Method for using C / Re composite foil for electron beam welding of molybdenum joint

Abstract

The invention discloses a method for using C / Re composite foil for electron beam welding of a molybdenum joint, and belongs to the technical field of welding. The method is characterized by comprising the following steps: plating a layer of carbon film on the section of molybdenum or / and molybdenum alloy by utilizing a vacuum magnetron sputtering technology, adding Re foil in the electron beam welding process, and controlling related processes to achieve the purposes of rapid carburization and microcell alloying in the welding process; and the C / Re composite film can also be prepared by a Re and C co-sputtering method through magnetron sputtering. The metal molybdenum joint prepared on the basis of the method has the excellent performance of high tensile strength, high hardness and the like, the tensile strength can reach 496.85 MPa, the hardness of a welding seam area can reach 344HV, the metal molybdenum joint can be widely applied to the field of refractory metal welding, and proper technical reference is provided for molybdenum alloy part welding process development and engineering application.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a method for adding carbon film and rhenium foil during electron beam welding of molybdenum or / and molybdenum alloy. Background Art

[0002] The refractory metal molybdenum has a high melting point, high hardness, high high-temperature strength, good electrical and thermal conductivity, small linear expansion coefficient, low high-temperature creep rate and good wear resistance, and is widely used in defense, military, metallurgical and nuclear industries. However, due to the hardness and brittleness of molybdenum and its alloys, they are often affected by grain boundary impurities (especially oxygen) and recrystallization during welding, resulting in poor welding performance. This problem limits its widespread use in some high-demand applications.

[0003] On the one hand, carburizing molybdenum alloy welded joints can greatly improve the mechanical properties of the joints. This is because the aggregation of C on the grain boundaries can replace the enrichment of oxygen on the grain boundaries, thereby reducing the brittleness of the joints, improving the strength of the joints, and improving the performance of the joints. However, traditional carburizing requires a long time (100 to 200 hours) of carburizing treatment at high temperatures (not less than 1200°C). Not only is the efficiency low, but long-term high-temperature aging will make the parent material grains coarse and reduce the performance of the parent material. On the other hand, the metal foil Re has higher chemical activity after high-temperature melting, and it is melted and alloyed with the powder metallurgy molybdenum matrix at the weld and mixed to form a solid solution, which plays a role in refining the grains and hindering the migration speed of the grain boundaries, and further improves the performance through the method of micro-area alloying.

[0004] The present invention provides a method for improving welding performance by using a composite foil during electron beam welding of a molybdenum joint, improves welding efficiency by using magnetron sputtering for rapid carburization, and further improves welding performance by the combined action of Re and C. Summary of the invention

[0005] The purpose of the present invention is to provide a method for using C / Re composite foil for electron beam welding of molybdenum joints, which can rapidly and synchronously carburize the welding area during high-energy beam welding, greatly improving the carburizing efficiency and further improving the mechanical properties of the molybdenum alloy welded joints through the effect of Re micro-area alloying.

[0006] The method of using C / Re composite foil for electron beam welding of molybdenum joints described in the present invention is implemented based on the following steps: Step 1: pre-treating the welding joint and Re foil material of the parts to be electron beam welded, wherein the material of the parts is molybdenum or / and molybdenum alloy; Step 2: Sputter a layer of carbon film at the welding interface of molybdenum or / and molybdenum alloy by magnetron sputtering technology, and then place metal Re foil at the weld of molybdenum or / and molybdenum alloy to be welded; or prepare C / Re composite film by co-sputtering Re and C by magnetron sputtering, and then perform electron beam welding; Step 3: Control relevant parameters and use electron beam welding to butt weld the molybdenum or / and molybdenum alloy samples processed in step 2, so that the purpose of synchronous carburizing and micro-area alloying can be achieved on the weld joint while electron beam welding the molybdenum or / and molybdenum.

[0007] Furthermore, the welded parts in step 1 may be in the form of thin plates, thin-walled tubes or other complex components.

[0008] Furthermore, the specific operation of pre-treating the welding interface in step 1 is: grinding and polishing the welding interface of the parts to be welded, and then immersing the polished parts seams in an acetone solution for ultrasonic cleaning, wherein the number of ultrasonic cleanings is greater than or equal to 3, and the acetone solution is replaced after each ultrasonic cleaning, and each cleaning time is greater than or equal to 10 minutes, and then the parts are blown dry. The specific operation of pre-treating the rhenium foil material is: after grinding the rhenium foil, immersing it in an acetone solution for ultrasonic treatment, and the subsequent steps are the same.

[0009] Furthermore, in step 2, the magnetron sputtering power is 200W, and the sputtering time is 0-4h. The thickness of the carbon film is generally not limited, and the sputtering time can be changed as needed. The thickness of the sputtered C film can be nanometer to micrometer level; the thickness of the Re foil is 0.1mm-0.5mm, and Re foils of different thicknesses can be added.

[0010] Furthermore, the electron beam welding in step 3 is argon-shielded vacuum electron beam welding. The welding process parameters can be selected as acceleration voltage 55KV, focusing beam current 650mA-670mA, welding speed 700mm / min-900mm / min, and welding beam current 20mA-24mA.

[0011] The present invention has the following beneficial effects:

[0012] The method of using a C / Re composite foil for electron beam welding of molybdenum joints described in the present invention, in the specific operation, pre-treats the interface of the electron beam welded molybdenum and molybdenum alloy joints and the rhenium foil. Then, a layer of carbon film is sputtered at the molybdenum or / and molybdenum alloy welding interface by using magnetron sputtering technology; finally, relevant parameters are controlled to add Re foil material during the electron beam welding process; the C / Re composite film can also be prepared by co-sputtering Re and C by magnetron sputtering, and electron beam welding is performed. At this time, the molten pool can be stirred to make the sputtered carbon atoms evenly distributed in the welding molten pool, so as to achieve the purpose of synchronous carburizing and micro-area alloying during electron beam welding, and greatly improve the mechanical properties of the molybdenum or / and molybdenum alloy joints. The tensile properties of the joints welded by this method are improved by 240% to 300%. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the principle diagram of magnetron sputtering carbon film on the interface of parts to be welded;

[0014] Figure 2 Schematic diagram of electron beam welding;

[0015] Figure 3 The hardness of the welded joints of pure molybdenum samples, samples with Re foil and C / Re composite foil film samples after welding. Among them, Mo is the Vickers hardness of the welded joint without adding any foil; Re=0.1 is the Vickers hardness of the welded joint after adding 0.1mm thick Re foil; Re=0.1C=2h is the Vickers hardness of the welded joint after magnetron sputtering for 2 hours and adding 0.1mm thick Re foil, and Re=0.1C=4h is the Vickers hardness of the welded joint after magnetron sputtering for 4 hours and adding 0.1mm thick Re foil.

[0016] Figure 4 The tensile strength (1) and tensile strength numerical bar graph (2) of the welded joints of pure molybdenum samples, samples with Re foil added, and C / Re composite foil film samples after welding. Among them, Mo is the tensile strength of the welded joint without adding any foil; Re=0.1 is the tensile strength of the welded joint after adding 0.1mm thick Re foil; Re=0.1C=2h is the tensile strength of the welded joint after magnetron sputtering for 2 hours and adding 0.1mm thick Re foil; Re=0.1C=4h is the tensile strength of the welded joint after magnetron sputtering for 4 hours and adding 0.1mm thick Re foil.

[0017] Figure 5 The figure shows the dimension drawing of the drawn part (1) and the schematic diagram of the cutting dimension of the drawn part (2). DETAILED DESCRIPTION

[0018] The following is a further description through embodiments and in combination with the figures, the purpose of which is to better understand and illustrate the content of the present invention, but is not limited to the following embodiments.

[0019] The method for using a C / Re composite foil for electron beam welding of a molybdenum joint according to the present invention comprises the following steps:

[0020] Step 1: pre-treating the welding interface and Re foil material of the electron beam welded parts, wherein the material of the parts is molybdenum or molybdenum alloy;

[0021] Step 2: Sputter a layer of carbon film on the molybdenum or molybdenum alloy welding interface using magnetron sputtering technology; or use magnetron sputtering to prepare a C / Re composite film by co-sputtering Re and C, and then perform electron beam welding.

[0022] Step 3: Control relevant parameters and weld the processed molybdenum or / and molybdenum alloy samples by electron beam welding, so that the weld joint can be quickly and synchronously carburized and micro-area alloyed while electron beam welding the molybdenum or / and molybdenum.

[0023] The welded parts in step 1) can be thin plates, thin-walled tubes or other complex components.

[0024] The specific operation of pre-treating the welding interface in step 1) is: grinding and polishing the welding interface of the parts to be welded, and then immersing the polished parts seam in an acetone solution for ultrasonic cleaning, wherein the number of ultrasonic cleaning is greater than or equal to 3, and the acetone solution is replaced after each ultrasonic cleaning, and each cleaning time is greater than or equal to 10 minutes, and then the parts are blown dry. The Re foil material is treated by ultrasonic treatment with acetone after grinding, and the rest of the operations are the same.

[0025] In step 2), the magnetron sputtering power is 200 W, the sputtering time is 0-4 hours, and the thickness of the Re foil is 0.1 mm-0.5 mm.

[0026] In step 3), the electron beam welding is argon-shielded vacuum electron beam welding, and its working parameters are: acceleration voltage 55KV, focusing beam current 668mA, welding speed 900mm / min, and welding beam current 22mA.

[0027] Example 1

[0028] Taking the electron beam welding joint of commercial molybdenum thin plate as an example, the size is 50*30*1.5㎜, the welding interface is in the width direction, and the electron beam welding steps of adding C / Re composite foil are as follows:

[0029] Step 1: Grind the welding interface with 320#, 600#, 800#, and 1200# sandpaper in turn, and grind the Re foil material with 1200# sandpaper. Then soak the polished sample and Re foil in acetone solution, and then use ultrasonic cleaning for at least three times. Replace the acetone solution after each cleaning. Each cleaning time should not be less than 10 minutes. Finally, blow dry the sample for use.

[0030] Step 2: Add Re foil to the polished welding interface, and the thickness of the Re foil should be 0.1mm.

[0031] Step 3: Electron beam welding is performed on the metal molybdenum sheets with different films by the same process, wherein the welding is butt welding, such as Figure 2 Its working parameters are: acceleration voltage 55KV, focusing beam current 668mA, welding speed 900mm / min, welding beam current 22mA; the properties measured after welding are: tensile strength 380.66MPa, hardness at the weld is 317.6HV.

[0032] Example 2

[0033] Taking the electron beam welding joint of commercial molybdenum thin plate as an example, the size is 50*30*1.5㎜, the welding interface is in the width direction, and the electron beam welding steps of adding C / Re composite foil are as follows:

[0034] Step 1: Grind the welding interface with 320#, 600#, 800#, and 1200# sandpaper in turn, and grind the Re foil material with 1200# sandpaper. Then soak the polished sample and Re foil in acetone solution, and then use ultrasonic cleaning for at least three times. Replace the acetone solution after each cleaning. Each cleaning time should not be less than 10 minutes. Finally, blow dry the sample for use.

[0035] Step 2: Use magnetron sputtering equipment to prepare C film on the cross section of the polished welding interface. The magnetron sputtering power is 200W and the sputtering time is 2h (the thickness of C film is 290.3nm). Figure 1 As shown. And add Re foil at the welding interface, the thickness of Re foil is selected to be 0.1mm.

[0036] Step 3: Electron beam welding is performed on the metal molybdenum sheets with different films by the same process, wherein the welding is butt welding, such as Figure 2 Its working parameters are: acceleration voltage 55KV, focusing beam current 668mA, welding speed 900mm / min, welding beam current 22mA; the properties measured after welding are: tensile strength 444.13MPa, hardness at the weld is 326.3HV.

[0037] Example 3

[0038] Taking the electron beam welding joint of commercial molybdenum thin plate as an example, the size is 50*30*1.5㎜, the welding interface is in the width direction, and the electron beam welding steps of adding C / Re composite foil are as follows:

[0039] Step 1: Grind the welding interface with 320#, 600#, 800#, and 1200# sandpaper in turn, and grind the Re foil material with 1200# sandpaper. Then soak the polished sample and Re foil in acetone solution, and then use ultrasonic cleaning for at least three times. Replace the acetone solution after each cleaning. Each cleaning time should not be less than 10 minutes. Finally, blow dry the sample for use.

[0040] Step 2: Use magnetron sputtering equipment to prepare C film on the cross section of the polished welding interface. The magnetron sputtering power is 200W, the sputtering time is 4h (the thickness of the C film is 587.6nm), and Re foil is added at the welding interface. The thickness of the Re foil is selected to be 0.1mm.

[0041] Step 3: Electron beam welding is performed on the metal molybdenum sheets with different films by the same process, wherein the welding is butt welding, such as Figure 2 Its working parameters are: acceleration voltage 55KV, focusing beam current 668mA, welding speed 900mm / min, welding beam current 22mA; the properties measured after welding are: tensile strength 496.85MPa, hardness at the weld is 344HV.

[0042] Table 1 shows the different process parameters of the specific embodiments.

[0043]

[0044] The hardness of the samples welded after different sputtering times was measured using a Vickers hardness tester, where BM is the base metal area, HAZ is the heat affected zone, and FZ is the molten pool area. The hardness results are as follows: Figure 3 As shown in the figure, the hardness of the center of the molten pool is significantly improved after electron beam welding with the addition of C / Re composite foil, which can reach 350HV, much higher than the hardness of pure metal molybdenum butt welding, and the hardness of the heat affected zone and the base material remains basically unchanged. Further tensile tests were carried out on samples welded with different foils (see the size diagram for details). Figure 5 ), the stretching result is as follows Figure 4 As shown, the tensile strength of the weld after only adding 0.1mm thick Re foil is 380.66MPa; the tensile strength of the weld after magnetron sputtering 2h and 4h C film and adding 0.1mm Re foil is 444.13MPa and 496.85MPa respectively; the strength of the original electron beam weld without any treatment is 110.27MPa. The tensile strength of the composite C / Re foil is increased by 240% to 350% compared with the strength of the original electron beam weld.

[0045] In summary, the present invention can achieve the purpose of significantly enhancing the hardness and tensile strength of molybdenum and molybdenum alloy joints during electron beam welding of C / Re composite foil.

Claims

1. A method for electron beam welding molybdenum joints using C / Re composite foil, characterized in that: The following steps are involved: Step 1: pre-treating the welding joint and Re foil material of the parts to be electron beam welded, wherein the parts are made of molybdenum or / and molybdenum alloy; Step 2: Sputter a layer of carbon film at the welding interface of molybdenum or / and molybdenum alloy by magnetron sputtering technology, and then place metal Re foil at the weld of molybdenum or / and molybdenum alloy to be welded; or prepare C / Re composite film by co-sputtering Re and C by magnetron sputtering, and then perform electron beam welding; Step 3: Control relevant parameters and use electron beam welding to butt weld the molybdenum or / and molybdenum alloy samples processed in step 2, so that the purpose of synchronous carburizing and micro-area alloying can be achieved on the weld joint while electron beam welding the molybdenum or / and molybdenum.

2. The method according to claim 1, characterized in that The welded parts in step 1 may be in the form of thin plates, thin-walled tubes or other complex hardware.

3. The method according to claim 1, characterized in that The specific operation of pre-treating the welding interface in step 1 is: grinding and polishing the welding interface of the parts to be welded, and then immersing the polished parts seams in an acetone solution for ultrasonic cleaning, wherein the number of ultrasonic cleanings is greater than or equal to 3, and the acetone solution is replaced after each ultrasonic cleaning, and each cleaning time is greater than or equal to 10 minutes, and then the parts are blown dry. The specific operation of pre-treating the rhenium foil material is: after grinding the rhenium foil, immerse it in an acetone solution for ultrasonic treatment, and the subsequent steps are the same.

4. The method according to claim 1, characterized in that In step 2, the magnetron sputtering power is 200 W and the sputtering time is 0-4 h.

5. The method according to claim 4, characterized in that The sputtering time can be changed as needed, and the thickness of the sputtered C film can be from nanometer to micrometer level.

6. The method according to claim 1, characterized in that The thickness of Re foil is 0.1mm-0.5mm.

7. The method according to claim 1, characterized in that The electron beam welding in step 3 is argon-shielded vacuum electron beam welding. The welding process parameters can be selected as acceleration voltage 55KV, focusing beam current 650mA-670mA, welding speed 700mm / min-900mm / min, and welding beam current 20mA-24mA.

8. A welded body prepared according to the method according to any one of claims 1 to 7.

Images