Graded aging heat treatment method for improving strength and plasticity of selective laser melting AlSi10Mg alloy

Abstract

The invention provides a graded aging heat treatment method for improving the strength and plasticity of a selective laser melting AlSi10Mg alloy, and belongs to the technical field of additive manufacturing. According to the method, AlSi10Mg powder serves as a raw material, AlSi1Mg alloy is prepared through a selective laser melting method, then graded aging heat treatment is conducted, the temperature of first-stage aging heat treatment and the temperature of second-stage aging heat treatment in the graded aging heat treatment are both 130-150 DEG C, and the time of the first-stage aging heat treatment and the time of the second-stage aging heat treatment are both 15-30 min. After the selective laser melting AlSi10Mg alloy is subjected to short graded aging heat treatment, a net-shaped eutectic silicon structure in the structure of the alloy is thickened, and a large number of Mg2Si hard phases are separated out, so that the structure of the AlSi10Mg alloy is effectively improved, meanwhile, the hardness, strength and plasticity of the AlSi10Mg alloy are improved, and the service life of the alloy is prolonged. The problems that a solid solution aging or single-stage aging heat treatment process is long in consumed time, and the strength and plasticity cannot be improved at the same time are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and particularly relates to a step aging heat treatment method for improving the strength and plasticity of selective laser melted AlSi10Mg alloy. Background Art

[0002] As a typical cast aluminum alloy, the main components of AlSi10Mg alloy are aluminum (Al), silicon (Si), magnesium (Mg) and other trace elements. Among them, aluminum as the basic element endows the material with light weight and corrosion resistance, and the addition of silicon and magnesium further enhances the casting fluidity, thermal stability and mechanical properties of the material. This makes the AlSi10Mg alloy have a low density (about 2.7 g / cm 3 ), a high thermal conductivity and good mechanical properties, and is widely used in various fields such as aviation, aerospace, automotive, machinery, and medical.

[0003] With the intensification of competition in various industries and the acceleration of product replacement, it is forced that aluminum alloy parts develop towards the direction of light weight, integrity and complexity. However, traditional casting methods are difficult to meet the rapid manufacturing requirements of current complex aluminum alloy parts. In recent years, additive manufacturing technology has developed rapidly and has attracted much attention because of its high degree of flexibility and the ability to form parts with any complex structure. Selective laser melting has been widely used as a manufacturing process directly for complex metal parts in additive manufacturing technology.

[0004] The selective laser melting technology (SLM) uses a laser as the heat source. According to the layer information of the STL format file converted from the three-dimensional model of the part, it selectively scans the metal powder in the powder bed, melts and deposits it, and stacks it layer by layer to prepare metal parts with complex structures. Because the temperature gradient is too large and the solidification rate is high during the preparation of AlSi10Mg alloy by selective laser melting, the structure of AlSi10Mg alloy is significantly refined, and its hardness and strength are also significantly improved compared with the traditional casting process, but the plasticity hardly improves, which seriously restricts the further popularization and application of the selective laser melting alloy process.

[0005] To improve the plasticity of selective laser melted AlSi10Mg alloy, generally T6 or single-stage aging heat treatment process is used to change the structure of selective laser melted AlSi10Mg alloy to improve its plasticity. Although these heat treatment processes improve the plasticity of AlSi10Mg alloy, their strength is significantly reduced, and the process cycle is long, the efficiency is low, and the energy consumption is high. Therefore, it is necessary to study a heat treatment method suitable for selective laser melted AlSi10Mg alloy to further improve the mechanical properties of selective laser melted AlSi10Mg alloy while shortening its energy consumption and time. Summary of the Invention

[0006] In view of the above defects or improvement requirements of the prior art, the present invention provides a stepwise aging heat treatment method for improving the strength and plasticity of selective laser melted AlSi10Mg alloy. The purpose is to heat-treat the selective laser melted AlSi10Mg alloy by a stepwise short aging process, so that the silicon element in the alloy structure is redistributed and a large amount of Mg2Si intermetallic phases are precipitated, effectively improving the hardness, strength and plasticity of the AlSi10Mg alloy, eliminating the solution treatment process and having a shorter time than the single-stage aging process, thereby solving the problems of reduced strength, increased plasticity, long cycle, low efficiency and high energy consumption after heat treatment of the existing selective laser melted AlSi10Mg alloy.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present invention:

[0009] A stepwise aging heat treatment method for improving the strength and plasticity of selective laser melted AlSi10Mg alloy, using AlSi10Mg powder as the raw material, preparing AlSi1Mg alloy by selective laser melting method, and then performing stepwise aging heat treatment. The number of steps of the stepwise aging heat treatment is two levels. The temperatures of the first-stage aging heat treatment and the second-stage aging heat treatment are both 130 - 150 °C, and the times are both 15 - 30 min. The temperatures and times of the first-stage aging heat treatment and the second-stage aging heat treatment can be the same or different.

[0010] Further, the stepwise aging heat treatment includes the following steps:

[0011] (1) First-stage aging heat treatment: Place the AlSi10Mg alloy prepared by selective laser melting method in a heat treatment furnace, heat and hold, and after the holding is completed, take out the AlSi10Mg alloy and cool it.

[0012] (2) Second-stage aging heat treatment: Place the AlSi10Mg alloy cooled in step (1) in the heat treatment furnace and hold it. After the holding is completed, take out the AlSi10Mg alloy and cool it, and then turn off the heat treatment furnace.

[0013] Even further, in step (1), the heating rate of the heating is ≤ 10 °C / min.

[0014] Even further, in steps (1) and (2), the cooling is air cooling to room temperature.

[0015] Further, the angle of repose of the AlSi10Mg powder is less than 15°, and the particle size is 15 - 53 μm.

[0016] Further, the laser power of the selective laser melting method is 260 W to 305 W, the scanning speed is 1800 mm / s to 2000 mm / s, the scanning spacing is 90 μm to 110 μm, and the powder laying thickness is 30 μm.

[0017] Further, the AlSi10Mg powder is used in the selective laser melting method after being washed and vacuum dried.

[0018] Furthermore, the washing is performed with absolute ethanol; the temperature of the vacuum drying is 80 °C, and the time is 2 to 4 h.

[0019] Further, after the AlSi10Mg alloy prepared by the selective laser melting method is subjected to step-by-step aging heat treatment, the hardness is greater than 150.34 HV 0.2 , the tensile strength is greater than 490 MPa, and the elongation is greater than 7.3%.

[0020] More specifically, a step-by-step aging heat treatment method for improving the strength and plasticity of the selective laser melting AlSi10Mg alloy of the present invention includes the following steps:

[0021] (1) According to the outer shape dimensions of the AlSi10Mg alloy part, after modeling it with 3D software, it is converted into a processing instruction for the selective laser melting equipment according to the forming direction and layer thickness information. Commonly used 3D modeling software and processing instruction software include Materialise Magics, AutoCAD, Ephatch, etc.;

[0022] (2) Select AlSi10Mg powder as the forming material, wash it with absolute ethanol and dry it in a vacuum drying oven at 80 °C for 2 to 4 h for standby. The angle of repose of the used AlSi10Mg powder is less than 15°, and the particle size is 15 to 53 μm;

[0023] (3) Load the AlSi10Mg alloy powder dried in step (2) into the selective laser melting equipment, and selectively scan the powder layer according to the processing instruction in an inert gas atmosphere and accumulate layer by layer to obtain the AlSi10Mg alloy part. The laser power during the selective laser melting process is 260 w to 305 w, the scanning speed is 1800 mm / s to 2000 mm / s, the scanning spacing is 90 μm to 110 μm, and the powder laying thickness is 30 μm;

[0024] (4) Place the selective laser melting AlSi10Mg alloy obtained in step (3) in a heat treatment furnace and heat it with the furnace. The heating rate is not greater than 10 °C / min. After heating to 130 to 150 °C, keep it warm for 15 to 30 min;

[0025] (5) After the heat preservation is completed, the AlSi10Mg alloy specimen is taken out of the heat treatment furnace for air cooling, and the heat treatment furnace continues to maintain a predetermined temperature of 130 - 150 °C;

[0026] (6) After the AlSi10Mg alloy specimen in step (5) is air cooled to room temperature, it is put into a heat treatment furnace at 130 - 150 °C for continuous heat preservation for 15 - 30 min;

[0027] (7) After the heat preservation is completed, the AlSi10Mg alloy specimen is taken out of the heat treatment furnace, air cooled to room temperature, and the heat treatment furnace is turned off.

[0028] The second technical solution of the present invention:

[0029] An AlSi10Mg alloy prepared by the step-by-step aging heat treatment method has a hardness greater than 150.34 HV 0.2 , a tensile strength greater than 490 MPa, and an elongation greater than 7.3%.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] (1) The present invention uses a step-by-step aging heat treatment process to heat-treat the AlSi10Mg alloy prepared by selective laser melting, eliminating the high-temperature heating of the solution treatment process and the long-time heat preservation of single-stage aging, greatly simplifying the heat treatment process and effectively improving the heat treatment efficiency.

[0032] (2) The step-by-step aging heat treatment process of the present invention is a two-stage short aging process. After heat-treating the AlSi10Mg alloy prepared by selective laser melting, a large amount of Mg2Si intermediate phases can be precipitated in the structure in a short time, and the Mg2Si particles are dispersed in the crystal, achieving the effect of dispersion precipitation strengthening, thereby improving the hardness, strength, and plasticity of the AlSi10Mg alloy.

[0033] (3) After the AlSi10Mg alloy is treated by the step-by-step aging heat treatment method of the present invention, the hardness is greater than 150.34 HV 0.2 , the tensile strength is greater than 490 MPa, and the elongation is greater than 7.3%, effectively solving the problem that the strength of the existing selectively laser melted AlSi10Mg alloy decreases and the plasticity increases after heat treatment. Description of the Drawings

[0034] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0035] Figure 1 is the process flow chart of the step-by-step aging heat treatment of the present invention;

[0036] Figure 2 Tensile strength and elongation measurement results of the AlSi1Mg alloy processed by the methods of Example 1 and Comparative Example 1 (0 represents Comparative Example 1, 15 + 15 represents Example 1);

[0037] Figure 3 Microhardness measurement results of the AlSi1Mg alloy processed by the methods of Example 1 and Comparative Example 1 (0 represents Comparative Example 1, 15 + 15 represents Example 1);

[0038] Figure 4 Tensile strength and elongation measurement results of the AlSi1Mg alloy processed by the methods of Example 2 and Comparative Example 2 (0 represents Comparative Example 2, 25 + 25 represents Example 2);

[0039] Figure 5 Microhardness measurement results of the AlSi1Mg alloy processed by the methods of Example 2 and Comparative Example 2 (0 represents Comparative Example 2, 25 + 25 represents Example 2);

[0040] Figure 6 Tensile strength and elongation measurement results of the AlSi1Mg alloy processed by the methods of Example 3 and Comparative Example 3 (0 represents Comparative Example 3, 30 + 30 represents Example 3);

[0041] Figure 7 Microhardness measurement results of the AlSi1Mg alloy processed by the methods of Example 3 and Comparative Example 3 (0 represents Comparative Example 3, 15 + 15 represents Example 3);

[0042] Figure 8 Mg2Si intermetallic phase distribution map of the AlSi1Mg alloy processed by the methods of Example 2 and Comparative Example 2 (0 represents Comparative Example 2, 25 + 25 represents Example 2). Detailed implementation manners

[0043] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0044] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0045] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0046] Without departing from the scope or spirit of this invention, various improvements and variations can be made to the specific embodiments of the description of this invention, which will be obvious to those skilled in the art. Other embodiments obtained from the description of this invention will be obvious to those skilled in the art. The description and examples of this invention are merely exemplary.

[0047] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0048] An embodiment of this invention proposes a stepwise aging heat treatment method for improving the strength and plasticity of selective laser melted AlSi10Mg alloy. Using AlSi10Mg powder as the raw material, an AlSi1Mg alloy is prepared by selective laser melting method, and then stepwise aging heat treatment is carried out. The number of steps of the stepwise aging heat treatment is two levels. The temperatures of the first-stage aging heat treatment and the second-stage aging heat treatment are both 130 - 150 °C, and the times are both 15 - 30 min (the temperatures and times of the first-stage aging heat treatment and the second-stage aging heat treatment can be the same or different); the stepwise aging heat treatment includes the following steps (for the process flow chart, see Figure 1 )

[0049] (1) First-stage aging heat treatment: Place the AlSi10Mg alloy prepared by selective laser melting method in a heat treatment furnace, heat and keep warm. After the heat preservation ends, take out the AlSi10Mg alloy and cool it.

[0050] (2) Second-stage aging heat treatment: Place the AlSi10Mg alloy cooled in step (1) back in the heat treatment furnace and keep warm. After the heat preservation ends, take out the AlSi10Mg alloy and cool it, then turn off the heat treatment furnace.

[0051] In step (1) of the preferred embodiment of this invention, the heating rate of the heating is ≤ 10 °C / min.

[0052] In steps (1) and (2) of the preferred embodiment of this invention, the cooling is air cooling to room temperature.

[0053] The step aging heat treatment in steps (1) and (2) is two-stage short aging treatment, and the treatment time is preferably 15-30 min, and the temperature is preferably 130-150 °C. This is because too short a time and too low a temperature will not significantly improve the performance of alloy parts; too long a time and too high a temperature will increase costs and reduce efficiency.

[0054] Since the powder particle size distribution affects the surface quality of the formed alloy parts and the absorption of laser energy, thereby affecting the mechanical properties of the alloy parts, in the preferred embodiment of the present invention, the angle of repose of the AlSi10Mg powder is less than 15°, and the particle size is 15-53 μm.

[0055] Appropriate process parameters should be selected for forming selective laser melting alloy parts to prevent defects in the alloy parts due to process parameter problems. Therefore, in the preferred embodiment of the present invention, the laser power of the selective laser melting method is 260 w-305 w, the scanning speed is 1800 mm / s-2000 mm / s, the scanning spacing is 90 μm-110 μm, and the powder spreading thickness is 30 μm.

[0056] In the preferred embodiment of the present invention, the AlSi10Mg powder is washed and vacuum dried and then used in the selective laser melting method. The washing is with absolute ethanol, the temperature of the vacuum drying is 80 °C, and the time is 2-4 h. After vacuum drying, some impurities in the powder can be removed, and the possible oxides on the powder surface can be removed, reducing the possibility of oxidation. At the same time, moisture is removed to avoid defects such as pores generated by the vaporization of moisture at high temperatures.

[0057] In the preferred embodiment of the present invention, according to the external dimensions of the AlSi10Mg alloy parts, after three-dimensional modeling with three-dimensional software, it is converted into a processing instruction for a selective laser melting device according to the forming direction and layer thickness information. Commonly used three-dimensional modeling software and processing instruction software include Materialise Magics, AutoCAD, Ephatch, etc. The method of modeling with these software is prior art and is not the key point of protection of the present invention, so it will not be elaborated.

[0058] In the preferred embodiment of the present invention, the hardness of the AlSi10Mg alloy prepared by the selective laser melting method is greater than 150.34 HV after step aging heat treatment 0.2 and the tensile strength is greater than 490 MPa, and the elongation is greater than 7.3%.

[0059] The embodiment of the present invention also proposes an AlSi10Mg alloy prepared by the step aging heat treatment method.

[0060] It should be noted that there are no special restrictions on the models of the selective laser melting equipment, heat treatment furnace, and vacuum drying oven in the embodiments of the present invention, and only the parameters for selective laser melting treatment, heat treatment, and vacuum drying need to be satisfied.

[0061] In the embodiments of the present invention, room temperature refers to "25 ± 2 °C".

[0062] AlSi10Mg alloy is an aluminum-based alloy. In the embodiments of the present invention, the AlSi10Mg alloy powder is provided by Beijing Zhonghang Maite Company. The elemental composition is shown in Table 1. Specifically, its angle of repose is 12° to 15°, and the particle size is 15 to 53 μm.

[0063] Table 1 Chemical composition of AlSi10Mg powder

[0064] Element Si Fe Mn Mg Zn Ni O N Al Wt% 10.24 0.14 0.01 0.35 0.011 0.022 0.035 0.001 Bal

[0065] The technical solution of the present invention will be further described below through embodiments.

[0066] Example 1

[0067] A step-by-step aging heat treatment method for selective laser melting of AlSi10Mg alloy, comprising the following steps:

[0068] (1) According to the external dimensions of the AlSi10Mg alloy part, after modeling it with three-dimensional software Materialise Magics, it is converted into a processing instruction for the selective laser melting equipment according to the forming direction and layer thickness information;

[0069] (2) Select AlSi10Mg powder as the forming material, clean it with absolute ethanol, and dry it in a vacuum drying oven at 80 °C for 2 h for standby. The angle of repose of the used AlSi10Mg powder is less than 15°, and the particle size is 15 to 53 μm;

[0070] (3) Load the AlSi10Mg alloy powder dried in step (2) into the selective laser melting equipment, and selectively scan the powder layer and accumulate it layer by layer in an inert gas atmosphere to obtain an AlSi10Mg alloy part. The laser power during the selective laser melting process is 305 W, the scanning speed is 2000 mm / s, the scanning spacing is 110 μm, and the powder spreading thickness is 30 μm;

[0071] (4) Place the selective laser melted AlSi10Mg alloy obtained in step (3) in a heat treatment furnace and heat it with the furnace. The heating rate is 6 °C / min. After heating to 130 °C, keep it warm for 15 min;

[0072] (5) After the heat preservation is completed, the AlSi10Mg alloy specimen is taken out of the heat treatment furnace for air cooling, and the heat treatment furnace continues to maintain the predetermined temperature of 130 °C;

[0073] (6) After the AlSi10Mg alloy specimen in step (5) is air cooled to room temperature, it is put into a heat treatment furnace at 130 °C for continuous heat preservation for 15 min;

[0074] (7) After the heat preservation is completed, the AlSi10Mg alloy specimen is taken out of the heat treatment furnace and air cooled to room temperature, and the heat treatment furnace is turned off.

[0075] Comparative Example 1

[0076] The steps of performing stepwise aging heat treatment on the AlSi1Mg alloy prepared by selective laser melting are omitted, that is, steps (4)-(7) are omitted on the basis of Example 1.

[0077] Referring to the tensile test method at room temperature (the core standard for measuring the room temperature tensile properties of metallic materials in China, GB / T 228.1, the same below), the tensile properties of the AlSi1Mg alloy treated by the method of Example 1 and Comparative Example 1 are tested. The results are shown in Figure 2 (0 represents Comparative Example 1, that is, no stepwise aging heat treatment is performed, 15 + 15 represents Example 1, that is, the heat preservation time for stepwise aging heat treatment is twice). It can be seen that the tensile strength of the AlSi10Mg alloy in Example 1 is increased compared with that in Comparative Example 1, reaching 476.24 Mpa, and the elongation rate reaches 7.01%.

[0078] Referring to the microhardness test method (the core standard for measuring the micro-Vickers hardness of metallic materials in China, GB / T 4342, the same below), the hardness of the AlSi10Mg alloy treated by the method of Example 1 and Comparative Example 1 is tested. The results are shown in Figure 3 (0 represents Comparative Example 1, that is, no stepwise aging heat treatment is performed, 15 + 15 represents Example 1, that is, the heat preservation time for stepwise aging heat treatment is twice). It can be seen that the microhardness of the AlSi10Mg alloy in Example 1 is increased compared with that in Comparative Example 1, reaching 139.44 HV 0.2 .

[0079] Example 2

[0080] A stepwise aging heat treatment method for selective laser melting of AlSi10Mg alloy, comprising the following steps:

[0081] (1) According to the external dimension of the AlSi10Mg alloy part, after modeling it by three-dimensional software Materialise Magics, it is converted into a processing instruction for a selective laser melting device according to the forming direction and layer thickness information;

[0082] (2) Select AlSi10Mg powder as the forming material. After cleaning with absolute ethanol, dry it in a vacuum drying oven at 80 °C for 4 h for standby. The angle of repose of the AlSi10Mg powder used is less than 15°, and the particle size is 15 - 53 μm;

[0083] (3) Load the dried AlSi10Mg alloy powder in step (2) into a selective laser melting equipment. Under an inert gas atmosphere, selectively scan the powder layer according to the processing instructions and accumulate layer by layer to obtain an AlSi10Mg alloy part. The laser power during the selective laser melting process is 260 W, the scanning speed is 1900 mm / s, the scanning spacing is 90 μm, and the powder spreading thickness is 30 μm;

[0084] (4) Place the selective laser melted AlSi10Mg alloy obtained in step (3) in a heat treatment furnace and heat it with the furnace. The heating rate is 6 °C / min. After heating to 150 °C, hold for 25 min;

[0085] (5) After the holding is completed, take out the AlSi10Mg alloy specimen from the heat treatment furnace and perform air cooling, while the heat treatment furnace continues to maintain the predetermined temperature of 150 °C;

[0086] (6) After the AlSi10Mg alloy specimen in step (5) is air cooled to room temperature, put it into a heat treatment furnace at 150 °C and continue to hold for 25 min;

[0087] (7) After the holding is completed, take out the AlSi10Mg alloy specimen from the heat treatment furnace, air cool it to room temperature and turn off the heat treatment furnace.

[0088] Comparative Example 2

[0089] Omit the steps of hierarchical aging heat treatment for the AlSi10Mg alloy prepared by the selective laser melting method, that is, omit steps (4) - (7) on the basis of Example 2.

[0090] Refer to the tensile test method at room temperature, and conduct tensile property tests on the AlSi1Mg alloy treated by the methods of Example 2 and Comparative Example 2. The results are shown in Figure 4 (0 represents Comparative Example 2, that is, without hierarchical aging heat treatment, 25 + 25 represents Example 2, that is, the holding time of hierarchical aging heat treatment twice). It can be seen that the tensile strength of the AlSi1Mg alloy in Example 2 is improved compared with that of Comparative Example 2, reaching 481.32 Mpa, and the elongation rate reaches 7.32%.

[0091] Refer to the microhardness test method, and conduct hardness tests on the AlSi1Mg alloy treated by the methods of Example 2 and Comparative Example 2. The results are shown in Figure 5(0 represents Comparative Example 2, i.e., without stepwise aging heat treatment, and 25+25 represents Example 2, i.e., stepwise aging heat treatment with two holding times). It can be seen that the elongation of the AlSi10Mg alloy in Example 2 is increased compared with Comparative Example 2, reaching 155.32.44HV 0.2 。

[0092] Example 3

[0093] A method for stepwise aging heat treatment of selective laser melted AlSi10Mg alloy, comprising the following steps:

[0094] (1) According to the external dimension of the AlSi10Mg alloy part, after modeling it by 3D software AutoCAD, it is converted into a processing instruction for the selective laser melting equipment according to the forming direction and layer thickness information;

[0095] (2) Select AlSi10Mg powder as the forming material, clean it with absolute ethanol and dry it in a vacuum drying oven at 80 °C for 3 h for standby. The angle of repose of the used AlSi10Mg powder is less than 15°, and the particle size is 15 - 53 μm;

[0096] (3) Load the dried AlSi10Mg alloy powder in step (2) into the selective laser melting equipment, and selectively scan the powder layer and accumulate layer by layer under an inert gas atmosphere to obtain an AlSi10Mg alloy part. The laser power during the selective laser melting process is 300 W, the scanning speed is 1800 mm / s, the scanning spacing is 100 μm, and the powder spreading thickness is 30 μm;

[0097] (4) Place the selective laser melted AlSi10Mg alloy obtained in step (3) in a heat treatment furnace and heat it with the furnace. The heating rate is 6 °C / min, and after heating to 140 °C, hold for 30 min;

[0098] (5) After the holding is completed, take out the AlSi10Mg alloy sample from the heat treatment furnace and air cool it, and the heat treatment furnace continues to maintain the predetermined temperature of 140 °C;

[0099] (6) After the AlSi10Mg alloy sample in step (5) is air cooled to room temperature, put it into a heat treatment furnace at 140 °C and continue to hold for 30 min;

[0100] (7) After the holding is completed, take out the AlSi10Mg alloy sample from the heat treatment furnace, air cool it to room temperature and turn off the heat treatment furnace.

[0101] Comparative Example 3

[0102] The steps of performing step-by-step aging heat treatment on the AlSi1Mg alloy prepared by selective laser melting are omitted, that is, steps (4)-(7) are omitted on the basis of Example 3.

[0103] Referring to the tensile test method at room temperature, the tensile properties of the AlSi1Mg alloy treated by the method of Example 3 and Comparative Example 3 were tested. The results are shown in Figure 6 (0 represents Comparative Example 3, that is, no step-by-step aging heat treatment is performed, 30+30 represents Example 3, that is, the holding time for step-by-step aging heat treatment is twice). It can be seen that the tensile strength of the AlSi1Mg alloy in Example 3 is higher than that in Comparative Example 3, reaching 483.13 Mpa, and the elongation rate reaches 7.19%.

[0104] Referring to the microhardness test method, the hardness of the AlSi1Mg alloy treated by the method of Example 3 and Comparative Example 3 was tested. The results are shown in Figure 7 (0 represents Comparative Example 3, that is, no step-by-step aging heat treatment is performed, 30+30 represents Example 3, that is, the holding time for step-by-step aging heat treatment is twice). It can be seen that the microhardness of the AlSi1Mg alloy in Example 3 is higher than that in Comparative Example 3, reaching 143.14 HV 0.2 。

[0105] Comparative Example 4

[0106] Single-stage aging heat treatment process, the specific process steps are as follows:

[0107] (1) According to the outer dimensions of the AlSi10Mg alloy parts, after modeling them with the 3D software Materialise Magics, they are converted into processing instructions for the selective laser melting equipment according to the forming direction and layer thickness information;

[0108] (2) Select AlSi10Mg powder as the forming material, clean it with absolute ethanol and dry it in a vacuum drying oven at 80°C for 4 h for standby. The angle of repose of the AlSi10Mg powder used is less than 15°, and the particle size is 15-53 μm;

[0109] (3) Load the AlSi10Mg alloy powder dried in step (2) into the selective laser melting equipment, and selectively scan the powder layer and accumulate it layer by layer under an inert gas atmosphere to obtain an AlSi10Mg alloy part. The laser power during the selective laser melting process is 260 W, the scanning speed is 1900 mm / s, the scanning spacing is 90 μm, and the powder spreading thickness is 30 μm;

[0110] (4) Place the selective laser melted AlSi10Mg alloy obtained in step (3) in a heat treatment furnace and heat it with the furnace. The heating rate is 6°C / min. After heating to 170°C, hold for 4 h;

[0111] (5) After the heat preservation is completed, take out the AlSi10Mg alloy specimen from the heat treatment furnace, air-cool it to room temperature, and then close the heat treatment furnace.

[0112] Comparative Example 5

[0113] The T6 aging heat treatment process is as follows:

[0114] (1) According to the external dimensions of the AlSi10Mg alloy part, model it through the 3D software Materialise Magics, and then convert it into a processing instruction for the selective laser melting equipment according to the forming direction and layer thickness information;

[0115] (2) Select AlSi10Mg powder as the forming material, clean it with absolute ethanol, and then dry it in a vacuum drying oven at 80 °C for 4 h for standby. The angle of repose of the used AlSi10Mg powder is less than 15°, and the particle size is 15 - 53 μm;

[0116] (3) Load the dried AlSi10Mg alloy powder in step (2) into the selective laser melting equipment, and selectively scan the powder layer and accumulate it layer by layer under an inert gas atmosphere to obtain an AlSi10Mg alloy part. During the selective laser melting process, the laser power is 260 W, the scanning speed is 1900 mm / s, the scanning spacing is 90 μm, and the powder spreading thickness is 30 μm;

[0117] (4) Solution treatment: Place the selective laser melted AlSi10Mg alloy obtained in step (3) in the heat treatment furnace, heat it to 530 °C with the furnace, the heating rate is 6 °C / min, and after holding for 1.5 h, quickly water-cool it to room temperature;

[0118] (5) Artificial aging: Put the solution-treated AlSi10Mg alloy back into the heat treatment furnace, heat it to 170 °C with the furnace, the heating rate is 6 °C / min, and hold for 6 h;

[0119] (6) After the heat preservation is completed, take out the AlSi10Mg alloy specimen from the heat treatment furnace, air-cool it to room temperature, and then close the heat treatment furnace.

[0120] Use the same method to test the performance of the AlSi1Mg alloy obtained by the treatment methods of Comparative Example 4 and Comparative Example 5. The comparison results of the alloy properties of Comparative Example 4 (single-stage aging), Comparative Example 5 (T6 aging), and the Example (two-stage aging) are shown in Table 2.

[0121] Table 2 Comparison results of properties

[0122]

[0123] As can be seen from Table 2, compared with the examples, when the T6 or single-stage aging heat treatment process is used to change the microstructure of the selective laser melted AlSi10Mg alloy to improve its plasticity, although these heat treatment processes improve the plasticity of the AlSi10Mg alloy, their strength is significantly reduced, and the process cycle is long, the efficiency is low, and the energy consumption is high.

[0124] The distribution map of the Mg2Si interphase of the AlSi1Mg alloy treated by the method of Example 2 and Comparative Example 2 is shown in Figure 8 (0 represents Comparative Example 2, 25 + 25 represents Example 2), and it can be seen that Figure 8 There is very little distribution of the left Mg2Si phase (the blue marked part), and the overall is mainly the aluminum matrix (red), and the distribution of silicon (yellow) is also relatively dispersed. It shows that when not subjected to aging treatment, the Si element does not fully participate in the formation of the strengthening phase. After the two-stage aging treatment, Figure 8 A large number of fine and dispersed Mg2Si particles are precipitated on the right, showing a more uniform and dispersed state in the aluminum matrix, indicating that the two-stage aging treatment promotes the precipitation and dispersion of the Mg2Si interphase.

[0125] Based on the above examples and comparative examples, it can be seen that the present invention uses a stepped aging heat treatment process to heat-treat the AlSi10Mg alloy prepared by selective laser melting, eliminating the high-temperature heating of the solution treatment process and the long-time heat preservation of single-stage aging, greatly simplifying the heat treatment process, effectively improving the heat treatment efficiency, enabling a large amount of Mg2Si interphase to precipitate in the structure in a relatively short time, and the Mg2Si particles are dispersed in the crystal, achieving the effect of dispersion precipitation strengthening, thereby improving the hardness, strength and plasticity of the AlSi10Mg alloy. After the AlSi10Mg alloy is treated by the stepped aging heat treatment method of the present invention, the hardness is greater than 150.34 HV 0.2 , the tensile strength is greater than 490 MPa, and the elongation is greater than 7.3%, effectively solving the problem that the strength of the existing selective laser melted AlSi10Mg alloy decreases and the plasticity increases after heat treatment.

[0126] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A step aging heat treatment method for improving the strength and plasticity of selective laser melted AlSi10Mg alloy, characterized in that, Using AlSi10Mg powder as the raw material, an AlSi1Mg alloy is prepared by selective laser melting, and then subjected to step aging heat treatment. The number of steps of the step aging heat treatment is two levels. The temperatures of the first-stage aging heat treatment and the second-stage aging heat treatment are both 130 to 150 °C, and the times are both 15 to 30 min.

2. The step-by-step aging heat treatment method for improving the strength and plasticity of the selective laser melted AlSi10Mg alloy according to claim 1, characterized in that, The step aging heat treatment includes the following steps: (1) Place the AlSi10Mg alloy prepared by selective laser melting in a heat treatment furnace, heat and hold, and after the holding is completed, take out the AlSi10Mg alloy and cool it; (2) Place the AlSi10Mg alloy cooled in step (1) back in the heat treatment furnace and hold, and after the holding is completed, take out the AlSi10Mg alloy and cool it, and then turn off the heat treatment furnace.

3. The stepwise aging heat treatment method for improving the strength and plasticity of selective laser melted AlSi10Mg alloy according to claim 2, characterized in that, In step (1), the heating rate of the heating is ≤10 °C / min.

4. The step-by-step aging heat treatment method for improving the strength and plasticity of the selective laser melted AlSi10Mg alloy according to claim 2, wherein, In steps (1) and (2), the cooling is air cooling to room temperature.

5. The step-by-step aging heat treatment method for improving the strength and plasticity of the selective laser melted AlSi10Mg alloy according to claim 1, characterized in that, The angle of repose of the AlSi10Mg powder is less than 15°, and the particle size is 15 to 53 μm.

6. The step-by-step aging heat treatment method for improving the strength and plasticity of the selective laser melted AlSi10Mg alloy according to claim 1, wherein, For the selective laser melting method, the laser power is 260 W to 305 W, the scanning speed is 1800 mm / s to 2000 mm / s, the scanning spacing is 90 μm to 110 μm, and the powder layer thickness is 30 μm.

7. The step-by-step aging heat treatment method for improving the strength and plasticity of the selective laser melted AlSi10Mg alloy according to claim 1, characterized in that, The AlSi10Mg powder is used in the selective laser melting method after being washed and vacuum dried.

8. The step-by-step aging heat treatment method for improving the strength and plasticity of selective laser melted AlSi10Mg alloy according to claim 7, characterized in that, The temperature of the vacuum drying is 80 °C, and the time is 2 to 4 h.

9. A step aging heat treatment method for improving the strength and plasticity of selective laser melted AlSi10Mg alloy according to any one of claims 1 to 8, characterized in that, The hardness of the AlSi10Mg alloy prepared by the described step-by-step aging heat treatment method is greater than 150.34 HV 0.2 , the tensile strength is greater than 490 MPa, and the elongation is greater than 7.3%.

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