阅读说明：本技术 一种3d打印用铝合金粉末材料及其制备方法与应用 (Aluminum alloy powder material for 3D printing and preparation method and application thereof ) 是由 祝弘滨 刘昱 孙帮成 龚明 于 2020-07-31 设计创作，主要内容包括：本发明属于3D打印用铝合金粉末材料技术领域,具体涉及一种3D打印用铝合金粉末材料及其制备方法与应用。本发明提供一种3D打印用铝合金粉末材料,其合金元素包括Mg、Sc、Zr、Mn、Fe、Ni、Si、Zn、Cr；其中Si+Mn总含量为铝合金粉末材料总质量的0.9～1.5wt％,且Si/Mn的质量比为1～2或≥5。本发明发现通过上述控制,所得铝合金粉末材料经SLM方法3D打印以及适当热处理后的拉伸强度可提升至570MPa以上,同时塑性可提升至17％以上,经多次测试,不存在打印后应力集中导致的开裂问题,解决了现有铝合金3D打印件拉伸强度与塑性难以兼顾的问题。(The invention belongs to the technical field of aluminum alloy powder materials for 3D printing, and particularly relates to an aluminum alloy powder material for 3D printing and a preparation method and application thereof. The invention provides an aluminum alloy powder material for 3D printing, wherein alloy elements of the aluminum alloy powder material comprise Mg, Sc, Zr, Mn, Fe, Ni, Si, Zn and Cr; wherein the total content of Si and Mn is 0.9-1.5 wt% of the total mass of the aluminum alloy powder material, and the mass ratio of Si/Mn is 1-2 or more than or equal to 5. According to the invention, through the control, the tensile strength of the obtained aluminum alloy powder material after 3D printing and proper heat treatment by the SLM method can be improved to more than 570MPa, meanwhile, the plasticity can be improved to more than 17%, and through multiple tests, the problem of cracking caused by stress concentration after printing does not exist, and the problem that the tensile strength and the plasticity of the existing aluminum alloy 3D printed part are difficult to take into account is solved.)

1. An aluminum alloy powder material for 3D printing comprises alloy elements including Mg, Sc, Zr, Mn, Fe, Ni, Si, Zn and Cr; the method is characterized in that the total content of Si and Mn is controlled to be 0.9-1.5 wt% of the total mass of the aluminum alloy powder material, and the mass ratio of Si/Mn is 1-2 or more than or equal to 5.

2. The aluminum alloy powder material for 3D printing according to claim 1, wherein the Si content is controlled within a range of 0.4 to 1 wt%;

and/or, the Mn content is controlled within the range of 0.05 to 0.6 wt%, preferably 0.15 to 0.5 wt%.

3. The aluminum alloy powder material for 3D printing according to claim 1 or 2, wherein the Mg content is controlled in the range of 4.7-10 wt.%, preferably 6.5-8.5%;

and/or, controlling the Sc content in the range of 0.3-0.6 wt%, preferably 0.45-0.65%;

and/or, the Zr content is controlled within the range of 0.1 to 0.4 wt%, preferably 0.22 to 0.33%.

4. The aluminum alloy powder material for 3D printing according to claim 3, wherein the total content of Si + Mg is controlled to be maintained in the range of 5 to 10 wt%, and Si/Mg is less than or equal to 0.58;

and/or the mass ratio of Sc/Zr is within the range of 1.5-2.5;

and/or, controlling the content of Fe and Ni in the range of 0.05-0.2 wt% respectively;

and/or controlling the content of Zn and the content of Cr to be in the range of 0.05 to 0.15 weight percent respectively.

5. The aluminum alloy powder material for 3D printing according to claim 1, comprising the following components in mass fraction: mg: 4.7-10 wt%; and (C) Sc: 0.10-1 wt%; zr: 0.1-0.5 wt%; mn: 0.05-0.6 wt%; fe: 0.05-0.2 wt%; ni: 0.05-0.2 wt%; si: 0.4-1%; zn: 0.05-0.15 wt%; cr: 0.05-0.15 wt%; the other trace elements are not more than 0.2 percent, and the balance is Al;

preferably, the other trace elements include one or more of Er, Ti, Ce or Sr.

6. The aluminum alloy powder material for 3D printing according to claim 5, comprising the following components in mass fraction: mg: 6.5-8.5 wt%; and (C) Sc: 0.45-0.65 wt%; zr: 0.22-0.33 wt%; mn: 0.15-0.5 wt%; fe: 0.04-0.06 wt%; ni: 0.06-0.08 wt%; si: 0.55-0.8 wt.%; zn: 0.07-0.09 wt%; cr: 0.05-0.08 wt%; other trace elements comprise Er and Ce, the total content is 0.05-0.06 wt%, and the balance is Al.

7. A method of producing an aluminium alloy powder material according to any one of claims 1 to 6, comprising: mixing the elements in proportion, performing vacuum induction melting-inert gas atomization powder preparation by adopting a one-step method, and performing vibration screening or airflow classification treatment on the obtained powder.

8. The production method according to claim 7, wherein the vacuum induction melting conditions are as follows: vacuum degree is less than or equal to 10^-2Pa, the smelting temperature is 750-820 ℃; preferably, the heating rate is controlled to be 10-25 ℃/min;

and/or during the inert gas atomization, the atomization pressure is 2.5-4.5 MPa; the atomizing nozzle is a retractable annular seam nozzle; the atomization cone angle is 45-60 degrees.

9. The process according to claim 8, wherein the process is carried out under conditions such that the degree of vacuum is (0.4 to 0.5) × 10^-2Pa, the smelting temperature is 780-820 ℃;

controlling the heating rate to be 10-15 ℃/min in the vacuum induction melting process;

the atomization pressure is 3.5-4.2MPa, and the atomization cone angle is 50-60 degrees.

10. A SLM powder bed 3D printed shape, characterized by being made of the aluminum alloy powder material for 3D printing according to any of claims 1-6.

Technical Field

The invention belongs to the technical field of aluminum alloy powder materials for 3D printing, and particularly relates to an aluminum alloy powder material for 3D printing and a preparation method and application thereof.

Background

In the 3D printing technology, the aluminum alloy powder commonly used at present is mainly AlSi₁₂Alloy and AlSi₁₀Mg alloy, but the strength of the two alloys after printing is lower and is not more than 350MPa, and the elongation is not more than 6%.

Foreign air passenger companies develop high-strength Scalmalloy aluminum alloy powder for 3D printing technology, the tensile strength and the elongation rate can reach 520MPa and 13% respectively, but in actual printing production, the fact that the strength and the elongation rate of a printed piece obtained by adopting the material still need to be improved, partial microcracks exist in a printed sample piece, fatigue performance is insufficient, failure is easy to occur in the using process, and the stress corrosion resistance is poor.

CN109487126A discloses an aluminum alloy powder for 3D printing, which has the advantages of fine structure, good mechanical properties, and strong stress corrosion resistance, but the tensile strength and elongation rate of the aluminum alloy powder cannot be considered at the same time, and when the maximum tensile strength is 580MPa, the elongation rate is reduced to 7%, and the mismatch of strength and plasticity easily causes stress concentration in the printing process of a sample piece, thereby causing cracking of the printed piece after printing.

Therefore, in order to obtain a better 3D printing effect, the tensile strength and the plasticity of a 3D printed product need to be improved at the same time, but the prior art has no effective means for solving the problem.

Disclosure of Invention

The first purpose of the invention is to provide an aluminum alloy powder material for 3D printing, wherein alloy elements of the aluminum alloy powder material comprise Mg, Sc, Zr, Mn, Fe, Ni, Si, Zn and Cr; wherein the total content of Si and Mn is controlled to be 0.9-1.5% of the total mass of the aluminum alloy powder material, and the mass ratio of Si/Mn is 1-2 or more than or equal to 5.

The invention finds that the tensile strength of the 3D printing piece obtained by the SLM method can be improved by controlling the conditions, and simultaneously, the problems of Si and Mn competition strengthening and overlapping strengthening are solved, so that the plasticity (elongation) of the printing piece is improved; tests show that after the obtained aluminum alloy powder material is subjected to 3D printing by an SLM method and conventional heat treatment, the tensile strength can be improved to more than 570MPa, and meanwhile, the plasticity can be improved to more than 17%; and through many tests, the cracking problem caused by stress concentration after printing does not exist, and the problem that the tensile strength and the plasticity (elongation) of the existing 3D printed piece are difficult to be considered is thoroughly solved.

Preferably, by controlling the content of Si within the range of 0.4-1 wt.%, the particle size and distribution of a compound formed by Si and Mg can be controlled, the particle size is not more than 50nm, and the grain boundary presents a discontinuous distribution state, so that the grain boundary can be pinned, the grain growth is hindered, the deformation resistance of the grain boundary is improved, the strength and the elongation are synchronously improved, and the flowability of a melt after powder melting is improved, the generation of microcracks in the laser printing process is hindered, and the number of microcracks is reduced to 0.3-0.7 × 10^-4μm/μm²Further, the compactness of the printed piece is improved to more than 99.8 percent, and the fatigue resistance of the printed piece is obviously improved.

Preferably, by controlling the Mn content in the range of 0.05-0.6%, on the one hand, the formation of Al by Mn element can be ensured₆Mn and other nano particles play a strengthening role; on the other hand, Al can be ensured₆The content and size of Mn are in a reasonable range, so that the compound particles formed by Si and Mg do not generate an overlapping strengthening effect, the elongation is reduced, and the effect of synchronously improving the strength and the elongation is ensured. Further preferably, the Mn content is 0.15 to 0.5%.

Preferably, the Mg content is controlled within the range of 4.7-10%, the effect of solid solution strengthening is realized while the material density is reduced, and the aim of improving the strength of a printed product is achieved. Further preferably, the Mg content is in the range of 6.5 to 8.5%.

As one of the specific implementation modes of the invention, the total content of Si and Mg is controlled to be kept at 5-10 wt%, and the mass ratio of Si/Mg is less than or equal to 0.58, so that Si and Mg completely react in the alloying process to form compound particles, the size of the compound particles is not more than 500nm, crystal boundaries can be pinned well, the crystal grains are prevented from growing, and the strength and the elongation are improved at the same time.

Preferably, the Sc content is controlled to be in the range of 0.3-0.6%, so that Al can be precipitated during printing and heat treatment₃The Sc nano particles play a role in strengthening, and simultaneously, the cost of the aluminum alloy powder is reduced. Further preferably, the Sc content is in the range of 0.45 to 0.65%.

As one embodiment of the present invention, controlling Zr content in the range of 0.1-0.4% and Sc/Zr mass ratio in the range of 1.5-2.5 further contributes to the formation of more Al in the printed matter₃The (Sc, Zr) complex phase compound, thereby improving the strength and high-temperature performance of the printed piece. Further preferably, the Zr content is in the range of 0.22 to 0.33%.

Preferably, the contents of Fe and Ni are controlled within the range of 0.05-0.2% respectively to improve the high-temperature performance of the printing member.

Preferably, the Zn and Cr contents are controlled to be in the range of 0.05-0.15% respectively to improve the corrosion resistance of the printed matter.

As one embodiment of the present invention, the aluminum alloy powder material comprises the following components in parts by mass: mg: 4.7-10 wt%; and (C) Sc: 0.10-1 wt%; zr: 0.1-0.5 wt%; mn: 0.05-0.6 wt%; fe: 0.05-0.2 wt%; ni: 0.05-0.2 wt%; si: 0.4-1%; zn: 0.05-0.15 wt%; cr: 0.05-0.15 wt%; the other trace elements are not more than 0.2 percent, and the balance is Al.

Preferably, the other trace elements comprise one or more of Er, Ti, Ce and Sr, so that the absorptivity and the thermal conductivity of the aluminum alloy powder to laser are improved, the manufacturability of the powder is improved, the crystal grains are further refined, and the performance of a printed piece is improved.

As one embodiment of the present invention, the aluminum alloy powder material comprises the following components in parts by mass: mg: 6.5-8.5 wt%; and (C) Sc: 0.45-0.65 wt%; zr: 0.22-0.33 wt%; mn: 0.15-0.5 wt%; fe: 0.04-0.06 wt%; ni: 0.06-0.08 wt%; si: 0.55-0.8 wt.%; zn: 0.07-0.09 wt%; cr: 0.05-0.08 wt%; other trace elements comprise Er and Ce, the total content is 0.05-0.06 wt%, and the balance is Al.

A second object of the present invention is to provide a method for producing an aluminum alloy powder material, comprising: mixing the elements in proportion, performing vacuum induction melting-inert gas atomization powder preparation by adopting a one-step method, and performing vibration screening or airflow classification treatment on the obtained powder.

Compared with the preparation method of smelting and ingot making before atomization powder making in the prior art, the aluminum alloy powder prepared by the one-step method has the characteristics of less element burning loss, higher powder sphericity, more uniform components, lower impurity content and more uniform particle size distribution; through detection, element burning loss in the powder can be controlled within 5% by one-step powder preparation, and the oxygen content is controlled below 300 ppm; and the preparation process is controllable, the requirements of a 3D printing process are met, and the method is suitable for industrial batch production.

The conditions of the vacuum induction melting are as follows: vacuum degree is less than or equal to 10^-2Pa, the smelting temperature is 750-820 ℃;

preferably, the heating rate is controlled to be 10-25 ℃/min, and the temperature is kept for 20-30min at the smelting temperature and the electromagnetic stirring is continuously carried out. This results in a more uniform powder composition and lower impurity levels.

Preferably, in the inert gas atomization, the atomization pressure is 2.5-4.5 MPa.

As one embodiment of the present invention, the degree of vacuum is 10 or less^-2Pa, the smelting temperature is 750-820 ℃; the atomization pressure is 2.5-4.5 MPa; the oxygen content of the obtained powder is controlled below 300ppm, the content of the hollow powder in the powder is lower, and the hollow powder rate can be reduced to below 1%.

In the inert gas atomization, a retractable annular seam nozzle is selected as an atomization nozzle; the atomization cone angle is 45-60 degrees. By accurately controlling the powder preparation process parameters, the sphericity of the powder can be controlled to be more than 0.88, the flowability of the powder is improved, and the manufacturability of the powder is further improved. According to verification, the Hall flow meter is adopted for detection, the Hall flowability of the aluminum alloy powder obtained by the method is improved to 80-120s/50g, and the flowability of the aluminum alloy powder in the prior art is too low to be detected almost.

Meanwhile, the hollow powder rate can be reduced to below 1 percent, and the oxygen content is controlled to be below 300ppm, so that the defects of pores, impurities and the like in a printed piece are reduced, the density of the printed piece is improved to above 99.8 percent, and the mechanical property and the fatigue property of the printed piece are improved.

Preferably, in the inert gas atomization, the inert gas used is argon and/or nitrogen.

As one embodiment of the invention, the vacuum induction melting is performed under the condition that the vacuum degree is (0.4-0.5) × 10^-2Pa, the smelting temperature is 780-820 ℃; controlling the heating rate to be 10-15 ℃/min in the vacuum induction melting process; after smelting is finished and stirring is uniform, determining that the oxygen content in the atomizing tank is lower than 500ppm, starting atomizing, feeding the molten alloy liquid into the atomizing tank through a tundish and a discharge spout to atomize, wherein the atomizing gas is high-purity argon, the atomizing nozzle is a retractable annular seam nozzle, the atomizing pressure is 3.5-4.2MPa, and the atomizing cone angle is 50-60 degrees. Tests show that by adopting the preferable scheme, the oxygen content of the aluminum alloy powder can be reduced to be less than 200ppm, the hollow powder rate is reduced to be less than 0.55 percent, the sphericity is between 0.88 and 0.95, and the Hall fluidity reaches 105-120s/50 g.

A third object of the invention is to provide an SLM powder bed 3D printed shape, which is produced using the above aluminum alloy powder. The high-strength steel has excellent tensile strength and elongation, and meanwhile, the number of microcracks is less, and the compactness is higher.

Drawings

FIG. 1 is a plot of the morphology and cross-section of the high strength aluminum alloy powder of example 1.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.