Mo-14Re alloy vacuum electron beam welding process

Abstract

The invention belongs to the technical field of nuclear fuel manufacturing, aims to solve the problems that pores exist in a molybdenum-rhenium alloy welding seam and the tensile strength of the welding seam is low, and discloses a Mo-14Re alloy vacuum electron beam welding process. Welding raw materials are assembled according to the requirements of a design drawing, a welding piece is installed on a welding machine tool clamp, a preheating electron beam shifts towards the end plug, electron beam preheating process parameters are set, and the electron beam is used for welding. Mo-14Re alloy welding seams welded through the welding process are good in appearance forming, no continuous or two or more air holes larger than 0.5 mm are generated, incomplete penetration, cracks and air expansion do not exist, and the tensile strength is not lower than 500 MPa.

Description

Technical Field

[0001] The present application belongs to the field of nuclear fuel manufacturing technology, and in particular relates to a Mo-14Re alloy vacuum electron beam welding process. Background Art

[0002] Molybdenum-rhenium alloy has a high melting point, excellent high-temperature mechanical properties, good thermal conductivity, good resistance to radiation swelling, good compatibility with UO2 and alkaline liquid metals, and the Re element is a good spectral shift absorber material, which can effectively reduce the risk of reactor critical accidents, making it the best candidate material for reactor core structures for fourth-generation high-temperature nuclear fission reactors, fusion reactors, space nuclear power sources, etc., to meet the preparation needs of structural parts in harsh environments such as high temperature, strong corrosion, and high-dose radiation.

[0003] Up to now, some achievements have been made in the field of molybdenum alloy welding, but there are relatively few literatures on the research of molybdenum-rhenium alloy welding. In the past, the preparation of molybdenum-rhenium alloy was mainly based on traditional powder metallurgy method. Therefore, the available research on molybdenum-rhenium alloy welding process is based on materials prepared by powder metallurgy method. There are a lot of pores, and the tensile strength does not meet the strength required by the engineering. Summary of the Invention

[0004] The purpose of this application is to provide a Mo-14Re alloy vacuum electron beam welding process to solve the problems of porosity and low tensile strength of molybdenum-rhenium alloy welds.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] A Mo-14Re alloy vacuum electron beam welding process, comprising:

[0007] Step 1: Use acetone reagent to ultrasonically clean, then rinse with running water, blow dry, and store in an oven before starting welding;

[0008] Step 2: Assemble the welding raw materials according to the design drawings and install the welded parts on the welding machine fixture;

[0009] Step 3: Close the door and vacuum;

[0010] Step 4: Deflect the preheating electron beam toward the end plug. The electron beam preheating process parameters are an acceleration voltage of 55mV to 60mV, a welding current of 9mA to 11mA, and a set speed.

[0011] Step 5: Use electron beam welding with an acceleration voltage of 55mV to 60mV, a welding current of 24mA to 28mA, and set the rotation speed.

[0012] According to one embodiment of the present application, in step 1, ultrasonic cleaning is performed using acetone reagent for 20 minutes to 30 minutes.

[0013] According to one embodiment of the present application, in step 1, use tap water to rinse and strong hot air to dry.

[0014] According to one embodiment of the present application, in step 3, the vacuum degree reaches 2.0×10 -5 .

[0015] According to one embodiment of the present application, in step 3, the welding machine is vacuumed to 2.0×10 -5 And keep it for more than 10 minutes.

[0016] According to one embodiment of the present application, in step 4, the rotation speed is set to 2000° / min.

[0017] According to one embodiment of the present application, in step 4, the electron beam preheating process parameters are an acceleration voltage of 55 mV and a welding current of 9 mA.

[0018] According to one embodiment of the present application, in step 5, welding is performed using an acceleration voltage of 55 mV, a welding current of 24 mA, and a rotation speed of 2000° / min.

[0019] According to one embodiment of the present application, in step 4, the electron beam preheating process parameters are an acceleration voltage of 60 mV and a welding current of 11 mA.

[0020] According to one embodiment of the present application, in step 5, welding is performed using an acceleration voltage of 60 mV, a welding current of 28 mA, and a rotation speed of 2000° / min.

[0021] According to one embodiment of the present application, in step 4, the weld is preheated.

[0022] According to one embodiment of the present application, in step 5, the rotation speed is set to 2000° / min.

[0023] Compared with the prior art, the Mo-14Re alloy vacuum electron beam welding process provided in this application has the following beneficial effects:

[0024] The Mo-14Re alloy weld welded using the welding process of the present application has a good appearance, no continuous or more than two pores larger than 0.5 mm are generated, there is no incomplete penetration, cracks, or bulging, and the tensile strength is not less than 500 MPa.

[0025] The welding process of the present application provides a beam offset scanning preheating method to preheat the weld to reduce the temperature gradient of the welding base material and solve the problem of weld appearance formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings required for the technical description.

[0027] Figure 1 Mo-14Re alloy vacuum electron beam welding flow chart provided for this application;

[0028] Figure 2 Schematic diagram of the vacuum electron beam welding process for Mo-14Re alloy provided in this application;

[0029] Figure 3 Schematic diagram of the lower limit parameter metallographic detection of weld penetration provided in the embodiment of the present application;

[0030] Figure 4 Schematic diagram of the upper limit parameter metallographic detection of weld penetration provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] The following is further explained in detail through specific implementation methods.

[0032] like Figure 1 and Figure 2 As shown, the present application provides a Mo-14Re alloy vacuum electron beam welding process, comprising:

[0033] Step 1: Ultrasonic clean the components to be welded using acetone for 20 to 30 minutes. Rinse with tap water and blow dry with strong hot air. Store in an oven until welding begins.

[0034] Step 2: Assemble the welding raw materials according to the design drawings and install the welded parts on the welding machine fixture.

[0035] Step 3: Close the door and vacuum.

[0036] Step 4: offset the preheating electron beam toward the end plug. The electron beam preheating process parameters are acceleration voltage 55mV~60mV, welding current 9mA~11mA, and rotation speed 2000° / min.

[0037] Step 5: Use electron beam welding with an acceleration voltage of 55mV to 60mV, a welding current of 24mA to 28mA, and a rotation speed of 2000° / min.

[0038] In step 1, because molybdenum-rhenium alloys are susceptible to oxidation and nitridation at high temperatures, welding must be performed in a vacuum. Therefore, ultrasonic cleaning with acetone is used. To remove oxides and impurities from the parent metal surface, surface degreasing and chemical cleaning are required before welding.

[0039] In step 2, the welding raw materials are assembled according to the requirements of the design drawings, and the welded parts are installed in the welding machine fixture. The fixture and the top block are used to act on the end plug and the cladding tube to make the weld contact surface close to each other.

[0040] In step 3, since molybdenum-rhenium alloy is a refractory material that is easily oxidized during high temperature welding, welding needs to be performed in a vacuum environment. In step 3, the door is closed and the vacuum is drawn to a degree of 2.0×10 -5 .

[0041] In step 4, since the thermal conductivity of molybdenum-rhenium alloy is high, in order to eliminate the influence of temperature gradient on weld quality, preheating treatment is required before formal welding. Step 4 preheats the weld.

[0042] The welding process parameters used in step 5 are the molybdenum-rhenium alloy welding process parameters suitable for the specifications and dimensions of this application, which are established through a series of welding process optimizations in order to obtain the welding performance requirements.

[0043] Example 1

[0044] The welding test pieces were cleaned with acetone ultrasonic for 20 min, assembled and placed in the welding chamber, and the welding machine was vacuumed to 2.0×10 -5 And keep it for more than 10 minutes, the preheating electron beam is offset towards the end plug, the electron beam preheating process parameters are acceleration voltage 55mV, welding current 9mA, speed 2000° / min; use acceleration voltage 55mV, welding current 24mA, speed 2000° / min for welding, metallographic inspection weld penetration, such as Figure 3 As shown, the tensile strength reaches 561.4MPa.

[0045] Example 2

[0046] The welding test pieces were cleaned with acetone ultrasonic for 20 min, assembled and placed in the welding chamber, and the welding machine was vacuumed to 2.0×10 -5 And keep it for more than 10 minutes, the preheating electron beam is offset towards the end plug, the electron beam preheating process parameters are acceleration voltage 60mV, welding current 11mA, speed 2000° / min; use acceleration voltage 60mV, welding current 28mA, speed 2000° / min for welding, metallographic inspection weld penetration, such as Figure 4 As shown, the tensile strength reaches 623.4MPa.

[0047] Therefore, the welding process of the present application provides a welding process parameter of voltage, current and rotation speed suitable for vacuum electron beam welding of Mo-14Re alloy.

[0048] The above description is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in this application should be covered by the scope of protection of the present application.

Claims

1. A Mo-14Re alloy vacuum electron beam welding process, characterized in that: include: Step 1: Use acetone reagent to ultrasonically clean, then rinse with running water, blow dry, and store in an oven before starting welding; Step 2: Assemble the welding raw materials according to the design drawings and install the welded parts on the welding machine fixture; Step 3: Close the door and vacuum; Step 4: Deflect the preheating electron beam toward the end plug. The electron beam preheating process parameters are an acceleration voltage of 55mV to 60mV, a welding current of 9mA to 11mA, and a set speed. Step 5: Use electron beam welding with an acceleration voltage of 55mV to 60mV, a welding current of 24mA to 28mA, and set the rotation speed.

2. The Mo-14Re alloy vacuum electron beam welding process according to claim 1, characterized in that: In step 1, ultrasonic cleaning is performed using acetone reagent for 20 to 30 minutes.

3. The Mo-14Re alloy vacuum electron beam welding process according to claim 1, characterized in that: In step 1, rinse with running water and blow dry with strong hot air.

4. The Mo-14Re alloy vacuum electron beam welding process according to claim 1, characterized in that: In step 3, the vacuum degree reaches 2.0×10 -5 .

5. The Mo-14Re alloy vacuum electron beam welding process according to claim 1, characterized in that: In step 3, the welding machine is vacuumed to 2.0×10 -5 And keep it for more than 10 minutes.

6. The Mo-14Re alloy vacuum electron beam welding process according to claim 1, characterized in that: In step 4, set the rotation speed to 2000° / min.

7. The Mo-14Re alloy vacuum electron beam welding process according to claim 1, characterized in that: In step 4, the electron beam preheating process parameters are an acceleration voltage of 55 mV and a welding current of 9 mA.

8. The Mo-14Re alloy vacuum electron beam welding process according to claim 7, characterized in that: In step 5, welding is performed using an acceleration voltage of 55 mV, a welding current of 24 mA, and a rotation speed of 2000° / min.

9. The Mo-14Re alloy vacuum electron beam welding process according to claim 1, characterized in that: In step 4, the electron beam preheating process parameters are an acceleration voltage of 60 mV and a welding current of 11 mA.

10. The Mo-14Re alloy vacuum electron beam welding process according to claim 9, characterized in that: In step 5, welding is performed using an acceleration voltage of 60 mV, a welding current of 28 mA, and a rotation speed of 2000° / min.

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