A method for simultaneous rapid carburizing during high-energy beam welding of molybdenum alloys

Abstract

A method for simultaneous and rapid carburizing of molybdenum alloys during high-energy beam welding, belonging to the field of welding technology, includes the following steps: pretreating the molybdenum or molybdenum alloy welding interface; sputtering a thin carbon film onto the molybdenum or molybdenum alloy welding interface using magnetron sputtering technology; controlling relevant parameters; and welding the pretreated molybdenum or / and molybdenum alloy sample using high-energy beam welding. This allows for rapid and simultaneous carburizing of the weld joint while simultaneously welding molybdenum or / and molybdenum with a high-energy beam. This method achieves rapid and simultaneous carburizing during high-energy beam welding, significantly improving the mechanical properties of the molybdenum or / and molybdenum alloy joint.

Description

Technical Field

[0001] This invention belongs to the field of welding technology, specifically relating to a method for simultaneous and rapid carburizing during high-energy beam welding of molybdenum alloys. Background Technology

[0002] Molybdenum and its alloys are high-performance refractory metals with advantages such as high melting point, good high-temperature strength, good thermal conductivity, low coefficient of linear expansion, and good corrosion resistance. Furthermore, their small neutron absorption cross-section makes them excellent materials for nuclear fuel cladding. However, because molybdenum and its alloys are hard and brittle, welding them can be challenging due to grain boundary impurities (especially oxygen) and recrystallization, leading to generally poor weldability and limiting their applications.

[0003] Carburizing molybdenum alloy welded joints can significantly improve their mechanical properties. This is because carburizing removes oxygen from the grain boundaries of the molybdenum alloy, and carbon combines with molybdenum to form Mo2C, which acts as a pinning agent at the grain boundaries, altering the fracture mode of the joint. However, traditional carburizing requires prolonged carburizing treatment at high temperatures (not lower than 1200℃) for an extended period (100–200 hours). This is not only inefficient, but the prolonged high-temperature aging also coarsens the grains in the base material, reducing its properties.

[0004] This invention provides a method for simultaneous and rapid carburizing during high-energy beam welding of molybdenum alloys, which allows for rapid and simultaneous carburizing of molybdenum alloys while high-energy beam welding is being performed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for simultaneous and rapid carburizing during high-energy beam welding of molybdenum alloys. This method enables rapid and simultaneous carburizing of the welding area while high-energy beam welding is being performed, greatly improving carburizing efficiency and enhancing the mechanical properties of the molybdenum alloy welded joint.

[0006] To achieve the above objectives, the method for simultaneous and rapid carburizing of molybdenum alloys during high-energy beam welding, as described in this invention, is implemented based on the following steps:

[0007] Step 1: Pre-treat the welding interface of the high-energy beam welded parts, wherein the material of the parts is molybdenum and / or molybdenum alloy;

[0008] Step 2: Sputter a thin carbon film onto the molybdenum or molybdenum alloy welding interface using magnetron sputtering technology;

[0009] Step 3: Control the relevant parameters and use high-energy beam welding to weld the treated molybdenum or / and molybdenum alloy sample. This allows for rapid and synchronous carburizing of the weld joint while simultaneously welding molybdenum or / and molybdenum with a high-energy beam.

[0010] Furthermore, the welded parts in step one can be thin plates, thin-walled tubes, or other complex components.

[0011] Furthermore, the specific operation of pre-treating the welding interface in step one is as follows: the welding interface of the parts to be welded is ground and polished, and then the polished parts are immersed in acetone solution for ultrasonic cleaning. The ultrasonic cleaning is performed at least 3 times, and the acetone solution is replaced after each ultrasonic cleaning. Each cleaning time is at least 10 minutes, and then the parts are dried.

[0012] Furthermore, in step two, the magnetron sputtering power is 200W, and the sputtering time can be 0–4 hours and is not zero. The thickness of the carbon film is generally not limited; it can be a very thin layer, ranging from nanometer to micrometer in thickness, depending on the requirements.

[0013] Furthermore, the high-energy beam welding in step three includes argon-protected / vacuum laser welding and vacuum electron beam welding.

[0014] Furthermore, the tensile strength of the joints welded using this method is improved by 200% to 220%.

[0015] The present invention has the following beneficial effects:

[0016] The present invention discloses a method for simultaneous and rapid carburizing of molybdenum alloys during high-energy beam welding. In specific operation, the welding interface of the molybdenum and molybdenum alloy parts to be welded by high-energy beam welding is pretreated. Then, a thin carbon film is sputtered onto the molybdenum or / and molybdenum alloy welding interface using magnetron sputtering technology. Finally, by controlling relevant parameters, the pretreated molybdenum or molybdenum alloy sample is welded using high-energy beam welding. At this time, the molten pool can be stirred to ensure that the sputtered carbon atoms are evenly distributed within the weld pool, achieving rapid and simultaneous carburizing while performing high-energy beam welding, thus greatly improving the mechanical properties of the molybdenum or / and molybdenum alloy joint. Attached Figure Description

[0017] Figure 1 Schematic diagram of magnetron sputtering of carbon thin film at the interface of parts to be welded;

[0018] Figure 2 A schematic diagram of high-energy beam welding for sputtering carbon thin films;

[0019] Figure 3 The values ​​represent the hardness of the welded joints of carbon film samples after welding at different magnetron sputtering times. Specifically, 21mAC = 0 represents the Vickers hardness of the joint welded directly without magnetron sputtering; 21mAC = 2h represents the Vickers hardness of the joint welded 2 hours after magnetron sputtering; and 21mAC = 4h represents the Vickers hardness of the joint welded 4 hours after magnetron sputtering.

[0020] Figure 4The tensile strength of the welded joints of carbon film samples after different magnetron sputtering times is given. Among them, 21mA C=0 represents the tensile strength of the joint directly welded without magnetron sputtering; 21mA C=2h represents the tensile strength of the joint welded 2 hours after magnetron sputtering; and 21mA C=4h represents the tensile strength of the joint welded 4 hours after magnetron sputtering.

[0021] Figure 5 This is a structural diagram of the tensile test sample;

[0022] Figure 6 The thickness of the thin film corresponds to different times of magnetron sputtering.

[0023] Figure 7 XRD phase analysis patterns of thin films at different magnetron sputtering times. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

[0025] The method for simultaneous rapid carburizing during high-energy beam welding of molybdenum alloys according to the present invention includes the following steps:

[0026] 1) Pre-treat the welding interface of high-energy beam welded parts, wherein the material of the parts is molybdenum or molybdenum alloy;

[0027] 2) A thin carbon film is sputtered at the molybdenum or molybdenum alloy welding interface using magnetron sputtering technology;

[0028] 3) By controlling the relevant parameters, the treated molybdenum or molybdenum alloy sample is welded using high-energy beam welding, which allows for rapid and synchronous carburizing of the weld joint while simultaneously welding the molybdenum alloy with a high-energy beam.

[0029] The welding parts in step 1) can be thin plates, thin-walled tubes or other complex components.

[0030] The specific operation for pre-treatment of the welding interface in step 1) is as follows: the welding interface of the parts to be welded is ground and polished, and then the polished parts are immersed in acetone solution for ultrasonic cleaning. The ultrasonic cleaning is performed at least 3 times, and the acetone solution is replaced after each ultrasonic cleaning. Each cleaning time is at least 10 minutes. Then the parts are dried.

[0031] In step 2), the magnetron sputtering power is 200W and the sputtering time is 0 to 4 hours.

[0032] Step 3) High-energy beam welding includes argon-protected / vacuum laser welding and vacuum electron beam welding.

[0033] Example 1

[0034] Taking a commercial molybdenum thin plate electron beam welding joint as an example, with dimensions of 50*30*1.5mm and the welding interface in the width direction, the electron beam welding and rapid synchronous carburizing steps are as follows:

[0035] Step 1: Grind the welding interface sequentially with 240#, 400#, 800#, and 1200# sandpaper. Then immerse the ground tensile specimen in acetone solution and ultrasonically clean it at least three times, changing the acetone solution after each cleaning. Each cleaning time should be no less than 10 minutes. Finally, blow-dry the specimen for later use.

[0036] Step 2: Apply a thin carbon film via magnetron sputtering to the polished weld interface, such as... Figure 1 As shown. The sputtering power was 200 W, and the sputtering times were 2 h and 4 h, respectively. The corresponding XRD phase analysis spectra of the thin films are shown below. Figure 7 ;

[0037] Step 3: Electron beam welding is performed on thin plates sputtered for different times using the same process. The welding is butt welding, such as... Figure 2 As shown. Its operating parameters are: accelerating voltage 55KV, focusing beam current 668mA, welding speed 900mm / min, and welding beam current 21mA;

[0038] The hardness of samples welded after different sputtering times was measured using a Vickers hardness tester, where BM represents the base metal region, HAZ represents the heat-affected zone, and FZ represents the molten pool region. The hardness results are as follows: Figure 3 As shown, the hardness of the molten pool region of the sample welded by electron beam welding with rapid synchronous carburizing was significantly higher than that of the uncarburized sample, while the hardness of the heat-affected zone and the base material remained essentially unchanged. Tensile tests were further conducted on samples welded after different sputtering times (see dimension diagram). Figure 5 The stretching results are as follows: Figure 4 As shown, the average tensile strengths of the welds welded after 2 hours and 4 hours of magnetron sputtering carbon film were 418.5 MPa and 387.7 MPa, respectively; the strength of the original electron beam weld without any treatment was 127.5 MPa. The strength of the electron beam weld with simultaneous carburizing was 200% to 220% higher than that of the original electron beam weld.

[0039] In summary, this invention enables rapid and simultaneous carburizing during high-energy beam welding, greatly improving carburizing efficiency and achieving the goal of significantly enhancing the hardness and tensile strength of molybdenum and molybdenum alloy joints.

Claims

1. A method of simultaneous rapid carburization during high energy beam welding of molybdenum alloys, characterized in that, The method comprises the following steps: Step 1: Preprocessing the welding interface of the high-energy beam welded part, wherein the material of the part is molybdenum or / and molybdenum alloy; Step 2: Spraying a carbon film on the molybdenum or molybdenum alloy welding interface by using a magnetron sputtering technology; the magnetron sputtering power is 200 W, and the sputtering time is 0-4 h and not 0; Step 3: Controlling the relevant parameters, and welding the treated molybdenum or / and molybdenum alloy sample by using a high-energy beam welding method, so that the molybdenum or / and molybdenum is welded and the welded joint is rapidly and synchronously carburized at the same time.

2. The method of claim 1, wherein, The form of the welded part in step 1 is a sheet or a thin-walled tube.

3. The method of claim 1, wherein, The specific operation of preprocessing the welding interface in step 1 is as follows: polishing the welding interface of the part to be welded, then immersing the polished part into an acetone solution for ultrasonic cleaning, wherein the number of ultrasonic cleaning is greater than or equal to 3, the acetone solution is replaced after each ultrasonic cleaning, and the cleaning time of each cleaning is greater than or equal to 10 min, and then the part is dried.

4. The method of claim 1, wherein, The high-energy beam welding in step 3 includes argon protection / vacuum laser welding and vacuum electron beam welding.

5. A welded part prepared by the method according to any one of claims 1-4.

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