Tantalum and titanium ultrathin plate dissimilar material welding method

Abstract

The invention discloses a tantalum and titanium ultra-thin plate dissimilar material welding method which comprises the following steps: pre-welding treatment: cleaning greasy dirt on the surface of a workpiece, and polishing with abrasive paper to remove an oxide layer; the end faces of the tantalum and titanium ultrathin plates are in butt joint and horizontally placed on a bottom plate, the tantalum and titanium ultrathin plates are fixed through pressing plates, and the distance between the end of the titanium side pressing plate and a butt joint line is smaller than the distance between the tantalum side pressing plate and the butt joint line; and welding operation: pulse micro-beam plasma arc welding is adopted, and an ion beam acts on one side of the wired tantalum ultra-thin plate. According to the dissimilar material welding method for the tantalum and titanium ultrathin plates, the problems that burn-through is prone to being generated in welding of the dissimilar material ultrathin plates, and welding seam forming is poor are solved.

Description

Technical Field

[0001] The invention relates to the technical field of welding ultra-thin plates of titanium and tantalum dissimilar materials, in particular to a method for welding ultra-thin plates of tantalum and titanium dissimilar materials. Background Art

[0002] Tantalum is a refractory metal with a melting point of 2996°C, a low coefficient of thermal expansion, and excellent toughness and ductility. Tantalum's most outstanding feature is its corrosion resistance, but it is expensive and is often used in the form of tantalum alloys or as key components in the semiconductor and electronics industries. During welding, after the oxide film on the tantalum surface decomposes at high temperatures, the tantalum atoms become sensitive to elements such as nitrogen, hydrogen, and oxygen in the air, causing problems such as pores and grain coarsening, reducing the overall performance of the welded joint. Therefore, during welding, it is difficult to control the weld formation of tantalum and tantalum alloys, making it difficult to obtain good welding quality. In addition, most research subjects are thin plates, and research on the welding of ultra-thin plates of tantalum and tantalum alloys is rare.

[0003] Titanium and its alloys are widely used in various fields due to their high strength-to-weight ratio, good machinability, high-temperature resistance, and corrosion resistance. While much research has been conducted on the joining of titanium and titanium alloys, most efforts have focused on thin and medium-thick plates, with little research on ultra-thin plates (less than 0.2 mm thick).

[0004] With the continuous development of modern industry, research in the field of welding continues to deepen. Welding materials are no longer limited to welding of homogeneous materials, but have expanded to include welding of dissimilar materials. Welding dissimilar materials is often more difficult due to differences in the physical and chemical properties of the parent materials. This is precisely why dissimilar welding has become an area of intensive research. Currently, research in the field of dissimilar welding of tantalum and titanium alloys is relatively in-depth, with occasional reports on ultra-thin plate welding. However, research in the field of butt welding of ultra-thin tantalum and titanium dissimilar plates is relatively rare.

[0005] Because the welding forming of ultra-thin plates has extremely strict requirements on welding processes and methods, burn-through and deformation will occur if the process parameters do not match. On this basis, the welding of ultra-thin plates of dissimilar materials must also consider the material properties, which undoubtedly increases the difficulty of welding ultra-thin plates. Therefore, few people have conducted research in the field of welding ultra-thin plates of dissimilar materials. Summary of the Invention

[0006] The object of the present invention is to provide a method for welding dissimilar materials of tantalum and titanium ultra-thin plates to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for welding dissimilar materials of tantalum and titanium ultra-thin plates, comprising the following steps:

[0008] a. Clean the workpiece before welding and remove oil stains on the surface of the workpiece;

[0009] b. Grinding to remove the surface oxide layer;

[0010] c. Place the treated tantalum ultra-thin plate and titanium ultra-thin plate end faces together on the bottom plate, and use pressing plates to press and fix them. The distance between the end of the pressing plate above the titanium ultra-thin plate and the butt joint is T1, and the distance between the end of the pressing plate above the tantalum ultra-thin plate and the butt joint is T2, T1 <T2;

[0011] d. Use pulsed micro plasma arc welding;

[0012] The e-ion beam acts on one side of the tantalum ultra-thin plate of the butt joint.

[0013] Preferably, the tantalum ultra-thin plate is made of pure tantalum.

[0014] Preferably, the titanium ultra-thin plate is made of TC4.

[0015] Preferably, the thickness of the tantalum ultra-thin plate and the titanium ultra-thin plate is 100 um.

[0016] Preferably, T1=0.1mm, T2=1.4mm.

[0017] Preferably, the ion gas and shielding gas used during welding are both high-purity argon, and the ion gas flow rate is 0.35 L / min, and the shielding gas flow rate is 2.5 L / min.

[0018] Preferably, the height between the welding gun and the surface of the ultra-thin plate is 1.5 mm, the diameter of the tungsten rod used during welding is 2 mm, the welding speed is 4.5 mm / s, and the welding current is a constant value.

[0019] Preferably, acetone is used to clean the workpiece in step a.

[0020] Preferably, in step c, 500#-2000# sandpaper is used for polishing.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] 1. Solve welding defects: Tantalum and titanium have large differences in thermal conductivity and latent heat of fusion. Traditional methods easily cause TC4 with a low melting point to melt rapidly and result in a discontinuous molten pool. For ultra-thin tantalum and titanium plates with a thickness of 100 μm, the present invention adopts asymmetrical clamping of double pressure plates along the butt joint line. The tantalum side pressure plate is 1.4 mm away from the butt joint line, and the ion beam acts on the tantalum side of the butt joint line 0.4 mm, effectively avoiding burn-through and deformation problems caused by the large difference in melting points of tantalum and titanium (a difference of 1393K).

[0023] 2. Ensure weld quality: Before welding, clean the workpiece with acetone to remove oil and dirt, and polish with 500#-2000# sandpaper to remove the surface oxide layer to reduce the impact on weld formation quality and ensure the density, strength, and corrosion resistance of the weld. At the same time, for ultra-thin tantalum and titanium plates with a thickness of 100um, select appropriate welding parameters, such as a tungsten rod diameter of 1mm, a 2mm indentation, a nozzle aperture of 1mm, an ion gas flow rate of 0.35L / min, a shielding gas flow rate of 2.5L / min, and a welding speed of 4.5mm / s. Ensure that each set of pulse parameters has the same heat input and a constant current, ensuring consistent weld formation and improving welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of tantalum-titanium ultra-thin plate welding;

[0025] Figure 2 This is a photo of the tantalum-titanium ultra-thin plate welding experimental sample. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the implementation regulations described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Before introducing the tantalum-titanium ultra-thin plate dissimilar metal pulsed micro-beam plasma arc welding method according to an embodiment of the present invention, the relevant terms are explained.

[0028] Ultra-thin plate: Metal plate with a thickness of less than or equal to 0.2mm.

[0029] Pulsed micro-plasma arc welding: The energy output of the plasma arc is controlled by high-frequency pulse current, and welding is performed using a plasma beam with an extremely small diameter (usually less than 1 mm).

[0030] Beam deviation: the deviation distance between the axis of the plasma arc and the weld joint.

[0031] The experimental dimensions of tantalum and titanium are 500×50×0.1mm 3 .

[0032] Use acetone to clean the workpiece before welding to remove oil stains on the workpiece surface.

[0033] Use 500#-2000# sandpaper to remove the surface oxide layer and minimize its impact on weld quality. When welding highly reactive metals (titanium and tantalum) or dissimilar metals, removing the surface oxide layer is a necessary step before welding, directly impacting the weld's density, strength, and corrosion resistance. Sandpaper polishing is crucial for dissimilar metal welding by physically removing the oxide film, removing reactive surfaces, and improving wettability.

[0034] The treated tantalum ultra-thin plate and titanium ultra-thin plate are butted end-to-end, and fixed on the left and right sides with a left pressure plate and a right pressure plate respectively. The pressure plate material is copper. As one of the key points of the present invention, the distance between the left and right pressure plates should be 1.5 mm. Because the pressure plate gap affects the formation of the weld, a larger pressure plate gap cannot effectively dissipate heat and is prone to burn-through defects. A smaller pressure plate gap can effectively reduce the accumulation of welding heat input, reduce burn-through and thermal deformation, but when the pressure plate gap is too narrow, the pressure plate absorbs too much energy, which will cause heat penetration.

[0035] As one of the key points of the present invention, the clamping method of the two thin plates is asymmetrical clamping along the butt joint line with double pressure plates. When the double pressure plates are asymmetrically clamped along the butt joint line, the tantalum side pressure plate is 1.4mm away from the butt joint line. When the double pressure plates are asymmetrically clamped along the butt joint line, the ion beam acts on the tantalum ultra-thin plate side of the butt joint line by 0.4mm. The use of asymmetrical clamping of the double pressure plates along the butt joint line has been verified through a large number of experiments to be able to effectively solve the burn-through problem. This is because the melting points of pure tantalum and TC4 titanium alloy are quite different, with a difference of 1393K. In addition, the thermal conductivity and latent heat of fusion of the two are quite different. When a very high temperature ion beam acts on pure tantalum and TC4 titanium alloy at the same time, the high temperature will quickly melt the TC4 with a low melting point, and then blow it up under the action of the airflow, making the molten pool discontinuous.

[0036] A key aspect of this invention is that after securing the workpiece with a pressure plate, the torch height is adjusted to 1.5 mm from the workpiece. The beam offset is 0.4 mm. This is because torch height significantly affects arc stability. Too high a height can cause the arc to stretch, weaken arc restraint, and reduce arc stability, making localized high temperatures more likely. Too low a height can compress the arc, increasing energy density and causing burn-through defects in ultra-thin sheet welding experiments.

[0037] As one of the key elements of this invention, a tungsten rod diameter of 1mm, a 2mm tungsten rod retraction, and a 1mm nozzle aperture are selected. Both the nozzle aperture and the rod retraction affect the arc compression level. When the nozzle aperture increases, the arc compression level decreases, while when the rod retraction increases, the arc compression level increases. Generally, when the current is not greater than 17A, a nozzle aperture of 1mm meets the requirements.

[0038] As one of the key points of the present invention, pulse micro-beam plasma arc welding is carried out under pure argon gas, wherein the ion gas flow is 0.35L / min and the shielding gas flow is 2.5L / min. Because the ion gas flow directly affects the energy density of the plasma beam, when the ion gas flow is insufficient, the energy density is reduced and thus affects the arc stability. When the ion gas flow is too large, the energy density is large, which will cause plasma cutting. The shielding gas flow directly affects the quality of the weld joint. If the shielding gas flow is low, the weld is not well protected. If the shielding gas flow is too high, the air flow will be unstable within the gap between the pressure plates, which will affect the arc stability and allow air to mix in. Therefore, in the pulse micro-beam plasma arc welding of dissimilar metals such as tantalum and titanium ultra-thin plates, it is very important to select a suitable shielding gas and a shielding gas flow that matches the ion gas flow.

[0039] A key aspect of the present invention is the required welding speed of 4.5 mm / s. This speed directly impacts the heat input, which decreases with increasing speed and increases with decreasing speed. Therefore, a suitable welding speed is crucial for weld formation in dissimilar metal welding of tantalum and titanium ultra-thin sheets.

[0040] In summary, the dissimilar metal welding of tantalum and titanium ultra-thin plates achieved according to the present invention can solve the current problem of burn-through during welding due to the large difference in melting points of tantalum and titanium, and can well achieve the dissimilar metal welding of tantalum and titanium ultra-thin plates.

[0041] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for welding dissimilar materials of tantalum and titanium ultra-thin plates, characterized in that: The following steps are involved: a. Clean the workpiece before welding and remove oil stains on the surface of the workpiece; b. Grinding to remove the oxide layer on the workpiece surface; c. Place the treated tantalum ultra-thin plate and titanium ultra-thin plate end faces together on the bottom plate, and use pressing plates to press and fix them respectively. The distance from the end of the pressing plate above the titanium ultra-thin plate to the butt joint line is T1, and the distance from the end of the pressing plate above the tantalum ultra-thin plate to the butt joint line is T2, T1 <T2; d. Use pulsed micro plasma arc welding; The e-ion beam acts on one side of the tantalum ultra-thin plate of the butt joint.

2. The method according to claim 1, wherein: Tantalum ultra-thin plates are made of pure tantalum.

3. The method according to claim 2, wherein: The material of titanium ultra-thin plate is TC4.

4. The method according to claim 3, wherein: The thickness of tantalum ultra-thin plate and titanium ultra-thin plate is 100um.

5. The method according to claim 4, characterized in that: The pressure plate and base plate are made of copper.

6. The method according to claim 5, characterized in that: T1=0.1mm, T2=1.4mm.

7. The method according to claim 4, characterized in that: The ion gas and shielding gas used in welding are both high-purity argon, and the ion gas flow rate is 0.35L / min and the shielding gas flow rate is 2.5L / min.

8. The method according to claim 7, characterized in that: The height of the welding gun from the surface of the ultra-thin plate is 1.5 mm. The diameter of the tungsten rod used during welding is 1 mm. The end of the tungsten rod is inside the nozzle and maintains a distance of 2 mm from the end of the nozzle. The welding speed is 4.5 mm / s and the welding current is a constant value.

9. The method according to claim 1, wherein: In step a, acetone is used to clean the workpiece.

10. The method according to claim 1, characterized in that: In step c, use 500#-2000# sandpaper for polishing.

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