Method for improving electron beam welding performance of Mo-14Re alloy pipe

Abstract

The application discloses a method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes, and the method is characterized by heat treatment after electron beam welding of the smelted Mo-14Re alloy pipes. The method can significantly improve the mechanical properties of the smelted Mo-14Re alloy pipes after welding, so that the tensile strength of the smelted Mo-14Re alloy pipes after welding is not less than 80% of the tensile strength before welding, and the yield strength of the smelted Mo-14Re alloy pipes after welding is not less than 70% of the yield strength before welding. The method can avoid the phenomenon that the smelted Mo-14Re alloy material has high impurity content, and welding pores, cracks and other defects are prone to occur, thereby affecting the welding performance, and is suitable for the technical field of Mo-14Re alloy pipe welding.

Description

Technical Field

[0001] This invention belongs to the field of refractory metal preparation technology, and in particular relates to a method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes. Background Technology

[0002] The preferred reactor type for fourth-generation advanced nuclear energy systems is the fast neutron reactor, representing the development direction of fourth-generation nuclear energy systems. Because this reactor type uses a closed-loop fuel cycle, it can increase the utilization rate of uranium resources to over 60% and minimize the amount of nuclear waste generated, thus achieving the goal of minimizing radioactive waste.

[0003] Molybdenum-rhenium alloys possess excellent high-temperature performance and resistance to neutron radiation, making them the preferred material for fast neutron reactors. In nuclear reactors, molybdenum-rhenium alloys are primarily used in the form of tubes, plates, and bars. Currently, molybdenum-rhenium alloy materials have a high impurity content, making them highly susceptible to defects such as weld porosity and cracks, which severely affect weldability. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for improving the electron beam welding performance of molten Mo-14Re alloy pipes. This method, by heat-treating the molten Mo-14Re alloy pipes after electron beam welding, can significantly improve the mechanical properties of the welded molten Mo-14Re alloy pipes, solving the problem of weld defects such as porosity and cracks that are prone to occur after welding molybdenum-rhenium alloys.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a method for improving the electron beam welding performance of molten Mo-14Re alloy pipes, characterized in that the molten Mo-14Re alloy pipes are subjected to heat treatment after electron beam welding.

[0006] The above-mentioned method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes is characterized in that the smelted Mo-14Re alloy pipes are prepared by electron beam melting ingot casting, extrusion, forging and rolling.

[0007] The above-mentioned method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes is characterized in that the rolling process is carried out using hydrogen flame heating, and the rolling temperature is 800℃~900℃.

[0008] The above-mentioned method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes is characterized in that the electron beam welding parameters are: focusing current 600mA~700mA, moving speed 10rpm / min~50rpm / min, sealing current 4mA~8mA, formal welding current 5mA~10mA, and total electron beam welding time 2s~4s.

[0009] The above-mentioned method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes is characterized in that the electron beam welding involves two formal welding processes.

[0010] This invention achieves a smooth surface finish and eliminates collapse after two formal welding processes.

[0011] The above-mentioned method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes is characterized in that the heat treatment method is: a vacuum degree of 5.0 × 10⁻⁶. -3 Pa ~ 1.0 × 10 -2 Under the condition of Pa, the temperature is increased to 900℃~1100℃ at a rate of 10℃ / min~12℃ / min, held for 1h~2h and then cooled with the furnace.

[0012] By optimizing the heat treatment process parameters, this invention can significantly improve the elongation of welded and melted Mo-14Re alloy pipes. For welded and melted Mo-14Re alloy pipes that have not undergone heat treatment, the elongation is increased by about 40%.

[0013] The above-mentioned method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes is characterized in that the room temperature tensile strength of the heat-treated smelted Mo-14Re alloy pipes is not less than 606 MPa, the yield strength is not less than 450 MPa, and the elongation is not less than 2%.

[0014] Compared with the prior art, the present invention has the following advantages: 1. By optimizing electron beam welding parameters and combining them with appropriate heat treatment parameters, this invention enables the tensile strength of the welded molten Mo-14Re alloy pipe to be no less than 80% of the tensile strength before welding, and the yield strength of the welded molten Mo-14Re alloy pipe to be no less than 70% of the yield strength before welding.

[0015] 2. The present invention uses molten Mo-14Re alloy pipes prepared by electron beam melting and casting, extrusion, forging and rolling. Compared with pipes prepared by powder metallurgy, molten Mo-14Re alloy pipes have no internal pore defects, smooth surface, better welding quality and no collapse at the weld.

[0016] 3. This invention uses electron beam welding to directly weld Mo-14Re alloy pipes without preheating, saving welding time. In addition, electron beam welding does not require the addition of any elements or other materials at the weld, reducing the addition of unnecessary impurity elements and avoiding the impact of other elements and materials on weld quality.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a macroscopic view of the Mo-14Re alloy pipe after heat treatment in Embodiment 1 of the present invention.

[0019] Figure 2 The image shows the metallographic structure of the Mo-14Re alloy pipe after heat treatment in Embodiment 1 of the present invention. Detailed Implementation

[0020] Example 1 The method for improving the electron beam welding performance of smelted Mo-14Re alloy tubes in this embodiment is as follows: the ends of two smelted Mo-14Re alloy tubes to be welded are ground with 2000# wet sandpaper to remove oxide scale, and ultrasonically cleaned with alcohol as the medium. Then, the two smelted Mo-14Re alloy tubes are clamped parallel to each other on the fixture in the chamber of the electron beam welding machine, with the weld seam clamped parallel to ensure that the tubes are on the same plane during rotary welding. The smelted Mo-14Re alloy tubes are prepared by electron beam melting ingot casting, extrusion, forging, and rolling at 800℃~900℃. The dimensions of the smelted Mo-14Re alloy tubes are: diameter 13.8mm, thickness 0.8mm, and length 100mm. Electron beam welding and heat treatment were then performed sequentially. The electron beam welding parameters were: focusing current 600mA, moving speed 10rpm / min, sealing current 4mA, and formal welding current 5mA. The total electron beam welding time was 2s, and the electron beam welding consisted of two formal welding passes. The heat treatment method was: vacuum degree 5.0×10⁻⁶. -3 Under the condition of Pa, the temperature is increased to 900℃ at a rate of 10℃ / min, held at that temperature for 1 hour, and then cooled with the furnace.

[0021] Upon inspection, the room temperature tensile test results of the heat-treated smelted Mo-14Re alloy pipe in this embodiment were as follows: tensile strength of 606 MPa, yield strength of 405 MPa, and elongation of 6%.

[0022] The heat-treated smelted Mo-14Re alloy pipe of this embodiment, such as Figure 1 As shown, the surface welding quality of the smelted Mo-14Re alloy pipe is good, with no defects such as collapse or pitting; microscopic analysis of the smelted Mo-14Re alloy pipe reveals, for example... Figure 2 As shown, the grains in the heat-affected zone and weld are smaller after heat treatment, which effectively improves the elongation of the smelted Mo-14Re alloy pipe.

[0023] Example 2 The method for improving the electron beam welding performance of smelted Mo-14Re alloy tubes in this embodiment is as follows: the ends of two smelted Mo-14Re alloy tubes to be welded are ground with 2000# wet sandpaper to remove oxide scale, and ultrasonically cleaned with alcohol as the medium. Then, the two smelted Mo-14Re alloy tubes are clamped parallel to each other on the fixture in the chamber of the electron beam welding machine, with the weld seam clamped parallel to ensure that the tubes are on the same plane during rotary welding. The dimensions of the smelted Mo-14Re alloy tubes are prepared by electron beam melting ingot casting, extrusion, forging, and rolling at 800℃~900℃. The dimensions of the smelted Mo-14Re alloy tubes are: diameter 13.8mm, thickness 0.8mm, and length 100mm. Electron beam welding and heat treatment were then performed sequentially. The parameters for electron beam welding were: focusing current 700mA, moving speed 30rpm / min, sealing current 8mA, and formal welding current 10mA. The total electron beam welding time was 4s, and the electron beam welding consisted of two formal welding passes. The heat treatment method was: vacuum degree 1.0×10⁻⁶. -2 Under the condition of Pa, the temperature was increased to 1100℃ at a rate of 12℃ / min, held for 1 hour, and then cooled with the furnace.

[0024] Upon inspection, the room temperature tensile test results of the heat-treated smelted Mo-14Re alloy pipe in this embodiment were as follows: tensile strength of 698 MPa, yield strength of 488 MPa, and elongation of 2%.

[0025] Example 3 The method for improving the electron beam welding performance of smelted Mo-14Re alloy tubes in this embodiment is as follows: the ends of two smelted Mo-14Re alloy tubes to be welded are ground with 2000# wet sandpaper to remove oxide scale, and ultrasonically cleaned with alcohol as the medium. Then, the two smelted Mo-14Re alloy tubes are clamped parallel to each other on the fixture in the chamber of the electron beam welding machine, with the weld seam clamped parallel to ensure that the tubes are on the same plane during rotary welding. The dimensions of the smelted Mo-14Re alloy tubes are prepared by electron beam melting ingot casting, extrusion, forging, and rolling at 800℃~900℃. The dimensions of the smelted Mo-14Re alloy tubes are: diameter 13.8mm, thickness 0.8mm, and length 100mm. Electron beam welding and heat treatment were then performed sequentially. The parameters for electron beam welding were: focusing current 650mA, moving speed 50rpm / min, sealing current 3mA, and formal welding current 6mA. The total electron beam welding time was 3s, and the formal welding was performed twice. The heat treatment method was: vacuum degree 9.0×10⁻⁶. -3 Under the condition of Pa, the temperature was increased to 1000℃ at a rate of 11℃ / min, held for 2 hours, and then cooled with the furnace.

[0026] Upon inspection, the room temperature tensile test results of the heat-treated smelted Mo-14Re alloy pipe in this embodiment were as follows: tensile strength of 650 MPa, yield strength of 450 MPa, and elongation of 4%.

[0027] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes, characterized in that, The heat treatment method for smelted Mo-14Re alloy pipes after electron beam welding is as follows: the temperature is raised to 900℃~1100℃ at a rate of 10℃ / min~12℃ / min, held for 1h~2h and then cooled in the furnace. The electron beam welding parameters are as follows: focusing current 600mA~700mA, moving speed 10rpm / min~50rpm / min, sealing current 4mA~8mA, formal welding current 5mA~10mA, and total electron beam welding time 2s~4s; the vacuum degree of the heat treatment is 5.0×10⁻⁶. -3 Pa ~ 1.0 × 10 -2 Pa.

2. The method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes according to claim 1, characterized in that, The smelted Mo-14Re alloy pipe is prepared by electron beam melting ingot casting, extrusion, forging and rolling.

3. The method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes according to claim 2, characterized in that, The rolling process is performed using hydrogen flame heating, and the rolling temperature is 800℃~900℃.

4. The method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes according to claim 1, characterized in that, The electron beam welding involves two formal welding processes.

5. The method for improving the electron beam welding performance of smelted Mo-14Re alloy pipes according to claim 1, characterized in that, The heat-treated smelted Mo-14Re alloy pipe has a room temperature tensile strength of not less than 606 MPa, a yield strength of not less than 450 MPa, and an elongation of not less than 2%.

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