WO2021000618A1 - Aluminum alloy powder for laser additive manufacturing, and use thereof - Google Patents

Abstract

Disclosed are an aluminum alloy powder for laser additive manufacturing, and a use thereof. The aluminum alloy powder for laser additive manufacturing comprises the following components in parts by mass: 5.0%-20% of Si, 0.1%-5.0% of Cu, 0.1%-5.0% of Mg, and 1.0%-12.0% of TiB₂, with the balance being Al and inevitable impurities. The aluminum alloy powder for laser additive manufacturing can be used for laser additive manufacturing. In the present invention, a product is obtained by testing, a sample obtained through SLM forming can achieve a density of 99% or more, after undergoing a heat treatment, has a yield strength of 420 MPa, a tensile strength of 550 MPa, and a elongation percentage after fracture of 7.8%, and has no obvious anisotropy, and the requirements for application in relevant fields can be met.

Description

Aluminum alloy powder for laser additive manufacturing and its application Technical field

The invention belongs to the technical field of material preparation, and relates to an aluminum alloy, in particular, to an aluminum alloy powder for laser additive manufacturing.

Background technique

The high-end fields have increasingly higher requirements for material performance and manufacturing technology. The deep integration of manufacturing technology and information technology is an important support for the implementation of the strategy of making a strong country.

Laser additive manufacturing uses a laser as a heat source for melting metal powder, based on three-dimensional model data, and constructs entities through layer-by-layer manufacturing, which can solve the technical problem of combining complex shapes and rapid manufacturing of high-performance metal components. At present, the use of laser additive manufacturing technology to prepare parts with higher dimensional accuracy has obtained some applications in medical and other fields. However, the metal powder available for laser additive manufacturing is very limited, mainly stainless steel, titanium alloy and nickel-based superalloy.

Aluminum alloy has the characteristics of low density and high specific strength, and has broad application prospects. However, due to the disadvantages of poor fluidity, high laser reflectivity, and easy oxidation of aluminum, samples formed by laser additive manufacturing often have many defects. Current research and applications are mostly limited to systems such as A356, AlSi10Mg, AlSi12, and AlMgScZr. It is far from meeting the usage requirements. Therefore, the development of aluminum alloy systems suitable for laser additive manufacturing is particularly important.

Summary of the invention

The purpose of the present invention is to provide an aluminum alloy powder for laser additive manufacturing and its application, so as to overcome the above-mentioned defects in the prior art and meet the needs of applications in related fields.

The aluminum alloy powder for optical additive manufacturing includes the following mass fraction components:

Si: 5.0-20.0%, preferably 5.0-12.0%, particularly preferably 6.5-10.5%

Cu: 0.1-5.0%, preferably 0.5-1.0%

Mg: 0.1-5.0%, preferably 0.3-5.0%, particularly preferably 0.3-3.0%

TiB ₂ : 1.0-12.0%, preferably 1.0-8.0%, particularly preferably, 1.5-6.5%

The balance is Al and unavoidable impurities;

The TiB ₂ exists in the form of ceramic particles with a particle size of 5-2000 nm.

Through the selected aluminum alloy, a vacuum atomization process can be used to prepare powders with better sphericity and higher laser absorption. The use of the aluminum alloy powder for laser additive manufacturing can improve uneven powder spreading, heat accumulation and other problems, thereby reducing defects and cracks in the forming process and improving forming quality.

The above-mentioned aluminum alloy contains Si in a mass fraction of 5.0-20.0%, preferably 5.0-12.0%, particularly preferably 6.5-10.5%. The addition of Si causes the alloy to have good casting properties, improves the fluidity of the aluminum alloy, and reduces the tendency of hot cracking during the laser additive manufacturing process.

The above-mentioned aluminum alloy contains Cu in a mass fraction of 0.1-5.0%, preferably 0.5-1.0%. The addition of Cu can form a supersaturated solid solution during the rapid cooling process of laser additive manufacturing, and improve the yield strength of the shaped sample.

The above-mentioned aluminum alloy contains Mg in a mass fraction of 0.1-5.0%, preferably 0.3-5.0%, and particularly preferably 0.3-3.0%. The addition of Mg enables the formed sample to generate a second phase, such as Mg2Si, Al2CuMg, etc., through the subsequent heat treatment process, which further improves the strength of the sample.

The above-mentioned aluminum alloy contains TiB _{2 in} a mass fraction of 1.0-12.0%, preferably 1.0-8.0%, and particularly preferably 1.5-6.5%. The TiB ₂ exists in the form of ceramic particles with a particle size of 5-2000 nm. TiB ₂ particles can not only serve as an effective nucleation substrate for Al, increase the nucleation rate, and refine the grain size; it can also affect the diffusion rate of alloying elements Si, Cu, and Mg, and improve the morphology and distribution of the second phase. In particular, TiB ₂ particles can also improve the heat distribution during the laser additive manufacturing process, and reduce residual stress and anisotropy.

The invention provides an aluminum alloy powder for laser additive manufacturing. The preparation method can refer to the method reported in patent CN100999018A. Specifically, it includes the following steps:

(1) Heating aluminum to 650～950℃ to obtain a melt;

(2) Mix KBF ₄ and K ₂ TiF ₆ , add them to the melt obtained in step (1) after drying, and react with stirring. Preferably, the reaction time is 5-60 min, and the scum is removed;

Preferably, in step (2), the mass ratio of KBF ₄ to K ₂ TiF ₆ is 1:0.5 to 1:2;

(3) Add Al-Si master alloy, Al-Cu master alloy and Mg to the melt obtained in step (2) in sequence, degas refining, temperature 650～800℃, 10～20min, strip off scum;

(4) Gas atomizing the melt obtained in step (3) to obtain the aluminum alloy powder.

The described aerosolization is a conventional technology, which can be referred to the method reported in patent CN107262730A. Specifically, it includes the following steps:

The melt is heated to 750-1200°C, and atomized under the protection of Ar and/or He gas, the atomization pressure is 0.5-10MPa, and the nozzle diameter used for atomization is 0.5-5mm.

The aluminum alloy powder for laser additive manufacturing provided by the present invention can be used for laser additive manufacturing and includes the following steps:

S1. Draw the three-dimensional graphics of the sample to be processed through the drawing software and save it in STL format;

S2. The aluminum alloy powder provided by the present invention is sieved to leave a powder with a particle size ranging from 15 to 53 μm, and a metal printer is used to prepare the sample drawn in step S1;

S3. Perform subsequent heat treatment on the sample obtained in step S2 to further improve performance.

Preferably, in step S2, Selective Laser Melting (SLM) technology is used, the laser power is 150-350 W, the scanning speed is 500-1500 mm/s, the scanning interval is 0.15-0.20 mm, and the layer thickness is 30-40 μm.

Preferably, the heat treatment process in step S3 is a heating temperature of 120 to 180° C., a holding time of 6 to 12 hours, and air cooling.

The beneficial effects of the present invention are:

Through the test, the product is obtained. The sample formed by SLM has a density of more than 99%, a yield strength of 420MPa after heat treatment, a tensile strength of 550MPa, an elongation after fracture of 7.8%, and no obvious anisotropy. It can meet the needs of applications in related fields.

Detailed ways

In the examples, the performance parameters of the obtained materials are tested according to the method specified in the standard ASTM B557-15.

Example 1

Component weight ratio:

The TiB ₂ exists in the form of ceramic particles with a particle size of 5-2000 nm.

Preparation:

1. Heat the aluminum to 680°C to obtain a melt;

2. Mix KBF ₄ and K ₂ TiF _{6 with a} mass ratio of 1:1.5 uniformly, add them to the melt after drying, and mechanically stir for 30 minutes to remove scum;

3. Add Al-Si master alloy, Al-Cu master alloy and Mg in sequence, degas and refine, control the temperature at 740℃ and let it stand for 15 minutes to remove scum;

4. The melt is heated to 880°C, and atomized under the protection of Ar gas, the atomization pressure is 4.0 MPa, and the diameter of the nozzle used for the atomization is 1.8 mm to obtain the aluminum alloy powder;

5. The above aluminum alloy powder is sieved to leave a powder with a particle size ranging from 15 to 53 μm, and the sample is formed using SLM technology. The process parameters are laser power 250W, scanning speed 1500mm/s, scanning distance 0.15mm, and layer thickness 30μm;

6. Heat the formed sample and heat it to 150°C for 12h.

Through the test, the density of the sample formed by the SLM of the powder can reach more than 99%, the yield strength after heat treatment is 420MPa, the tensile strength is 550MPa, the elongation after fracture is 7.8%, and there is no obvious anisotropy.

Example 2

Component weight ratio:

The TiB ₂ exists in the form of ceramic particles with a particle size of 5-2000 nm.

Preparation:

1. Heat the aluminum to 700°C to obtain a melt;

2. Mix KBF ₄ and K ₂ TiF _{6 with a} mass ratio of 1:1.5 uniformly, add them to the melt after drying, and mechanically stir for 30 minutes to remove scum;

3. Add Al-Si master alloy, Al-Cu master alloy and Mg in sequence, degas and refine, control the temperature at 760℃ and let it stand for 15 minutes to remove scum;

4. The melt is heated to 900°C, and atomized under the protection of He gas, the atomization pressure is 3.0MPa, and the nozzle diameter used for atomization is 1.7mm to obtain the aluminum alloy powder;

5. The above aluminum alloy powder is sieved to leave a powder with a particle size ranging from 15 to 53μm, and the sample is formed using SLM technology. The process parameters are laser power 325W, scanning speed 1000mm/s, scanning distance 0.19mm, and layer thickness 30μm;

6. Heat the formed sample and heat it to 150°C for 12h.

Through the test, the density of the sample after the powder is formed by SLM can reach more than 99%, the yield strength after heat treatment is 410MPa, the tensile strength is 530MPa, the elongation after fracture is 8.3%, and there is no obvious anisotropy.

Example 3

Component weight ratio:

The preparation method is as follows:

1. Heat the aluminum to 660°C to obtain a melt;

2. Mix KBF ₄ and K ₂ TiF _{6 with a} mass ratio of 1:1.5 uniformly, add them to the melt after drying, and mechanically stir for 30 minutes to remove scum;

3. Add Al-Si master alloy, Al-Cu master alloy and Mg in sequence, degas and refine, control the temperature at 700℃ and let it stand for 15 minutes to remove scum;

4. The melt is heated to 780°C, and atomized under the protection of He gas, the atomization pressure is 2.5MPa, and the diameter of the nozzle used for atomization is 2.2mm to obtain the aluminum alloy powder;

5. The above aluminum alloy powder is sieved to leave a powder with a particle size ranging from 15 to 53μm, and the sample is formed using SLM technology. The process parameters are laser power 300W, scanning speed 1000mm/s, scanning distance 0.19mm, and layer thickness 30μm;

6. Heat the formed sample and heat it to 120°C for 12h.

Through the test, the density of the sample formed by the powder through SLM can reach more than 99%, the yield strength after heat treatment is 448MPa, the tensile strength is 498MPa, the elongation after fracture is 2.3%, and there is no obvious anisotropy.

Example 4

Component weight ratio:

The preparation method is as follows:

1. Heat the aluminum to 700°C to obtain a melt;

2. Mix KBF ₄ and K ₂ TiF _{6 with a} mass ratio of 1:1.5 uniformly, add them to the melt after drying, and mechanically stir for 30 minutes to remove scum;

3. Add Al-Si master alloy, Al-Cu master alloy and Mg in sequence, degas and refine, control the temperature at 780℃ and let it stand for 15 minutes to remove scum;

4. The melt is heated to 980°C, and atomized under the protection of He gas, the atomization pressure is 4.5MPa, and the diameter of the nozzle used for atomization is 1.5mm, to obtain the aluminum alloy powder;

5. The above aluminum alloy powder is sieved to leave a powder with a particle size ranging from 15 to 53 μm, and the sample is formed using SLM technology. The process parameters are laser power 175W, scanning speed 700mm/s, scanning distance 0.20mm, and layer thickness 40μm;

6. Heat the formed sample and heat it to 180°C for 6h.

Through the test, the density of the sample formed by the powder through SLM can reach more than 99%, the yield strength after heat treatment is 354MPa, the tensile strength is 445MPa, the elongation after fracture is 4.6%, and there is no obvious anisotropy.

Claims (10)

1. Aluminum alloy powder for laser additive manufacturing is characterized in that it includes the following mass fraction components:

   Si: 5.0-20.0%

   Cu: 0.1-5.0%

   Mg: 0.1-5.0%

   TiB ₂ : 1.0-12.0%

   The balance is Al and unavoidable impurities.
2. The aluminum alloy powder for laser additive manufacturing according to claim 1, characterized in that it comprises the following mass fraction components:

   Si: 5.0-12.0%

   Cu: 0.5-1.0%

   Mg: 0.3-5.0%

   TiB ₂ : 1.0-8.0%

   The balance is Al and unavoidable impurities.
3. The aluminum alloy powder for laser additive manufacturing according to claim 1, characterized in that it comprises the following mass fraction components:

   Si: 6.5-10.5%

   Cu: 0.5-1.0%

   Mg: 0.3-3.0%

   TiB ₂ : 1.5-6.5%

   The balance is Al and unavoidable impurities.
4. The aluminum alloy powder for laser additive manufacturing according to any one of claims 1 to 3, wherein the TiB ₂ exists in the form of ceramic particles.
5. The aluminum alloy powder for laser additive manufacturing according to claim 4, wherein the particle size is 5-2000 nm.
6. The application of the aluminum alloy powder for laser additive manufacturing according to any one of claims 1 to 5, characterized in that it is used for laser additive manufacturing.
7. The application according to claim 6, characterized in that it comprises the following steps:

   S1. Draw the three-dimensional graphics of the sample to be processed through the drawing software and save it in STL format;

   S2. The aluminum alloy powder provided by the present invention is sieved to leave a powder with a particle size ranging from 15 to 53 μm, and a metal printer is used to prepare the sample drawn in step S1;

   S3. Perform heat treatment on the sample obtained in step S2.
8. The application according to claim 7, characterized in that in step S2, laser selective melting is used, the laser power is 150-350W, the scanning speed is 500-1500mm/s, the scanning distance is 0.15-0.20mm, and the layer thickness is 30- 40μm.
9. The application according to claim 7, characterized in that, in the heat treatment in step S3, the heating temperature is 120-180°C, the holding time is 6-12h, and air cooling.
10. The application according to claim 8, characterized in that, in the heat treatment in step S3, the heating temperature is 120-180°C, the holding time is 6-12h, and air cooling.