A heterogeneous titanium alloy and a method for manufacturing the same

Abstract

The present application discloses a heterogeneous titanium alloy and a manufacturing method thereof, and relates to the technical field of titanium alloy manufacturing. The manufacturing method of the heterogeneous titanium alloy comprises the following steps: mixing a first titanium alloy powder and a second titanium alloy powder to obtain a heterogeneous titanium alloy powder; performing a component analysis on a target part to be formed to obtain a transition layer component content gradient and a transition layer thickness; and performing a printing process through a laser melting deposition device based on the transition layer component content gradient and the transition layer thickness to obtain a target part.

Description

Technical Field

[0001] The present application relates to the technical field of titanium alloy manufacturing, and in particular to a heterogeneous titanium alloy and a manufacturing method thereof. Background Art

[0002] Improving the performance of aerospace vehicles requires that their components have multiple properties such as load-bearing, high temperature resistance, oxidation resistance, and corrosion resistance. In addition, since the components belong to different parts, they have different performance requirements. Therefore, heterogeneous titanium alloys with different compositions are formed into one piece through connection technology to achieve the multi-performance requirements of the components.

[0003] However, due to different compositions, heterogeneous titanium alloys have differences in melting point, constituent phase content, microstructure morphology, etc. During the manufacturing process, quality defects are easily generated at the interface of heterogeneous titanium alloys, which cannot satisfactorily meet application requirements. Summary of the invention

[0004] The main purpose of the present application is to provide a heterogeneous titanium alloy and a method for manufacturing the same, aiming to solve the technical problem that the quality of the heterogeneous titanium alloy produced by the existing manufacturing method is not sufficient to meet application requirements.

[0005] In order to solve the above technical problems, the present application embodiment proposes: a method for manufacturing a heterogeneous titanium alloy, comprising the following steps:

[0006] Mixing the first titanium alloy powder and the second titanium alloy powder to obtain a heterogeneous titanium alloy powder;

[0007] Based on the target part to be formed, the component analysis is performed to obtain the transition layer component content gradient and transition layer thickness;

[0008] Based on the transition layer component content gradient and transition layer thickness, a laser melting deposition device is used for printing to obtain a target part;

[0009] The printing process includes:

[0010] The first stage: based on the first titanium alloy powder, printing is stopped at the interface of the transition layer;

[0011] The second stage: based on the heterogeneous titanium alloy powder, continue printing according to the composition content gradient, thickness and format of the transition layer to obtain the transition layer;

[0012] The third stage: after the transition layer is printed, printing is continued based on the second titanium alloy powder to obtain the target part.

[0013] As some optional implementations of the present application, the thickness of the transition layer is 1 to 5 mm, and the gradient of the content of the transition layer components is less than 3 wt.% / mm.

[0014] As some optional embodiments of the present application, the mixing mass ratio of the first titanium alloy powder and the second titanium alloy powder is 2:1 to 1:2.

[0015] As some optional embodiments of the present application, the amount of the heterogeneous titanium alloy powder satisfies the following relationship:

[0016] W=ρSh / a

[0017] Wherein: W is the amount of the heterogeneous titanium alloy powder; ρ is the bulk density of the heterogeneous titanium alloy powder; S is the width area of ​​the transition zone; h is the thickness of the transition zone; a is the powder coating rate, and the value range is 40% to 60%.

[0018] As some optional embodiments of the present application, the first titanium alloy powder includes at least one of TC4, TA15, TC11, TC21 and Ti60, with a particle size of 53μm to 150μm; the second titanium alloy powder includes at least one of TC4, TA15, TC11, TC21 and Ti60, with a particle size of 53μm to 150μm.

[0019] As some optional embodiments of the present application, the mixing of the first titanium alloy powder and the second titanium alloy powder to obtain the heterogeneous titanium alloy powder includes:

[0020] The first titanium alloy powder and the second titanium alloy powder are placed in a planetary ball mill for low-speed ball milling and mixing to obtain heterogeneous titanium alloy powder; wherein the ball-to-material ratio is 8:1-10:1, the ball milling speed is 80-120 rpm, and the ball milling time is 2-4 hours.

[0021] As some optional embodiments of the present application, the low-speed ball milling mixing process includes: pausing for 20 minutes after each 1-hour treatment to control the fluidity of the mixed powder after ball milling to 35 to 38 s / 50 g.

[0022] As some optional implementations of the present application, the parameters of the printing process include: laser power of 3.5-4KW, scanning speed of 1200-1800mm / min, powder feeding rate of 24-28g / min; the printing path is: outlining first and then filling.

[0023] As some optional implementations of the present application, the filling path is zigzag, and the filling direction is rotated 60 to 90 degrees for each layer printed.

[0024] In order to solve the above technical problems, the embodiments of the present application further propose: a heterogeneous titanium alloy, which is manufactured by the above method.

[0025] Compared with the prior art, the manufacturing method of the heterogeneous titanium alloy described in the present application is to mix the first titanium alloy powder and the second titanium alloy powder to obtain the heterogeneous titanium alloy powder; based on the target part to be formed, the composition analysis is performed to obtain the transition layer composition content gradient and the transition layer thickness; the transition layer composition content gradient refers to the composition content gradient of the main elements in the transition layer with a content of more than 3wt.% in the heterogeneous titanium alloy powder; by controlling the composition content gradient of the main elements in the transition layer, the microstructure stability at the interface of the heterogeneous titanium alloy is ensured, thereby improving the quality stability of the heterogeneous titanium alloy component. Based on the transition layer composition content gradient and the transition layer thickness, the laser melting deposition equipment is used for printing processing to obtain the target part; wherein the printing processing includes: based on the first titanium alloy powder, printing to the transition layer interface, stopping printing; based on the heterogeneous titanium alloy powder, continuing printing according to the composition content gradient, thickness and width of the transition layer to obtain the transition layer; after the transition layer is printed, continuing printing based on the second titanium alloy powder to obtain the target part. It can be seen that the present application controls the printing process based on the transition layer component content gradient and transition layer thickness, and is suitable for laser melting and integrated forming of heterogeneous titanium alloy components with various different compositions, and can effectively improve the microstructure and mechanical property stability at the interface of heterogeneous titanium alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of a TC4 / TA15 heterogeneous titanium alloy part according to an embodiment of the present application;

[0027] Figure 2 is a microstructure diagram of the TC4 alloy layer described in the embodiment of the present application;

[0028] Figure 3 is a microstructure diagram of the transition layer described in the embodiment of the present application;

[0029] Figure 4 It is a microstructure diagram of the TA15 alloy described in the examples of the present application. DETAILED DESCRIPTION

[0030] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0031] The improvement of aerospace vehicle performance requires that its components have multiple characteristics such as load-bearing, high temperature resistance, oxidation resistance, and corrosion resistance. Since titanium alloys with different compositions have different mechanical, chemical, and physical properties, according to the performance requirements of different parts of the components, heterogeneous titanium alloys with different compositions are formed into one piece through connection technology to achieve the multi-performance requirements of the components.

[0032] Laser melting deposition additive manufacturing technology is based on the laser powder feeding process, which has the characteristics of flexible manufacturing and high precision, and is expected to be applied to the preparation of heterogeneous titanium alloy components. However, due to different compositions, the melting points, constituent phase contents, and microstructure morphology of heterogeneous titanium alloys are different. During the laser melting deposition manufacturing process, printing defects are easily generated at the interface of heterogeneous titanium alloys, making it difficult to improve the quality of heterogeneous titanium alloy components manufactured by laser melting deposition.

[0033] Among them, laser additive manufacturing is carried out in an inert gas-protected processing chamber, using laser as the heat source and titanium alloy powder transported synchronously by gas or gravity to form titanium alloy integral parts with gradient structure without molds.

[0034] Based on this, the embodiment of the present application proposes: a method for manufacturing a heterogeneous titanium alloy, comprising the following steps:

[0035] Step S10: Mix the first titanium alloy powder and the second titanium alloy powder to obtain heterogeneous titanium alloy powder.

[0036] In specific applications, the first titanium alloy and the second titanium alloy are both spherical powders prepared by gas atomization or rotating electrode method; specifically, the first titanium alloy powder includes at least one of TC4, TA15, TC11, TC21 and Ti60, with a particle size of 53μm to 150μm; the second titanium alloy powder includes at least one of TC4, TA15, TC11, TC21 and Ti60, with a particle size of 53μm to 150μm.

[0037] In a specific application, the mixing mass ratio of the first titanium alloy powder and the second titanium alloy powder is 2:1 to 1:2. At the same time, in order to obtain a more uniformly mixed heterogeneous titanium alloy powder, the embodiment of the present application defines the mixing step of the first titanium alloy powder and the second titanium alloy powder, that is, the first titanium alloy powder and the second titanium alloy powder are mixed in step S10 to obtain a heterogeneous titanium alloy powder, including: putting the first titanium alloy powder and the second titanium alloy powder into a planetary ball mill for low-speed ball milling and mixing treatment to obtain a heterogeneous titanium alloy powder; wherein the ball-to-material ratio is 8:1 to 10:1, the ball milling speed is 80 to 120 rpm, and the ball milling time is 2 to 4 hours. Specifically, the low-speed ball milling mixing treatment includes: pausing for 20 minutes after each 1 hour of treatment to control the fluidity of the mixed powder after ball milling to 35 to 38s / 50g.

[0038] Step S20: Based on the target part to be formed, a component analysis is performed on it to obtain the transition layer component content gradient and transition layer thickness.

[0039] In a specific application, based on the composition analysis results of the target parts to be formed, the composition content gradient of the main elements with a content of >3wt.% in the heterogeneous titanium alloy powder in the transition layer is controlled, that is, the composition content gradient of the transition layer is <3wt.% / mm; at the same time, to ensure that the surface of the target parts to be formed does not collapse after forming, the thickness of the transition layer is 1 to 5mm; further, the thickness of the transition layer is 1mm.

[0040] Step S30: Based on the transition layer component content gradient and transition layer thickness, a laser melting deposition device is used to perform printing processing to obtain a target part.

[0041] The printing process includes:

[0042] Stage 1: Printing the first titanium alloy powder to the interface of the transition layer, and then stop printing. In a specific application, after the first stage of printing is completed, the first titanium alloy powder in the powder storage tank of the powder feeder needs to be emptied, such as by removing the residual first titanium alloy powder in the powder feeding pipe through the powder feeding airflow.

[0043] The second stage: Based on the heterogeneous titanium alloy powder, continue printing according to the composition content gradient, thickness and format of the transition layer to obtain the transition layer. In a specific application, after the first titanium alloy powder in the powder storage tank of the powder feeder is emptied, the heterogeneous titanium alloy powder is placed in the powder storage tank of the powder feeder for the second stage of printing. Furthermore, in order to ensure the printing quality of the target parts, it is better to control the above powder replacement work time within 30 minutes.

[0044] In a specific application, the amount of the heterogeneous titanium alloy powder satisfies the following relationship:

[0045] W=ρSh / a

[0046] Wherein: W is the amount of the heterogeneous titanium alloy powder; ρ is the bulk density of the heterogeneous titanium alloy powder; S is the width area of ​​the transition zone; h is the thickness of the transition zone; a is the powder coating rate, and the value range is 40% to 60%.

[0047] The third stage: After the transition layer is printed, the second titanium alloy powder is used to continue printing to obtain the target part. In a specific application, after the second stage of printing is completed, the heterogeneous titanium alloy powder is emptied and then the second titanium alloy powder is added to continue printing. Furthermore, in order to ensure the printing quality of the target part, the powder replacement time is preferably controlled within 10 minutes.

[0048] In specific applications, in order to ensure that the printed thickness is stable at about 1mm and the surface of the target part does not collapse after printing, the printing parameters of the first, second and third stages include: laser power of 3.5-4KW, scanning speed of 1200-1800mm / min, powder feeding rate of 24-28g / min; the printing path is: first stroke and then fill. Furthermore, the filling path is zigzag, and the printing and filling direction rotates 60-90° for each layer printed.

[0049] Based on the above manufacturing method, an embodiment of the present application further proposes: a heterogeneous titanium alloy, which is manufactured by the above method.

[0050] The method described in this application is described in detail below with reference to specific embodiments:

[0051] Example 1

[0052] This embodiment is based on Figure 1 The technical solution of the TC4 / TA15 heterogeneous titanium alloy parts shown is further explained.

[0053] Among them, the size of the TC4 / TA15 heterogeneous titanium alloy part is: 400mm*400mm*800mm, the lower end of the TC4 / TA15 heterogeneous titanium alloy part is designed to use the TC4 alloy with low temperature and low cost; the upper end is designed to use the temperature of >400℃ and use the TA15 alloy with strong heat resistance; that is, the initial height of the TC4 alloy layer is 400mm, and the initial height of the TA15 alloy is 400mm.

[0054] The main manufacturing steps are as follows:

[0055] 1) According to the composition difference between TC4 (Ti-6Al-4V wt.%) and TA15 (Ti-6.5Al-2Zr-1Mo-1V wt.%), the transition layer thickness is designed to be 2mm, and the transition layer composition content gradient is designed to be 50% TC4 + 50% TA15, that is, the composition is Ti-6.25Al-2.5V-1Zr-0.5Mo wt.%, that is, the composition gradient of all major elements is <3wt.% / mm. That is: the design height of the TC4 alloy layer is 399mm, the design height of the transition layer is 2mm, and the design height of the TA15 alloy is 399mm.

[0056] 2) Select TC4 alloy spherical powder and TA15 alloy spherical powder prepared by a rotating electrode method, with a particle size of 53-150 μm, and mix the titanium alloy powders in a ratio of 50% TC4 + 50% TA15 through a planetary ball mill. The ball-to-material ratio of the mixed powder is 8:1-10:1, the ball milling speed is 80-120 rpm, and the ball milling time is 2-4 hours, wherein the mixing is paused for 20 minutes after each hour of mixing, so that the fluidity of the mixed powder after ball milling is controlled at 35-38 s / 50 g; obtain heterogeneous titanium alloy powder.

[0057] 3) According to the width and width of the transition layer, the amount of the heterogeneous titanium alloy powder is calculated according to the following formula:

[0058] W=ρSh / a

[0059] Wherein, W is the amount of heterogeneous titanium alloy powder; ρ is the bulk density of heterogeneous titanium alloy powder (), S is the area of ​​transition layer (1600cm 2 ), h is the thickness of the transition layer (0.2 cm), a is the powder coating rate (40% to 60%), that is, the mixed powder is about 2 kg;

[0060] In this embodiment, the bulk density of the heterogeneous titanium alloy powder is 2.6 g / cm 3 ; Transition layer area is 1600cm 2 ; The thickness of the transition layer is 0.2cm; the powder coating rate is 40% to 60%.

[0061] Based on this, it is calculated that the amount of the heterogeneous titanium alloy powder used is about 2 kg.

[0062] 4) Fix the printed substrate in the laser selective melting forming equipment, close the equipment furnace door, turn on the vacuum pump, and fill it with high-purity Ar gas at the same time. When the oxygen content in the furnace is less than 50ppm, start printing the TC4 alloy test block. The selected printing process parameters are laser power of 3.5-4KW, scanning speed of 1200-1800mm / min, and powder feeding rate of 24-28g / min. At this time, the printing thickness of each layer can be controlled at 1mm; the selected printing path is to stroke first and then fill, and the filling path is zigzag. The printing and filling direction rotates 60-90° for each printed layer.

[0063] 5) When the printing height of the TC4 test block reaches 399 mm (i.e., printing 399 layers), the remaining TC4 powder in the powder feeder storage tank is emptied, and the residual powder in the powder feeding tube is removed by the powder feeding airflow, and then the mixed titanium alloy powder is placed in the powder feeder. The powder replacement time is controlled within 30 minutes.

[0064] 6) After changing the powder, continue to print the transition layer. After the transition layer is printed for 2 mm (i.e. 2 layers), the mixed powder is consumed. Add TC15 powder to the powder feeder and continue printing.

[0065] 7) After printing is completed, wait for the test block to cool down to room temperature, open the furnace door and take out the test block. Analyze the microstructure of each area, among which: the microstructure of the TC4 alloy layer is shown in Figure 2 The microstructure of the transition layer is shown in Figure 3 As shown in the figure, the microstructure of TA15 alloy is as follows Figure 4 As shown; it can be seen that there are no obvious printing defects in each area and the microstructure is uniform.

[0066] It is proved that the heterogeneous titanium alloy described in the embodiment of the present application is obtained by mixing the first titanium alloy powder and the second titanium alloy powder; based on the target part to be formed, the composition analysis is performed to obtain the transition layer composition content gradient and the transition layer thickness; the transition layer composition content gradient refers to the composition content gradient of the main elements in the transition layer with a content of more than 3wt.% in the heterogeneous titanium alloy powder; by controlling the composition content gradient of the main elements in the transition layer, the microstructure stability at the interface of the heterogeneous titanium alloy is ensured, thereby improving the quality stability of the heterogeneous titanium alloy component. Based on the transition layer composition content gradient and the transition layer thickness, the laser melting deposition equipment is used for printing processing to obtain the target part; wherein the printing processing includes: based on the first titanium alloy powder, printing to the transition layer interface, stopping printing; based on the heterogeneous titanium alloy powder, continuing to print according to the composition content gradient, thickness and width of the transition layer to obtain the transition layer; after the transition layer is printed, continue printing based on the second titanium alloy powder to obtain the target part. It can be seen that the present application controls the printing process based on the transition layer composition content gradient and transition layer thickness, and is applicable to laser melting integrated forming of various heterogeneous titanium alloy components with different compositions, which can effectively improve the microstructure and mechanical property stability at the interface of heterogeneous titanium alloys. Moreover, compared with the prior art, the method described in the present application does not require a mold, and the subsequent processing allowance is small, which can realize the rapid and low-cost manufacturing of complex structural parts that cannot be manufactured by traditional manufacturing technology.

[0067] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for manufacturing a heterogeneous titanium alloy, It is characterized in that The following steps are involved: The first titanium alloy powder and the second titanium alloy powder are mixed to obtain a heterogeneous titanium alloy powder; based on the target part to be formed, the component analysis is performed to obtain the transition layer component content gradient and the transition layer thickness; Based on the transition layer component content gradient and transition layer thickness, a laser melting deposition device is used for printing to obtain a target part; The printing process includes: The first stage: based on the first titanium alloy powder, printing is stopped at the interface of the transition layer; The second stage: based on the heterogeneous titanium alloy powder, continue printing according to the composition content gradient, thickness and format of the transition layer to obtain the transition layer; The third stage: after the transition layer is printed, printing is continued based on the second titanium alloy powder to obtain the target part; The thickness of the transition layer is 1 to 5 mm, and the gradient of the content of the transition layer components is less than 3 wt.% / mm.

2. The method for producing a heterogeneous titanium alloy according to claim 1, It is characterized in that The mixing mass ratio of the first titanium alloy powder to the second titanium alloy powder is 2:1 to 1:

2.

3. The method for producing a heterogeneous titanium alloy according to claim 1, It is characterized in that The amount of the heterogeneous titanium alloy powder satisfies the following relationship: W=ρSh / a Wherein: W is the amount of the heterogeneous titanium alloy powder; ρ is the bulk density of the heterogeneous titanium alloy powder; S is the width area of ​​the transition zone; h is the thickness of the transition zone; a is the powder coating rate, and the value range is 40% to 60%.

4. The method for producing a heterogeneous titanium alloy according to claim 1, It is characterized in that The first titanium alloy powder includes at least one of TC4, TA15, TC11, TC21 and Ti60, and has a particle size of 53 μm to 150 μm; the second titanium alloy powder includes at least one of TC4, TA15, TC11, TC21 and Ti60, and has a particle size of 53 μm to 150 μm.

5. The method for producing a heterogeneous titanium alloy according to claim 1, It is characterized in that The step of mixing the first titanium alloy powder and the second titanium alloy powder to obtain the heterogeneous titanium alloy powder comprises: The first titanium alloy powder and the second titanium alloy powder are placed in a planetary ball mill for low-speed ball milling and mixing to obtain heterogeneous titanium alloy powder; wherein the ball-to-material ratio is 8:1-10:1, the ball milling speed is 80-120 rpm, and the ball milling time is 2-4 hours.

6. The method for producing a heterogeneous titanium alloy according to claim 5, It is characterized in that The low-speed ball milling mixing process includes: pausing for 20 minutes after each 1-hour process to control the fluidity of the mixed powder after ball milling to be 35-38s / 50g.

7. The method for producing a heterogeneous titanium alloy according to claim 1, It is characterized in that The parameters of the printing process include: laser power of 3.5-4KW, scanning speed of 1200-1800mm / min, powder feeding rate of 24-28g / min; and printing path of: outlining first and then filling.

8. The method for producing a heterogeneous titanium alloy according to claim 7, It is characterized in that The filling path is zigzag, and the printing filling direction rotates 60 to 90 degrees for each printing layer.

9. A heterogeneous titanium alloy, It is characterized in that The heterogeneous titanium alloy is manufactured by the method according to any one of claims 1 to 8.

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