3D printing powder, and 3D printed aluminum alloy part and preparation method therefor

Abstract

A 3D printing powder. The 3D printing powder comprises an aluminum alloy powder, a Ti powder and a Ta powder, and is formed by mixing the aluminum alloy powder with the Ti powder and the Ta powder. The Ti powder and the Ta powder jointly exert a synergistic effect to effectively restrain the growth of aluminum alloy crystal grains during the growing process of the crystal grains, thereby making the crystal grains refined; therefore, the compactness and mechanical properties of the 3D printing powder are improved, and the problem of cracking of an aluminum alloy part is ameliorated. The present invention further relates to a 3D printed aluminum alloy part and a preparation method therefor.

Description

3D printing powder, 3D printing aluminum alloy part and preparation method thereof Technical Field

[0001] The present invention belongs to the technical field of 3D printing materials, and specifically relates to a 3D printing powder, a 3D printing aluminum alloy part and a preparation method thereof. Background Art

[0002] High-strength aluminum alloys, due to their high specific strength, low density, and low cost, can be used as lightweight, high-strength structural materials. They are commonly used to manufacture a variety of lightweight, high-load parts and structures, and are widely used in civil and military fields such as automobiles, ships, and aerospace. However, due to their wide solidification temperature range, high-strength aluminum alloys are subject to large residual stresses during the complex thermal history of high-energy beam-based 3D printing (additive manufacturing), making them very susceptible to thermal cracking, which drastically reduces the material's formability and mechanical properties. In addition, it is usually difficult to obtain crack-free parts with excellent density (>99%) by adjusting the process parameters during the printing process.

[0003] Summary of the Invention

[0004] Aiming at the problem that 3D printed aluminum alloy parts obtained by laser 3D printing technology in the prior art are prone to thermal cracking and have poor mechanical properties, a 3D printing powder, a 3D printed aluminum alloy part and a preparation method thereof are disclosed.

[0005] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0006] In one aspect, the present invention provides a 3D printing powder, comprising aluminum alloy powder, Ti powder, and Ta powder, wherein the aluminum alloy powder is mixed with the Ti powder and the Ta powder.

[0007] Optionally, based on the total weight of the 3D printing powder, the total weight composition of the Ti powder and the Ta powder is 1 to 5 parts.

[0008] Optionally, based on the total weight of the 3D printing powder, the aluminum alloy powder is 90 to 95 parts.

[0009] Optionally, the particle size of the aluminum alloy powder, the Ti powder and the Ta powder is 15 to 53 μm.

[0010] Optionally, the aluminum alloy powder includes one or more of 2xxx series, 5xxx series, 6xxx series and 7xxx series.

[0011] On the other hand, the present invention provides a 3D printed aluminum alloy part, comprising the 3D printing powder.

[0012] In another aspect, the present invention provides a method for preparing a 3D printed aluminum alloy part, comprising the following steps:

[0013] Fully mixing aluminum alloy powder, Ti powder and Ta powder to obtain a mixed powder;

[0014] After the mixed powder is dried, it is 3D printed to obtain a 3D printed aluminum alloy part. Optionally, the 3D printing is laser printing with a laser power of 180 to 380W.

[0015] Optionally, the scanning rate of the laser printing is 200 to 2000 mm / s, and the scanning interval is 0.08 to 0.12 mm.

[0016] Optionally, in the 3D printing, the powder spreading thickness of the mixed powder is 30 to 90 μm.

[0017] The 3D printing powder provided by the present invention utilizes the aluminum alloy powder, the Ti powder, and the Ta powder to be mixed together. During the mixing process, the Ti powder and the Ta powder are simultaneously introduced into the aluminum alloy powder. At this time, the aluminum in the aluminum alloy powder rapidly reacts chemically with the Ti powder and the Ta powder to produce a highly efficient heterogeneous nucleating agent Al3(Ti, Ta), which is beneficial to the nucleation of primary aluminum. A large number of heterogeneous nucleation points promote the formation of a fine equiaxed crystal structure, thereby refining the grains. In addition, the shape restriction factor values ​​of Ti and Ta elements in aluminum alloys are the highest. When the Ti powder and the Ta powder are jointly added to the aluminum alloy powder, the growth of the aluminum alloy grains can be effectively restricted during their growth, resulting in grain refinement, thereby improving the density and mechanical properties of the 3D printing powder and improving the problem of cracks in aluminum alloy parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is an optical microscope microstructure image of a 3D printed aluminum alloy part provided in Example 1 of the present invention;

[0019] FIG2 is a high-magnification scanning electron microscope microstructure image of a 3D-printed aluminum alloy part provided in Example 1 of the present invention;

[0020] FIG3 is an optical microscope microstructure image of a 3D printed aluminum alloy part provided in Example 2 of the present invention;

[0021] FIG4 is a scanning electron microscope microstructure image of a 3D printed aluminum alloy part provided in Comparative Example 1 of the present invention;

[0022] FIG5 is a high-magnification scanning electron microscope microstructure image of a 3D printed aluminum alloy part provided in Comparative Example 1 of the present invention;

[0023] FIG6 is a scanning electron microscope microstructure image of the 3D printed aluminum alloy part provided in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] The present invention provides a 3D printing powder, comprising aluminum alloy powder, Ti powder and Ta powder, wherein the aluminum alloy powder is mixed with the Ti powder and the Ta powder.

[0026] It should be noted that 3D printing technology has the advantages of no molds, free structural design, fast production process, high precision, and the ability to manufacture complex parts. It is widely used in the manufacture of industrial and aerospace parts. High-strength aluminum alloys are mostly composed of Zn, Mg, and Al as the main alloying elements and have high strength. However, aluminum alloy 3D printed products are very prone to cracking and have low product strength, which limits the development of aluminum alloy 3D printing technology.

[0027] The 3D printing powder provided by the invention is mixed with the aluminum alloy powder, the Ti powder and the Ta powder. During the mixing process, the Ti powder and the Ta powder are simultaneously introduced into the aluminum alloy powder. At this time, the aluminum in the aluminum alloy powder rapidly reacts chemically with the Ti powder and the Ta powder to produce a highly efficient heterogeneous nucleating agent Al3 (Ti, Ta), which is beneficial to the nucleation of primary aluminum. A large number of heterogeneous nucleation points promote the formation of a fine equiaxed crystal structure, thereby refining the grains. In addition, the shape restriction factor values ​​of the two elements Ti and Ta in aluminum alloys are the highest. When the Ti powder and the Ta powder are added together, the growth of the grains can be effectively restricted during the growth of the aluminum alloy grains, so that the grains are refined, thereby improving the density and mechanical properties of the 3D printing powder and improving the problem of cracking in the aluminum alloy.

[0028] In some embodiments, based on the total weight of the 3D printing powder, the total weight composition of the Ti powder and the Ta powder is 1 to 5 parts.

[0029] The Ti powder is mixed with the aluminum alloy powder. The mixed Ti-Al has a high melting point, high specific stiffness, high specific strength and low high temperature creep resistance. That is, the mixing of the Ti powder and the aluminum alloy powder is beneficial to improving the mechanical properties and formability of the 3D printing powder under high temperature environment.

[0030] Specifically, since the Ta powder has a high density and a high cost, in the embodiment of the present application, the weight ratio of the Ti powder to the Ta powder is preferably 3:1.

[0031] In some embodiments, the aluminum alloy powder accounts for 90 to 95 parts by weight based on the total weight of the 3D printing powder.

[0032] Specifically, the aluminum alloy powder has the advantages of high specific strength, corrosion resistance, and strong recyclability, and therefore has been used in combination with 3D printing to develop complex and special parts.

[0033] In some embodiments, the particle size of the aluminum alloy powder, the Ti powder, and the Ta powder is 15 to 53 μm.

[0034] In some embodiments, the aluminum alloy powder includes one or more of 2xxx series, 5xxx series, 6xxx series, and 7xxx series.

[0035] It should be noted that the 2xxx series aluminum alloy powder includes 2024 and 2618; the 5xxx series aluminum alloy powder includes 5052 aluminum alloy and 5083 aluminum alloy; the 6xxx series aluminum alloy powder includes 6061 aluminum alloy and 6063 aluminum alloy; the 7xxx series aluminum alloy powder includes 7050 aluminum alloy and 7075 aluminum alloy;

[0036] The 2000 series aluminum alloy is characterized by high hardness, with copper content being the highest, approximately 3-5%. The 2000 series aluminum alloy belongs to aviation aluminum materials and is currently rarely used in conventional industries.

[0037] The 5000 series aluminum alloy belongs to the more commonly used alloy aluminum plate series. Its main element is magnesium, with a magnesium content between 3-5%. It is also called aluminum-magnesium alloy. Its main characteristics are low density, high tensile strength, high elongation, and good fatigue strength, but it cannot be heat-treated and strengthened.

[0038] The 6000 series aluminum alloy mainly contains two elements, magnesium and silicon, and is a cold-treated aluminum forging product suitable for use in environments with high requirements for corrosion resistance and oxidation resistance.

[0039] The 7000 series aluminum alloy mainly contains zinc elements; has excellent mechanical properties and high strength, is a super-hard aluminum alloy, can be heat-treated, has good wear resistance and weldability, and is often used in high-stress structural components.

[0040] Specifically, in the preferred embodiment of the present application, the aluminum alloy powder is selected from one or more of the 6061 aluminum alloy and the 7075 aluminum alloy;

[0041] The 7075 aluminum alloy Al-Zn-Mg-Cu is a super-hard aluminum, which roughly includes 5.6-6.1% Zn, 2.1-2.5% Mg, and 1.2-2.0% Cu. It has a hardness of up to 150HB, corrosion resistance, good mechanical properties and anodic reaction, good plasticity and heat treatment strengthening effects, high strength below 150°C, and good low-temperature strength.

[0042] The magnesium and silicon alloying elements in the 6061 aluminum alloy form a Mg2Si phase, comprising 0.8-1.2% Mg, 0.25% Cu, 1.0% Mg, and 0.09% Cr. The Mg / Si ratio in the Mg2Si is 1.73. Under heat treatment, the Mg2Si is dissolved in the aluminum, giving the alloy an artificial aging hardening function.

[0043] In another embodiment, the present invention provides a 3D printed aluminum alloy part, which is prepared by including the 3D printing powder.

[0044] In another embodiment, the method for preparing the 3D printed aluminum alloy part comprises the following steps:

[0045] Fully mixing aluminum alloy powder, Ti powder and Ta powder to obtain a mixed powder;

[0046] After the mixed powder is dried, 3D printed aluminum alloy parts are prepared through 3D printing.

[0047] In some embodiments, the 3D printing is laser printing, and the laser power is 180 to 380 W. The laser power of the selective laser melting forming equipment is 180 to 380 W.

[0048] Specifically, the laser power is preferably 300-380W; in a specific embodiment, the laser power may be preferably 300W, 320W, 340W, 360W or 380W.

[0049] The 3D laser printing uses Selective Laser Melting (SLM), a type of 3D printing technology that can directly print high-precision metal parts. SLM technology uses a high-energy laser beam to scan pre-laid metal powder according to a predetermined scanning path to completely melt it, and then cool and solidify it into shape.

[0050] During the specific forming process, layered slicing is performed according to the layer thickness, and appropriate process parameters such as the scanning path are selected to generate corresponding data files that are imported into the selective laser melting forming equipment; the powder spreading device spreads a uniform and thin layer of metal powder on the substrate of the forming cylinder; the laser beam selectively scans and melts the metal powder on the substrate according to the data information of the current layer; after the current layer scan is completed, the forming cylinder descends, the powder cylinder rises, and the powder spreading device spreads another layer of powder on the forming cylinder, and then the laser scans the next layer, and this cycle repeats until the entire part is formed. The forming accuracy is high, and terminal metal parts can be directly made, especially complex parts with complex and special-shaped structures inside. The mechanical properties of SLM formed parts are better than those of castings of the same material, and the material utilization rate is high. During forming, the metal powder is selectively melted, and the unmelted powder can be reused, and the powder utilization rate is high.

[0051] In some embodiments, the scanning rate of the laser printing is 200-2000 mm / s, and the scanning pitch is 0.08-0.12 mm.

[0052] Specifically, the scanning rate is preferably 1400-1800 mm / s; in a specific embodiment, the laser power may be preferably 1400 mm / s, 1600 mm / s or 1800 mm / s.

[0053] Specifically, in a preferred embodiment, the scanning interval is 0.08 mm, 0.10 mm or 0.12 mm.

[0054] In some embodiments, the powder mixture is spread to a thickness of 30 to 90 μm in the selective laser melting forming device.

[0055] The present invention is further described below with reference to the following examples.

[0056] Example 1

[0057] This embodiment is used to illustrate a 3D printed aluminum alloy part and a method for preparing the same disclosed in the present invention, and includes the following steps:

[0058] 95% by mass of aluminum alloy powder (7075 series Al-Zn-Mg-Cu) and 5% by mass of Ti and Ta powder were placed in a three-dimensional rocking powder mixer, quickly flipped, inverted, and evenly mixed for 3 hours to obtain a mixed powder.

[0059] After the mixed powder is dried, it is placed in a selective laser melting forming device and printed at a laser power of 320 W, a scanning rate of 1600 mm / s, and a scanning spacing of 0.1 mm to obtain the 3D printed aluminum alloy part.

[0060] Example 2

[0061] This embodiment is used to illustrate a 3D printed aluminum alloy part and a method for preparing the same disclosed in the present invention, and includes the following steps:

[0062] 98% by mass of aluminum alloy powder (6061Al-Mg-Si) and 2% by mass of Ti and Ta powder were placed in a three-dimensional rocking powder mixer, quickly flipped, inverted, and evenly mixed for 2 hours to obtain a mixed powder.

[0063] After drying, the mixed powder is placed in a selective laser melting forming device, and printed at a laser power of 300 W, a scanning rate of 1600 mm / s, and a scanning spacing of 0.1 mm to obtain the 3D printed aluminum alloy part.

[0064] Comparative Example 1

[0065] This comparative example is used to compare and illustrate a 3D printed aluminum alloy part and a preparation method thereof disclosed in the present invention, including most of the operations in Example 1, except that:

[0066] The Ti and Ta powders were not added.

[0067] Comparative Example 2

[0068] This comparative example is used to compare and illustrate a 3D printed aluminum alloy part and a preparation method thereof disclosed in the present invention, including most of the operations in Example 2, except that:

[0069] The Ti and Ta powders were not added.

[0070] Comparative Example 3

[0071] This comparative example is used to compare and illustrate a 3D printed aluminum alloy part and a preparation method thereof disclosed in the present invention, including most of the operations in Example 2, except that:

[0072] The Ti powder was not added.

[0073] Comparative Example 4

[0074] This comparative example is used to compare and illustrate a 3D printed aluminum alloy part and a preparation method thereof disclosed in the present invention, including most of the operations in Example 2, except that:

[0075] The Ta powder was not added.

[0076] Performance Testing

[0077] The 3D printed aluminum alloy parts prepared in Examples 1 to 2 and Comparative Examples 1 to 4 were subjected to microstructural observation and mechanical property testing:

[0078] Conduct mechanical property tests on 3D printed aluminum alloy parts according to GB / T228-2010 standard;

[0079] The test results are entered in Table 1.

[0080] Table 1

[0081] In the test results of Table 1, the density and microstructure hardness test data of Examples 1 to 2 are better than those of Comparative Examples 1 to 4. The increase in hardness is beneficial to improving the mechanical properties of the 3D printed aluminum alloy parts, and the increase in density is beneficial to alleviating or inhibiting the generation of thermal cracks in the 3D printed aluminum alloy parts. Compared with Comparative Example 1, Example 1 shows that the hardness of Comparative Example 1 is significantly lower than that of Example 1 in specific tests because the Ti and Ta powders are not added to the comparative example. Compared with Comparative Examples 2 to 4, Example 2 shows that the hardness of Comparative Example 2, which does not contain Ti and Ta powders, is the worst. That is, the preparation method provided by the present application can effectively improve the density and mechanical properties of the 3D printed aluminum alloy parts and improve the problem of cracks in 3D printed aluminum alloy parts.

[0082] As can be seen from Figures 1 and 2 of Example 1, the 3D printed aluminum alloy part in the optical microscope microstructure morphology in Figure 1 has no obvious thermal cracks and only a few pores. In the high-magnification scanning electron microscope microstructure morphology in Figure 2, Al3 (Ti, Ta) particles are present inside some crystals of the 3D printed aluminum alloy part, and the grains are relatively fine, which is conducive to improving the mechanical properties of the 3D printed aluminum alloy part.

[0083] In Example 2, in the microstructure of Figure 3 , the 3D printed aluminum alloy part has no obvious thermal cracks, but some pores exist;

[0084] Figures 4 and 5 are scanning electron microscope microstructure observations of the 3D printed aluminum alloy part prepared in Comparative Example 1. The 3D printed aluminum alloy part has multiple thermal cracks and holes. In the high-magnification microstructure morphology of Figure 5, the thermal cracks are obvious;

[0085] FIG6 is a microstructure diagram of Comparative Example 2, from which it can be seen that the 3D printed aluminum alloy part has obvious thermal cracks and voids;

[0086] Compare Figures 1 to 3 with Figures 4 to 6 From the microstructure of the 3D printed aluminum alloy part, it can be seen that the simultaneous addition of the Ti and Ta powders is beneficial to improving the mechanical properties of the aluminum alloy and reducing the occurrence of hot cracks. Without adding Ti powder and Ta powder or without adding Ti powder and Ta powder at the same time, the prepared 3D printed aluminum alloy part produces obvious hot cracks and voids. In addition, some pores appear in Figure 3 of Example 2. Compared with Example 1, this is due to the difference in the selected aluminum alloy powder. Example 2 uses 6061 aluminum alloy powder. Compared with 7075 in Example 1, 6061 is mainly alloyed with magnesium and silicon, has a lower total component ratio, and has a lower strength than 7005. In summary, the 3D printing powder provided by the present invention utilizes the aluminum alloy powder, the Ti powder and the Ta powder to be mixed together. When the Ti powder and the Ta powder are added together, the Ti powder and the Ta powder jointly exert a synergistic effect, which can effectively limit the growth of the grains during the growth of the aluminum alloy grains, refine the grains, and thereby improve the density and mechanical properties of the 3D printed powder, and improve the problem of cracks in the 3D printed aluminum alloy part.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A 3D printing powder, characterized in that: The invention comprises aluminum alloy powder, Ti powder and Ta powder, wherein the aluminum alloy powder is mixed with the Ti powder and the Ta powder.

2. A 3D printing powder according to claim 1, characterized in that: Based on the total weight of the 3D printing powder, the total weight composition of the Ti powder and the Ta powder is 1 to 5 parts.

3. A 3D printing powder according to claim 1, characterized in that: Based on the total weight of the 3D printing powder, the aluminum alloy powder is 90 to 95 parts.

4. The 3D printing powder according to claim 1, characterized in that: The particle sizes of the aluminum alloy powder, the Ti powder, and the Ta powder are 15 to 53 μm.

5. The 3D printing powder according to claim 1, characterized in that: The aluminum alloy powder includes one or more of 2xxx series, 5xxx series, 6xxx series and 7xxx series.

6. A 3D printed aluminum alloy part, characterized in that: Prepared from the 3D printing powder according to any one of claims 1 to 5.

7. The method for preparing a 3D printed aluminum alloy part according to claim 6, characterized in that: The following steps are involved: Fully mixing aluminum alloy powder, Ti powder and Ta powder to obtain a mixed powder; After the mixed powder is dried, a 3D printed aluminum alloy part is prepared by 3D printing.

8. The method for preparing a 3D printed aluminum alloy part according to claim 7, characterized in that: The 3D printing is laser printing, and the laser power is 180-380W.

9. The method for preparing a 3D printed aluminum alloy part according to claim 7, characterized in that: The scanning rate of laser printing is 200-2000 mm / s, and the scanning spacing is 0.08-0.12 mm.

10. The method for preparing a 3D printed aluminum alloy part according to claim 7, characterized in that: In the 3D printing, the powder spreading thickness of the mixed powder is 30 to 90 μm.

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