A graded aging heat treatment method for improving the strength and ductility of selective laser melting AlSi10Mg alloy

Abstract

The application provides a graded aging heat treatment method for improving the strength and plasticity of selective laser melting AlSi10Mg alloy, and belongs to the technical field of additive manufacturing. The method uses AlSi10Mg powder as a raw material, prepares AlSi10Mg alloy through selective laser melting, and then performs graded aging heat treatment. The temperature of the first-stage aging heat treatment and the second-stage aging heat treatment in the graded aging heat treatment is 130-150 DEG C, and the time is 15-30 min. After the selective laser melting AlSi10Mg alloy is subjected to the graded aging heat treatment for a short time, the network eutectic silicon structure in the organization becomes thick, and a large amount of Mg2Si hard phase is precipitated, which not only effectively improves the organization structure of the AlSi10Mg alloy, but also improves the hardness, strength and plasticity of the AlSi10Mg alloy, and solves the problems that the solid solution aging or single-stage aging heat treatment process is time-consuming, and the strength and plasticity cannot be simultaneously improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of additive manufacturing, and particularly relates to a hierarchical aging heat treatment method for improving the strength and plasticity of selective laser melting AlSi10Mg alloy. BACKGROUND

[0002] AlSi10Mg alloy, as a typical cast aluminum alloy, mainly contains aluminum (Al), silicon (Si), magnesium (Mg) and other trace elements. Among them, aluminum as the base element endows the material with light weight and corrosion resistance, and the addition of silicon and magnesium further strengthens the casting fluidity, thermal stability and mechanical properties of the material. This makes the AlSi10Mg alloy have a relatively 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, automobile, machinery and medical treatment.

[0003] With the intensification of competition in various industries and the intensification of product upgrading, aluminum alloy parts are forced to develop in the direction of lightweight, integration and complexity, and the traditional casting method is difficult to meet the current rapid manufacturing needs of 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 ability to form complex structural parts. Selective laser melting is widely used as a manufacturing process for complex metal parts in additive manufacturing technology.

[0004] Selective laser melting technology (SLM) uses laser as a heat source, selectively scans metal powder in the powder bed according to the layer information of the STL format file converted from the three-dimensional model of the part, and makes it melt and deposit and accumulate layer by layer to prepare complex metal parts. Because of the large temperature gradient and high solidification rate in the process of preparing AlSi10Mg alloy by selective laser melting, the microstructure of AlSi10Mg alloy is significantly refined, and the hardness and strength are also significantly improved compared with traditional casting process, but the plasticity is almost not improved, which seriously restricts the further promotion and application of the alloy process of selective laser melting.

[0005] In order to improve the plasticity of selective laser melting AlSi10Mg alloy, T6 or single-stage aging heat treatment process is generally used to change the microstructure of selective laser melting AlSi10Mg alloy to improve its plasticity. Although these heat treatment processes improve the plasticity of AlSi10Mg alloy, the 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 melting AlSi10Mg alloy, which can shorten the energy consumption and time while further improving the mechanical properties of selective laser melting AlSi10Mg alloy. SUMMARY

[0006] In view of the above defects or improvement needs of the prior art, the application provides a hierarchical aging heat treatment method for improving the strength and plasticity of selective laser melting AlSi10Mg alloy, which aims to heat treat the selective laser melting AlSi10Mg alloy by using a hierarchical short aging process, so that the silicon element in the alloy organization is redistributed and a large amount of Mg2Si intermediate phase is precipitated, the hardness, strength and plasticity of the AlSi10Mg alloy are effectively improved, the solid solution treatment process is avoided, and the time is shorter than that of the single-stage aging process, thereby solving the problems of reduced strength, increased plasticity, long cycle, low efficiency and high energy consumption of the existing selective laser melting AlSi10Mg alloy after heat treatment.

[0007] To achieve the above object, the application provides the following technical scheme:

[0008] One of the technical schemes of the application is:

[0009] A hierarchical aging heat treatment method for improving the strength and plasticity of selective laser melting AlSi10Mg alloy, which uses AlSi10Mg powder as a raw material, prepares AlSi1Mg alloy by selective laser melting method, and then performs hierarchical aging heat treatment, the hierarchical aging heat treatment has two stages, the temperature of the first-stage aging heat treatment and the second-stage aging heat treatment is 130-150 DEG C, and the time is 15-30 min, the temperature and time of the first-stage aging heat treatment and the second-stage aging heat treatment can be the same or different.

[0010] Further, the hierarchical aging heat treatment comprises the following steps:

[0011] (1) First-stage aging heat treatment: the AlSi10Mg alloy prepared by the selective laser melting method is placed in a heat treatment furnace, heated and held, and then taken out and cooled after holding is completed;

[0012] (2) Second-stage aging heat treatment: the AlSi10Mg alloy cooled in step (1) is continuously placed in the heat treatment furnace and held, and then taken out and cooled after holding is completed, and the heat treatment furnace is closed.

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

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

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

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

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

[0018] Further, the washing is washing with anhydrous ethanol, and the temperature of the vacuum drying is 80℃, and the time is 2-4h.

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

[0020] More specifically, the step aging heat treatment method for improving the strength and plasticity of the selective laser melting AlSi10Mg alloy comprises the following steps:

[0021] (1) According to the outer shape size of the AlSi10Mg alloy part, the part is modeled by a three-dimensional software, and then the modeling is converted into a selective laser melting equipment processing instruction according to the forming direction and layer thickness information, wherein the commonly used three-dimensional modeling software and processing instruction software are Materialise Magics, AutoCAD, Ephatch, etc.

[0022] (2) AlSi10Mg powder is selected as the forming material, washed with anhydrous ethanol, and then dried in a vacuum drying oven at 80℃ for 2-4h for standby, wherein the rest angle of the AlSi10Mg powder used is less than 15°, and the particle size is 15-53μm;

[0023] (3) The AlSi10Mg alloy powder dried in step (2) is loaded into the selective laser melting equipment, and the powder layer is selectively scanned according to the processing instruction under an inert gas atmosphere and is accumulated layer by layer to obtain an AlSi10Mg alloy part, wherein the laser power of the selective laser melting process is 260w-305w, the scanning speed is 1800mm / s-2000mm / s, the scanning interval is 90μm-110μm, and the powder laying thickness is 30μm;

[0024] (4) The selective laser melting AlSi10Mg alloy obtained in step (3) is placed in a heat treatment furnace and heated with the furnace, the heating rate is not greater than 10℃ / min, heated to 130-150℃ and kept for 15-30min;

[0025] (5) After the heat preservation is ended, the AlSi10Mg alloy sample is taken out from the heat treatment furnace to be air-cooled, and the heat treatment furnace continues to keep the predetermined temperature of 130-150 DEG C;

[0026] (6) The AlSi10Mg alloy sample in step (5) is air-cooled to room temperature and then put into the heat treatment furnace at 130-150 DEG C to continue heat preservation for 15-30 min.

[0027] (7) After the heat preservation is ended, the AlSi10Mg alloy sample is taken out from the heat treatment furnace to be air-cooled to room temperature and the heat treatment furnace is closed.

[0028] The second technical scheme of the present application is:

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

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

[0031] (1) The present application adopts the hierarchical aging heat treatment process to heat treat the AlSi10Mg alloy prepared by the selective laser melting method, eliminates the high-temperature heating and long-time heat preservation of the single aging process, greatly simplifies the heat treatment process, and effectively improves the heat treatment efficiency.

[0032] (2) The hierarchical aging heat treatment process of the present application is a two-stage short aging process, which can make a large number of Mg2Si intermediate phases precipitate in the structure in a short time after heat treatment of the AlSi10Mg alloy prepared by the selective laser melting method, and the Mg2Si particles are dispersedly distributed in the crystal, achieving the effect of dispersion strengthening, so that the hardness, strength and plasticity of the AlSi10Mg alloy are improved.

[0033] (3) After the AlSi10Mg alloy is treated by the hierarchical aging heat treatment method of the present application, 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 of the decrease of the strength and the increase of the plasticity of the existing selective laser melting AlSi10Mg alloy after heat treatment. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0035] Figure 1 It is the process flow chart of the hierarchical aging heat treatment of the present application;

[0036] Figure 2 Tensile strength and elongation of the AlSi1Mg alloy after the process of Example 1 and Comparative Example 1 (0 represents Comparative Example 1, 15+15 represents Example 1) were measured.

[0037] Figure 3 Microhardness of the AlSi1Mg alloy after the process of Example 1 and Comparative Example 1 (0 represents Comparative Example 1, 15+15 represents Example 1) was measured.

[0038] Figure 4 Tensile strength and elongation of the AlSi1Mg alloy after the process of Example 2 and Comparative Example 2 (0 represents Comparative Example 2, 25+25 represents Example 2) were measured.

[0039] Figure 5 Microhardness of the AlSi1Mg alloy after the process of Example 2 and Comparative Example 2 (0 represents Comparative Example 2, 25+25 represents Example 2) was measured.

[0040] Figure 6 Tensile strength and elongation of the AlSi1Mg alloy after the process of Example 3 and Comparative Example 3 (0 represents Comparative Example 3, 30+30 represents Example 3) were measured.

[0041] Figure 7 Microhardness of the AlSi1Mg alloy after the process of Example 3 and Comparative Example 3 (0 represents Comparative Example 3, 15+15 represents Example 3) was measured.

[0042] Figure 8 Distribution of Mg2Si interphase of the AlSi1Mg alloy after the process of Example 2 and Comparative Example 2 (0 represents Comparative Example 2, 25+25 represents Example 2) was measured. DETAILED DESCRIPTION

[0043] Various illustrative embodiments of the present application are now described in detail below. The following description includes specific details for the purpose of providing a thorough understanding of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced without these specific details. In other instances, well-known structures and functions have not been described in detail in order to avoid obscuring the understanding of this description.

[0044] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, for a range of values of a parameter, unless otherwise indicated, each intervening value by each intervening value, as well as any other stated or intervening value in that stated range is encompassed. In addition, any combination of the above values, as well as any other stated or intervening value in that stated range is encompassed. Unless otherwise stated, the above values are not inclusive of the endpoints described.

[0045] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this application pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described therein. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.

[0046] Many modifications and variations of this application can be made in the light of the above teachings without departing from the spirit or scope of the application. Other implementations of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0047] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean inclusion, but not limited to, the listed materials and methods.

[0048] The embodiment of the present application provides a hierarchical aging heat treatment method for improving the strength and plasticity of selective laser melting AlSi10Mg alloy, taking AlSi10Mg powder as a raw material, preparing AlSi10Mg alloy through selective laser melting method, and then performing hierarchical aging heat treatment, the hierarchical aging heat treatment is two-stage, the temperature of the first-stage aging heat treatment and the second-stage aging heat treatment is 130-150 ℃, and the time is 15-30 min (the temperature and time of the first-stage aging heat treatment and the second-stage aging heat treatment can be the same or different); the hierarchical aging heat treatment comprises the following steps (see the process flow chart Figure 1 ):

[0049] (1) First-stage aging heat treatment: the AlSi10Mg alloy prepared by the selective laser melting method is placed in a heat treatment furnace, heated and kept, and after the keeping is finished, the AlSi10Mg alloy is taken out and cooled;

[0050] (2) Second-stage aging heat treatment: the AlSi10Mg alloy cooled in step (1) is continuously placed in the heat treatment furnace and kept, and after the keeping is finished, the AlSi10Mg alloy is taken out and cooled, and the heat treatment furnace is closed.

[0051] In step (1) of the preferred embodiment of the present application, the heating rate of the heating is ≤10 ℃ / min.

[0052] In step (1) and step (2) of the preferred embodiment of the present application, the cooling is air cooling to room temperature.

[0053] The two-stage short-time aging treatment in step (1) and step (2) has a treatment time of 15-30 min and a temperature of 130-150 DEG C, preferably, because too short time and too low temperature do not obviously improve the performance of the alloy part, and too long time and too high temperature increase the cost and reduce the efficiency.

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

[0055] The formed selective laser melting alloy part should use appropriate process parameters to prevent defects in the alloy part due to process parameter problems, so in the preferred embodiment of the present application, the laser power of the selective laser melting method is 260-305 W, the scanning speed is 1800-2000 mm / s, the scanning interval is 90-110 μm, and the powder laying thickness is 30 μm.

[0056] In the preferred embodiment of the present application, the AlSi10Mg powder is used in the selective laser melting method after being washed and vacuum dried, the washing is with anhydrous ethanol, and the vacuum drying temperature is 80 DEG C and the time is 2-4 h. Vacuum drying can remove some impurities in the powder and remove the oxides that may exist on the surface of the powder, reduce the possibility of oxidation, and remove moisture to avoid the generation of pores and other defects due to the vaporization of moisture at high temperature.

[0057] In the preferred embodiment of the present application, the AlSi10Mg alloy part is modeled by a three-dimensional software according to the outer shape size, and the forming direction and layer thickness information are converted into processing instructions of the selective laser melting equipment, wherein the commonly used three-dimensional modeling software and processing instruction software are Materialise Magics, AutoCAD, Ephatch, etc. The modeling method using these software is prior art and is not the protection point of the present application, and is not described in detail.

[0058] In the preferred embodiment of the present application, the AlSi10Mg alloy prepared by the selective laser melting 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%.

[0059] The embodiment of the present application also proposes an AlSi10Mg alloy prepared by the above-mentioned graded aging heat treatment method.

[0060] It should be noted that the model of the selective laser melting device, the heat treatment furnace and the vacuum drying box in the embodiments of the present application is not particularly limited, and only needs to meet the parameters of selective laser melting treatment, heat treatment and vacuum drying.

[0061] In the embodiments of the present application, room temperature refers to "25±2℃".

[0062] The AlSi10Mg alloy is an aluminum-based alloy, and the AlSi10Mg alloy powder in the embodiments of the present application is provided by Beijing Zhonghang Mai Te Company, the element composition of which is shown in Table 1, and the specific rest angle thereof is 12°-15°, and the particle size is 15-53 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 solutions of the present application are further described below through examples.

[0066] Example 1

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

[0068] (1) According to the outer shape size of the AlSi10Mg alloy part, modeling is carried out by three-dimensional software Materialise Magics, and then the processing instructions of the selective laser melting device are converted according to the forming direction and layer thickness information;

[0069] (2) AlSi10Mg powder is selected as the forming material, washed with anhydrous ethanol, and then dried in a vacuum drying box at 80℃ for 2h for standby, wherein the rest angle of the AlSi10Mg powder used is less than 15°, and the particle size is 15-53 μm;

[0070] (3) The AlSi10Mg alloy powder dried in step (2) is loaded into the selective laser melting device, and the powder layer is selectively scanned and accumulated layer by layer to obtain the AlSi10Mg alloy part under the inert gas atmosphere according to the processing instructions, wherein the laser power of the selective laser melting process is 305W, the scanning speed is 2000mm / s, the scanning interval is 110 μm, and the powder laying thickness is 30 μm;

[0071] (4) The selective laser melted AlSi10Mg alloy obtained in step (3) is placed in a heat treatment furnace and heated with the furnace, and the heating rate is 6℃ / min, and after heating to 130℃, it is kept for 15min;

[0072] (5) After the end of the heat preservation, the AlSi10Mg alloy sample is taken out from the heat treatment furnace for air cooling, and the heat treatment furnace continues to maintain the predetermined temperature of 130℃;

[0073] (6) After the AlSi10Mg alloy sample in step (5) is air cooled to room temperature, it is placed in the heat treatment furnace at 130℃ for continued heat preservation for 15min;

[0074] (7) After the end of the heat preservation, the AlSi10Mg alloy sample is taken out from the heat treatment furnace for air cooling to room temperature and the heat treatment furnace is turned off.

[0075] Comparative Example 1

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

[0077] According to the tensile test method at room temperature (China Core Standard for Determining Tensile Properties of Metallic Materials at Room Temperature GB / T 228.1, same below), the AlSi1Mg alloy after the method treatment of Example 1 and Comparative Example 1 is tested for tensile properties, and the results are shown in Table 1. Figure 2 (0 represents Comparative Example 1, i.e. no step aging heat treatment, 15+15 represents Example 1, i.e. step aging heat treatment twice for heat preservation time), it can be seen that the tensile strength of the AlSi10Mg alloy of Example 1 is improved compared with Comparative Example 1, reaching 476.24Mpa, and the elongation reaches 7.01%.

[0078] According to the microhardness test method (China Core Standard for Determining Micro Vickers Hardness of Metallic Materials GB / T 4342, same below), the AlSi10Mg alloy after the method treatment of Example 1 and Comparative Example 1 is tested for hardness, and the results are shown in Table 2. Figure 3 (0 represents Comparative Example 1, i.e. no step aging heat treatment, 15+15 represents Example 1, i.e. step aging heat treatment twice for heat preservation time), it can be seen that the microhardness of the AlSi10Mg alloy of Example 1 is improved compared with Comparative Example 1, reaching 139.44HV 0.2 .

[0079] Example 2

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

[0081] (1) According to the outer shape size of the AlSi10Mg alloy part, the part is modeled by three-dimensional software Materialise Magics, and then converted into processing instructions for selective laser melting equipment according to the forming direction and layer thickness information;

[0082] (2) Select AlSi10Mg powder as forming material, clean with anhydrous ethanol and dry in a vacuum drying oven at 80°C for 4h, wherein the angle of repose of the AlSi10Mg powder is less than 15° and the particle size is 15-53μm;

[0083] (3) Put the AlSi10Mg alloy powder dried in step (2) into a selective laser melting device, and selectively scan the powder layer according to the processing instructions under an inert gas atmosphere and accumulate layer by layer to obtain an AlSi10Mg alloy part, wherein the laser power of the selective laser melting process is 260W, the scanning speed is 1900mm / s, the scanning interval is 90μm, and the powder laying thickness is 30μm;

[0084] (4) Put the selective laser melted AlSi10Mg alloy obtained in step (3) into a heat treatment furnace for heating with the furnace, and heat at a rate of 6°C / min to 150°C and keep for 25min;

[0085] (5) After the heat preservation is completed, take the AlSi10Mg alloy sample out of the heat treatment furnace for air cooling, and the heat treatment furnace continues to maintain the predetermined temperature of 150°C;

[0086] (6) After the AlSi10Mg alloy sample in step (5) is air-cooled to room temperature, it is placed in a heat treatment furnace at 150°C for further heat preservation for 25min;

[0087] (7) After the heat preservation is completed, take the AlSi10Mg alloy sample out of the heat treatment furnace for air cooling to room temperature and turn off the heat treatment furnace.

[0088] Comparative Example 2

[0089] The step of performing step aging heat treatment on the AlSi10Mg alloy prepared by selective laser melting is omitted, i.e., steps (4)-(7) in Example 2 are omitted.

[0090] According to the tensile test method at room temperature, the tensile properties of the AlSi1Mg alloy treated by the method of Example 2 and Comparative Example 2 are tested, and the results are shown in Figure 4 (0 represents Comparative Example 2, i.e., no step aging heat treatment, and 25+25 represents Example 2, i.e., step aging heat treatment twice), it can be seen that the tensile strength of the AlSi1Mg alloy of Example 2 is improved compared with Comparative Example 2, reaching 481.32Mpa, and the elongation reaches 7.32%.

[0091] According to the microhardness test method, the hardness of the AlSi1Mg alloy treated by the method of Example 2 and Comparative Example 2 is tested, and the results are shown in Figure 5(0 represents Comparative Example 2, i.e. without step aging heat treatment, 25+25 represents Example 2, i.e. step aging heat treatment twice holding time) It can be seen that the elongation of the AlSi10Mg alloy of Example 2 is improved compared with Comparative Example 2, reaching 155.32.44HV 0.2 .

[0092] Example 3

[0093] A step aging heat treatment method of selective laser melting AlSi10Mg alloy, comprising the following steps:

[0094] (1) According to the outer shape size of the AlSi10Mg alloy part, modeling is carried out by three-dimensional software AutoCAD, and then the processing instructions of selective laser melting equipment are converted according to the forming direction and layer thickness information;

[0095] (2) AlSi10Mg powder is selected as the forming material, washed with anhydrous ethanol and dried in a vacuum drying oven at 80℃ for 3h for standby, wherein the rest angle of the used AlSi10Mg powder is less than 15°, and the particle size is 15-53μm;

[0096] (3) The AlSi10Mg alloy powder dried in step (2) is loaded into the selective laser melting equipment, and the powder layer is selectively scanned and accumulated layer by layer to obtain the AlSi10Mg alloy part under the inert gas atmosphere according to the processing instructions, wherein the laser power of the selective laser melting process is 300W, the scanning speed is 1800mm / s, the scanning interval is 100μm, and the powder laying thickness is 30μm;

[0097] (4) The selective laser melted AlSi10Mg alloy obtained in step (3) is placed in a heat treatment furnace and heated with the furnace, the heating rate is 6℃ / min, heated to 140℃ and held for 30min;

[0098] (5) After the holding is completed, the AlSi10Mg alloy sample is taken out from the heat treatment furnace for air cooling, and the heat treatment furnace continues to maintain the predetermined temperature of 140℃;

[0099] (6) The AlSi10Mg alloy sample in step (5) is air cooled to room temperature and then placed in the heat treatment furnace at 140℃ for continuous holding for 30min;

[0100] (7) After the holding is completed, the AlSi10Mg alloy sample is taken out from the heat treatment furnace and air cooled to room temperature and the heat treatment furnace is closed.

[0101] Comparative Example 3

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

[0103] The AlSi1Mg alloys treated by the method of Example 3 and Comparative Example 3 are tested for tensile properties according to the tensile test method at room temperature, and the results are shown in Table 2. Figure 6 (0 represents Comparative Example 3, that is, no aging heat treatment, and 30+30 represents Example 3, that is, aging heat treatment twice) It can be seen that the tensile strength of the AlSi1Mg alloy of Example 3 is improved compared with Comparative Example 3, reaching 483.13 MPa, and the elongation reaches 7.19%.

[0104] The AlSi1Mg alloys treated by the method of Example 3 and Comparative Example 3 are tested for hardness according to the microhardness test method, and the results are shown in Table 3. Figure 7 (0 represents Comparative Example 3, that is, no aging heat treatment, and 30+30 represents Example 3, that is, aging heat treatment twice) It can be seen that the microhardness of the AlSi1Mg alloy of Example 3 is improved compared with Comparative Example 3, reaching 143.14 HV 0.2 .

[0105] Comparative Example 4

[0106] The single-stage aging heat treatment process is as follows:

[0107] (1) According to the shape and size of the AlSi10Mg alloy part, the part is modeled by three-dimensional software Materialise Magics, and then converted into processing instructions for selective laser melting equipment according to the forming direction and layer thickness information;

[0108] (2) AlSi10Mg powder is selected as the forming material, washed with anhydrous ethanol, and then dried in a vacuum drying oven at 80°C for 4h for standby, wherein the angle of repose of the AlSi10Mg powder used is less than 15°, and the particle size is 15-53μm;

[0109] (3) The AlSi10Mg alloy powder dried in step (2) is loaded into the selective laser melting equipment, and the powder layer is selectively scanned and accumulated layer by layer to obtain the AlSi10Mg alloy part under an inert gas atmosphere according to the processing instructions, wherein the laser power of the selective laser melting process is 260W, the scanning speed is 1900mm / s, the scanning interval is 90μm, and the powder laying thickness is 30μm;

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

[0111] (5) After the end of the holding, the AlSi10Mg alloy sample was taken out of the heat treatment furnace and air-cooled to room temperature and the heat treatment furnace was closed.

[0112] Comparative Example 5

[0113] The T6 aging heat treatment process, the specific process steps are as follows:

[0114] (1) According to the shape size of the AlSi10Mg alloy part, modeling was carried out by three-dimensional software Materialise Magics, and then the processing instructions of the selective laser melting equipment were converted according to the forming direction and layer thickness information;

[0115] (2) AlSi10Mg powder was selected as the forming material, washed with anhydrous ethanol and dried in a vacuum drying oven at 80°C for 4h for standby, wherein the angle of repose of the AlSi10Mg powder used was less than 15°, and the particle size was 15-53μm;

[0116] (3) The AlSi10Mg alloy powder dried in step (2) was loaded into the selective laser melting equipment, and the powder layer was selectively scanned under an inert gas atmosphere according to the processing instructions and accumulated layer by layer to obtain the AlSi10Mg alloy part, wherein the laser power of the selective laser melting process was 260W, the scanning speed was 1900mm / s, the scanning interval was 90μm, and the powder laying thickness was 30μm;

[0117] (4) Solution treatment: the selective laser melted AlSi10Mg alloy obtained in step (3) was placed in a heat treatment furnace, heated to 530°C at a rate of 6°C / min, and held for 1.5h, then rapidly water-cooled to room temperature;

[0118] (5) Artificial aging: the AlSi10Mg alloy after solution treatment was put back into the heat treatment furnace, heated to 170°C at a rate of 6°C / min, and held for 6h;

[0119] (6) After the end of the holding, the AlSi10Mg alloy sample was taken out of the heat treatment furnace and air-cooled to room temperature and the heat treatment furnace was closed.

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

[0121] Table 2 Performance comparison results

[0122]

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

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

[0125] As can be seen from the above examples and comparative examples, the AlSi10Mg alloy prepared by selective laser melting is subjected to heat treatment by using the grading aging heat treatment process of the present application, which eliminates the high-temperature heating of the solid solution process and the long-time holding of the single-stage aging, greatly simplifies the heat treatment process, effectively improves the heat treatment efficiency, and can make a large number of Mg2Si intermediate phases precipitate in a short time, the Mg2Si particles are dispersedly distributed in the crystal, and the dispersion precipitation strengthening effect is achieved, so that the hardness, strength and plasticity of the AlSi10Mg alloy are improved. After the AlSi10Mg alloy is treated by the grading aging heat treatment method of the present application, the hardness is greater than 150.34HV 0.2 , the tensile strength is greater than 490MPa, and the elongation is greater than 7.3%, effectively solving the problem of the existing selective laser melting AlSi10Mg alloy after heat treatment, the strength is reduced and the plasticity is increased.

[0126] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements easily thought of by those skilled in the art within the technical range disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for improving the strength and ductility of an AlSi10Mg alloy prepared by selective laser melting through a two-stage aging heat treatment, wherein the AlSi10Mg alloy is prepared by selective laser melting using AlSi10Mg powder as raw material, and then subjected to the two-stage aging heat treatment, the two-stage aging heat treatment has two stages, the first-stage aging heat treatment and the second-stage aging heat treatment are both at a temperature of 130-150℃ for a time of 15-30 min. The two-stage aging heat treatment comprises the following steps: (1) placing the AlSi10Mg alloy prepared by selective laser melting in a heat treatment furnace, heating and holding, and then taking out the AlSi10Mg alloy and cooling after the holding is completed; (2) continuing to place the AlSi10Mg alloy cooled in step (1) in the heat treatment furnace and holding, and then taking out the AlSi10Mg alloy and cooling after the holding is completed, and closing the heat treatment furnace; In step (1), the heating rate is ≤10℃ / min; In steps (1) and (2), the cooling is air cooling to room temperature; The selective laser melting method has a laser power of 260-305 W, a scanning speed of 1800-2000 mm / s, a scanning interval of 90-110 μm, and a powder laying thickness of 30 μm; The AlSi10Mg powder has a rest angle of less than 15° and a particle size of 15-53 μm. The AlSi10Mg alloy prepared by the hierarchical aging heat treatment method has a hardness greater than 150.34 HV, a tensile strength greater than 490 MPa, and an elongation greater than 7.3%. 0.2 ​ 2. The method of claim 1, wherein the method is characterized by: The AlSi10Mg powder is washed and vacuum dried before being used in the selective laser melting method.

3. The method of claim 1, wherein the method is characterized by: The vacuum drying is performed at a temperature of 80℃ for a time of 2-4 h.

4. The method of claim 3, wherein the method is characterized by: ​

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