Laser printing method for copper alloy powder, three-dimensional member, and heat treatment method for three-dimensional member

Abstract

The invention provides a laser printing method for copper alloy powder. The laser printing method comprises the steps that (a) a copper alloy powder layer with the thickness ranging from 0.05 mm to 0.07 mm is laid on a base plate in a forming cavity or a previous solidification layer; (b) under the protection atmosphere of inert gas, according to preset three-dimensional model slice data, infrared laser beams are controlled to selectively scan and irradiate the copper alloy powder layer according to a preset scanning strategy, the power of the infrared laser is 500-800 W, the scanning speed is 600-900 mm / s, and the scanning interval is selected from 0.07-0.10 mm; (c) completely melting and solidifying the copper alloy powder in the scanned area to form a cladding layer; (d) repeating the steps (a) to (c), and printing layer by layer until the three-dimensional component is completed; wherein in the step (b), the infrared laser power is 500 to 600 W, and the scanning interval is 0.08 to 0.10 mm; or the power of the infrared laser is 700 to 800 W, and the scanning distance is 0.07 to 0.09 mm. In addition, the invention further provides a three-dimensional component and a heat treatment method thereof.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser additive manufacturing, in particular to a laser printing method of copper alloy powder, a three-dimensional component and a heat treatment method thereof. BACKGROUND

[0002] Selective Laser Melting (SLM) technology has significant advantages in manufacturing complex structural parts, but due to the low absorption rate of copper alloy to conventional infrared laser (1064nm), which is only about 3%-5%, the density is difficult to guarantee. In order to improve the density, the industry usually uses blue or green light laser with higher absorption rate, but such equipment has extremely high cost and complex technical requirements, which limits its practical application. At the same time, when using traditional low-power infrared laser (200W or 500W) to print copper alloy, the layer thickness is limited to a very small range (<20μm), which seriously affects the printing efficiency and cannot meet the manufacturing needs of large-size parts. SUMMARY

[0003] In view of this, the present application provides a laser printing method of copper alloy powder to realize the forming of large-thickness layer (≥50μm) and low porosity of copper alloy powder by infrared laser equipment.

[0004] In addition, it is also necessary to provide a three-dimensional component and a heat treatment method thereof.

[0005] A laser printing method of copper alloy powder, comprising the steps of: (a) laying a copper alloy powder layer with a thickness of 0.05-0.07mm on the substrate or the previous solidified layer in the forming cavity; (b) under the protection of inert gas atmosphere, according to the preset three-dimensional model slice data, controlling the infrared laser beam to selectively scan and irradiate the copper alloy powder layer according to the predetermined scanning strategy, wherein the power of the infrared laser is 500-800W, the scanning speed is 600-900mm / s, and the scanning interval is selected from 0.07-0.10mm; (c) making the copper alloy powder in the scanned area completely melt and solidify to form a cladding layer; (d) repeating steps (a) to (c) to print layer by layer until the three-dimensional component is completed; Wherein, the process parameter combination of step (b) is selected from any one of the following groups: (1) infrared laser power 500-600W, scanning interval 0.08-0.10mm; (2) infrared laser power 700-800W, scanning interval 0.07-0.09mm.

[0006] In some possible implementations, the predetermined scanning strategy includes: performing an S-shaped reciprocating filling scan on an inner region of a two-dimensional cross section corresponding to the three-dimensional model slice data.

[0007] In some possible implementations, the predetermined scanning strategy further includes: rotating the filling scanning direction of each layer by 67° relative to the previous layer, and performing a contour scan of the two-dimensional cross section after completing the filling scan of the internal area.

[0008] In some possible implementations, the following steps are further included: for the first 20 layers on the substrate, a scanning pitch of 0.1 mm, a laser power of 350 W, a scanning speed of 1200 mm / s, and an energy density of 58.33 J / mm is used. 3 Print the process parameters.

[0009] In some possible implementations, the scanning pitch is 0.07 mm, the laser power is 600 W, the scanning speed is 900 mm / s, and the energy density is 148.15 J / mm 3 , the porosity of the three-dimensional component is 0.004%.

[0010] In some possible implementations, the scanning pitch is 0.07 mm, the laser power is 750 W, the scanning speed is 700 mm / s, and the energy density is 306.12 J / mm 3 , the porosity of the three-dimensional component is 0.004%.

[0011] In some possible implementations, in step (a), the copper alloy powder layer has a thickness of 0.05 mm.

[0012] In some possible implementations, the inert gas is argon or nitrogen, and the wavelength of the infrared laser beam is 1064 nm.

[0013] A three-dimensional component of a copper alloy prepared by the above laser printing method, wherein the porosity of the three-dimensional component does not exceed 0.004%.

[0014] A heat treatment method for the above-mentioned three-dimensional component includes the steps of: heating the three-dimensional component to 500°C-600°C, holding it for 1 hour-8 hours, cooling it in the furnace, or heating the three-dimensional component to 650°C-750°C, holding it for 1 hour-2 hours, and air cooling it.

[0015] In the present application, by selecting the infrared laser printing process parameters, including specific laser power (500-800 W), scanning speed (600-900 mm / s) and scanning pitch (0.07-0.10 mm), and two sets of optimal process parameter combinations (laser power 500-600 W with scanning pitch 0.08-0.10 mm, laser power 700-800 W with scanning pitch 0.07-0.09 mm) are defined, the melting efficiency of copper alloy powder to infrared laser is effectively improved, thereby overcoming the technical bottleneck of low absorption rate of copper alloy powder to infrared laser (1064 nm) and difficulty in densification forming. Therefore, the present application can significantly increase the single-layer powder thickness to 0.05-0.07 mm (i.e. 50-70 μm), breaking through the technical difficulty of low printing efficiency caused by the limitation of layer thickness (usually less than 20 μm) in traditional technology. At the same time, the optimized laser scanning parameter combination not only ensures that the larger layer thickness can be completely melted to form a dense cladding layer, but also ensures that the porosity of the prepared component is extremely low (not more than 0.004%), realizing the dual improvement of densification and printing efficiency. Therefore, the present application effectively solves the problem of difficult to balance large layer thickness and high densification printing in copper alloy SLM technology, and has significant technical progress significance and practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The flow chart of the laser printing method of the copper alloy powder provided by an embodiment of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments.

[0018] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or can exist with a middle element. When an element is considered to be "disposed on" another element, it can be directly disposed on the other element or can exist with a middle element.

[0019] In the present application, the laser printing device includes a laser generator, an optical system, a forming cavity, a powder laying device, an inert gas protection system and a control system. The working principle of the laser printing device is that the control system controls the laser generator to generate a laser beam with a specific power and wavelength according to the preset three-dimensional model slicing data, and the laser beam is focused by the optical system to selectively scan and melt the laid metal powder layer in the inert gas protected forming cavity, so that the powder is melted and solidified to form a three-dimensional solid component by layering.

[0020] In this application, heat treatment equipment includes a heat treatment furnace, a temperature control system, a protective atmosphere system, and a cooling system. The heat treatment equipment operates by precisely controlling the temperature within the heat treatment furnace through the temperature control system and uniformly heating the printed 3D component according to predetermined process conditions (such as temperature and holding time). The protective atmosphere system ensures a stable furnace environment to prevent oxidation. The cooling system gradually reduces the component temperature according to a predetermined cooling method, such as furnace cooling or air cooling, to achieve the target structural properties.

[0021] See Figure 1 One embodiment of the present application provides a method for laser printing of copper alloy powder, which is used to achieve high-efficiency production of dense copper alloy with large layer thickness. The laser printing method comprises the following steps: S1: Lay a layer of copper alloy powder with a thickness of 0.05-0.07mm on the substrate or the previous solidified layer in the molding cavity.

[0022] In this embodiment, the copper alloy powder in step S1 is a CuCrZr alloy, with the following composition by weight: Cu: 98.6%-99.8%, Cr: 0.1-0.8%, and Zr: 0.1-0.6%. This copper alloy powder has an infrared laser absorption rate of 3%-5%. The copper alloy powder is produced by gas atomization and has a regular spherical shape with a particle size range of 15-53 μm.

[0023] S2: Under an inert gas atmosphere, based on preset 3D model slice data, an infrared laser beam is controlled to selectively scan and irradiate the copper alloy powder layer according to a predetermined scanning strategy, wherein the infrared laser power is 500-800W, the scanning speed is 600-900mm / s, and the scanning pitch is selected from 0.07-0.10mm. The scanning speed refers to the speed at which the laser beam moves across the surface of the powder layer. The scanning pitch refers to the distance between two adjacent scanning paths.

[0024] In this embodiment, the wavelength of the infrared laser beam in step S2 is 1064 nm, and an infrared laser with a maximum power of 1000 W is used. The specific equipment used is an HBD-P400-6 laser printer. Specifically, when the power of the infrared laser is 500-600 W, the scanning pitch is selected to be 0.08-0.10 mm; preferably, the scanning pitch is 0.07 mm, the laser power is 600 W, the scanning speed is 900 mm / s, and the energy density is 148.15 J / mm³. Alternatively, when the power of the infrared laser is 700-800 W, the scanning pitch is selected to be 0.07-0.09 mm. Preferably, the scanning pitch is 0.07 mm, the laser power is 750 W, the scanning speed is 700 mm / s, and the energy density is 306.12 J / mm³.

[0025] In this embodiment, the predetermined scanning strategy of step S2 includes performing an S-shaped reciprocating filling scan within the interior area of ​​the 2D cross-section corresponding to the 3D model slice data. This S-shaped reciprocating filling refers to the laser beam continuously scanning along a single direction within each layer's internal filling area, with its path exhibiting a continuous S-shaped or zigzag motion. Specifically, after scanning along a parallel line to the end point of the line segment, the laser beam does not shut down or raise the laser head. Instead, the laser beam directly scans the next parallel line at the adjacent scanning interval in a direction completely opposite to the previous line segment, repeatedly alternating directions until the internal area of ​​the layer is completely filled.

[0026] The predetermined scanning strategy of step S2 also includes: the filling scanning direction of each layer is rotated 67° relative to the previous layer to reduce residual stress; after completing the filling scan of the internal area, the scanning of the two-dimensional cross-sectional profile is performed to improve the surface accuracy and density of the component.

[0027] In this embodiment, in step S2, the first 20 layers on the substrate are printed using process parameters of a scanning pitch of 0.1 mm, a laser power of 350 W, a scanning speed of 1200 mm / s, and an energy density of 58.33 J / mm³ to ensure a strong bond between the initial printed layer and the substrate and reduce delamination of the component and the substrate.

[0028] S3: The copper alloy powder in the scanned area is completely melted and solidified to form a cladding layer.

[0029] In this embodiment, in step S3, the copper alloy powder melted by laser beam scanning is rapidly solidified into a uniform and dense cladding layer. This process is carried out under the protection of inert gas to prevent oxidation of the molten pool, thereby ensuring that the internal structure of the formed component is uniform and fine, and a high density is obtained.

[0030] S4: Repeat steps S1 to S3, printing layer by layer until the entire three-dimensional component is completed. The porosity of the three-dimensional component is controlled to no more than 0.004%. Porosity refers to the volume ratio of the voids within the component. Lower porosity means higher component strength, better electrical conductivity, and better thermal conductivity.

[0031] In some embodiments, infrared laser equipment can be used to achieve high-efficiency production of copper alloy three-dimensional components with large layer thickness, and the efficiency of 6 laser printing per unit time can be as high as 87480mm³ / h.

[0032] Compared with the prior art, the laser printing method of copper alloy powder provided in this application has the following advantages: (1) This application optimizes the printing parameters for large layer thickness (50μm) and clarifies the specific ranges of laser power (500-800W), scanning speed (600-900mm / s), and scanning spacing (0.07-0.10mm), thereby effectively achieving dense forming of copper alloy materials under high-power infrared laser conditions.

[0033] (2) This application effectively promotes good bonding between the CuCrZr copper alloy powder and the 304 substrate by adding 20 layers of low-energy input (scanning spacing 0.1 mm, laser power 350 W, scanning speed 1200 mm / s) buffer layers before dense parameter printing, stabilizes the temperature of the initial printing process, and reduces the risk of cracking caused by drastic temperature changes.

[0034] An embodiment of the present application further provides a method for heat treatment of a three-dimensional component, comprising one of the following steps: (1) The three-dimensional component in step S4 is placed in a heat treatment device, and the heat treatment temperature is set to 500°C-600°C, the holding time is 1 hour-8 hours, and the furnace is cooled with the furnace to achieve high electrical and thermal conductivity and moderate mechanical properties, see Table 1.

[0035] (2) The three-dimensional component in step S4 is placed in a heat treatment device, and the heat treatment temperature is set to 650°C-750°C, the holding time is 1 hour-2 hours, and air cooling is performed to obtain higher mechanical properties while moderately reducing the electrical and thermal conductivity, see Table 1.

[0036] Table 1. Heat treatment parameters, mechanical properties, and electrical / thermal conductivity of three-dimensional components In the aforementioned heat treatment method, after furnace cooling at a relatively low temperature (500°C-600°C), the material exhibits high yield strength (360 MPa) and tensile strength (470 MPa), low elongation (15%), and moderate electrical conductivity (75% IACS) and thermal conductivity (310 W / mK). This treatment method is suitable for applications requiring high strength but moderate electrical and thermal conductivity.

[0037] After air cooling at a relatively high temperature (650°C to 750°C), the yield strength and tensile strength significantly decrease (to 170 MPa and 300 MPa, respectively), while the elongation significantly increases to 35%. Electrical conductivity (90% IACS) and thermal conductivity (380 W / mK) also significantly improve. This treatment method is suitable for applications requiring high electrical and thermal conductivity but lower mechanical strength requirements.

[0038] Therefore, by adjusting different heat treatment temperatures and cooling methods, the mechanical properties, electrical conductivity and thermal conductivity of the three-dimensional component can be flexibly regulated to meet the specific needs of copper alloy component performance in different scenarios.

[0039] The present application will be described in detail below with reference to representative embodiments to help understand the spirit of the present application, but in no way limit the scope of the present application.

[0040] First, CuCrZr copper alloy spherical powder with certain composition and particle size (15-53 μm) was prepared, and the printing layer thickness was set to 50 μm. Then, different parameter combinations of laser power (500-900 W), scanning speed (600-900 mm / s), and scanning spacing (0.07-0.10 mm) were used for selective laser melting (SLM) printing of the powder to obtain samples. Next, the samples prepared by printing were subjected to metallographic polishing and polishing treatment, the microstructure was observed, and the porosity was measured to evaluate the density of the samples, and the best parameter combination was selected. See Table 2 for details.

[0041] Table 2. Laser printing parameter combinations and porosities As can be seen, among the multiple laser parameter tests, the samples prepared by No. 16 (power 600 W, spacing 0.09 mm, scanning speed 900 mm / s, energy density 148.15 J / mm³) and No. 18 (power 750 W, spacing 0.07 mm, scanning speed 700 mm / s, energy density 306.12 J / mm³) have the lowest porosities, both being 0.004%. This shows that this parameter range can significantly improve the density of the copper alloy printed component, ensuring excellent structural integrity and performance stability.

[0042] For the sample prepared by the process parameter with the best printing performance (lowest porosity 0.004%), different heat treatment schemes (including 550℃ / 8h furnace cooling, 700℃ / 2h air cooling, etc.) were implemented, and the yield strength, tensile strength, elongation, electrical conductivity and thermal conductivity were measured. See Table 3 for details.

[0043] Table 3. Heat treatment parameter combinations and performance test results This demonstrates the significant impact of heat treatment on material properties. When heat treated at 550°C, held for 8 hours, and then cooled (Table 3, Group I), the material achieved a yield strength of 366 MPa, a tensile strength of 470 MPa, an elongation of 15%, an electrical conductivity of 75% IACS, and a thermal conductivity of 310 W / mK. This solution achieves high mechanical properties and is suitable for applications requiring high strength.

[0044] When heat-treated at 700°C, held for 2 hours, and then air-cooled (Group II in Table 3), the material's yield strength dropped to 170 MPa, its tensile strength reached 300 MPa, and its elongation increased significantly to 35%. Its electrical conductivity reached 90% IACS, and its thermal conductivity reached 380 W / mK. This solution achieves high electrical and thermal conductivity, making it suitable for applications requiring high electrical and thermal conductivity but moderate mechanical properties.

[0045] In addition, those skilled in the art may also make other changes within the spirit of this application. Of course, these changes made in accordance with the spirit of this application should be included in the scope of protection required by this application.

Claims

1. A method for laser printing of copper alloy powder, characterized in that: Including steps: (a) Laying a copper alloy powder layer with a thickness of 0.05-0.07 mm on the substrate or the previous solidified layer in the molding cavity; (b) in an inert gas atmosphere, controlling an infrared laser beam to selectively scan and irradiate the copper alloy powder layer according to a predetermined scanning strategy based on preset three-dimensional model slice data, wherein the infrared laser power is 500-800 W, the scanning speed is 600-900 mm / s, and the scanning pitch is selected from 0.07-0.10 mm; (c) completely melting and solidifying the copper alloy powder in the scanned area to form a cladding layer; (d) Repeating steps (a) to (c), printing layer by layer until the three-dimensional component is completed; The process parameter combination of step (b) is selected from any one of the following groups: (1) Infrared laser power 500-600W, scanning spacing 0.08-0.10mm; (2) Infrared laser power 700-800W, scanning spacing 0.07-0.09mm.

2. The laser printing method according to claim 1, wherein: The predetermined scanning strategy includes: performing an S-shaped reciprocating filling scan in an inner area of ​​a two-dimensional cross section corresponding to the three-dimensional model slice data.

3. The laser printing method according to claim 2, wherein: The predetermined scanning strategy further includes: rotating the filling scanning direction of each layer by 67° relative to the previous layer, and performing a contour scan of the two-dimensional cross section after completing the filling scan of the internal area.

4. The laser printing method according to claim 3, wherein: The method also includes the following steps: for the first 20 layers on the substrate, a scanning pitch of 0.1 mm, a laser power of 350 W, a scanning speed of 1200 mm / s, and an energy density of 58.33 J / mm is used. 3 Print the process parameters.

5. The laser printing method according to claim 1, wherein: The scanning pitch is 0.07 mm, the laser power is 600 W, the scanning speed is 900 mm / s, and the energy density is 148.15 J / mm 3 , the porosity of the three-dimensional component is 0.004%.

6. The laser printing method according to claim 1, wherein: The scanning pitch is 0.07 mm, the laser power is 750 W, the scanning speed is 700 mm / s, and the energy density is 306.12 J / mm 3 , the porosity of the three-dimensional component is 0.004%.

7. The laser printing method according to claim 1, wherein: In step (a), the thickness of the copper alloy powder layer is 0.05 mm.

8. The laser printing method according to claim 1, wherein: The inert gas is argon or nitrogen, and the wavelength of the infrared laser beam is 1064 nm.

9. A three-dimensional component of a copper alloy produced by the laser printing method according to any one of claims 1 to 8, characterized in that: The porosity of the three-dimensional component does not exceed 0.004%.

10. A heat treatment method for a three-dimensional component according to claim 9, characterized in that: Including steps: The three-dimensional component is heated to 500-600° C., kept at this temperature for 1-8 hours, and then cooled in the furnace; or the three-dimensional component is heated to 650-750° C., kept at this temperature for 1-2 hours, and then cooled in air.

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