Process for connecting fusion reactor material copper and steel through low-activation brazing filler metal and tool racking device

Abstract

The invention discloses a process for connecting fusion reactor material copper and steel through low-activation brazing filler metal and a tool racking device, and relates to the field of metal welding. The process comprises the following steps: preparing a copper block, a steel block and low-activation brazing filler metal required by vacuum brazing, grinding and polishing a to-be-welded surface, cleaning and packaging for later use; the low-activation brazing filler metal is placed between the copper block and the steel block to be overlapped, positioned and pressed; a vacuum brazing method is adopted for welding treatment; and the welded workpiece is subjected to vacuum solid solution and aging heat treatment. A positioning reference piece and an adjustable positioning assembly in the tool mounting frame device are arranged on the two opposite sides of a bottom plate correspondingly, the multiple positioning locking pieces are arranged on the periphery of the upper surface of the bottom plate, and a pressing plate is connected with the tops of the positioning locking pieces. The method is used for solving the problems of low activation requirements of fusion reactor materials and reduction of high-level reaction products generated between brazing filler metal and copper and steel, effectively improves the slow-release stress capacity, and can complete connection between copper and steel without brazing flux assistance.

Description

Technical Field

[0001] The invention belongs to the field of metal welding, and in particular relates to a process and a tooling mounting device for connecting fusion reactor material copper and steel by using low-activated solder. Background Art

[0002] In the Chinese Fusion Engineering Test Reactor and various demonstration reactors abroad, the first wall module needs to withstand 14MeV neutrons and other high-energy particle irradiation generated by the deuterium + tritium reaction, and can effectively transfer the heat absorbed by the first wall to the cooling system to ensure the safe operation of the fusion reactor. Therefore, the local components of the first wall module are usually connected by two different types of materials: one is a material with excellent thermal conductivity and high-temperature strength, such as chromium zirconium copper, which is used to efficiently conduct heat; the other is a structural material, such as low-activated ferrite or martensitic steel, which is used to provide sufficient strength and stability. However, copper and steel are two dissimilar metal materials with large differences in thermophysical properties. Not only do they have large differences in linear expansion coefficients, which will produce large thermal stresses, but they will also generate brittle reaction products, thereby weakening the welding performance of the joints.

[0003] In current domestic and international research, vacuum brazing is considered to be a potential copper / steel connection technology. However, the selection of brazing filler metal is a big problem, because the brazing filler metal not only needs to be able to improve the welding performance of copper / steel, such as increasing the connection strength, reducing the interface reaction products, relieving thermal stress, etc., but also needs to be able to adapt to the demanding requirements of the first wall material service environment of future fusion reactors. Including:

[0004] Low activation: Since the D+T reaction will produce 14MeV neutrons, the material elements are required to have low activation to meet the standards for low-emission nuclear waste;

[0005] Thermal shock resistance: D, T impurity particle flow requires the material to have good thermal shock resistance under plasma irradiation conditions.

[0006] However, the intermediate layer materials currently used in copper / steel connections cannot meet the above requirements:

[0007] Ag-based solder: Although Ag-based solder has good wettability and fluidity and can form a strong bond at the solder joint, Ag is a highly activated element and is not suitable for the future fusion reactor's demand for low-activated materials.

[0008] Ni-based brazing filler metal: Ni-based brazing filler metal has excellent high temperature resistance and corrosion resistance, and is suitable for harsh working environments. However, it is easy to form brittle reaction products such as Ni3Cu and Ni3Cr, which weaken the performance of the joint and reduce the strength and toughness of the welded joint.

[0009] Therefore, the existing copper / steel connection technology has the problem of difficulty in selecting solder, and there is an urgent need for a new method to connect copper and steel materials in fusion reactors that can meet the material requirements of the first wall of future fusion reactors. Summary of the invention

[0010] The present invention provides a process and a tooling mounting device for connecting fusion reactor material copper and steel using low-activation solder, which solves the problem of low activation requirements for fusion reactor materials and reducing the high-radiation reaction products generated between the solder and the copper and steel, effectively improves the stress release capability, and completes the connection between copper and steel without the assistance of solder.

[0011] The technical solutions used in the present invention are as follows:

[0012] A process for connecting fusion reactor materials copper and steel using low-activation solder, comprising the following steps:

[0013] Step 1: prepare the copper block, steel block and low-activated solder required for vacuum brazing, and then grind and polish the surfaces of the copper block, steel block and low-activated solder to be welded, clean them after grinding and polishing, and package them for standby use;

[0014] Step 2: Place the low-activated solder between the copper block and the steel block, overlap them, and place them in a tooling mounting device for positioning and pressing;

[0015] Step 3, using vacuum brazing method to weld the copper block, steel block and low-activation brazing filler metal;

[0016] Step 4: Perform vacuum solution treatment and aging heat treatment on the welded workpiece to achieve the connection between the copper block and the steel block.

[0017] Furthermore, in step 1, the surface roughness of the surfaces to be welded of the copper block, the steel block and the solder after grinding and polishing is Ra≤3.2 μm.

[0018] Furthermore, the steel block is low-activation ferrite or martensitic steel, the copper block is chromium-zirconium-copper, and the low-activation solder is GeCu solder.

[0019] Furthermore, the process parameters of the vacuum brazing method in step three are: vacuum degree ≤10-3Pa, preheating at 300℃-500℃ for 5-10min, welding temperature 1000℃-1100℃, and insulation time 5-30min.

[0020] Furthermore, when the vacuum brazing method is adopted in step three, the heating rate is 10-20°C / min, and the cooling rate is 5-10°C / min.

[0021] Furthermore, after the vacuum brazing method is used for welding in step three, vacuum heat treatment is also required.

[0022] A tooling mounting device is used for the above-mentioned process of connecting copper and steel of fusion reactor materials using low-activation solder, comprising a base plate, a pressure plate, a positioning reference part, an adjustable positioning component and a positioning locking part.

[0023] The positioning reference member and the adjustable positioning assembly are respectively arranged on opposite sides of the base plate. There are multiple positioning locking members, and the multiple positioning locking members are arranged around the upper surface of the base plate. The pressure plate is connected to the top of the positioning locking members.

[0024] Furthermore, the positioning reference member is F-shaped, a protruding portion of the positioning reference member faces the adjustable positioning assembly, and a bottom of the positioning reference member is fixedly connected to one side of the base plate.

[0025] Furthermore, the adjustable positioning assembly includes an adjusting bolt and a support member, the bottom of the support member is fixedly connected to the other side of the base plate, and a plurality of adjusting bolts are provided, and the plurality of adjusting bolts are threadedly connected to the support member.

[0026] Furthermore, the raw material of the tooling mounting device is a high-temperature alloy.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention adopts low-activation solder, such as GeCu solder, which can reduce the reaction products generated between the solder and copper and steel, and is conducive to stress relief, so as to meet the service environment requirements of the first wall material of the fusion reactor, including low activation and thermal shock resistance, and can complete the connection between copper and steel without the assistance of flux, thus providing a new and effective method for the connection of copper and steel in fusion reactors.

[0029] 2. The tool mounting device of the present invention realizes the rapid and accurate positioning of the copper block and the steel block by adopting structures such as a base plate, a pressure plate, a positioning reference part, an adjustable positioning assembly and a positioning locking part, and exerts a stable axial pressure on the tool through the joint action of the pressure plate and the positioning locking part, thereby ensuring the stability of the clamping and improving the quality of the welded joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the application of the tooling mounting device provided by the present invention;

[0031] Figure 2 This is a schematic diagram of the overall structure of the tooling mounting device provided by the present invention.

[0032] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0033] 1. Copper block; 2. Steel block; 3. Low-activated solder; 4. Base plate; 5. Pressing plate; 6. Positioning reference part; 7. Support part; 8. Adjusting bolt; 9. Positioning locking part; 10. Nut; 11. Bolt. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings.

[0036] Example 1

[0037] This embodiment provides a process for connecting fusion reactor material copper and steel using low-activation solder 3, comprising the following steps:

[0038] Step 1: Preparation and polishing

[0039] 1. Prepare the copper block 1, steel block 2 and low-activation solder 3 required for vacuum brazing. Specifically, the steel block 2 is low-activation ferrite or martensitic steel, the copper block 1 is chromium-zirconium copper, and the low-activation solder 3 is GeCu solder.

[0040] Here, GeCu solder is selected as the low-activation solder 3 because: selecting a Cu-based solder from the perspective of chemical compatibility can improve the diffusion between copper and steel. Ge is a low-activation element and can meet the demand for low-activation materials in future fusion reactors. The thermal expansion coefficient of the GeCu alloy is between that of copper and steel, which can alleviate the residual stress problem caused by the difference in thermal expansion coefficients between copper and steel. Therefore, GeCu solder is selected to braze the copper block 1 and the steel block 2.

[0041] 2. The surfaces to be welded of the copper block 1, the steel block 2 and the low-activated solder 3 are ground and polished, and the surface roughness Ra after the grinding and polishing treatment is ≤3.2μm.

[0042] Grinding and polishing can remove impurities such as oxide layer, oil, dust, etc. on the surface to be welded, ensure the cleanliness of the welding surface, and reduce the surface roughness to Ra≤3.2μm, which can reduce defects such as pores and slag inclusions caused by uneven surface during welding, thereby improving the quality and strength of the welded joint.

[0043] 3. After grinding and polishing, clean and vacuum package for standby use to ensure the cleanliness of the surface to be welded and avoid oxidation.

[0044] Step 2: Positioning and pressing

[0045] The low-activated solder 3 is placed between the copper block 1 and the steel block 2 to overlap each other, and the copper block 1 and the steel block 2 are positioned and pressed by a tooling mounting device to ensure accurate alignment of the welding materials and improve the quality of the welding joint.

[0046] Step 3: Vacuum brazing

[0047] 1. The copper block 1, the steel block 2 and the low-activated brazing filler metal 3 are welded by vacuum brazing method. The process parameters of vacuum brazing method are as follows: vacuum degree ≤10-3Pa, preheating at 300℃-500℃ for 5-10min, welding temperature 1000℃-1100℃, holding time 5-30min, heating rate 10-20℃ / min, cooling rate 5-10℃ / min.

[0048] The selection of these parameters can ensure the full melting and diffusion of the solder, while avoiding excessive reaction or deformation of the copper block 1 and the steel block 2 due to high temperature. The welding environment with a vacuum degree of ≤10-3Pa can effectively remove gases such as oxygen and nitrogen during the welding process, preventing them from chemically reacting with the welding material at high temperature to generate compounds that are not conducive to welding quality; the preheating temperature helps the welding material to reach a certain temperature gradient, reduce the thermal stress during the welding process, and prevent cracks in the welded joint. At the same time, the heating rate is controlled at 10-20℃ / min and the cooling rate is controlled at 5-10℃ / min, which can avoid the thermal stress caused by the rapid temperature change during the welding process and ensure the stability and reliability of the welded joint; the welding temperature is controlled at 1000℃-1100℃ to ensure that the low-activated solder 3 can fully melt and fill the gap between the copper block 1 and the steel block 2.

[0049] 2. After welding, vacuum heat treatment is performed.

[0050] Through vacuum heat treatment, the welded joint can undergo plastic deformation at high temperature, thereby releasing and eliminating residual stress, while optimizing the organizational structure of the welded joint, thereby improving the performance of the welded joint.

[0051] Step 4: Vacuum solution and aging heat treatment

[0052] The welded workpieces are subjected to vacuum solution treatment and aging heat treatment to achieve the connection between the copper block 1 and the steel block 2, so as to further improve the structure and performance of the welded joint.

[0053] Through vacuum solution treatment, the copper block 1 and the steel block 2 form a uniform solid solution at the welding joint to achieve reliable metallurgical connection; through aging heat treatment, the elements in the welding joint are precipitated in a more reasonable form, thereby improving the hardness and strength of the welding joint and improving the welding quality.

[0054] Example 2

[0055] like Figure 1 and Figure 2 As shown, this embodiment provides a tooling mounting device for the above-mentioned process of connecting fusion reactor material copper and steel using low-activation solder 3, including a base plate 4, a pressure plate 5, a positioning reference member 6, an adjustable positioning assembly and a positioning locking member 9. The positioning reference member 6 and the adjustable positioning assembly are respectively arranged on opposite sides of the base plate 4. There are multiple positioning locking members 9, and four are arranged in this embodiment. The four positioning locking members 9 are respectively arranged at the four corners of the upper surface of the base plate 4. The pressure plate 5 is connected to the top of each positioning locking member 9, and the up and down adjustment is achieved through a nut 10.

[0056] Specifically, Figure 2 As shown, the positioning reference member 6 is F-shaped, and the protruding portion of the positioning reference member 6 faces the adjustable positioning assembly. In this embodiment, two positioning reference members 6 are provided, and the bottoms of the two positioning reference members 6 are fixedly connected to one side of the base plate 4 by bolts 11.

[0057] In this embodiment, two groups of adjustable components corresponding to the positioning reference member 6 are also provided. The adjustable positioning components include adjusting bolts 8 and support members 7. The bottom of the support member 7 is fixedly connected to the other side of the base plate 4 by bolts 11. There are multiple adjusting bolts 8. In this embodiment, each group of adjustable positioning components includes two adjusting bolts 8. Each adjusting bolt 8 is threadedly connected to the support member 7 and is opposite to the protruding part of the positioning reference member 6, thereby realizing the positioning and fixation of the copper block 1 and the steel block 2.

[0058] Specifically, in order to ensure that the tooling mounting device can withstand the pressure in a high temperature environment and maintain the stability and precision of the structure, the material of the tooling mounting device is a high temperature alloy.

[0059] The operating principle of this embodiment is as follows.

[0060] In the process of using low-activation solder 3 to connect fusion reactor materials copper and steel, the low-activation solder 3 needs to be placed between the copper block 1 and the steel block 2 to overlap each other, and then placed into a tooling mounting device to position and press the copper block 1 and the steel block 2.

[0061] Specifically, Figure 1As shown, the superimposed copper block 1, steel block 2 and low-activated solder 3 are placed on the bottom plate 4, and the copper block 1 and the steel block 2 are quickly positioned using the positioning reference part 6 and the adjustable positioning assembly, wherein one side of the copper block 1 and the steel block 2 is affixed to the positioning reference part 6, and the positioning reference part 6 provides an accurate reference point for the placement of the copper block 1 and the steel block 2, which can ensure the flatness of the copper block 1 and the steel block 2 in the tooling mounting device, and then the adjusting bolt 8 is rotated so that the adjusting bolt 8 is tightly against the other side of the copper block 1 and the steel block 2, and the adjustable assembly works together with the positioning reference part 6 to provide a uniform clamping force for the copper block 1 and the steel block 2 to complete the positioning, and by adjusting the position and tightness of the adjusting bolt 8, it is possible to flexibly cope with workpieces of different sizes, thereby improving the versatility and practicality of the tooling mounting device.

[0062] The nut 10 is turned to slide the pressing plate 5 downward on the positioning and locking member 9 until it is close to the upper surface of the copper block 1 and the steel block 2 after being overlapped, and the pressing plate 5 works together with the bottom plate 4 to apply axial pressure to the tooling to position and press it. All the links of step 3 in the process of connecting the fusion reactor material copper and steel using the low-activated solder 3 are completed.

[0063] The above two embodiments of the present invention are described in detail, but the contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A process for connecting fusion reactor materials copper and steel using low-activation solder, characterized in that: The following steps are involved: Step 1: preparing the copper block (1), steel block (2) and low-activated solder (3) required for vacuum brazing, and then grinding and polishing the surfaces to be welded of the copper block (1), steel block (2) and low-activated solder (3), cleaning them after grinding and polishing, and packaging them for standby use; Step 2: placing the low-activation solder (3) between the copper block (1) and the steel block (2) to overlap each other, and placing them into a tooling mounting device for positioning and pressing; Step 3: Using vacuum brazing method to weld the copper block (1), the steel block (2) and the low-activation brazing material (3); Step 4: Perform vacuum solution treatment and aging heat treatment on the welded workpiece to achieve the connection between the copper block (1) and the steel block (2).

2. A process for connecting fusion reactor material copper and steel using low-activation solder according to claim 1, characterized in that: In step 1, the surfaces to be welded of the copper block (1), the steel block (2) and the solder are ground and polished to have a surface roughness Ra≤3.2 μm.

3. The process for connecting fusion reactor material copper and steel using low-activation solder according to claim 1, characterized in that: The steel block (2) is low-activation ferrite or martensitic steel, the copper block (1) is chromium-zirconium-copper, and the low-activation solder (3) is GeCu solder.

4. A process for connecting fusion reactor material copper and steel using low-activation solder according to claim 1, characterized in that: The process parameters of the vacuum brazing method in step three are: vacuum degree ≤10-3Pa, preheating at 300℃-500℃ for 5-10min, welding temperature 1000℃-1100℃, and insulation time 5-30min.

5. A process for connecting fusion reactor material copper and steel using low-activation solder according to claim 1 or 4, characterized in that: When the vacuum brazing method is used in step 3, the heating rate is 10-20°C / min, and the cooling rate is 5-10°C / min.

6. The process for connecting fusion reactor material copper and steel using low-activation solder according to claim 1, characterized in that: After the vacuum brazing method is used for welding in step 3, vacuum heat treatment is required.

7. A tooling and mounting device for use in the process of connecting fusion reactor material copper and steel using low-activation solder according to any of the preceding claims, characterized in that: It comprises a base plate (4), a pressure plate (5), a positioning reference member (6), an adjustable positioning component and a positioning locking member (9), The positioning reference member (6) and the adjustable positioning assembly are respectively arranged on opposite sides of the base plate (4), a plurality of positioning locking members (9) are provided, and the plurality of positioning locking members (9) are arranged around the upper surface of the base plate (4), and the pressure plate (5) is connected to the top of the positioning locking members (9).

8. The tooling mounting device according to claim 7, characterized in that: The positioning reference member (6) is F-shaped, the protruding portion of the positioning reference member (6) faces the adjustable positioning assembly, and the bottom of the positioning reference member (6) is fixedly connected to one side of the base plate (4).

9. A tool mounting device according to claim 8, characterized in that: The adjustable positioning assembly comprises an adjusting bolt (8) and a support member (7); the bottom of the support member (7) is fixedly connected to the other side of the base plate (4); a plurality of adjusting bolts (8) are provided, and the plurality of adjusting bolts (8) are threadedly connected to the support member (7).

10. The tool mounting device according to claim 7, characterized in that: The raw material of the tooling mounting device is high temperature alloy.

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