melting method is used to sequentially perform a first melting scan and a second remelting scan on each formed layer to obtain a titanium alloy component. The starting angle of the first melting scan is 0° to 10°, the starting angle of the second remelting scan is 55° to 65°, and the angle between the scanning vector direction of the second remelting scan and the direction of the protective gas flow is 55° to 65°.

2. The method according to claim 1, characterized in that, The titanium alloy powder contains, by mass fraction, 5.5wt%–6.5wt% Al, 3.5wt%–4.5wt% V, 0.05wt%–0.15wt% Fe, and 0.005wt%–0.015wt% C, with the balance being Ti and unavoidable trace impurities.

3. The method according to claim 1, characterized in that, The second remelting scan selectively scans only the overlapping area of ​​the adjacent first melting scan trajectory.

4. The method according to claim 1 or 3, characterized in that, The remelting width of the second remelting scan is 30% to 50% of the spacing of the first melting scan.

5. The method according to claim 1, characterized in that, The ratio of the scanning speed to the protective gas flow rate of the second remelting scan ranges from 0.8 to 1.

2.

6. The method according to claim 1, characterized in that, The laser spot diameter of the first melting scan is 85μm to 110μm, the laser power is 280W to 320W, the scanning speed is 600mm / s to 1200mm / s, and the scanning spacing is 75μm to 125μm.

7. The method according to claim 1, characterized in that, The laser spot diameter of the second remelting scan is 90μm to 100μm, the laser power is 160W to 300W, and the scanning speed is 600mm / s to 1600mm / s.

8. The method according to claim 1, characterized in that, The steps following obtaining the titanium alloy powder also include: The titanium alloy powder is placed in a protective atmosphere and then subjected to heat treatment.

9. The method according to claim 8, characterized in that, The heat treatment step of the titanium alloy powder specifically includes: The titanium alloy powder is heat-treated at 200℃~400℃ for 1h~3h, wherein the oxygen content of the heat-treated titanium alloy powder increases by no more than 0.05wt%, and the thickness of the surface oxide layer is 5nm~20nm.

10. The method according to claim 1, characterized in that, The steps for obtaining titanium alloy powder specifically include: Titanium alloy powder was processed using a gas atomization process to obtain titanium alloy powder powder.

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