A brazing method for titanium alloy

Abstract

This invention provides a brazing method for titanium alloys, relating to the field of welding technology. In the brazing process, firstly, during heating, a pulsed current is applied to the upper and lower titanium alloy skins of the assembly, causing electroplasticity in the titanium alloy. Then, during the heat preservation process, pressure and a high-temperature field are simultaneously applied to the assembly. Since the upper and lower titanium alloy skins have already undergone electroplasticity during heat preservation, the pressure and high-temperature field further enhance the fit between the various components in the brazed titanium alloy component, thereby improving the brazing rate and ultimately the forming quality of the titanium alloy component. In summary, the method of this invention can improve the brazing rate of the brazed titanium alloy component, thus improving the forming quality of the titanium alloy component.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more specifically, to a brazing method for titanium alloys. Background Technology

[0002] Titanium alloys are widely used in the aerospace field. Increasing the amount of titanium alloys used is one of the significant indicators of the advancement of new-generation aircraft and engines, which can greatly improve structural weight reduction and safety reliability. Ti-based alloys, with their high specific strength, optimize parameters such as engine thermal efficiency and thrust-to-weight ratio, and are gradually becoming the preferred material for improving the performance of aerospace engines. Welding is one of the key technologies for connecting titanium alloy components.

[0003] Titanium alloy joining methods include fusion welding, friction welding, diffusion welding, and brazing. Fusion welding of titanium alloys suffers from uneven heating and cooling, uneven stress distribution, and is prone to cracking, resulting in poor weldability. Friction welding, under the influence of thermomechanical forces, leads to uneven microstructure distribution in the joint area, making joint performance difficult to control and limiting joint shape. Diffusion welding, with its high pressure, high joining temperature, and long holding time, alters the microstructure of the base material, degrading its properties. Brazing, as a simple, efficient, low-cost method with high joint strength, can better meet joining requirements. However, in related technologies, due to the diversity of component materials and shapes, brazed titanium alloy components often exhibit poor brazing rates and poor component forming quality. Summary of the Invention

[0004] The problem addressed by this invention is: how to further improve the brazing rate of titanium alloy components obtained by brazing.

[0005] To address the above problems, this invention provides a brazing method for titanium alloys, comprising:

[0006] Step S1: Assemble the titanium alloy upper skin, upper foil with brazing filler metal, titanium alloy base material, lower foil with brazing filler metal, and titanium alloy lower skin in order from top to bottom to obtain the assembly.

[0007] Step S2: Under vacuum conditions, the assembly is heated to a preset temperature at a preset rate, held at the temperature for a preset time, and cooled to room temperature to obtain a titanium alloy component; during the heating process, pulsed currents are applied to the upper and lower titanium alloy skins respectively; during the holding process, a preset pressure is applied in the thickness direction of the assembly.

[0008] Optionally, in step S2, the density of the pulse current is 10 A / mm. 2 Up to 15A / mm 2 The duty cycle is 15% to 25%, and the frequency is 90Hz to 110Hz.

[0009] Optionally, in step S2, the preset rate is 9°C / min to 11°C / min, and the preset temperature is 930°C to 940°C.

[0010] Optionally, the preset time is 8 to 12 minutes.

[0011] Optionally, in step S2, the preset pressure is between 0.9 MPa and 1.1 MPa.

[0012] Optionally, in step S2, the application of a preset pressure in the thickness direction of the assembly is performed by a plurality of retractable pressure heads arranged in an array along the plane of the assembly.

[0013] Optionally, in step S1, the materials of the upper titanium alloy skin, the titanium alloy base material, and the lower titanium alloy skin are each independently selected from one of Ti2AlNb alloy and Ti60 alloy.

[0014] Optionally, in step S1, both the upper foil brazing filler metal and the lower foil brazing filler metal are Ti-Zr-Cu-Ni alloy foils.

[0015] Optionally, in step S1, the upper foil brazing filler metal is fixed between the upper titanium alloy skin and the titanium alloy base material by spot welding; the lower foil brazing filler metal is fixed between the lower titanium alloy skin and the titanium alloy base material by spot welding.

[0016] Optionally, in step S1, the gap shape between the upper titanium alloy skin and the titanium alloy base material matches the shape of the upper foil strip solder; the gap shape between the lower titanium alloy skin and the titanium alloy base material matches the shape of the lower foil strip solder.

[0017] Compared with related technologies, the present invention, in the brazing process, firstly, applies a pulsed current to the upper and lower titanium alloy skins of the assembly during the heating process, causing electroplasticity in the titanium alloy. Then, during the heat preservation process, pressure and a high-temperature field are simultaneously applied to the assembly. Since the upper and lower titanium alloy skins have already undergone electroplasticity during heat preservation, the pressure and high-temperature field further improve the fit between the various components in the brazed titanium alloy component, thereby increasing the brazing rate and ultimately improving the forming quality of the titanium alloy component. In summary, the method of the present invention can improve the brazing rate of the brazed titanium alloy component, thereby improving the forming quality of the titanium alloy component. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the brazing method for titanium alloys in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the assembly structure in an embodiment of the present invention;

[0020] Figure 3 The image shows the weld ratio test results of the titanium alloy component prepared in Example 1.

[0021] Figure 4 This is a graph showing the weld ratio of the titanium alloy component prepared in Comparative Example 1.

[0022] Explanation of reference numerals in the attached figures:

[0023] 1. Titanium alloy upper skin; 2. Upper foil with brazing filler metal; 3. Titanium alloy base material; 4. Lower foil with brazing filler metal; 5. Titanium alloy lower skin; 6. Telescopic pressure head. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0026] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. It should be noted that, as Figure 2As shown, in this invention, the thickness direction of the assembly refers to... Figure 2 The vertical direction in the text refers to the direction the X arrow points.

[0027] In response to the problems existing in the aforementioned related technologies, such as Figure 1 As shown, an embodiment of the present invention provides a brazing method for titanium alloys, comprising:

[0028] Step S1, as follows Figure 2 As shown, the titanium alloy upper skin 1, upper foil with brazing filler metal 2, titanium alloy base material 3, lower foil with brazing filler metal 4 and titanium alloy lower skin 5 are assembled in sequence from top to bottom to obtain the assembly.

[0029] Step S2: Under vacuum conditions, the assembly is heated to a preset temperature at a preset rate, held at the temperature for a preset time, and cooled to room temperature to obtain a titanium alloy component; during the heating process, pulsed currents are applied to the upper titanium alloy skin 1 and the lower titanium alloy skin 5 respectively; during the holding process, a preset pressure is applied in the thickness direction of the assembly.

[0030] In this embodiment of the invention, during the brazing process, firstly, a pulsed current is applied to the upper titanium alloy skin 1 and the lower titanium alloy skin 5 of the assembly during the heating process, causing electroplasticity in the titanium alloy. Then, during the heat preservation process, pressure and a high-temperature field are simultaneously applied to the assembly. Since the upper titanium alloy skin 1 and the lower titanium alloy skin 5 have already undergone electroplasticity during the heat preservation process, the pressure and high-temperature field further improve the fit between the various components in the brazed titanium alloy component, thereby improving the brazing rate of the brazed titanium alloy component and thus improving the forming quality of the titanium alloy component. In summary, the method of this embodiment of the invention can improve the brazing rate of the brazed titanium alloy component, thereby improving the forming quality of the titanium alloy component.

[0031] In some embodiments of the present invention, in step S2, the density of the pulse current is 10 A / mm². 2 Up to 15A / mm 2 The duty cycle is 15% to 25%, and the frequency is 90Hz to 110Hz.

[0032] In some embodiments of the present invention, in step S2, the preset rate is 9°C / min to 11°C / min, the preset temperature is 930°C to 940°C, and the preset time is 8 min to 12 min.

[0033] In some embodiments of the present invention, in step S2, the preset pressure is 0.9 MPa to 1.1 MPa.

[0034] In some embodiments of the present invention, in step S2, as follows: Figure 2As shown, the preset pressure applied in the thickness direction of the assembly is applied by a plurality of retractable pressure heads 6 arranged in an array along the plane of the assembly. In this embodiment, the two sets of retractable pressure heads 6 arranged in an array apply pressure to the assembly from above and below, respectively, which can enable the assembly to achieve better fit during brazing and further improve the brazing rate of the brazed titanium alloy component.

[0035] In some embodiments of the present invention, in step S1, the materials of the upper titanium alloy skin 1, the titanium alloy base material 3, and the lower titanium alloy skin 5 are each independently selected from one of Ti2AlNb alloy and Ti60 alloy.

[0036] In some embodiments of the present invention, in step S1, the upper foil brazing filler metal 2 and the lower foil brazing filler metal 4 are both Ti-Zr-Cu-Ni alloy foils; by weight percentage, the composition of the Ti-Zr-Cu-Ni alloy foil includes: Zr: 11% to 14%, Cu: 21% to 24%, Ni: 8% to 10%, and the balance is Ti.

[0037] In some embodiments of the present invention, in step S1, the upper foil brazing filler metal 2 is fixed between the upper titanium alloy skin 1 and the titanium alloy base material 3 by spot welding; the lower foil brazing filler metal 4 is fixed between the lower titanium alloy skin 5 and the titanium alloy base material 3 by spot welding.

[0038] In some embodiments of the present invention, in step S1, the gap shape between the upper titanium alloy skin 1 and the titanium alloy base material 3 matches the shape of the upper foil brazing filler metal 2; the gap shape between the lower titanium alloy skin 5 and the titanium alloy base material 3 matches the shape of the lower foil brazing filler metal 4.

[0039] The present invention will be further described below with reference to specific embodiments.

[0040] Example 1

[0041] A1, such as Figure 2As shown, the titanium alloy upper skin, upper foil brazing filler metal, titanium alloy base material, lower foil brazing filler metal, and titanium alloy lower skin are assembled sequentially from top to bottom to obtain the assembly. The upper and lower titanium alloy skins are both made of Ti2AlNb alloy, the titanium alloy base material is made of Ti60 alloy, and the upper and lower foil brazing filler metals are both Ti-Zr-Cu-Ni alloy foils. By weight percentage, the Ti-Zr-Cu-Ni alloy foil comprises: Zr: 12.5%, Cu: 22.5%, Ni: 9%, with the balance being Ti; the titanium alloy upper skin, titanium alloy base material, and titanium alloy lower skin used were sequentially sanded and cleaned; the upper foil strip brazing filler metal was fixed between the titanium alloy upper skin and the titanium alloy base material by spot welding; the lower foil strip brazing filler metal was fixed between the titanium alloy lower skin and the titanium alloy base material by spot welding; the gap shape between the titanium alloy upper skin and the titanium alloy base material matched the shape of the upper foil strip brazing filler metal; the gap shape between the titanium alloy lower skin and the titanium alloy base material matched the shape of the lower foil strip brazing filler metal.

[0042] A2. Under vacuum conditions, the assembly is heated to a preset temperature at a preset rate, held at that temperature for a preset time, and then cooled to room temperature to obtain a titanium alloy component. During the heating process, pulsed currents are applied to the upper and lower titanium alloy skins respectively. During the holding process, a preset pressure is applied in the thickness direction of the assembly. The density of the pulsed current is 10 A / mm². 2 The duty cycle is 20%, the frequency is 100Hz, the preset rate is 10℃ / min, the preset temperature is 935℃, the preset time is 10min, and the preset pressure is 1MPa.

[0043] Example 2

[0044] The difference from Example 1 is that, in step A2, the density of the pulse current is 10 A / mm. 2 The duty cycle is 20%, the frequency is 100Hz, the preset rate is 10℃ / min, the preset speed is 9℃ / min, the preset temperature is 930℃, the preset time is 12min, and the preset pressure is 0.9Mpa.

[0045] Example 3

[0046] The difference from Example 1 is that, in step A2, the density of the pulse current is 10 A / mm. 2 The duty cycle is 20%, the frequency is 100Hz, the preset rate is 10℃ / min, the preset speed is 11℃ / min, the preset temperature is 940℃, the preset time is 8min, and the preset pressure is 1.1Mpa.

[0047] Comparative Example 1

[0048] The difference from Example 1 is that, in step A2, during the heating process, no pulsed current is applied to the upper skin of the titanium alloy, nor is a pulsed current applied to the lower skin of the titanium alloy.

[0049] Experimental Example

[0050] The weld ratio of the titanium alloy components prepared in Example 1 and Comparative Example 1 was tested using a computer-controlled ultrasonic transducer. The results are shown in [Figure Number]. Figure 3 and Figure 4 ,from Figure 3 and Figure 4 It can be seen that the titanium alloy component prepared in Comparative Example 1 has local defects in the welding area, and some structures are not completely welded, which affects the welding quality. The welding rate of the titanium alloy component prepared in Comparative Example 1 is 91.36%. The overall welding effect of the titanium alloy component prepared in Example 1 is significantly improved, and there are no large areas of unwelded areas. This effectively improves the welding quality and enhances the stability and reliability of the structure. The titanium alloy component prepared in Example 1 has a welding rate of 97.52%, indicating that the titanium alloy component prepared in Example 1 has a higher welding rate.

[0051] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A brazing method for titanium alloys, characterized in that, include: Step S1: Assemble the titanium alloy upper skin (1), upper foil brazing filler metal (2), titanium alloy base material (3), lower foil brazing filler metal (4), and titanium alloy lower skin (5) in order from top to bottom to obtain the assembly; the materials of the titanium alloy upper skin (1), the titanium alloy base material (3), and the titanium alloy lower skin (5) are independently selected from Ti2AlNb alloy and Ti60 alloy respectively; the upper foil brazing filler metal (2) and the lower foil brazing filler metal (4) are both Ti-Zr-Cu-Ni alloy foils; the upper foil brazing filler metal (2) is fixed between the titanium alloy upper skin (1) and the titanium alloy base material (3) by spot welding; the lower foil brazing filler metal (4) is fixed between the titanium alloy lower skin (5) and the titanium alloy base material (3) by spot welding. Step S2: Under vacuum conditions, the assembly is heated to a preset temperature at a preset rate, held at the temperature for a preset time, and cooled to room temperature to obtain a titanium alloy component; during the heating process, pulse currents are applied to the upper titanium alloy skin (1) and the lower titanium alloy skin (5) respectively. During the heat preservation process, a preset pressure is applied in the thickness direction of the assembly; the density of the pulse current is 10A / mm². 2 Up to 15A / mm 2 The duty cycle is 15% to 25%, and the frequency is 90Hz to 110Hz; the preset rate is 9℃ / min to 11℃ / min, the preset temperature is 930℃ to 940℃, the preset time is 8min to 12min, and the preset pressure is 0.9Mpa to 1.1Mpa; the preset pressure is applied in the thickness direction of the assembly by multiple retractable pressure heads arranged in an array along the plane of the assembly.

2. The brazing method for titanium alloys according to claim 1, characterized in that, In step S1, the gap shape between the upper titanium alloy skin (1) and the titanium alloy base material (3) matches the shape of the upper foil brazing filler metal (2); the gap shape between the lower titanium alloy skin (5) and the titanium alloy base material (3) matches the shape of the lower foil brazing filler metal (4).

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