Method for forming high-density and high-hardness Fe-Cu-based alloy material through selective laser melting

Abstract

The invention relates to a method for forming a high-density and high-hardness Fe-Cu-based alloy material through selective laser melting. The method for forming the high-density and high-hardness Fe-Cu-based alloy material through selective laser melting comprises the following steps that S1, Fe-Cu-based alloy powder is prepared, specifically, all component raw materials are weighed according to the proportion, mixed to be uniform and dried in vacuum; s2, scanning and filling path planning: performing three-dimensional modeling on a required component, and planning the scanning and filling path of each layer of slice after slicing a three-dimensional model; s3, melting and forming: introducing protective gas, preheating the substrate, and then starting a laser beam; and the alloy powder with a certain thickness is laid on each layer of slices, layer-by-layer printing forming is conducted on a printing substrate according to the scanning filling path, a component is obtained, and the Fe-Cu-based alloy material is obtained. According to the preparation method, macrosegregation of the Fe-Cu-based alloy material can be effectively improved, the microstructure and performance of the material are homogenized, and the high-density and high-hardness Fe-Cu-based alloy material is obtained.

Description

Technical Field

[0001] The present invention relates to the field of laser additive manufacturing, and particularly to a method for forming a high-density and high-hardness Fe-Cu-based alloy material by selective laser melting. Background Art

[0002] Monotectic alloys are also known as immiscible alloys or unmixable alloys. From the phase diagram, it can be seen that there is an immiscible phase region. When the temperature drops to a certain specific temperature, the homogeneous monotectic alloy melt will undergo liquid phase separation, decomposing from a single liquid phase into liquid phases enriched with different components, such as Cu-Pb, Cu-Fe, Fe-Ag, Cu-Co, etc. Monotectic alloys have excellent lubricating, heat-conducting, and magnetic properties and can be used as self-lubricating materials, magnetohydrodynamic generator materials, and permanent magnet materials, etc., which have attracted extensive attention from researchers. For example, Cu-Pb monotectic alloys have high load-carrying capacity and good temperature resistance and can be used for the journal bearings of automotive engines; Cu-Co alloys exhibit a large magnetoresistance effect and special physical properties. Fe-Cu-based alloys have the strength, hardness, low thermal expansion coefficient, soft magnetic properties of iron, as well as the good thermal conductivity of copper, and have broad application prospects in the fields of aerospace, medical equipment, and electro-vacuum packaging materials. However, at 1083°C, the solid solubility of Fe in the Cu matrix is only 3.95 wt.%; at 1094°C, the solid solubility of Cu in the Fe matrix is only 8.5 wt.%. Using traditional means such as casting or forging to prepare will cause relatively serious macrosegregation, greatly limiting the application of Fe-Cu-based alloys.

[0003] Selective laser melting technology uses a laser as a heat source and, according to the scanning path planned in the three-dimensional slice model, layer-by-layer prints the metal powder bed. The scanned metal powder undergoes melting and rapid solidification to achieve the effect of metallurgical bonding, and finally obtains the metal part designed by the model. At a cooling rate of 103 K / s - 108 K / s, selective laser melting technology can well suppress the macrosegregation of iron-rich droplets during the metallurgical process of iron-copper alloys, providing an effective way to prepare iron-copper alloys with uniform composition. Currently, selective laser melting technology is also used to print and form copper-based copper-iron alloys, obtaining good properties. However, this material cannot meet the use environment with high hardness requirements, limiting its application scenarios. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a method for forming a high-density and high-hardness Fe-Cu-based alloy material by selective laser melting, improving the macrosegregation of Fe-Cu-based alloy materials, making the microstructure and properties of the materials uniform, obtaining a high-density and high-hardness Fe-Cu-based alloy material, effectively overcoming the defect of liquefaction cracking of traditional Fe-Cu-based alloy materials, and effectively enhancing the mechanical properties of the materials.

[0005] The present invention is realized through the following technical solutions:

[0006] A method for laser selective melting and forming a high-density and high-hardness Fe-Cu-based alloy material, comprising the following steps:

[0007] S1, preparing Fe-Cu-based alloy powder: weighing each component raw material according to the ratio, mixing evenly and drying in vacuum;

[0008] S2, planning the scanning and filling path: performing three-dimensional modeling on the required component, and planning the scanning and filling path of each layer of slice after slicing the three-dimensional model;

[0009] S3, melting and forming: introducing a protective gas, preheating the substrate, and then turning on the laser beam; laying a certain thickness of the alloy powder for each layer of slice, and performing layer-by-layer printing and forming on the printing substrate according to the scanning and filling path to obtain a component; performing post-treatment on the formed component to obtain an Fe-Cu-based alloy material.

[0010] The present invention can perform three-dimensional modeling on the Fe-Cu-based alloy material with complex structural features, and then adopt laser selective melting and forming, which can effectively improve the macrosegregation of the Fe-Cu-based alloy material, make the microstructure and properties of the material uniform, and obtain an Fe-Cu-based alloy material with high density and high hardness.

[0011] Further, the alloy powder includes the following components by weight percentage:

[0012] Cu: 9.2% - 11.3%;

[0013] Mo: 2.5% - 3%;

[0014] Cr: 0.45% - 0.55%;

[0015] Ni: 0.23% - 0.28%;

[0016] C: 0.13% - 0.17%;

[0017] V: 0.09% - 0.11%;

[0018] Fe: the balance.

[0019] It should be noted that the precipitation of Cu particles and Mo particles in the Fe matrix will significantly enhance its mechanical properties; and the Cu content is crucial for the laser melting forming of Fe-Cu-based materials. Excessive Cu content will cause serious liquefaction cracking in the Fe-Cu-based materials during the laser melting forming process, affecting its application in industrial production. In the present invention, by reasonably controlling the ratio between Fe, Cu and each component, good metallurgical bonding is achieved for the Fe-Cu-based alloy material under the selective laser melting process. In the molten pool edge region of the Fe-Cu-based alloy material, Cu grows in a fibrous shape in the solidification direction; part of the Cu is enriched in the grain boundaries of Fe grains, forming a unique continuous network structure; part of the Cu is solid-solved with Fe to form an iron-copper solid solution. The Cu solute causes lattice distortion in the Fe matrix, increasing the resistance to dislocation movement, thereby increasing the strength and hardness of the alloy material. And Cu and Mo particles precipitate in the Fe matrix, thereby improving the performance of the Fe-Cu-based alloy.

[0020] Preferably, the alloy powder includes each component by weight percentage: Cu 10.25%; Mo 2.75%, Cr 0.5%, Ni 0.25%, C 0.15%, V 0.1%, and the balance is Fe.

[0021] Further, in step S1, the raw materials of each component are placed in a three-dimensional motion mixer for powder mixing. The powder mixing time is 8 - 12 h, and the rotation speed is 6 - 11 r / min.

[0022] Further, in step S1, the drying temperature of the alloy powder is 100 - 120 °C, and the drying time is 0.5 - 2 h.

[0023] Further, in step S1, the alloy powder is spherical powder prepared by gas atomization, and the particle size is 15 - 53 μm.

[0024] Further, in step S3, the powder layer thickness is 30 - 50 μm.

[0025] Further, in step S3, the laser spot diameter is 80 - 100 μm, the laser power is 100 - 300 W, the scanning rate is 500 - 1000 mm / s, the scanning spacing is 90 - 110 μm, and the volumetric energy density range is 20 - 150 J / mm 3 , and the substrate preheating temperature is 80 - 120 °C.

[0026] Further, in step S3, the continuous interlayer laser scanning rotation angle is 65° - 70°. Preferably, the continuous interlayer laser scanning rotation angle is 67°.

[0027] Further, the substrate is made of stainless steel. Preferably, the substrate is 304 stainless steel or 316 stainless steel.

[0028] Furthermore, the protective gas is argon or nitrogen, and the oxygen content of the protective gas is 500 - 1000 ppm.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) By three-dimensionally modeling the Fe-Cu-based alloy material with complex structural features and then preparing it using the selective laser melting forming technology, the macrosegregation of the Fe-Cu-based alloy material can be effectively improved, and the microstructure and properties of the material can be homogenized;

[0031] (2) By reasonably controlling the ratios among Fe, Cu and each component element, good metallurgical bonding of the Fe-Cu-based alloy material is achieved under the selective laser melting process;

[0032] (3) In the Fe-Cu-based alloy material prepared by the present invention, Cu in the molten pool edge region grows in a fibrous shape along the solidification direction; part of Cu is enriched in the grain boundaries of Fe grains, forming a unique continuous network structure; part of Cu is solid-solved with Fe to form an iron-copper solid solution, and the Cu solute causes lattice distortion in the Fe matrix, increasing the resistance to dislocation movement, thereby increasing the strength and hardness of the alloy; nano-scale Cu and Mo particles precipitate in the Fe matrix, thus improving the performance of the Fe-Cu-based alloy;

[0033] (4) The Fe-Cu-based alloy prepared by the present invention has no liquefaction cracking defect, the density can reach more than 99.9%, and it has excellent mechanical properties. Its Rockwell hardness reaches 52 ± 0.4 HRC, showing high density and high hardness, and has very strong industrial application prospects.

[0034] For better understanding and implementation, the present invention will be described in detail below with reference to the accompanying drawings. Description of the Drawings

[0035] Figure 1 It is the cross-section polished state diagram of the Fe-Cu-based alloy material prepared in Example 1;

[0036] Figure 2 It is the EDS diagram of the Fe-Cu-based alloy material prepared in Example 1;

[0037] Figure 3 It is the cross-section polished state diagram of the Fe-Cu-based alloy material prepared in Example 2;

[0038] Figure 4 It is the cross-section polished state diagram of the Fe-Cu-based alloy material prepared in Comparative Example 1. Specific Embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] A method for forming a high-density and high-hardness Fe-Cu-based alloy material by selective laser melting includes the following steps:

[0041] S1, Prepare Fe-Cu-based alloy powder: Weigh the following components by weight percentage according to the ratio: Cu: 9.2% - 11.3%; Mo: 2.5% - 3%; Cr: 0.45% - 0.55%; Ni: 0.23% - 0.28%; C: 0.13% - 0.17%; V: 0.09% - 0.11%; Fe: the balance; Place the raw materials of each component in a three-dimensional motion mixer for powder mixing, and the powder mixing time is 8 - 12h, and the rotation speed is 6 - 11r / min; Then dry the alloy powder at 100 - 120°C for 0.5 - 2h.

[0042] S2, Plan the scanning filling path: Perform three-dimensional modeling on the required component, and plan the scanning filling path of each layer of slice after slicing the three-dimensional model;

[0043] S3, Melting and forming: Introduce a protective gas to make the oxygen content in the selective laser melting device 500 - 1000ppm; Preheat the substrate to 80 - 120°C, and then turn on the laser beam; Lay alloy powder with a thickness of 30 - 50μm for each layer of slice, and adjust the process parameters of selective laser melting forming to: laser spot diameter 80 - 100μm, laser power 100 - 300W, scanning speed 500 - 1000mm / s, scanning spacing 90 - 110μm, and the volume energy density range is 20 - 150J / mm 3 , The continuous layer-by-layer laser scanning rotation angle is 65° - 70°. Perform layer-by-layer printing and forming on the printing substrate according to the scanning filling path to obtain the component; After powder treatment of the formed component, obtain the Fe-Cu-based alloy material.

[0044] Example 1

[0045] (1) Prepared by using gas atomized spherical powder, and the components are in weight percentage: Cu 10.25%, Mo2.75%, Cr 0.5%, Ni 0.25%, C 0.15%, V 0.1%, Fe balance; The powder particle size is 15 - 53μm. After mixing evenly by a three-dimensional motion mixer for 12h, vacuum dry at 120°C for 2h.

[0046] (2) The three-dimensional model of the component is sliced, and the scanning filling path of each sliced layer is planned.

[0047] (3) Argon is introduced to make the oxygen content in the selective laser melting device 500 - 1000 ppm. The 316 stainless steel substrate is heated to 80 °C, and then the laser beam is turned on. The 30-μm alloy powder is laid on each layer and melted and formed. In this embodiment, the process parameters for selective laser melting and forming are set as follows: the spot diameter is 100 μm, the laser power is 100 W, the scanning speed is 750 mm / s, the scanning spacing is 90 μm, and the volumetric energy density is 49.38 J / mm 3 , and the continuous interlayer laser scanning angle rotates 67°; layer-by-layer printing and forming are carried out on the printing substrate according to the scanning filling path to obtain the component; the component is taken out and the Fe-Cu-based alloy material is obtained after powder treatment.

[0048] Example 2

[0049] (1) Prepared from gas atomized spherical powder with the following composition by weight percentage: Cu 10.25%, Mo 2.75%, Cr 0.5%, Ni 0.25%, C 0.15%, V 0.1%, and the balance is Fe; the powder particle size is 15 - 53 μm. After being mixed evenly by a three-dimensional motion mixer for 12 h, it is vacuum dried at 120 °C for 2 h.

[0050] (2) The three-dimensional model of the component is sliced, and the scanning filling path of each sliced layer is planned.

[0051] (3) Argon is introduced to make the oxygen content in the selective laser melting device 500 - 1000 ppm. The 316 stainless steel substrate is heated to 80 °C, and then the laser beam is turned on. The 30-μm alloy powder is laid on each layer and melted and formed. In this embodiment, the process parameters for selective laser melting and forming are set as follows: the spot diameter is 100 μm, the laser power is 240 W, the scanning speed is 750 mm / s, the scanning spacing is 90 μm, and the volumetric energy density is 188.52 J / mm 3 , and the continuous interlayer laser scanning angle rotates 67°. Layer-by-layer printing and forming are carried out on the printing substrate according to the scanning filling path to obtain the component; the component is taken out and the Fe-Cu-based alloy material is obtained after powder treatment.

[0052] Example 3

[0053] (1) It is prepared from gas atomized spherical powder with the following composition by weight percentage: Cu 10.25%, Mo 2.75%, Cr 0.5%, Ni 0.25%, C 0.15%, V 0.1%, and the balance is Fe; the powder particle size is 15 - 53 μm. After being mixed evenly by a three-dimensional motion mixer for 12 h, it is vacuum dried at 120 °C for 2 h.

[0054] (2) For the three-dimensional model of the component, after slicing, the scanning filling path of each layer of slice is planned.

[0055] (3) Argon is introduced to make the oxygen content in the laser selective melting device be 500 - 1000 ppm. The 316 stainless steel substrate is heated to 80 °C, and then the laser beam is turned on. The 30 - μm alloy powder is laid for each layer and melted and formed. In this embodiment, the process parameters of laser selective melting forming are set as follows: spot diameter 100 μm, laser power 240 W, scanning speed 1000 mm / s, scanning spacing 90 μm, and volumetric energy density 188.52 J / mm 3 , and the continuous interlayer laser scanning angle rotates by 67°. It is printed and formed layer by layer on the printing substrate according to the scanning filling path to obtain the component; the component is taken out and the Fe-Cu based alloy material is obtained after powder treatment.

[0056] Comparative Example 1

[0057] In this comparative example, except for the process parameters of laser melting forming, the other steps are the same as those in Example 1 and will not be elaborated here.

[0058] The process parameters of laser selective melting forming in this comparative example are: spot diameter 100 μm, laser power 180 W, scanning speed 1000 mm / s, scanning spacing 130 μm, and volumetric energy density 46.15 J / mm 3 , and the continuous interlayer laser scanning angle rotates by 67°.

[0059] Test Analysis

[0060] The Fe-Cu based alloy materials prepared in Examples 1 - 3 and Comparative Example 1 are subjected to Rockwell hardness test, relative density test, EDS test, and cross-section polished state test; the test methods for all tests are conventional test methods in this field and will not be elaborated here.

[0061] The Fe-Cu based alloy materials prepared in Examples 1 - 3 are subjected to Rockwell hardness test and relative density test, and the test data are shown in Table 1.

[0062] Table 1 Rockwell hardness and relative density of Fe-Cu based alloy materials prepared in Examples 1 - 3

[0063] Item Density (%) Rockwell Hardness (HRC) Example 1 99.91 51.8±0.3 Example 2 99.92 52±0.4 Example 3 99.90 51.5±0.4

[0064] As can be seen from Table 1, the relative density of the Fe-Cu-based alloy materials prepared in Examples 1-3 is greater than 99%, and they are considered fully dense. The Rockwell hardness of the Fe-Cu-based alloy materials prepared in Examples 1-3 ranges from 51.1 to 52.4 HRC, showing high hardness. Figure 1 and Figure 3 are respectively the cross-sectional polished state diagrams of the Fe-Cu-based alloy materials prepared in Example 1 and Example 2. Combining with Table 1, it can be seen that the microstructures of the Fe-Cu-based alloy materials prepared in Example 1 and Example 2 are uniform, and no liquefaction cracking defects are found. This is because Cu grows in a fibrous shape along the solidification direction in the edge region of the molten pool; part of Cu is enriched in the grain boundaries of Fe grains, forming a unique continuous network structure; part of Cu is solid-solved with Fe to form an iron-copper solid solution, and the Cu solute causes lattice distortion in the Fe matrix, increasing the resistance to dislocation movement, thereby increasing the strength and hardness of the alloy; nano-scale Cu and Mo particles precipitate in the Fe matrix, thereby improving the performance of the Fe-Cu-based alloy.

[0065] Comparing with the cross-sectional polished state diagram of the Fe-Cu-based alloy material prepared in Comparative Example 1, as Figure 4 shown, when observed under an optical microscope, there are a large number of crack and pore defects in the Fe-Cu-based alloy material prepared in Comparative Example 1. This shows that the Fe-Cu-based alloy material prepared by the present invention exhibits high relative density and high hardness.

[0066] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and the present invention also intends to include these modifications and improvements.

Claims

1. A method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting, characterized in that: The steps include: S1, preparing Fe-Cu based alloy powder: weighing raw materials of each component according to the proportion, mixing evenly and vacuum drying; S2, planning the scanning and filling path: 3D modeling of the required components, and planning the scanning and filling path of each slice after slicing the 3D model; S3, melting and forming: introducing protective gas to preheat the substrate, and then turning on the laser beam; laying a certain thickness of the alloy powder on each slice, and printing and forming the component layer by layer on the printing substrate according to the scanning and filling path to obtain the Fe-Cu based alloy material.

2. The method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting according to claim 1, characterized in that: The alloy powder comprises the following components by weight percentage: Cu: 9.2%~11.3%; Mo: 2.5%~3%; Cr：0.45％～0.55％； Ni: 0.23%~0.28%; C：0.13％～0.17％； V：0.09％～0.11％； Fe: balance.

3. The method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting according to claim 2, characterized in that: The alloy powder comprises the following components in percentage by weight: Cu 10.25%, Mo 2.75%, Cr 0.5%, Ni 0.25%, C 0.15%, V 0.1% and Fe balance.

4. The method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting according to claim 1, characterized in that: In step S1, each component raw material is placed in a three-dimensional motion mixer for mixing, the mixing time is 8-12 hours, and the rotation speed is 6-11 r / min.

5. The method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting according to claim 1, characterized in that: In step S1, the alloy powder is dried at a temperature of 100-120° C. and a drying time of 0.5-2 h.

6. The method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting according to claim 1, characterized in that: In step S1, the alloy powder is a spherical powder prepared by gas atomization, and the particle size is 15-53 μm.

7. The method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting according to claim 1, characterized in that: In step S3, the laser spot diameter is 80-100 μm, the laser power is 100-300 W, the scanning rate is 500-1000 mm / s, the scanning interval is 90-110 μm, and the volume energy density range is 20-150 J / mm 3 .

8. The method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting according to claim 7, characterized in that: In step S3, the continuous interlayer laser scanning is rotated at an angle of 65° to 70°.

9. The method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting according to claim 1, characterized in that: The substrate is made of stainless steel.

10. The method for forming a high-density and high-hardness Fe-Cu based alloy material by laser selective melting according to claim 1, characterized in that: The protective gas is argon or nitrogen, and the oxygen content of the protective gas is 500-1000 ppm.

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