Welding method for connecting molybdenum alloy and niobium alloy dissimilar materials

Abstract

Embodiments of the present application relate to the technical field of electron beam welding, and particularly relate to a welding method for connecting molybdenum alloy and niobium alloy dissimilar materials, which comprises the following steps: S1, preparing a molybdenum alloy test sample and a niobium alloy test sample, and adopting an electron beam welding process to perform bias welding on the molybdenum alloy test sample and the niobium alloy test sample with a first bias beam amount, to obtain a welded test sample; S2, determining a molybdenum alloy side fusion line of the welded test sample, and determining an included angle between a butt joint surface of the molybdenum alloy test sample and the molybdenum alloy side fusion line of the welded test sample; S3, determining actual welding parameters for performing bias welding on a molybdenum alloy actual sample and a niobium alloy actual sample by using the electron beam welding process, according to the included angle, the first bias beam amount and a thickness of the molybdenum alloy test sample; and S4, welding the molybdenum alloy actual sample and the niobium alloy actual sample according to the actual welding parameters. The welding method provided by the embodiments of the present application is conducive to improving the welding quality.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of electron beam welding, in particular to a welding method for connecting molybdenum alloy and niobium alloy dissimilar materials. BACKGROUND

[0002] This part of the content is only to provide background information related to the present application, and does not necessarily constitute the prior art.

[0003] Molybdenum alloy and niobium alloy are refractory alloys, which are widely used in nuclear industry, aerospace, chemical metallurgy and electronic industry due to their good high temperature resistance and corrosion resistance. In the process of application of molybdenum alloy and niobium alloy in the above-mentioned fields, in some cases, molybdenum alloy and niobium alloy need to be welded.

[0004] Although electron beam welding has the advantages of high power density, large depth-width ratio and strong penetration ability, it is often used for welding refractory metals and dissimilar alloys. However, in the welding of molybdenum alloy and niobium alloy dissimilar materials, the welding process still has defects, resulting in poor welding quality. SUMMARY

[0005] In the following, a brief summary of the present application is given to provide a basic understanding of some aspects of the present application. It should be understood that this summary is not an exhaustive overview of the present application. It is not intended to identify key or important parts of the present application, nor is it intended to limit the scope of the present application. Its purpose is only to give some concepts in a simplified form as a prelude to the more detailed description discussed later.

[0006] In view of the above technical problems, embodiments of the present application provide a welding method for connecting molybdenum alloy and niobium alloy dissimilar materials.

[0007] In a first aspect, embodiments of the present application provide a welding method for connecting molybdenum alloy and niobium alloy dissimilar materials, which can include: S1, preparing a molybdenum alloy test sample and a niobium alloy test sample, and performing offset beam welding on the molybdenum alloy test sample and the niobium alloy test sample by using an electron beam welding process to obtain a welded test sample; in the offset beam welding, the offset amount of the electron beam from the butt joint surface of the molybdenum alloy test sample is a first offset amount; S2, determining the molybdenum alloy side fusion line of the welded test sample, and determining the included angle between the butt joint surface of the molybdenum alloy test sample and the molybdenum alloy side fusion line of the welded test sample as a first angle; S3, determining the actual welding parameters for offset beam welding on a molybdenum alloy actual sample and a niobium alloy actual sample by using the electron beam welding process according to the first angle, the first offset amount and the thickness of the molybdenum alloy test sample; S4, welding the molybdenum alloy actual sample and the niobium alloy actual sample according to the actual welding parameters.

[0008] The embodiment of the present application provides a welding method for connecting molybdenum alloy and niobium alloy dissimilar materials, the actual welding parameters of the electron beam welding process for the actual molybdenum alloy sample and the actual niobium alloy sample are determined according to the first angle, the first offset amount and the thickness of the molybdenum alloy test sample, so that the melting amount of the molybdenum alloy is reduced, the generation of brittle oxides in the welding metallurgical reaction is reduced, the formation of pores in the weld area 40 is reduced, and thus the welding quality of the molybdenum alloy and the niobium alloy dissimilar materials is improved, and the plasticity and toughness of the welded joint are improved.

[0009] In a second aspect, the embodiment of the present application provides a welding method for connecting molybdenum alloy and niobium alloy dissimilar materials, which can include: S10, preparing a molybdenum alloy test sample and a niobium alloy test sample, and performing offset beam welding on the molybdenum alloy test sample and the niobium alloy test sample by using an electron beam welding process; S20, determining the angle at which the electron beam is inclined relative to the actual molybdenum alloy sample and the actual niobium alloy sample and the second offset amount of the electron beam offsetting the butt joint surface of the actual molybdenum alloy sample when the actual molybdenum alloy sample and the actual niobium alloy sample are offset beam welded by using the electron beam welding process according to the result of the offset beam welding in the S10 step; and S30, welding the actual molybdenum alloy sample and the actual niobium alloy sample according to the angle and the second offset amount determined in the S20 step.

[0010] These and other advantages of the present application will no doubt become apparent to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to further illustrate the above and other advantages and features of the present application, the specific embodiments of the present application will be described in further detail below with reference to the accompanying drawings. The drawings, together with the following detailed description, form a part of the present application and are included herein to further illustrate the application. Elements having the same function and structure are denoted by the same reference signs. It should be understood that these drawings only describe typical examples of the present application and should not be regarded as limiting the scope of the present application.

[0012] Figure 1 is a schematic view of offset beam welding on a molybdenum alloy test sample and a niobium alloy test sample according to an embodiment of the present application;

[0013] Figure 2 is a schematic view of offset beam welding on a molybdenum alloy test sample and a niobium alloy test sample according to an embodiment of the present application;

[0014] Figure 3 is Figure 2 is a partial enlarged view of the weld formed by welding the actual molybdenum alloy sample and the actual niobium alloy sample shown in the figure;

[0015] Figure 4 is a schematic view of offset beam welding on a molybdenum alloy test sample and a niobium alloy test sample according to an embodiment of the present application; Figure 1A weld cross-sectional metallographic photograph of a weld test sample obtained by the illustrated welding method;

[0016] Figure 5 is according to Figure 2 A weld cross-sectional metallographic photograph of a weld actual sample obtained by the illustrated welding method.

[0017] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are merely intended to show illustrative aspects in a schematic manner.

[0018] BRIEF DESCRIPTION OF DRAWINGS

[0019] 10, molybdenum alloy test sample; 11, molybdenum alloy actual sample;

[0020] 20, niobium alloy test sample; 21, niobium alloy actual sample;

[0021] 30, electron beam;

[0022] 40, weld zone; 41, butt surface; 42, molybdenum alloy side fusion line;

[0023] 50, backing plate;

[0024] hi, first deflection amount; h2, second deflection amount; d, thickness; y, electron beam direction. DETAILED DESCRIPTION

[0025] Exemplary embodiments of the present application will be described herein below with reference to the accompanying drawings. In the description, all features that are not described in the specification of the actual embodiments are not described in the specification for the sake of clarity and conciseness. However, it should be appreciated that many embodiment-specific decisions must be made in the process of developing any such actual embodiments in order to achieve the specific goals of the developers, such as compliance with those constraints associated with a system and business, which can vary from one embodiment to another. In addition, it should be appreciated that, although the development work can be very complex and time-consuming, it is merely a routine task for those skilled in the art who benefit from the contents of the present application.

[0026] It should also be noted herein that, in order to avoid obscuring the present application with unnecessary details, only the device structures and / or processing steps closely related to the scheme according to the present application are illustrated in the accompanying drawings, and other details not closely related to the present application are omitted.

[0027] It should be noted that, unless otherwise defined, technical or scientific terms used in the present application should be understood as having their usual meanings to those skilled in the art.

[0028] In the description of the embodiments of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited.

[0029] The inventors of the present application found that molybdenum alloy and niobium alloy as refractory alloys have great differences in physical properties such as melting point, thermal conductivity, linear expansion coefficient, etc., and direct welding of the two is prone to generate large welding stress, increasing the joint crack tendency. In addition, molybdenum alloy is easy to oxidize to form low-boiling-point oxides such as MoO3 at high temperature, which is easy to form porosity defects, and react with impurity elements (O, N, C, etc.) to form brittle phases, resulting in reduced plasticity and toughness of the welded joint.

[0030] For molybdenum alloy / niobium alloy dissimilar material fusion welding, reducing the melting amount of molybdenum alloy helps to reduce welding stress, control weld porosity defects, and improve joint plasticity and toughness. When using an electron beam to perform molybdenum alloy / niobium alloy dissimilar material welding, a deflected beam welding method can be used to adjust the fusion ratio of the molybdenum alloy / niobium alloy base material.

[0031] The inventors of the present application found that simply using a deflected beam welding method to adjust the fusion ratio of molybdenum alloy / niobium alloy still has some problems, such as not being able to completely control the melting of molybdenum alloy, and the welded joint has a large defect of brittleness.

[0032] Based on this, the embodiments of the present application provide a welding method for connecting molybdenum alloy and niobium alloy dissimilar materials. Referring to Figure 1 and Figure 2 , Figure 1 is a schematic diagram of deflected beam welding of a molybdenum alloy test sample and a niobium alloy test sample according to an embodiment of the present application; Figure 2 is a schematic diagram of deflected beam welding of a molybdenum alloy actual sample and a niobium alloy actual sample according to an embodiment of the present application, the welding method provided by the embodiments of the present application can include: S1, preparing a molybdenum alloy test sample 10 and a niobium alloy test sample 20, and using an electron beam welding process to perform deflected beam welding on the molybdenum alloy test sample 10 and the niobium alloy test sample 20 to obtain a welded test sample; in the deflected beam welding, the deflection amount of the electron beam 30 from the butt joint surface 41 of the molybdenum alloy test sample 10 is a first deflection amount h1; S2, determining a molybdenum alloy side fusion line 42 of the welded test sample, and determining an included angle between the butt joint surface 41 of the molybdenum alloy test sample 10 and the molybdenum alloy side fusion line 42 of the welded test sample as a first angle β; S3, determining actual welding parameters for deflected beam welding of a molybdenum alloy actual sample 11 and a niobium alloy actual sample 21 using the electron beam welding process according to the first angle β, the first deflection amount h1, and the thickness of the molybdenum alloy test sample 10; S4, welding the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 according to the actual welding parameters.

[0033] The welding method for connecting molybdenum alloy and niobium alloy dissimilar materials provided by the embodiment of the present application determines the actual welding parameters of the bias welding of the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 by using the electron beam welding process according to the first angle β, the first deflection amount h1 and the thickness of the molybdenum alloy test sample 10, which is beneficial to reduce the melting amount of the molybdenum alloy, reduce the generation of brittle oxides in the welding metallurgical reaction, reduce the formation of pores in the weld area 40, thereby improving the welding quality of the molybdenum alloy and the niobium alloy dissimilar materials and improving the plasticity and toughness of the welded joint.

[0034] In some embodiments, the molybdenum alloy test sample 10, the niobium alloy test sample 20, the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 are all plate-shaped samples, and the thickness d of the plate-shaped sample is 2-3 mm. It is easy to understand that, since molybdenum and niobium are refractory metals, a thicker sample is difficult to be penetrated by the electron beam 30 during welding. Therefore, a thinner plate-shaped sample with a thickness of 2-3 mm is used in the present embodiment. Such thickness is beneficial to the penetration of the sample by the electron beam 30, so that the heat can be quickly transferred to the weld area 40, while reducing the pores and cracks in the weld.

[0035] The thicknesses of the molybdenum alloy test sample 10, the niobium alloy test sample 20, the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 are the same.

[0036] In some embodiments, the molybdenum content in the molybdenum alloy can be 100%, i.e. metallic molybdenum.

[0037] In some embodiments, the niobium content in the niobium alloy can be 100%, i.e. metallic niobium.

[0038] In some embodiments, in the S1 step, the butt joint surfaces 41 of the molybdenum alloy test sample 10 and the niobium alloy test sample 20 to be welded can be mechanically polished before welding, and the cleaned molybdenum alloy test sample 10 and the niobium alloy test sample 20 are obtained after cleaning.

[0039] In some embodiments, in the S1 step, the molybdenum alloy test sample 10 and the niobium alloy test sample 20 can be fixed by using a clamp, so that the butt joint surfaces 41 of the molybdenum alloy test sample 10 and the niobium alloy test sample 20 are butted to facilitate bias welding, and the surface of the molybdenum alloy test sample 10 and the niobium alloy test sample 20 can be constrained by using the clamp to prevent warping deformation during welding.

[0040] In some embodiments, in the S1 step, the molybdenum alloy test sample 10 and the niobium alloy test sample 20 can be fixed on the backing plate 50, thereby improving the stability during welding.

[0041] In some embodiments, the backing plate 50 can be made of metal molybdenum or metal niobium, so as to facilitate reducing stress and deformation caused by difference in thermal expansion coefficient of different materials during welding.

[0042] The molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 are welded to obtain a welded actual sample.

[0043] In some embodiments, in the S3 step, the actual welding parameters can include an angle at which the electron beam 30 is inclined relative to the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21, and a second deflection amount h2 of the electron beam 30 from the butt joint surface 41 of the molybdenum alloy actual sample 11. The inventors of the present application have found that increasing the deflection amount of the electron beam 30 from the butt joint surface 41 of the molybdenum alloy sample facilitates reducing the melting amount of the molybdenum alloy, but the bottom end of the butt joint surface of the molybdenum alloy sample in the welded actual sample can not be melted. The embodiments of the present application still use the electron beam welding process to perform deflection welding on the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 by inclining the electron beam 30 relative to the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 at a preset angle, which facilitates reducing the melting amount of the molybdenum alloy, and also facilitates complete fusion of the molybdenum alloy and the niobium alloy, avoiding the phenomenon that the bottom of the weld area 40 is not fused.

[0044] In some embodiments, in the S3 step, the actual welding parameters can further include a vacuum degree, an acceleration voltage, a focusing current, a welding beam current, and a welding speed. These welding parameters can be the same as those used in the S1 step to perform deflection welding on the molybdenum alloy test sample 10 and the niobium alloy test sample 20 by using the electron beam welding process.

[0045] In some embodiments, the vacuum degree can be 10 -3 ~ 10 -1 Pa, the acceleration voltage can be 50 kV ~ 70 kV, the focusing current can be 680 ~ 700 mA, the welding beam current can be 25 mA ~ 45 mA, and the welding speed can be 500 mm / min ~ 1000 mm / min.

[0046] In some embodiments, in the S3 step, the angle at which the electron beam 30 is inclined relative to the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 is the same as the first angle β. The inventors of the present application have found that the molybdenum alloy side fusion line 42 of the welded test sample is basically a straight line, so when the angle at which the electron beam 30 or the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 is inclined is the same as the first angle β, the molybdenum alloy side fusion line 42 basically coincides with the butt joint surface 41 at this time, so by adjusting the second deflection amount h2, the melting amount of the molybdenum alloy can be reduced, and meanwhile, the molybdenum alloy and the niobium alloy are uniformly fused, the fusion ratio of the molybdenum alloy and the niobium alloy is effectively adjusted, and thus the welding quality of the molybdenum alloy and the niobium alloy is improved.

[0047] In some embodiments, when welding is performed using the gun-type electron beam welding device, in order to achieve the above-mentioned inclination angle of the electron beam 30 relative to the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21, the inclination angle of the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 can be adjusted.

[0048] In some embodiments, in the S3 step, the butt joint surfaces 41 of the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 to be welded can be mechanically polished, and after cleaning, the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 are obtained.

[0049] In some embodiments, in the S3 step, the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 can be fixed using a clamp, and the butt joint surfaces 41 of the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 are butted to facilitate the offset beam welding; the upper surfaces of the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 can also be constrained using the clamp to prevent warping deformation during welding; after the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 are loaded on the clamp, the inclination angle of the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 can be adjusted, so that the inclination angle of the electron beam 30 relative to the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 is the same as the first angle β.

[0050] In some embodiments, in the S3 step, the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 can be fixed on the backing plate 50, thereby facilitating the stability during welding.

[0051] Referring to Figure 3 , Figure 3 is Figure 2 a partial enlarged view of the weld formed by welding the molybdenum alloy actual sample and the niobium alloy actual sample, wherein the end point a1 and the end point a2 correspond to the lower end point and the upper end point of the butt joint surface 41 of the molybdenum alloy actual sample 11, y represents the direction of the electron beam 30, y1 is the foot of the perpendicular line passing through the end point a1 and perpendicular to the direction y of the electron beam 30, and y2 is the foot of the perpendicular line passing through the end point a2 and perpendicular to the direction y of the electron beam 30. The end point a1, the end point a2, the foot y2 and the foot y1 form a right trapezoid. The line connecting the end point a1 and the foot y1 is the first offset amount h1, the line connecting the end point a2 and the foot y2 is the second offset amount h2, the length of the line connecting the end points a1 and a2 is the thickness d of the molybdenum alloy test sample 10, and the angle between the line connecting the end points a1 and a2 and the direction y is the inclination angle α of the electron beam 30 relative to the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21.

[0052] It can be seen that in the S3 step, the second deflection amount h2 of the electron beam 30 from the butt surface 41 of the molybdenum alloy actual sample 11 can be determined by the following expression:

[0053] h2 = h1 + d x sin a.

[0054] wherein h2 is the second deflection amount, h1 is the first deflection amount; d is the thickness of the molybdenum alloy test sample 10; a is the angle of the electron beam 30 relative to the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21. Since the value of a is equal to the first angle b, the second deflection amount h2 of the electron beam 30 during actual welding can be determined according to the thickness d of the molybdenum alloy test sample 10, the first deflection amount h1 and the first angle b. By the above method, the deflection amount of the electron beam 30 can be adjusted to the maximum deflection amount, further reducing the melting amount of the molybdenum alloy, while ensuring complete fusion of the molybdenum alloy and the niobium alloy, avoiding the phenomenon of incomplete fusion at the bottom of the weld area 40, and improving the quality of the dissimilar material welded joint of the molybdenum alloy and the niobium alloy.

[0055] In some embodiments, in the S3 step, the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 are arranged to be inclined at a first angle b relative to the electron beam 30; the distance between the electron beam 30 and the upper end of the butt surface 41 of the molybdenum alloy actual sample 11 is adjusted to a second deflection amount h2. In such embodiments, the distance from the endpoint a1 to the foot y1 is the first deflection amount h1, the distance from the endpoint a2 to the foot y2 is the second deflection amount h2, the distance from the endpoint a1 to the endpoint a2 is the thickness d of the molybdenum alloy actual sample 11, and the included angle between the butt surface 41 and the molybdenum side fusion line 42 is the first angle b, so that the second deflection amount h2 can be calculated according to the expression h2 = h1 + d x sin a.

[0056] In some embodiments, in the S1 step, a plurality of groups of molybdenum alloy test samples 10 and niobium alloy test samples 20 are prepared; the electron beam welding process is used to perform deflection welding on the molybdenum alloy test sample 10 and the niobium alloy test sample 20 of each group to obtain a plurality of groups of welded test samples, wherein the deflection amount of the electron beam 30 from the butt surface 41 of the molybdenum alloy test sample 10 is different for different groups of deflection welding; and the first deflection amount h1 is determined according to the welding quality of the plurality of groups of welded test samples. This embodiment can determine the first deflection amount h1 based on the welding quality, providing an optimized parameter basis for subsequent determination of the second deflection amount h2, thereby facilitating improvement of the welding quality of the molybdenum alloy and the niobium alloy.

[0057] In some embodiments, in the S1 step, the deflection amount can be adjusted in the range of 0-0.9 mm for different groups of deflection welding.

[0058] In some embodiments, the welding quality includes the microstructure at the weld of the welding test sample and the mechanical properties of the welding test sample. In such embodiments, an optical microscope can be used to observe the crystal phase, pores, and microcracks at the weld; a mechanical testing machine can be used to test the tensile strength of the welding test sample. If the crystal phase structure in the weld microstructure is dense, the number of pores and microcracks is small, and the tensile strength is high, the welding quality is good; if the crystal phase structure is loose, the number of pores and microcracks is large, and the tensile strength is low, the welding quality is poor.

[0059] In some embodiments, in step S2, the molybdenum alloy side fusion line 42 of the welding test sample can be determined based on the metallographic photograph of the cross-section of the weld of the welding test sample.

[0060] See Figure 4 and Figure 5 , Figure 4 is the metallographic photograph of the cross-section of the weld of the welding test sample obtained by the welding method shown in Figure 1 ; Figure 5 is the metallographic photograph of the cross-section of the weld of the actual welding sample obtained by the welding method shown in Figure 2 . It can be seen from Figure 4 and Figure 5 that the cross-section of the weld between the molybdenum alloy sample and the niobium alloy sample is bowl-shaped, the molybdenum alloy side fusion line 42 is close to a straight line, and there is an included angle of the first angle β between the molybdenum alloy side fusion line 42 and the butt joint surface 41. See Figure 5 . After tilting the electron beam 30 at the first angle β with respect to the actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 and determining the beam offset amount according to the above expression, the molybdenum alloy side fusion line 42 can be made to coincide basically with the butt joint surface 41, which is beneficial to reducing the melting amount of the molybdenum alloy.

[0061] In some embodiments, in step S3, when performing beam offset welding on the actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 using an electron beam welding process, the value range of the second beam offset amount h2 can be: h1 < h2 ≤ h1 + d × sinα, so that the melting amount of the molybdenum alloy can be adjusted by selecting different second beam offset amounts h2.

[0062] The embodiment of the present application also provides a welding method for connecting molybdenum alloy and niobium alloy dissimilar materials, which can comprise the following steps: S10, preparing a molybdenum alloy test sample 10 and a niobium alloy test sample 20, and performing partial beam welding on the molybdenum alloy test sample 10 and the niobium alloy test sample 20 by using an electron beam welding process; S20, determining an angle at which an electron beam 30 is inclined relative to a molybdenum alloy actual sample 11 and a niobium alloy actual sample 21 and a second partial beam amount h2 at which the electron beam 30 deviates from a butt joint surface 41 of the molybdenum alloy actual sample 11 when partial beam welding is performed on the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 by using the electron beam welding process according to the result of the partial beam welding in the step S10; and S30, welding the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 according to the angle and the second partial beam amount h2 determined in the step S20.

[0063] The welding method for connecting molybdenum alloy and niobium alloy dissimilar materials provided by the embodiment of the present application is advantageous in reducing the melting amount of the molybdenum alloy, reducing the generation of brittle oxides in the metallurgical reaction of the weld, reducing the formation of pores in the weld area 40, thereby improving the welding quality of the molybdenum alloy and the niobium alloy dissimilar materials and improving the plasticity and toughness of the welded joint.

[0064] The embodiment of the present application is advantageous in obtaining an electron beam welded joint with high strength and good plasticity by inclining the partial beam welding and selecting reasonable welding process parameters.

[0065] In some embodiments, the step S10 can comprise the following steps: S101, preparing a plurality of groups of molybdenum alloy test samples 10 and niobium alloy test samples 20; S102, performing partial beam welding on the molybdenum alloy test sample 10 and the niobium alloy test sample 20 of each group by using an electron beam welding process to obtain a plurality of groups of welded test samples, wherein the partial beam amount at which the electron beam 30 deviates from the butt joint surface 41 of the molybdenum alloy test sample 10 is different in the partial beam welding of different groups; and S103, determining the optimal partial beam amount h1 at which the electron beam 30 deviates from the butt joint surface 41 of the molybdenum alloy test sample 10 in the partial beam welding according to the welding quality of the plurality of groups of welded test samples. The embodiment can evaluate the influence of different partial beam amounts on the welding quality by preparing a plurality of groups of molybdenum alloy test samples 10 and niobium alloy test samples 20 and performing partial beam welding on each group of samples with different partial beam amounts, which is helpful to determine the optimal partial beam amount h1 at which the electron beam 30 deviates from the butt joint surface 41 of the molybdenum alloy test sample 10 in the partial beam welding, thereby providing optimized welding parameters for the welding of subsequent actual samples, and thus being advantageous in improving the welding quality.

[0066] In some embodiments, the step S20 can include: S201, determining the molybdenum alloy side fusion line 42 of the welding test sample obtained by adopting the optimal deflection amount h1 for deflection welding, and determining the first angle β between the butt joint surface 41 of the molybdenum alloy test sample 10 and the molybdenum alloy side fusion line 42 of the welding test sample; S202, determining the angle α of the electron beam 30 relative to the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 and the second deflection amount h2 when the electron beam welding process is used for deflection welding of the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 according to the first angle β, the optimal deflection amount h1 and the thickness d of the molybdenum alloy test sample 10. In such embodiments, by determining the angle α of the electron beam 30 relative to the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 and the second deflection amount h2 when the deflection welding is performed on the molybdenum alloy actual sample 11 and the niobium alloy actual sample 21 by the above method, it is beneficial to reduce the melting amount of the molybdenum alloy in the actual welding, reduce the generation of brittle oxides in the weld metallurgical reaction, thereby improving the welding quality of the molybdenum alloy and the niobium alloy dissimilar materials and improving the plasticity and toughness of the welded joint.

[0067] The welding method for connecting the molybdenum alloy and the niobium alloy dissimilar materials in the embodiments of the present application is further described below with specific embodiments.

[0068] (1) Prepare the molybdenum alloy test sample 10 and the niobium alloy test sample 20

[0069] Prepare three groups of molybdenum alloy test samples 10 and niobium alloy test samples 20, each group of samples is plate-shaped, and the thickness d is 2mm; mechanically polish the butt joint surface 41 of the molybdenum alloy test sample 10 and the niobium alloy test sample 20 using sandpaper to ensure that the butt joint surface 41 is flat; clean the polished molybdenum alloy test sample 10 and the niobium alloy test sample 20 with ethanol to remove oil stains and impurities, obtaining clean molybdenum alloy test sample 10 and niobium alloy test sample 20; use a clamp to fix the molybdenum alloy test sample 10 and the niobium alloy test sample 20, so that the butt joint surfaces 41 of the molybdenum alloy test sample 10 and the niobium alloy test sample 20 are butted, ensuring that the butt joint surfaces 41 are tightly fitted without gaps; fix the molybdenum alloy test sample 10 and the niobium alloy test sample 20 on the backing plate 50, the backing plate 50 is made of metallic niobium, and the thickness of the backing plate 50 is 2mm; adjust the clamp to constrain the upper surface of the molybdenum alloy test sample 10 and the niobium alloy test sample 20 to prevent warping deformation during welding.

[0070] (2) Deflection welding test on the molybdenum alloy test sample 10 and the niobium alloy test sample 20

[0071] Place the three groups of molybdenum alloy test samples 10 and niobium alloy test samples 20 in the electron beam welding machine, and vacuumize to 3x10 -2Pa; parameters of electron beam welding are set as follows: acceleration voltage is 60 kV, focusing current is 691 mA, welding beam current is 36 mA, and welding speed is 600 mm / min; the first group of molybdenum alloy test samples 10 and niobium alloy test samples 20 are subjected to offset beam welding, and the offset amount of the electron beam 30 offsetting the butt joint surface 41 of the molybdenum alloy test sample 10 is set to 0.2 mm; the second group of molybdenum alloy test samples 10 and niobium alloy test samples 20 are subjected to offset beam welding, and the offset amount of the electron beam 30 offsetting the butt joint surface 41 of the molybdenum alloy test sample 10 is set to 0.4 mm; the third group of molybdenum alloy test samples 10 and niobium alloy test samples 20 are subjected to offset beam welding, and the offset amount of the electron beam 30 offsetting the butt joint surface 41 of the molybdenum alloy test sample 10 is set to 0.8 mm; and the welded test samples are taken out after being cooled in the furnace for 15 minutes.

[0072] (3) Evaluating the quality of the welded test samples

[0073] The crystal phase, pores and microcracks of each group of welded test samples are observed using an optical microscope; the tensile strength of each group of welded test samples is tested using a mechanical testing machine; and the welding quality is comprehensively evaluated; when the offset amount is 0.4 mm, the crystal phase structure in the weld microstructure is dense, the number of pores and microcracks is small, the tensile strength is high, and the welding quality is best.

[0074] (4) Observing the weld cross-section metallographic photos of the welded test samples

[0075] The weld cross-section metallographic photos of the welded test samples with the offset amount of 0.4 mm are observed using an optical microscope, the molybdenum alloy side fusion line 42 is determined, and the first angle β between the butt joint surface 41 of the molybdenum alloy test sample 10 and the molybdenum alloy side fusion line 42 is measured to be 8°.

[0076] (5) Calculating the second offset amount h2

[0077] According to the expression h2 = h1 + d x sin a, the second offset amount h2 is calculated, wherein h1 is the first offset amount (0.4 mm), d is the thickness of the molybdenum alloy test sample 10 (2 mm), and a is the same as the first angle β (8°), and the second offset amount h2 is calculated to be 0.4 mm + 2 mm x sin 8° ≈ 0.68 mm.

[0078] (6) Preparing molybdenum alloy actual samples 11 and niobium alloy actual samples 21

[0079] Both the actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 are plate-shaped with a thickness d of 2 mm. The mating surfaces 41 of the actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 are mechanically polished with sandpaper to ensure flatness. The polished actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 are then cleaned with ethanol to remove oil and impurities, resulting in clean samples. The actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 are fixed with clamps to ensure a tight fit without gaps. The actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 are then fixed onto a backing plate 50 made of niobium metal with a thickness d of 2 mm. The clamps are adjusted to constrain the upper surfaces of the actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 to prevent warping or deformation during welding.

[0080] (7) Perform off-beam welding tests on actual molybdenum alloy sample 11 and actual niobium alloy sample 21.

[0081] The actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 were placed in an electron beam welder and evacuated to a vacuum of 3 × 10⁻⁶. - 2 Pa; Set the electron beam welding parameters: accelerating voltage 60kV, focusing current 691mA, welding beam current 36mA, welding speed 600mm / min; Adjust the tilt angle of the actual molybdenum alloy sample 11 and the actual niobium alloy sample 21 so that the angle between them and the horizontal plane is 8°; Set the second deflection h2 of the electron beam 30 away from the mating surface 41 of the molybdenum alloy test sample 10 to 0.68mm; Perform deflection welding on the actual molybdenum alloy sample 11 and the actual niobium alloy sample 21; Remove the welded actual samples after furnace cooling for 15 minutes.

[0082] (8) Observe the metallographic photographs of the weld cross-section of the actual welded sample.

[0083] When the metallographic photographs are observed using an optical microscope, the fusion line 42 on the side of the molybdenum alloy basically coincides with the mating surface 41 of the molybdenum alloy test sample 10.

[0084] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0085] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A welding method for connecting dissimilar materials of molybdenum alloy and niobium alloy, characterized by, The method comprises the following steps: S1, preparing a molybdenum alloy test sample and a niobium alloy test sample, and performing offset beam welding on the molybdenum alloy test sample and the niobium alloy test sample by using an electron beam welding process to obtain a welded test sample; wherein in the offset beam welding, the offset amount of the electron beam from the butt joint surface of the molybdenum alloy test sample is a first offset amount; S2, determining the molybdenum alloy side fusion line of the welded test sample, and determining the included angle between the butt joint surface of the molybdenum alloy test sample and the molybdenum alloy side fusion line of the welded test sample as a first angle; S3, determining actual welding parameters for offset beam welding of a molybdenum alloy actual sample and a niobium alloy actual sample by using an electron beam welding process according to the first angle, the first offset amount, and the thickness of the molybdenum alloy test sample; S4, welding the molybdenum alloy actual sample and the niobium alloy actual sample according to the actual welding parameters.

2. The welding method according to claim 1, characterized in that, In the step S3, the actual welding parameters include an angle at which the electron beam is inclined relative to the molybdenum alloy actual sample and the niobium alloy actual sample, and a second offset amount of the electron beam from the butt joint surface of the molybdenum alloy actual sample.

3. The welding method according to claim 2, characterized in that, In the step S3, the angle at which the electron beam is inclined relative to the molybdenum alloy actual sample and the niobium alloy actual sample is the same as the first angle.

4. The welding method of claim 2, wherein, In the step S3, the second offset amount of the electron beam from the butt joint surface of the molybdenum alloy actual sample is determined by the following expression: h2 = h1 + d × sin α; wherein h2 is the second offset amount, h1 is the first offset amount, d is the thickness of the molybdenum alloy test sample, and α is the angle at which the electron beam is inclined relative to the molybdenum alloy actual sample and the niobium alloy actual sample.

5. The welding method of claim 2, wherein, In the step S3, the molybdenum alloy actual sample and the niobium alloy actual sample are arranged to be inclined relative to the electron beam by the first angle; the distance between the electron beam and the upper end of the butt joint surface of the molybdenum alloy actual sample is adjusted to the second offset amount.

6. The welding method of claim 1, wherein, In the step S1, a plurality of groups of molybdenum alloy test samples and niobium alloy test samples are prepared; offset beam welding is performed on the molybdenum alloy test sample and the niobium alloy test sample of each group by using an electron beam welding process to obtain a plurality of groups of welded test samples, wherein the offset amount of the electron beam from the butt joint surface of the molybdenum alloy test sample is different in the offset beam welding of different groups; the first offset amount is determined according to the welding quality of the plurality of groups of welded test samples.

7. The welding method of claim 6, wherein, The welding quality includes the microstructure at the weld of the welded test sample and the mechanical properties of the welded test sample.

8. The welding method of claim 1, wherein, In the step S2, the molybdenum alloy side fusion line of the welded test sample is determined according to the metallographic photos of the cross section of the weld of the welded test sample.

9. The welding method of claim 1, wherein, The molybdenum alloy test sample, the niobium alloy test sample, the molybdenum alloy actual sample, and the niobium alloy actual sample are all plate-shaped samples, and the thickness of the plate-shaped sample is 2-3 mm.

10. A welding method for connecting a molybdenum alloy and a niobium alloy dissimilar material, characterized by, The method comprises the following steps: S10, preparing a molybdenum alloy test sample and a niobium alloy test sample, and performing offset beam welding on the molybdenum alloy test sample and the niobium alloy test sample by using an electron beam welding process; S20, according to the result of the step S10, determining an angle at which the electron beam is inclined relative to the molybdenum alloy actual sample and the niobium alloy actual sample and a second offset amount of the electron beam from the butt joint surface of the molybdenum alloy actual sample when the electron beam welding process is used to offset weld the molybdenum alloy actual sample and the niobium alloy actual sample; S30, according to the angle and the second offset amount determined in the step S20, welding the molybdenum alloy actual sample and the niobium alloy actual sample.

11. The welding method according to claim 10, characterized in that, characterized in that, The step S10 comprises: S101, preparing a plurality of groups of molybdenum alloy test samples and niobium alloy test samples; S102, using the electron beam welding process to offset weld each group of the molybdenum alloy test sample and the niobium alloy test sample to obtain a plurality of groups of welded test samples, wherein the offset amount of the electron beam from the butt joint surface of the molybdenum alloy test sample is different in the offset welding of different groups; S103, determining the optimal offset amount of the electron beam from the butt joint surface of the molybdenum alloy test sample in the offset welding according to the welding quality of the plurality of groups of welded test samples.

12. The welding method according to claim 11, characterized in that, characterized in that, The step S20 comprises: S201, determining the molybdenum alloy side fusion line of the welded test sample obtained by using the optimal offset amount to offset weld, and determining that the included angle between the butt joint surface of the molybdenum alloy test sample and the molybdenum alloy side fusion line of the welded test sample is a first angle; S202, according to the first angle, the optimal offset amount and the thickness of the molybdenum alloy test sample, determining the angle at which the electron beam is inclined relative to the molybdenum alloy actual sample and the niobium alloy actual sample and the second offset amount when the electron beam welding process is used to offset weld the molybdenum alloy actual sample and the niobium alloy actual sample.

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