CN112941439A - Heat treatment method for regulating and controlling mechanical property of SLM (selective laser melting) titanium alloy static and dynamic load and anisotropy - Google Patents

Heat treatment method for regulating and controlling mechanical property of SLM (selective laser melting) titanium alloy static and dynamic load and anisotropy Download PDF

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CN112941439A
CN112941439A CN202110218136.XA CN202110218136A CN112941439A CN 112941439 A CN112941439 A CN 112941439A CN 202110218136 A CN202110218136 A CN 202110218136A CN 112941439 A CN112941439 A CN 112941439A
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CN112941439B (en
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窦振
张安峰
王豫跃
吴梦杰
王普强
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Xian Jiaotong University
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
    • C22F1/18High-melting or refractory metals or alloys based thereon
    • C22F1/183High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24After-treatment of workpieces or articles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B33ADDITIVE MANUFACTURING TECHNOLOGY
    • B33YADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y40/00Auxiliary operations or equipment, e.g. for material handling
    • B33Y40/20Post-treatment, e.g. curing, coating or polishing
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    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/02Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working in inert or controlled atmosphere or vacuum
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
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    • B22F2003/248Thermal after-treatment

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Abstract

The invention discloses a thermal treatment method for regulating and controlling the static and dynamic load mechanical property and anisotropy of SLM titanium alloy. And (3) performing heat treatment of circulating spheroidizing annealing and solid solution aging on the SLM Ti-6Al-4V formed piece to obtain a two-state structure. After heat treatment, the plasticity of the sample piece is greatly improved (the elongation rate reaches 18.35%), the mechanical property exceeds the standard of a forged piece, the stability of the sample is improved, and the anisotropy of the plasticity is greatly reduced; the fracture toughness of the sample piece after the circulating spheroidizing annealing and the solution aging heat treatment is 85.5MPa, and the anisotropy is less than or equal to 15 percent; when the strain amplitude is more than or equal to 0.9%, the low cycle fatigue performance of the sample piece after heat treatment is higher than that of the forged piece; because the crack propagation path in the binary structure is longer than that of forgings; when the strain amplitude is 0.7-0.9%, the low cycle fatigue performance of the alloy is equivalent to that of a forged piece; when the strain amplitude is less than or equal to 0.7 percent, the low cycle fatigue performance of the forging is less than that of a forging.

Description

Heat treatment method for regulating and controlling mechanical property of SLM (selective laser melting) titanium alloy static and dynamic load and anisotropy
Technical Field
The invention belongs to the technical field of metal laser additive manufacturing, and a manufactured titanium alloy structural member can be applied to the fields of aerospace, chemical equipment, medical construction and shipbuilding industries, in particular to the field of industrial manufacturing with certain requirements on static and dynamic load mechanical properties and anisotropy, so that the invention perfectly supplements the heat treatment system of Selective Laser Melting (SLM) titanium alloy and provides a new method for processing and manufacturing the aviation titanium alloy structural member.
Background
The SLM additive manufacturing technology is developed on the basis of the selective laser sintering technology, and is one of the most popular near-net forming methods in recent years. The SLM technology slices the model through slicing software of a system, then uses high-energy laser beams to melt alloy powder layer by layer, and finally accumulates the alloy powder into a three-dimensional part, so that the material utilization rate is high, and the SLM technology is suitable for parts with complex cavities. The SLM technology can be used for directly preparing parts with good mechanical properties and high density, overcomes the defects of low utilization rate and difficult processing of the traditional titanium alloy manufacturing materials, and promotes the development of the titanium alloy in the fields of aerospace and the like.
The titanium alloy has the characteristics of high specific strength, good corrosion resistance and strong heat resistance, is widely applied to the field of aerospace, is one of the first choice materials of important components such as an aircraft engine fan, a gas compressor wheel disc, a blade, an undercarriage and the like, has wide application in various fields, and is a classical (alpha + beta) biphase alloy. In the SLM forming process, a sample piece is rapidly heated and rapidly cooled, and thick beta columnar crystals can be generated, so that the matching degree of the plasticity and toughness is poor, the strength of the titanium alloy manufactured through the SLM is high, but the plasticity and toughness of the titanium alloy is relatively low, and the anisotropy difference of the mechanical properties of parts formed by the same forming process is large.
Many scholars research and search the heat treatment process of the forged titanium alloy, and the matching degree of plasticity and toughness can be improved through heat treatment; due to the particularity of the laser additive manufacturing forming mode and the cooling mode, the SLM TI-6AL-4V forming piece structure has great difference with the forging piece structure, and therefore a heat treatment process suitable for the SLM TI-6AL-4V forming piece needs to be explored to improve the comprehensive performance of the SLM TI-6AL-4V forming piece structure.
The circulating spheroidizing annealing heat treatment is to carry out spheroidizing annealing near the T beta temperature, and then to circulate for many times to break the columnar crystal grain boundary and reduce the length-width ratio of the crystal grains, thereby reducing the anisotropy and eliminating the internal stress; but the circulating spheroidizing annealing can coarsen crystal grains, the strength is greatly reduced, and therefore, the comprehensive mechanical property is relatively low; therefore, on one hand, the heat preservation time of the circular annealing is strictly controlled, so that the coarsening phenomenon of crystal grains in the annealing process is reduced, and on the other hand, the solution aging treatment is added after the circular spheroidizing annealing heat treatment, so that the crystal grains grown by annealing can be newly refined, the anisotropy of the crystal grains is reduced, and the comprehensive mechanical property of the crystal grains is improved.
Disclosure of Invention
The invention aims to provide a heat treatment method for regulating and controlling dynamic and static load mechanical properties and anisotropy of SLM TI-6AL-4V titanium alloy, wherein after the SLM TI-6AL-4V is subjected to circulating spheroidizing annealing and solution aging heat treatment, a structure is changed into a two-state structure from a lath alpha-phase and acicular alpha-phase coexisting structure. Compared with the lamellar structure, the bimodal structure has higher yield strength, plasticity, thermal stability and fatigue strength. Compared with an equiaxed structure, the bimodal structure has higher endurance strength, creep strength and fracture toughness and lower crack propagation rate, and the anisotropy of the material can be reduced while the dynamic and static loading mechanical properties of the material are improved.
The technical scheme of the invention is realized as follows: the SLM titanium alloy static and dynamic load mechanical property and the anisotropic heat treatment method are regulated, the SLM TI-6AL-4V tissue is converted into a two-state tissue from a lath alpha phase and acicular alpha phase coexisting tissue, a certain content of equiaxial alpha phase and lath alpha phase are distributed on a beta conversion matrix, a TI-6AL-4V forming piece with the best matching strength, plasticity, toughness and low cycle fatigue is obtained, and the comprehensive mechanical property is higher than the standard of a forging piece; the material has excellent plasticity, the anisotropy of the plasticity is greatly reduced relative to the deposition state, and the anisotropy of the fracture toughness is less than or equal to 15 percent; the low cycle fatigue performance of the heat treatment sample piece is higher than the standard of the forged piece under the condition of larger strain amplitude (not less than 0.9 percent), and the heat treatment method comprises the following steps:
1.1 circulating spheroidizing annealing, placing the SLM TI-6AL-4V sample piece into a tubular atmosphere furnace with an argon atmosphere, heating to 910-; then immediately heating, starting a second cycle, totally circulating for 4 times or 5 times, and finally cooling the sample piece in a furnace;
1.2 solid solution treatment, namely heating the SLM TI-6AL-4V sample piece subjected to the circulating spheroidizing annealing to 910-and 930 ℃ along with the furnace in a tubular atmosphere furnace in an argon atmosphere, preserving the temperature for 50-70min, and air cooling to room temperature;
1.3 aging treatment, namely heating the SLM TI-6AL-4V forming piece subjected to the circulating spheroidizing annealing and the solution treatment to 560 ℃ along with the furnace in a tubular atmosphere furnace in an argon atmosphere, preserving the temperature for 250min at 230 ℃ and air cooling to room temperature.
The samples used in the experiment were TI-6AL-4V alloy obtained by a selective laser melting process, and the sizes of the formed samples were phi 8X 45mm, 45X 8mm, 40X 18X 38mm, and 72X 14mm, respectively.
The vacuum degree of the heat treatment furnace is 10 < -2 > -10 < -3 > Pa, and the temperature difference of an effective working area of the furnace temperature is controlled within +/-5 ℃; the heat treatment sequence is circulating spheroidizing annealing, then solid solution treatment and finally aging treatment.
The cooling speed of furnace cooling is 4-6 ℃/min, and the cooling speed of air cooling is 100-.
Controlling the heating rate of the sample piece during heat treatment to be 9-11 ℃/min; the cooling rate in the circulation process is 4-6 ℃/min.
The method is continuously carried out with circulating heat treatment, and needs to carry out solution treatment after furnace cooling to room temperature, carry out aging treatment by reheating after solution air cooling to room temperature, repeatedly heat and crush coarse beta columnar crystals, refine crystal grains through solution aging, and finally obtain a structure with a two-state structure.
After heat treatment, the room temperature mechanical property of the SLM TI-6AL-4V sample piece exceeds the requirement of GJB2744A-2007 standard, the elongation reaches 18%, the reduction of area reaches 47%, and the fracture toughness is 85 MPa.m 0.5. The strength anisotropy of the sample piece is less than or equal to 5 percent, the plastic anisotropy is less than or equal to 10 percent, and the fracture toughness anisotropy is less than or equal to 15 percent; when the strain amplitude is more than or equal to 0.9%, the low cycle fatigue performance of the alloy is higher than that of a forged piece; when the strain amplitude is 0.7-0.9%, the low cycle fatigue performance of the alloy is equivalent to that of a forged piece; when the strain amplitude is less than or equal to 0.7 percent, the low cycle fatigue performance of the forging is less than that of a forging.
The method crushes coarse beta columnar crystals by adjusting the heating temperature, the heat preservation time, the cycle times and the cooling mode, and regulates and controls the size and the distribution of new crystal grains; because the heating and heat preservation are carried out for 4 times in the two-phase region, the high internal stress caused by laser material increase manufacturing and the dislocation plugging product caused by a fast heating and fast cooling forming mode are fundamentally weakened, the anisotropy of the material can be greatly reduced, and the static and dynamic performance of the SLM TI-6AL-4V forming piece is improved. The mechanical property index of the sample subjected to heat treatment is more stable; by the method, the tensile strength reaches 946MPa, the elongation is as high as 18.3 percent (1.5 times of the elongation in a deposition state), and the tensile mechanical property indexes exceed the national standard of forgings; the fracture toughness reaches 85.25 MPa.m 0.5, and when the strain amplitude is more than or equal to 0.9 percent, the low cycle fatigue performance is higher than the standard of forgings.
Drawings
FIG. 1 is a flow chart of a heat treatment process for performing a heat treatment in a vacuum-assisted argon atmosphere furnace according to the method of the present invention;
FIG. 2 is a microstructure diagram of an SLM Ti-6Al-4V deposition state (a) and a circulating spheroidizing annealing + solid solution aging state (b) in the present invention;
FIG. 3 is a graph comparing anisotropy of different mechanical property indicators for as-deposited and cyclic spheroidizing annealing plus solution aging.
FIG. 4 is a comparison of the heat treatment of SLM Ti-6Al-4V alloy and the strain life curve of a standard forging;
Detailed Description
In order to more fully understand the technical content of the present invention, the technical solutions provided by the present invention will be further described and explained below with reference to the specific implementation processes and the accompanying drawings.
FIG. 1 is a flow chart of the heat treatment process of the present invention, in which the horizontal line part represents the heat-retaining process, the number above the horizontal line represents the heat-retaining time, the diagonal line part represents the heating or cooling process, and the number beside represents the heating or cooling rate.
FIG. 2(a) is a microstructure diagram of the as-deposited SLM Ti-6Al-4V phase, consisting of lath alpha phase and acicular alpha phase; FIG. 2(b) shows the morphology of the SLM Ti-6Al-4V heat-treated structure, and it can be seen that coarse beta-columnar crystals disappear, and the structure is a bimodal structure composed of an equiaxial alpha phase, a lath alpha phase and a beta matrix phase.
FIG. 3 is a comparison graph of anisotropy of the cycle annealing + solution aging and the as-deposited state, and it can be seen that the anisotropy of the elongation and the reduction of area of the sample piece is reduced to different degrees after the heat treatment, because the heat treatment eliminates dislocation and internal stress while breaking the crystal grains, thereby improving plasticity and making the structure more uniform, and although the anisotropy of the strength is slightly increased, the anisotropy is lower than 5%.
FIG. 4 is a comparison graph of the standard strain life curves of the heat-treated part and the forged part, and it can be seen from the graph that when the strain amplitude is larger than or equal to 0.9%, the low cycle fatigue performance of the forged part is higher than that of the forged part because the crack propagation path is longer relative to the forged part and the propagation of cracks is hindered; when the strain amplitude is 0.7-0.9%, the low cycle fatigue performance of the alloy is equivalent to that of a forged piece; when the strain amplitude is less than or equal to 0.7 percent, the low cycle fatigue performance of the alloy is less than that of a forged piece, and probably the low cycle fatigue performance under lower strain amplitude mainly depends on the comprehensive tensile property.
Step 1: the particle size range of the titanium alloy raw material powder is 25-65 mu m;
step 2: firstly, uniformly laying titanium alloy raw material powder for laser additive manufacturing, designing a three-dimensional model of a formed part, and then forming by using a selective laser melting manufacturing process;
and step 3: sample forming technological parameters, laser power of 280W, spot diameter of 0.043mm and filling scanning speed of 1200 mm/s; the profile is divided into an inner profile and an outer profile, the scanning speed of the inner profile is 1250mm/s, the scanning power of the inner profile is 150W, the scanning speed of the outer profile is 800mm/s, and the scanning power of the outer profile is 80W; the powder layer is 0.03mm thick, the distance between two times of scanning is 0.14mm, the filling is vertical filling, the oxygen content of the working chamber is less than or equal to 1300ppm, the oxygen content is less than or equal to 600ppm after six hours of printing, and the oxygen content is less than or equal to 300ppm after about ten hours;
samples having a size of Φ 8X 45mm, 45X 8mm, 40X 18X 38mm, 72X 14mm were formed, respectively, and the TI-6AL-4V sample formed by SLM was cleaned with ultrasonic waves to remove impurities on the surface of the sample. And performing a metallographic experiment on the sample, observing the microstructure of the sample, and performing a heat treatment and tensile experiment, a fracture toughness experiment and a low cycle fatigue experiment on the sample.
Placing the sample piece into a tubular atmosphere furnace with an argon atmosphere, heating to 910-; and then cooling to 540-560 ℃ along with the furnace, recording as a first cycle, immediately heating, starting a second cycle, circulating for 4 times in total, and then cooling along with the furnace.
And (3) solution treatment, namely raising the completely cooled sample piece subjected to circulating spheroidizing annealing to 910-930 ℃ along with the furnace in a tubular atmosphere furnace in an argon atmosphere, preserving the temperature for 50-70min, and cooling the sample piece to room temperature in air.
And (4) aging treatment, namely raising the sample drawing piece subjected to the cyclic annealing and solution treatment to 540-560 ℃ along with the furnace in a tubular atmosphere furnace in an argon atmosphere, preserving the temperature for 230-250min, and cooling the sample drawing piece to room temperature in air.
The heat treatment furnace is a quartz tube type atmosphere electric furnace, the oxygen content in the argon atmosphere in the heat treatment is lower than 10ppm, the heating rate of the heat treatment is 9-11 ℃/min, and the cooling rate is 4-6 ℃/min.
The microstructure morphology of the SLM TI-6AL-4V alloy mainly comprises lath alpha phase and acicular alpha' phase, after the cyclic spheroidizing annealing and the solution aging heat treatment, the microstructure of the SLM TI-6AL-4V alloy is changed into a dual-state microstructure composed of equiaxial alpha phase, lath alpha phase and beta matrix phase, the dislocation is reduced, the internal stress is reduced, the anisotropy of the SLM TI-6AL-4V alloy is reduced, and a good strong plastic matching forming piece is obtained.
The invention specifically relates to a method for preparing Ti-6Al-4V alloy by laser additive manufacturing, which comprises the following steps of carrying out heat treatment as shown in figure 1, testing the tensile property at the normal temperature, wherein the strength and the plasticity both exceed the national standard, the strength anisotropy does not exceed 5%, and the plasticity anisotropy is lower than 10%. The anisotropy of the fracture toughness is less than 15%.
Placing Ti-6Al-4V powder with particle size of 25-65 μm in a drying oven, drying at 100 deg.C for 60min, and removing water from the powder.
Table 1: the element content of each component of the powder
Figure BDA0002954742270000051
Determining a laser additive manufacturing procedure and a scanning path, preparing a titanium alloy forming substrate, carrying out surface treatment on the substrate, removing surface burrs and an oxidation layer, polishing until the surface is bright, and removing surface impurities by using acetone.
Fixing the titanium alloy substrate on a workbench, adjusting the position of a laser head, opening an air outlet of a processing chamber, introducing high-purity argon to exhaust air, then controlling the oxygen content through a gas circulation system, and when detecting that the oxygen content in the working chamber is lower than 1300ppm, opening a laser to perform selective laser melting deposition.
In the printing process, the laser beam is controlled by a computer to irradiate the designated area, the powder in the designated area is rapidly solidified after being melted, after one layer is printed, the forming substrate is lowered to a designated height, meanwhile, a layer of new TI-6AL-4V alloy powder is laid by a scraper, the steps are repeated in this way, after the printing is finished, the substrate is lifted, and the redundant powder is swept out, so that the SLM forming titanium alloy workpiece can be obtained.
And cutting the part from the substrate by a laser linear cutting machine, and dividing the part into a transverse direction and a longitudinal direction according to the space position of the maximum side length and the deposition direction, wherein the part with the maximum side length vertical to the deposition direction is called a horizontal sample, and the part with the maximum side length parallel to the deposition direction is called a vertical sample.
The heat treatment process of the deposited Ti-6Al-4V alloy sample comprises the following specific steps:
step one, uniformly dispersing a sample in a porcelain crucible or a quartz boat, and ensuring that each part is uniformly heated and the heating area is maximum;
secondly, placing the ceramic crucible or the quartz boat with the formed piece in the middle of a glass tube of the high-temperature electric furnace, and closing the door of the bin;
thirdly, opening a vacuum pump until the relative vacuum degree in the glass tube is about-0.1 MPa, closing the vacuum pump, then introducing argon, closing an argon valve after the air pressure in the glass tube is about equal to the atmospheric pressure, opening the vacuum pump again, repeating the operation for three times, and then closing the vacuum pump, wherein the glass tube is in a near-vacuum environment;
the air inlet valve is opened to slowly introduce argon, and the air outlet valve is opened when the pressure in the glass tube is slightly higher than the atmospheric pressure, so that stable and uniform argon flow is ensured to slowly pass through the glass tube.
And fifthly, debugging the heat treatment program shown in the figure 1, and turning on a heating switch to carry out heat treatment.
Sixthly, after the procedure is finished, the furnace cooling of the sample piece is required to be cooled to below 200 ℃ along with the furnace, and then the sample piece is taken out for air cooling; air cooling needs to draw out the crucible or the quartz boat from one end of the glass tube quickly, and sample pieces are uniformly dispersed on an iron wire net placed in air, so that the actual air cooling conditions of all the sample pieces are consistent; and finally, closing the heat treatment furnace.
And (3) carrying out tensile property test on the heat-treated Ti-6Al-4V forming piece, wherein the tensile test standard is GB/T228.1-2010, the normal-temperature tensile test samples are horizontally 5 in one group, the vertical 5 in one group, the fracture toughness test samples are 5 in one group, the tensile test standard is GB/T-4161-processed sample 2007, the total 15 groups of samples with low cycle fatigue are obtained, and the adopted test standard is GB/T15248-processed sample 2008.
The results of the room temperature tensile properties of the experimental Ti-6Al-4V in the deposition state and the heat treatment state are shown in Table 2, and the results of the fracture toughness are shown in Table 3.
Table 2 shows the results of room temperature tensile properties of Ti-6Al-4V in the as-deposited state and in the as-heat treated state.
Figure BDA0002954742270000061
H-horizontal direction sample; v-vertical direction test specimen
Table 3: experimental result of TI-6AL-4V heat treatment fracture toughness
Figure BDA0002954742270000062
Table 4: experimental result of Ti-6Al-4V heat treatment state low cycle fatigue performance
Figure BDA0002954742270000063
Figure BDA0002954742270000071

Claims (7)

1. The method is characterized in that the SLM TI-6AL-4V tissue is converted into a two-state tissue from a lath alpha phase and acicular alpha phase coexisting tissue, a certain content of equiaxial alpha phase and lath alpha phase are distributed on a beta conversion matrix, a TI-6AL-4V forming piece with strength-plasticity-toughness-low cycle fatigue best matching is obtained, and the comprehensive mechanical property is higher than the forging standard; the material has excellent plasticity, the anisotropy of the plasticity is greatly reduced relative to the deposition state, and the anisotropy of the fracture toughness is less than or equal to 15 percent; the low cycle fatigue performance of the heat treatment sample piece is higher than the standard of the forged piece under the condition of larger strain amplitude (not less than 0.9 percent), and the heat treatment method comprises the following steps:
1.1 circulating spheroidizing annealing, placing the SLM TI-6AL-4V sample piece into a tubular atmosphere furnace with an argon atmosphere, heating to 910-; then immediately heating, starting a second cycle, totally circulating for 4 times or 5 times, and finally cooling the sample piece in a furnace;
1.2 solid solution treatment, namely heating the SLM TI-6AL-4V sample piece subjected to the circulating spheroidizing annealing to 910-and 930 ℃ along with the furnace in a tubular atmosphere furnace in an argon atmosphere, preserving the temperature for 50-70min, and air cooling to room temperature;
1.3 aging treatment, namely heating the SLM TI-6AL-4V forming piece subjected to the circulating spheroidizing annealing and the solution treatment to 560 ℃ along with the furnace in a tubular atmosphere furnace in an argon atmosphere, preserving the temperature for 250min at 230 ℃ and air cooling to room temperature.
2. The method for regulating and controlling the static and dynamic load mechanical property and the anisotropic heat treatment of the SLM titanium alloy according to claim 1, characterized in that: the samples used in the experiment were TI-6AL-4V alloy obtained by a selective laser melting process, and the sizes of the formed samples were phi 8X 45mm, 45X 8mm, 40X 18X 38mm, and 72X 14mm, respectively.
3. The heat treatment method for regulating and controlling the static and dynamic load mechanical property and the anisotropy of the SLM titanium alloy according to claim 1, characterized in that: the degree of vacuum of the heat treatment furnace was 10-2-10-3Pa, controlling the temperature difference of the effective working area of the furnace temperature within +/-5 ℃; the heat treatment sequence is circulating spheroidizing annealing, then solid solution treatment and finally aging treatment.
4. The heat treatment method for regulating and controlling the static and dynamic load mechanical property and the anisotropy of the SLM titanium alloy according to claim 1, characterized in that: the cooling speed of furnace cooling is 4-6 ℃/min, and the cooling speed of air cooling is 100-.
5. The heat treatment method for regulating and controlling the static and dynamic load mechanical property and the anisotropy of the SLM titanium alloy according to claim 1, characterized in that: controlling the heating rate of the sample piece during heat treatment to be 9-11 ℃/min; the cooling rate in the circulation process is 4-6 ℃/min.
6. The heat treatment method for regulating and controlling the static and dynamic load mechanical property and the anisotropy of the SLM titanium alloy according to claim 1, characterized in that: the method is continuously carried out with circulating heat treatment, and needs to carry out solution treatment after furnace cooling to room temperature, carry out aging treatment by reheating after solution air cooling to room temperature, repeatedly heat and crush coarse beta columnar crystals, refine crystal grains through solution aging, and finally obtain a structure with a two-state structure.
7. According to the claimsThe heat treatment method for regulating and controlling the mechanical property and the anisotropy of the SLM titanium alloy in the step 1 is characterized by comprising the following steps: after heat treatment, the room temperature mechanical property of the SLM TI-6AL-4V sample piece exceeds the requirement of GJB2744A-2007 standard, the elongation reaches 18%, the reduction of area reaches 47%, and the fracture toughness is 85 MPa.m0.5. The strength anisotropy of the sample piece is less than or equal to 5 percent, the plastic anisotropy is less than or equal to 10 percent, and the fracture toughness anisotropy is less than or equal to 15 percent; when the strain amplitude is more than or equal to 0.9%, the low cycle fatigue performance of the alloy is higher than that of a forged piece; when the strain amplitude is 0.7-0.9%, the low cycle fatigue performance of the alloy is equivalent to that of a forged piece; when the strain amplitude is less than or equal to 0.7 percent, the low cycle fatigue performance of the forging is less than that of a forging.
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Cited By (3)

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Publication number Priority date Publication date Assignee Title
CN113996812A (en) * 2021-10-15 2022-02-01 中国航发北京航空材料研究院 Heat treatment method for improving fatigue performance of laser selective melting alpha-beta type titanium alloy
CN114131043A (en) * 2021-11-18 2022-03-04 上海电气集团股份有限公司 Method for improving utilization rate of TC4 titanium alloy powder
CN114570947A (en) * 2022-04-12 2022-06-03 南京工业大学 Near-net forming method and application of titanium alloy component with gradient structure

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