Brazing method for titanium alloy

Abstract

The invention provides a titanium alloy brazing method, and relates to the technical field of welding, in the brazing process, firstly, pulse current is applied to an upper titanium alloy skin and a lower titanium alloy skin in an assembly part in the heating process, so that the titanium alloy is subjected to electroplasticity, then, pressure and a high-temperature field are applied to the assembly part in the heat preservation process at the same time, and the titanium alloy is subjected to electroplasticity; due to the fact that the titanium alloy upper skin and the titanium alloy lower skin are subjected to electroplasticity during heat preservation, under the action of pressure and a high-temperature field, the attaching degree of all components in the titanium alloy component obtained through brazing can be better improved, the brazing rate of the titanium alloy component obtained through brazing can be improved, and then the forming quality of the titanium alloy component is improved. According to the method, the brazing rate of the titanium alloy component obtained through brazing can be increased, and therefore the forming quality of the titanium alloy component is improved.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a brazing method for titanium alloy. Background Art

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

[0003] The titanium alloy connection methods include fusion welding, friction welding, diffusion welding, and brazing. Titanium alloys are connected by fusion welding because of uneven heating and cooling, uneven stress distribution, and easy cracking, and poor weldability. Friction welding, under the influence of thermal mechanical forces, causes uneven distribution of tissue in the joint area, and the joint performance is difficult to control. At the same time, the joint shape is restricted. Diffusion welding uses higher pressure, higher connection temperature, and longer insulation time, which changes the tissue structure of the parent material and reduces the performance. Brazing, as a simple, efficient, low-cost method with high joint strength, can better meet the connection requirements. However, in the related art, due to the diversity of materials and shapes of components, the brazing rate of titanium alloy components obtained by brazing is poor, and the resulting component forming quality is poor. Summary of the invention

[0004] The problem solved by the invention is how to further improve the brazing rate of the titanium alloy component obtained by brazing.

[0005] In order to solve the above problems, the present invention provides a brazing method of titanium alloy, comprising:

[0006] Step S1, assembling the titanium alloy upper skin, the upper foil strip brazing filler metal, the titanium alloy base material, the lower foil strip brazing filler metal and the titanium alloy lower skin in order from top to bottom to obtain an assembly part;

[0007] Step S2, under vacuum conditions, heating the assembly to a preset temperature at a preset rate, keeping it warm for a preset time, and cooling it to room temperature to obtain a titanium alloy component; during the heating process, applying pulse current to the titanium alloy upper skin and the titanium alloy lower skin respectively; during the keeping warm process, applying a preset pressure in the thickness direction of the assembly.

[0008] Optionally, in step S2, the density of the pulse current is 10A / 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 minutes to 12 minutes.

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

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

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

[0014] Optionally, in step S1, the upper foil strip solder and the lower foil strip solder are both Ti—Zr—Cu—Ni alloy foil strips.

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

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

[0017] Compared with the related art, in the brazing process of the present invention, first, a pulse current is applied to the titanium alloy upper skin and the titanium alloy lower skin in the assembly during the heating process to make the titanium alloy electroplastic, and then, pressure and a high temperature field are simultaneously applied to the assembly during the heat preservation process. Since the titanium alloy upper skin and the titanium alloy lower skin have undergone electroplasticity during the heat preservation process, under the action of pressure and high temperature field, it is more conducive to improving the fit between the various components in the titanium alloy component obtained by brazing, thereby helping to improve the brazing rate of the titanium alloy component obtained by brazing, and then improve the forming quality of the titanium alloy component. In summary, the method of the present invention can improve the brazing rate of the titanium alloy component obtained by brazing, thereby improving the forming quality of the titanium alloy component. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 2 It is a structural schematic diagram of an assembly part in an embodiment of the present invention;

[0020] Figure 3 This is a welding rate detection diagram of the titanium alloy component prepared in Example 1;

[0021] Figure 4 This is a welding rate detection diagram of the titanium alloy component prepared in Comparative Example 1.

[0022] Description of reference numerals:

[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. Retractable pressure head. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes 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 the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0026] The term "including" and its variations used in this article are open inclusions, that is, "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 other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more. It should be noted that, for example Figure 2As shown, in the present invention, the thickness direction of the assembly part refers to Figure 2 The up and down direction in the diagram is the direction that the X arrow points to.

[0027] In view of the problems existing in the above-mentioned related technologies, such as Figure 1 As shown, an embodiment of the present invention provides a brazing method for titanium alloy, comprising:

[0028] Step S1: Figure 2 As shown, the titanium alloy upper skin 1, the upper foil strip brazing material 2, the titanium alloy base material 3, the lower foil strip brazing material 4 and the titanium alloy lower skin 5 are assembled in sequence from top to bottom to obtain an assembly part;

[0029] Step S2, under vacuum conditions, heating the assembly to a preset temperature at a preset rate, keeping it warm for a preset time, and cooling it to room temperature to obtain a titanium alloy component; during the heating process, applying pulse current to the titanium alloy upper skin 1 and the titanium alloy lower skin 5 respectively; during the keeping warm process, applying a preset pressure in the thickness direction of the assembly.

[0030] In the brazing process of the embodiment of the present invention, first, a pulse current is applied to the titanium alloy upper skin 1 and the titanium alloy lower skin 5 in the assembly during the heating process to make the titanium alloy electroplastic. Then, pressure and a high temperature field are simultaneously applied to the assembly during the heat preservation process. Since the titanium alloy upper skin 1 and the titanium alloy lower skin 5 have already undergone electroplasticity during the heat preservation process, under the action of pressure and high temperature field, it is more conducive to improving the fit between the various components in the titanium alloy component obtained by brazing, thereby helping to improve the brazing rate of the titanium alloy component obtained by brazing, and then improve the forming quality of the titanium alloy component. In summary, the method of the embodiment of the present invention can improve the brazing rate of the titanium alloy component obtained by brazing, 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 10A / mm 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 8min to 12min.

[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, Figure 2As shown, the preset pressure applied in the thickness direction of the assembly is applied by a plurality of retractable pressure heads 6 distributed in an array along the plane direction of the assembly. In this embodiment, two groups of retractable pressure heads 6 distributed in an array apply pressure to the assembly from above and below the assembly respectively, which can make the assembly better fit during the brazing process and further improve the brazing rate of the titanium alloy component obtained by brazing.

[0035] In some embodiments of the present invention, in step S1, 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 one of Ti2AlNb alloy and Ti60 alloy.

[0036] In some embodiments of the present invention, in step S1, the upper foil solder 2 and the lower foil solder 4 are both Ti-Zr-Cu-Ni alloy foil; in terms of weight percentage, the components of the Ti-Zr-Cu-Ni alloy foil include: 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 solder 2 is fixed between the titanium alloy upper skin 1 and the titanium alloy base material 3 by spot welding; the lower foil solder 4 is fixed between the titanium alloy lower skin 5 and the titanium alloy base material 3 by spot welding.

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

[0039] The present invention is further described below in conjunction with specific embodiments.

[0040] Example 1

[0041] A1. Figure 2As shown, the titanium alloy upper skin, the upper foil brazing filler metal, the titanium alloy base material, the lower foil brazing filler metal and the titanium alloy lower skin are assembled in sequence from top to bottom to obtain an assembly part; wherein the titanium alloy upper skin and the titanium alloy lower skin are both made of Ti2AlNb alloy, the titanium alloy base material is made of Ti60 alloy, the upper foil brazing filler metal and the lower foil brazing filler metal are both Ti-Zr-Cu-Ni alloy foil strips, and the components of the Ti-Zr-Cu-Ni alloy foil strips include, by weight percentage: Zr: 12.5%, Cu: 22.5%, Ni: 9%, the remainder being Ti; the titanium alloy upper skin, titanium alloy base material and titanium alloy lower skin used are respectively and successively polished and cleaned by sandpaper; the upper foil solder is fixed between the titanium alloy upper skin and the titanium alloy base material by spot welding; the lower foil solder is fixed between the titanium alloy lower skin and the titanium alloy base material by spot welding; the shape of the gap between the titanium alloy upper skin and the titanium alloy base material matches the shape of the upper foil solder; the shape of the gap between the titanium alloy lower skin and the titanium alloy base material matches the shape of the lower foil solder.

[0042] A2. Under vacuum conditions, the assembly is heated to a preset temperature at a preset rate, kept at a preset 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 titanium alloy upper skin and the titanium alloy lower skin respectively; during the keeping temperature process, a preset pressure is applied in the thickness direction of the assembly; wherein the density of the pulse current is 10A / mm 2 , duty cycle is 20%, frequency is 100 Hz, the preset rate is 10°C / min, the preset temperature is 935°C, 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 10A / mm 2 , the duty cycle is 20%, the frequency is 100 Hz, the preset rate is 10°C / min, the preset rate is 9°C / min, the preset temperature is 930°C, the preset time is 12 min, and the preset pressure is 0.9 Mpa.

[0045] Example 3

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

[0047] Comparative Example 1

[0048] The difference from Example 1 is that in step A2, during the heating process, no pulse current is applied to the titanium alloy upper skin, and no pulse current is applied to the titanium alloy lower skin.

[0049] Experimental example

[0050] The welding rate 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 3 and Figure 4 ,from Figure 3 and Figure 4 It can be seen that there are local defects in the welding area of ​​the titanium alloy component prepared in Comparative Example 1, and some structures cannot be 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 is no large area of ​​unwelded area, which effectively improves the welding quality and enhances the stability and reliability of the structure. The welding rate of the titanium alloy component prepared in Example 1 is 97.52%, indicating that the welding rate of the titanium alloy component prepared in Example 1 is higher.

[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 method for brazing titanium alloy, characterized in that: include: Step S1, assembling the titanium alloy upper skin (1), the upper foil strip brazing material (2), the titanium alloy base material (3), the lower foil strip brazing material (4) and the titanium alloy lower skin (5) in order from top to bottom to obtain an assembly part; Step S2, under vacuum conditions, heating the assembly to a preset temperature at a preset rate, keeping the temperature for a preset time, and cooling to room temperature to obtain a titanium alloy component; during the heating process, applying pulse current to the titanium alloy upper skin (1) and the titanium alloy lower skin (5), respectively; During the heat preservation process, a preset pressure is applied in the thickness direction of the assembly.

2. The brazing method of titanium alloy according to claim 1, characterized in that: In step S2, the density of the pulse current is 10A / mm 2 Up to 15A / mm 2 , the duty cycle is 15% to 25%, and the frequency is 90Hz to 110Hz.

3. The brazing method of titanium alloy according to claim 1, characterized in that: In the step S2, the preset rate is 9°C / min to 11°C / min, and the preset temperature is 930°C to 940°C.

4. The brazing method of titanium alloy according to claim 3, characterized in that: The preset time is 8 minutes to 12 minutes.

5. The method for brazing titanium alloy according to claim 1, characterized in that: In the step S2, the preset pressure is 0.9 MPa to 1.1 MPa.

6. The method for brazing titanium alloy according to claim 1, characterized in that: In the step S2, the preset pressure is applied in the thickness direction of the assembly part by means of a plurality of retractable pressure heads distributed in an array along the plane direction of the assembly part.

7. The method for brazing titanium alloy according to claim 1, characterized in that: In the step S1, 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 one of Ti2AlNb alloy and Ti60 alloy.

8. The method for brazing titanium alloy according to claim 1, characterized in that: In the step S1, the upper foil strip solder (2) and the lower foil strip solder (4) are both Ti-Zr-Cu-Ni alloy foil strips.

9. The method for brazing titanium alloy according to claim 1, characterized in that: In the step S1, the upper foil solder (2) is fixed between the titanium alloy upper skin (1) and the titanium alloy base material (3) by spot welding; and the lower foil solder (4) is fixed between the titanium alloy lower skin (5) and the titanium alloy base material (3) by spot welding.

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

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