Titanium alloy current-assisted vacuum brazing tool and process method

Abstract

The invention provides a titanium alloy current-assisted vacuum brazing tool and process method. The titanium alloy current-assisted vacuum brazing tool and process method comprises the steps that S1, a titanium alloy columnar body to be welded is machined; s2, TiZrCuNi brazing filler metal alloy powder is adopted for preparing a brazing middle layer; s3, polishing the welding surface of the titanium alloy cylindrical body to be welded; s4, the welding face of one to-be-welded titanium alloy base material is placed upwards, brazing filler metal alloy powder of a brazing middle layer is evenly spread, the welding face of the other titanium alloy base material is placed above the middle layer downwards, and a three-layer structure is formed; s5, a workpiece to be welded and a thermocouple are inserted into a titanium alloy current auxiliary vacuum brazing tool and then placed in a vacuum hot-pressing brazing furnace, graphite cushion blocks are arranged at the top of the upper-layer base metal and the bottom of the lower-layer base metal correspondingly, and an electrode pressing head makes contact with the graphite cushion blocks at the top of the upper-layer base metal; and S6, titanium alloy current auxiliary vacuum brazing is conducted. According to the method, the workpiece is rapidly and uniformly heated in a heating and current applying mode, and the titanium alloy brazed joint which is good in bonding strength and excellent in performance is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy brazing, and in particular relates to a titanium alloy current-assisted vacuum brazing tool and a process method. Background Art

[0002] Titanium and its alloys are a kind of metal material with high heat resistance, high strength, high toughness and high corrosion resistance, and are widely used in aerospace, biomedicine, petrochemical and other fields. Titanium alloy radiators are gradually replacing existing aluminum alloy, copper alloy and stainless steel radiators with excellent properties such as small size, light weight, corrosion resistance and high temperature resistance. Titanium-based brazing filler metal is the preferred brazing filler metal to ensure that the performance of the titanium alloy radiator weld is similar to that of the matrix, but there is no highly mature corresponding brazing process in China at present, which leads to problems such as brazing seam leakage and excessive melting when brazing the radiator core, and its promotion and application are greatly limited.

[0003] The existing alloy brazing materials used for titanium alloy brazing have a high melting point, and the brazing temperature is usually around 930°C. Traditional vacuum brazing heats the workpiece through radiation heating and heat conduction, which is slow and time-consuming. When the high temperature time is too long for complex components applied to titanium alloy materials, a large amount of brittle phases will form at the brazing joint interface, which will lead to the inability to obtain high-performance welding. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a titanium alloy current-assisted vacuum brazing process method, which adopts the current-assisted vacuum brazing method to heat the workpiece quickly and evenly by heating and adding current, thereby preparing a titanium alloy brazing joint with good bonding strength and excellent performance.

[0005] The present invention also provides a titanium alloy current-assisted vacuum brazing tool, which is used for placing the assembled workpieces to be welded in the titanium alloy current-assisted vacuum brazing process method and supporting the workpieces to be welded.

[0006] The present invention also provides a titanium alloy brazed joint prepared according to the titanium alloy current-assisted vacuum brazing process method, in which the brazing material and the base material form a good metallurgical bond, no defects such as pores and welding cracks appear at the brazing interface, no obvious residual brazing material is present at the weld, and the structure is dense.

[0007] The present invention can be applied to the preparation of high-efficiency titanium alloy heat exchanger materials, and the welded joint structure obtained by the present method is denser and has no gaps than that obtained by the existing method.

[0008] Note that the description of these objectives does not prevent the existence of other objectives. One embodiment of the present invention does not need to achieve all of the above objectives. Objectives other than the above objectives can be extracted from the description of the specification, drawings, and claims.

[0009] The present invention achieves the above technical objectives through the following technical means.

[0010] A titanium alloy current-assisted vacuum brazing process method comprises the following steps:

[0011] Step S1: processing at least one pair of titanium alloy columns to be welded with a diameter of R and a height of L as a base material;

[0012] Step S2: using TiZrCuNi (titanium zirconium copper nickel) brazing alloy powder to prepare a brazing intermediate layer, the alloy melting point is T0;

[0013] Step S3: grinding the welding surface of the titanium alloy column to be welded with sandpaper, cleaning the ground surface with alcohol and blowing it dry;

[0014] Step S4: assembling the workpieces to be welded, placing the welding surface of one titanium alloy base material to be welded in each titanium alloy column facing upward, evenly smearing the brazing alloy powder of the middle layer, and placing the welding surface of the other titanium alloy base material facing downward on the middle layer to form a workpiece to be welded with a three-layer structure of upper, middle and lower layers;

[0015] Step S5: placing the workpiece to be welded assembled in step S4 in a titanium alloy current-assisted vacuum brazing tool, inserting a thermocouple into the titanium alloy current-assisted vacuum brazing tool, and then placing the whole workpiece in a vacuum hot-pressing brazing furnace, with graphite pads respectively provided on the top of the upper parent material and the bottom of the lower parent material, and the electrode pressure head contacts the graphite pad on the top of the upper parent material, so that the current passes through the titanium alloy column to be welded to form a loop;

[0016] Step S6: Start the vacuum hot-pressing brazing furnace, set the brazing parameters and the welding temperature T1, and perform current-assisted vacuum brazing of the titanium alloy to obtain a titanium alloy workpiece.

[0017] In the above scheme, the titanium alloy in step S1 is TA2, the base material diameter R is 10 mm, and the height L is 30 mm.

[0018] In the above scheme, the weight of the TiZrCuNi solder alloy powder in step S2 is 0.05 g.

[0019] In the above scheme, in step S2, the composition of the TiZrCuNi alloy is 37.5Ti37.5Zr15Cu10Ni, 15Ti64Zr8Cu13Ni or 22Ti54Zr8Cu16Ni, and three different solders are used. By adjusting the content of Zr element in the Ti-based solder, the melting point of the solder is reduced, thereby reducing the brazing temperature and improving the corrosion of the base material.

[0020] In the above scheme, in step S2, the melting point T0 of the alloy is 800-820°C.

[0021] In the above scheme, in step S3, the roughness of the welding surface of the titanium alloy columnar body to be welded is polished with sandpaper to be below Ra1.6.

[0022] In the above scheme, in step S6, the vacuum degree of the vacuum hot pressing brazing furnace is 0.002Pa, the heating rate is 10℃ / min, the current is set to 1500A, the brazing temperature T1 is 890℃, the holding time is 20min, and radiation heating and pressure head conduction current auxiliary heating are used to make the workpiece heated evenly and heat up quickly, thereby improving welding production efficiency and reducing welding energy consumption.

[0023] A titanium alloy current-assisted vacuum brazing tool is used to place the assembled workpiece to be welded in the titanium alloy current-assisted vacuum brazing process method, and the workpiece to be welded includes steel; a plurality of sample placement through holes and thermocouple placement through holes are processed on the steel, and the sample placement through holes and the thermocouple placement through holes are connected, and the sample placement through holes are used to place the assembled workpiece to be welded with an upper, middle and lower three-layer structure, and the thermocouple placement through holes are used to place thermocouples. The titanium alloy current-assisted vacuum brazing tool is used to support the workpiece to be welded.

[0024] In the above scheme, the steel material is H13; the inner diameter of the through hole for placing the sample is 11 mm, and the diameter of the through hole for placing the thermocouple is 4 mm.

[0025] Furthermore, in the step S1, three pairs of titanium alloy columns to be welded are processed as base materials; three sample placement through holes and three thermocouple placement through holes are processed on the steel, and base materials with TiZrCuNi alloy compositions of 37.5Ti37.5Zr15Cu10Ni, 15Ti64Zr8Cu13Ni or 22Ti54Zr8Cu16Ni can be processed simultaneously, thereby improving processing efficiency.

[0026] A titanium alloy brazing joint is prepared according to the titanium alloy current-assisted vacuum brazing process method.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention adopts the process of current-assisted vacuum brazing, which generates Joule heat with the help of current so that the inside of the workpiece is quickly and evenly heated, effectively shortening the brazing temperature rise time, improving welding production efficiency, reducing welding energy consumption, and reducing welding costs;

[0029] 2. The current used in the present invention assists the interface gap between the workpiece and the solder assembly. The current discharge forms plasma, which allows the oxide layer to disappear quickly and ensures that the interface reaction of the joint proceeds basically synchronously, controls the metallurgical reaction time, and avoids the generation of excessive brittle phases.

[0030] 3. The three different solders used in the present invention adjust the content of Zr element in the Ti-based solder to reduce the melting point of the solder, thereby reducing the brazing temperature and improving the corrosion of the base material.

[0031] Note that the description of these effects does not prevent the existence of other effects. One embodiment of the present invention does not necessarily have all of the above effects. Effects other than the above can be clearly seen and extracted from the description of the specification, drawings, claims, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the titanium alloy current-assisted vacuum brazing process method of the present invention.

[0033] Figure 2 This is a top view design diagram of the titanium alloy current-assisted vacuum brazing tooling of the present invention.

[0034] Figure 3 This is a temperature setting curve diagram for current-assisted vacuum brazing of titanium alloy according to the present invention.

[0035] Figure 4 This is the interface metallographic image of the titanium alloy brazing joint prepared in Example 1.

[0036] Figure 5 This is the interface metallographic image of the titanium alloy brazing joint prepared in Example 2.

[0037] Figure 6 This is the interface metallographic image of the titanium alloy brazing joint prepared in Example 3.

[0038] The numbers in the figure represent:

[0039] In the figure, 1-steel; 2-through hole for placing the sample; 3-through hole for placing the thermocouple. DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0041] Example 1

[0042] A titanium alloy current-assisted vacuum brazing process method comprises the following steps:

[0043] Step S1: processing a pair of titanium alloy columns to be welded with a diameter R of 10 mm and a height L of 30 mm as a base material;

[0044] Step S2: using TiZrCuNi (titanium zirconium copper nickel) brazing alloy powder to prepare a brazing intermediate layer, the alloy melting point T0 is 800-820°C;

[0045] Step S3: grinding the welding surface of the titanium alloy column to be welded with sandpaper, cleaning the ground surface with alcohol and blowing it dry;

[0046] Step S4: assembling the workpieces to be welded, placing the welding surface of one titanium alloy base material to be welded in each titanium alloy column facing upward, evenly smearing the brazing alloy powder of the middle layer, and placing the welding surface of the other titanium alloy base material facing downward on the middle layer to form a workpiece to be welded with a three-layer structure of upper, middle and lower layers;

[0047] Step S5: placing the workpiece to be welded assembled in step S4 in the sample placement through hole 2 of the titanium alloy current-assisted vacuum brazing tool, inserting the thermocouple into the thermocouple placement through hole 3 of the titanium alloy current-assisted vacuum brazing tool, and then placing the whole in a vacuum hot-pressing brazing furnace, with graphite pads respectively provided on the top of the upper parent material and the bottom of the lower parent material, and the electrode pressure head contacts the graphite pad on the top of the upper parent material, so that the current passes through the titanium alloy column to be welded to form a loop;

[0048] Step S6: Start the vacuum hot-pressing brazing furnace, set the brazing parameters and the welding temperature T1, and perform current-assisted vacuum brazing of the titanium alloy to obtain a titanium alloy workpiece.

[0049] In the step S1, the titanium alloy is TA2.

[0050] In the step S2, the TiZrCuNi alloy composition is 37.5Ti37.5Zr15Cu10Ni.

[0051] In step S3, the roughness of the surface to be welded is polished with sandpaper to be below Ra1.6.

[0052] The titanium alloy current-assisted vacuum brazing tooling is made of H13 steel, has a height of 55 mm, an inner diameter of the sample placement through hole 2 is 11 mm, and a diameter of the thermocouple placement through hole 3 is 4 mm.

[0053] In this embodiment, in step S6, the vacuum degree of the vacuum hot-pressing brazing furnace is 0.002 Pa, the heating rate is 10°C / min, the current is set to 1500A, the brazing temperature T1 is 890°C, and the holding time is 20min. Figure 3 shown.

[0054] In this embodiment, in step S6, the titanium alloy workpiece is prepared, the brazing material and the base material form a good metallurgical bond, no defects such as pores and welding cracks appear on the brazing interface, no obvious residual brazing material is present at the weld, the structure is dense and defect-free, and the metallographic structure is as follows: Figure 4 shown.

[0055] Example 2

[0056] The specific preparation steps are the same as those in Example 1. The difference between this example and Example 1 is that:

[0057] The Ti-based brazing filler metal composition in step S2 is 15Ti64Zr8Cu13Ni to explore the influence of different brazing filler metal compositions on the microstructure and properties of the prepared titanium alloy brazed joints. The brazing temperature T1 is set to 890°C, the holding time is 20 min, and the other parameters are the same as those in Example 1.

[0058] The microstructure of the titanium alloy workpiece welded joint prepared using the brazing filler metal and brazing parameters is as follows: Figure 5 As shown, the brazing filler metal and the base material form a good metallurgical bond, there are no defects such as pores and welding cracks at the brazing interface, there is no obvious residual brazing filler metal at the weld, and the structure is dense and defect-free.

[0059] Example 3

[0060] The specific preparation steps are the same as those in Example 1. The difference between this example and Example 1 is that:

[0061] The Ti-based brazing filler metal composition in step S2 is 22Ti54Zr8Cu16Ni in order to explore the influence of different brazing filler metal compositions on the microstructure and properties of the prepared titanium alloy brazed joints. The brazing temperature T1 is set to 890°C, the holding time is 20 min, and the other parameters are the same as those in Example 1.

[0062] The microstructure of the titanium alloy workpiece welded joint prepared using the brazing filler metal and brazing parameters is as follows: Figure 6 As shown, the brazing filler metal and the base material form a good metallurgical bond, there are no defects such as pores and welding cracks at the brazing interface, there is no obvious residual brazing filler metal at the weld, and the structure is dense and defect-free.

[0063] In Examples 1-3 of the present invention, three kinds of alloy brazing materials are designed, and the main welding process parameters are specified: brazing temperature 890°C, holding time 20min. The present invention provides titanium alloy current-assisted vacuum brazing process steps, which can be applied to the preparation of high-efficiency titanium alloy heat exchanger materials, and the welded joint structure obtained by the existing method is more dense and seamless.

[0064] It can be seen that the titanium alloy TA2 of the present invention is brazed by current-assisted vacuum brazing, which takes advantage of the current-assisted vacuum brazing technology, reduces the brazing temperature to process the titanium alloy TA2, reduces the residual amount of brazing material and the melting of the base material, and has simple preparation, short process and high efficiency. The radiation heating and the pressure head conduction current auxiliary heating are used to make the workpiece evenly heated, quickly heat up, improve welding production efficiency, and reduce welding energy consumption. Therefore, the present invention can fully meet the industry's demand for such materials.

[0065] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0066] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A titanium alloy current-assisted vacuum brazing process, characterized in that: The following steps are involved: Step S1: processing at least one pair of titanium alloy columns to be welded with a diameter of R and a height of L as a base material; Step S2: using TiZrCuNi solder alloy powder to prepare a brazing intermediate layer, the alloy melting point is T0; Step S3: grinding the welding surface of the titanium alloy column to be welded with sandpaper, cleaning the ground surface with alcohol and blowing it dry; Step S4: assembling the workpieces to be welded, placing the welding surface of one titanium alloy base material to be welded in each titanium alloy column facing upward, evenly smearing the brazing alloy powder of the middle layer, and placing the welding surface of the other titanium alloy base material facing downward on the middle layer to form a workpiece to be welded with a three-layer structure of upper, middle and lower layers; Step S5: placing the workpiece to be welded assembled in step S4 in a titanium alloy current-assisted vacuum brazing tool, inserting a thermocouple into the titanium alloy current-assisted vacuum brazing tool, and then placing the whole workpiece in a vacuum hot-pressing brazing furnace, with graphite pads respectively provided on the top of the upper parent material and the bottom of the lower parent material, and the electrode pressure head contacts the graphite pad on the top of the upper parent material, so that the current passes through the titanium alloy column to be welded to form a loop; Step S6: Start the vacuum hot-pressing brazing furnace, set the brazing parameters and the welding temperature T1, and perform current-assisted vacuum brazing of the titanium alloy to obtain a titanium alloy workpiece.

2. The titanium alloy current-assisted vacuum brazing process according to claim 1, characterized in that: In step S1, the titanium alloy is TA2, the base material diameter R is 10 mm, and the height L is 30 mm.

3. The titanium alloy current-assisted vacuum brazing process according to claim 1, characterized in that: The weight of the TiZrCuNi solder alloy powder in step S2 is 0.05 g.

4. The titanium alloy current-assisted vacuum brazing process according to claim 1, characterized in that: In the step S2, the composition of the TiZrCuNi alloy is 37.5Ti37.5Zr15Cu10Ni, 15Ti64Zr8Cu13Ni or 22Ti54Zr8Cu16Ni.

5. The titanium alloy current-assisted vacuum brazing process according to claim 1, characterized in that: In the step S2, the alloy melting point T0 is 800-820°C.

6. The titanium alloy current-assisted vacuum brazing process according to claim 1, characterized in that: In the step S3, the welding surface roughness of the titanium alloy columnar body to be welded is polished with sandpaper to be less than Ra1.

6.

7. The titanium alloy current-assisted vacuum brazing process according to claim 1, characterized in that: In step S6, the vacuum degree of the vacuum hot-pressing brazing furnace is 0.002 Pa, the heating rate is 10°C / min, the current is set to 1500A, the brazing temperature T1 is 890°C, and the holding time is 20min.

8. A titanium alloy current-assisted vacuum brazing tool, characterized in that: Used to place the assembled workpiece to be welded in the titanium alloy current-assisted vacuum brazing process method described in any one of claims 1 to 7, comprising a steel material (1); a plurality of sample placement through holes (2) and thermocouple placement through holes (3) are processed on the steel material (1), the sample placement through holes (2) and the thermocouple placement through holes (3) are connected to each other, the sample placement through holes (2) are used to place the assembled workpiece to be welded with a three-layer structure of upper, middle and lower, and the thermocouple placement through holes (3) are used to place thermocouples.

9. The titanium alloy current-assisted vacuum brazing process according to claim 1, characterized in that: The steel material (1) is H13; the inner diameter of the sample placement through hole (2) is 11 mm, and the diameter of the thermocouple placement through hole (3) is 4 mm.

10. A titanium alloy brazed joint, characterized in that: Prepared by the titanium alloy current-assisted vacuum brazing process method according to any one of claims 1 to 7.

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