Aluminum-titanium dissimilar metal composite laser welding method and aluminum-titanium welding head
By using ceramic thin film and composite laser beam welding methods in aluminum-titanium dissimilar metal welding, the problems of weld cracking and high porosity were solved, and high strength and high ductility of the weld were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-03-27
AI Technical Summary
In aluminum-titanium dissimilar metal welding, there are problems such as weld cracking tendency, high porosity and insufficient mechanical properties. In particular, it is difficult to control the heat input and weld quality in laser welding.
Welding is performed by depositing a ceramic thin film on the surface of titanium metal parts and combining a composite laser beam with blue light, point infrared and ring infrared lasers. The ceramic thin film reduces the formation of intermetallic compounds, blue light increases the absorption rate, infrared laser controls the heat input, and the composite laser beam oscillates and stirs to refine the grains and reduce porosity.
It significantly reduces the porosity of the weld, improves the mechanical properties and ductility of the weld, and meets the requirements of high-quality aluminum-titanium welded joints.
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Figure CN121732993A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of laser welding, in particular to an aluminum-titanium dissimilar metal composite laser welding method and an aluminum-titanium welded joint. BACKGROUND
[0002] The aluminum-titanium dissimilar metal composite structure has the advantages of low density, good economy of aluminum alloy and high specific strength, good corrosion resistance of titanium alloy, and can reduce the structure weight and save energy, and has a wide application in the fields of aerospace, shipbuilding and automobile manufacturing.
[0003] However, aluminum and titanium are dissimilar metals, the melting points of the two are different by about 800℃, the crystal lattice types and crystal lattice parameters of the two are quite different, the thermal conductivity and linear expansion coefficient of aluminum are 16 times and 3 times of titanium respectively, the residual stress of the welded joint is large, and the limited mutual solubility leads to the formation of a large number of high-fragility intermetallic compound phases (such as TiAl, TiAl2, TiAl3, etc.) at the weld, which reduces the strength and ductility of the welded joint.
[0004] In addition, aluminum and titanium are both active metals and are easily oxidized, and have a high reflectivity to infrared laser. In conventional laser welding, the laser energy acting on the weld area is very limited, and the minimum power of laser welding needs to be improved, and the porosity in the weld is significantly increased. For laser-brazing welding process, aluminum-titanium dissimilar metal can form a good joint, but the heat input in the welding process is difficult to control, which easily causes the titanium alloy layer to melt intensively and form a thick intermetallic compound layer, and the wettability of Al-Si and other brazing materials on the titanium metal surface is poor, which also easily produces defects such as pores. For ultrasonic energy field assisted laser welding process, the grains and intermetallic compound phases in the aluminum-titanium dissimilar metal weld can be effectively refined, but the cavitation bubbles generated by ultrasonic vibration easily cause the weld to have more holes, which is particularly obvious in the connection of aluminum-titanium thin plates. SUMMARY
[0005] The purpose of the embodiments of the present application is to provide an aluminum-titanium dissimilar metal composite laser welding method and an aluminum-titanium welded joint, which can reduce the cracking tendency and porosity in the weld, and improve the mechanical properties and ductility of the weld.
[0006] In one aspect, the present application provides an aluminum-titanium dissimilar metal composite laser welding method, comprising the following steps: S1, depositing a ceramic film on the surface of a titanium metal part or an aluminum metal part; S2, stacking and fixing the aluminum metal part and the titanium metal part to obtain a to-be-welded part; S3, focusing a blue laser, a point infrared laser and a ring infrared laser to a welding site on the surface of the to-be-welded part to form a composite laser beam; S4, welding the to-be-welded part in a manner that the composite laser beam is kept oscillating and swinging.
[0007] When the ceramic film is deposited on the surface of the titanium metal part, the instantaneous Ti dissolution rate can be effectively reduced in the initial moment of laser heating (when the ceramic film is deposited on the surface of the aluminum metal part, the aluminum metal part can be effectively reduced in the high-temperature residence time and the instantaneous dissolution rate during the welding process), the generation of intermetallic compound phases is delayed, and the ceramic film peeled off into the molten pool under the impact of heat can act as nucleation particles to refine the weld structure; the surface of the aluminum metal part or the titanium metal part is preheated using blue laser, the laser absorption rate of the high-reflective metal is improved by the action of blue light; the deep penetration welding (also called spoon hole welding) mode is maintained during the welding of the high-reflective metal by using the high energy density characteristics of the point infrared laser (central infrared beam); the temperature gradient of the material surface during welding is reduced by using the composite of the ring infrared laser (annular infrared beam), and the welding spoon is stabilized, thereby further reducing the heat input; the oscillation of the composite laser beam can provide stirring force for the molten pool, which is beneficial to the floating of bubbles, thereby achieving the purpose of reducing pores, and is beneficial to the mixing of dissimilar metal base materials and the refinement of the grain in the weld zone, and improves the mechanical properties and ductility of the weld.
[0008] In some embodiments, the aluminum metal part comprises aluminum or an aluminum alloy, and the titanium metal part comprises titanium or a titanium alloy.
[0009] In some embodiments, in S1, the thickness of the ceramic film is 1-5 μm.
[0010] In some embodiments, in S2, when the ceramic film is deposited on the surface of the titanium metal part, the aluminum metal part and the titanium metal part are stacked in an up-down manner; when the ceramic film is deposited on the surface of the aluminum metal part, the titanium metal part and the aluminum metal part are stacked in an up-down manner.
[0011] In some embodiments, in S3, a blue laser and an infrared adjustable mode laser are used to emit blue laser, point infrared laser and ring infrared laser, and the waist positions of each laser beam are located at the welding site by beam combining to form the composite laser beam.
[0012] In some embodiments, the radius of the blue laser is 0.8-1 mm, the diameter of the point infrared laser is 0.01-0.05 mm, the diameter of the ring infrared laser is 0.1-0.3 mm, and the center energy density is >10 6 W / mm 2 .
[0013] In some embodiments, the oscillation mode of the composite laser beam comprises at least one of ∞ type, 8 type, o type and straight line type.
[0014] In the technical scheme, the oscillation mode composite laser beam has a strong stirring effect on the welding pool, can significantly refine the grains and inhibit the welding seam pores, and the ceramic film peeled off by the thermal impact into the welding pool can refine the grains as a heterogeneous nucleation point, which is a feasible way to realize high-quality welding.
[0015] In some embodiments, the power of the blue laser is 100-500 W, the power of the point infrared laser is 500-1000 W, the power of the ring infrared laser is 500-1000 W, the amplitude of the oscillation is 0.5-2 mm, the frequency is 50-200 Hz, the welding speed is 10-100 mm / s, and the defocusing amount is 0-0.5 mm.
[0016] In some embodiments, in S2, an inert medium is used to protect the welding area during welding, and the flow rate of the inert medium is 5-20 L / min.
[0017] In some embodiments, the aluminum-titanium welding joint is obtained by using the above-mentioned aluminum-titanium dissimilar metal composite welding method, the aluminum-titanium welding joint comprises an aluminum metal part and a titanium metal part stacked and welded together, the porosity in the welding seam is <0.5 vol.%, the shear strength is 95-120 MPa, and the elongation rate is 5%-15%. BRIEF DESCRIPTION OF DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.
[0019] Figure 1 A macroscopic morphology diagram of a titanium metal and an aluminum metal surface coating provided by the embodiments of the present application; Figure 2 A schematic diagram of an aluminum-titanium dissimilar metal composite laser welding method provided by the embodiments of the present application; Figure 3 A macroscopic morphology diagram of the aluminum-titanium welding joint of embodiment 1 at the welding seam; Figure 4 A shear performance diagram of the welding seam of the aluminum-titanium welding joint of embodiment 1; Figure 5 A macroscopic morphology diagram of the aluminum-titanium welding joint of embodiment 2 at the welding seam; Figure 6 A shear performance diagram of the welding seam of the aluminum-titanium welding joint of embodiment 2; Figure 7Macrograph of the aluminum titanium weld joint of Example 3 at the weld; Figure 8 Shear performance of the weld of the aluminum titanium weld joint of Example 3; Figure 9 Macrograph of the aluminum titanium weld joint of Example 4 at the weld; Figure 10 Shear performance of the weld of the aluminum titanium weld joint of Example 4; Figure 11 Macrograph of the aluminum titanium weld joint of Comparative Example 1 at the weld; Figure 12 Shear performance of the weld of the aluminum titanium weld joint of Comparative Example 1; Figure 13 Macrograph of the aluminum titanium weld joint of Comparative Example 2 at the weld; Figure 14 Shear performance of the weld of the aluminum titanium weld joint of Comparative Example 2; Figure 15 Macrograph of the aluminum titanium weld joint of Comparative Example 3 at the weld; Figure 16 Shear performance of the weld of the aluminum titanium weld joint of Comparative Example 3; Figure 17 Macrograph of the aluminum titanium weld joint of Comparative Example 4 at the weld; Figure 18 Shear performance of the weld of the aluminum titanium weld joint of Comparative Example 4. DETAILED DESCRIPTION
[0020] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.
[0021] The terms "first", "second", "third", etc. are only for descriptive purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.
[0022] In the description of the present application, it should be noted that unless otherwise expressly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0023] Aluminum-titanium welded joints can meet the requirements of high strength, light weight and economy, and have become the focus of attention in the fields of aerospace and automobile manufacturing. However, aluminum and titanium have quite different chemical and physical properties such as thermal conductivity, thermal expansion coefficient, melting point, etc. Moreover, the limited mutual solubility leads to the formation of a large number of high-fragility intermetallic compound phases and high residual stress in the weld, thereby reducing the strength and ductility of the welded joint.
[0024] Aluminum and titanium metals are highly active and have high reflectivity to infrared laser (1064 nm). In laser welding, the laser energy acting on the weld area is very limited, which increases the minimum power of dissimilar metal laser welding and significantly increases the porosity in the weld. Blue light and infrared laser composite technology can improve the absorption rate of high reflectivity aluminum-titanium metal to laser, reduce heat input, make the penetration depth easy to control, and can improve the strength of the welded joint. However, due to the active nature of aluminum and titanium metals, they are easily oxidized, and hydrogen pores and gas cavities formed by the collapse of part of the pores are easily formed in the weld, which reduces the performance of the welded joint.
[0025] At present, the main method to reduce the porosity in laser welding is to increase the stirring effect of the molten pool. Through analysis of the existing technology, it can be found that the existing technology discloses a method of introducing ultrasonic vibration and pulse stirring to increase the fluidity of the aluminum alloy molten pool in ultrasonic-assisted pulse laser-MIG composite heat source welding, which effectively solves the problem of easy formation of more pores in the aluminum alloy laser-MIG composite heat source welded joint. However, introducing an external auxiliary energy field device in aluminum-titanium sheet lap laser welding is not conducive to high-efficiency mass production. Another existing technology is to use laser-arc composite welding technology, which uses laser to preheat or melt the titanium side first, and then uses TIG / MIG arc to fill aluminum alloy welding wire to form a transition layer containing aluminum-titanium alloy, which effectively reduces the content of pores and brittle phases in the weld. However, its welding speed is relatively slow. In addition, another existing technology is to introduce an oscillating scanning laser beam in laser-arc composite welding, which has stronger pore suppression ability in the weld. However, the oscillating laser beam is around the arc action point in a small local area to achieve synergistic reinforcement, and the welding effect needs to be improved.
[0026] The applicant found through research that, based on the red and blue laser and surface modified aluminum-titanium dissimilar metal composite welding method, the original in-situ preheating stable molten pool can be realized, the intermetallic compound phase generation is delayed, the porosity is reduced, the cracks are prevented, the weld structure is refined, and the mechanical properties of the weld are improved, so as to overcome the shortcomings of the prior art and meet the urgent needs of high-quality Al / Ti welded joints.
[0027] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. If specific conditions are not specified in the embodiments, conventional conditions or manufacturer recommended conditions are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.
[0028] The aluminum-titanium dissimilar metal composite laser welding method of the embodiments of the present application will be described in detail below.
[0029] Please refer to Figure 1 and Figure 2 , the embodiments of the present application provide an aluminum-titanium dissimilar metal composite laser welding method, comprising the following steps: S1, depositing a ceramic film with a thickness of 1-5 μm on the surface of the titanium metal plate by a physical method.
[0030] In some embodiments of the present application, the titanium metal includes pure titanium (produced by Baoji Hongyan Titanium Nickel Metal Co., Ltd., such as TA0 and TA1 grades) or titanium alloy (produced by Baoji Hongyan Titanium Nickel Metal Co., Ltd., such as TC4 and TA15 grades), the titanium metal plate is selected from the above-mentioned titanium metal plate, the surface should be clean without oxidation layer, the thickness of the titanium metal plate is 0.1-2 mm, and the thickness tolerance is controlled within ±0.05 mm.
[0031] In some embodiments of the present application, in S1, the surface of the titanium metal plate is ultrasonically cleaned and dried, then clamped in a vacuum chamber, vacuumed to a base pressure ≤5*10 -4 Pa, etching the surface with Ar plasma for 5-10 min, selecting CrAl target material for sputter deposition coating, and obtaining a ceramic film with a target thickness of 1-5 μm.
[0032] S2, stacking and fixing the aluminum metal plate and the titanium metal plate to obtain a welded part.
[0033] In some embodiments of the present application, the aluminum metal includes pure aluminum (produced by Henan Mingtai Aluminum Co., Ltd., such as 1050 and 1060) or aluminum alloy (produced by Henan Mingtai Aluminum Co., Ltd., such as 5052 and 6061), the aluminum metal plate is selected from the above-mentioned aluminum metal plate, the surface should be clean without oxidation layer, the thickness of the aluminum metal plate is 0.1-1 mm, and the thickness tolerance is controlled within ±0.05 mm. The titanium metal plate is selected from the above-mentioned titanium metal plate coated with a ceramic film with a thickness of 1-5 μm.
[0034] In some embodiments of the present application, in S1, the to-be-welded plate: the aluminum metal plate is polished, cleaned (acetone scrubbing and ultrasonic cleaning) and dried, and then is stacked and fixed with a welding clamp. The polishing method can be selected from sandpaper, and the cleaning method can be selected from acetone scrubbing and ultrasonic cleaning. In S1, the aluminum metal plate can be directly contacted and fixed above or below the titanium metal plate, and the ceramic film with a thickness of 1-5 μm is an interface layer for the contact between the aluminum and titanium metal plates. Correspondingly, the aluminum metal plate and the titanium metal plate are stacked in an up-down manner or in a down-up manner.
[0035] Figure 1 (b) of FIG. is the ceramic film on the surface of the aluminum metal plate (i.e., the titanium metal plate and the aluminum metal plate are stacked in an up-down manner); and (a) is the ceramic film on the surface of the titanium metal plate (i.e., the aluminum metal plate and the titanium metal plate are stacked in an up-down manner).
[0036] S3, focusing blue laser, point infrared laser and ring infrared laser to the welding site on the surface of the to-be-welded piece to form a composite laser beam; In some embodiments of the present application, in S2, a blue laser and an infrared adjustable mode laser are used to emit a blue laser, a point infrared laser (central infrared beam) and a ring infrared laser (annular infrared beam), and the three lasers are combined through a welding head. For example, the used laser is a beam mode adjustable laser, YDFL-2000 / 4000-PAM+ of Shanghai Feibo Laser Technology Co., Ltd.; and a blue laser, BLF-455-800-2 of Guangdong Guangdong-Hong Kong-Macao Greater Bay Area Hard Technology Innovation Institute, is used in combination (the same equipment is used in subsequent examples and comparative examples, and will not be described herein again). In other embodiments, other lasers that can emit a blue laser, a point infrared laser and a ring infrared laser can be used, which can be a single laser or a combination of different lasers.
[0037] The focusing method is to adjust the distance from the focal point of each laser to the welding site, so that the waist positions of each laser beam are located at the same plane of the welding site to form a composite laser beam. The "waist position" is a point with the best energy and quality of the light beam emitted by the laser, and the waists of the above-mentioned three lasers (blue laser, point infrared laser and ring infrared laser) coincide,Figure 2 The welding site is the upper surface of the aluminum metal plate.
[0038] In some embodiments of the present application, the composite laser beam refers to the composite laser beam formed after the above-mentioned three laser beams (blue laser, point infrared laser and ring infrared laser) are combined and focused. During the welding process, the composite laser beam remains combined and focused. In the formed composite laser beam, the radius of the blue laser is 0.8-1 mm, the diameter of the point infrared laser is 0.01-0.05 mm, the diameter of the ring infrared laser is 0.1-0.3 mm, and the center energy density is >10 6 W / mm 2 , so as to achieve a keyhole welding mode.
[0039] The size and shape of each laser beam are based on the size and shape of each laser beam on the same plane (such as the upper surface of the aluminum metal plate) that receives welding. The size refers to the outer diameter size. The center energy density of the composite laser beam is mainly determined by the point infrared laser, and the energy density of the remaining beams is much smaller than that of the point infrared laser. Therefore, the center energy density of the composite laser beam can be controlled by adjusting the energy density of the point infrared laser.
[0040] S4, welding the to-be-welded piece in a manner that the composite laser beam remains oscillating and swinging. During the welding process, the blue laser is used to preheat the surface of the aluminum metal plate or the titanium metal plate, the center infrared laser is used to form a keyhole welding (also called keyhole welding) mode, and the ring infrared laser is used to stabilize the keyhole and reduce spatter.
[0041] During the welding process, the oscillation frequency and amplitude of the composite laser beam are adjusted so that the composite laser beam remains oscillating and swinging, and at the same time, the welding speed is controlled by a mechanical arm to form a continuous weld. The swinging mode of the composite laser beam includes at least one of ∞ type, 8 type, o type and straight line type.
[0042] During the welding process, the power of the three laser beams is set respectively, and the dissimilar metal is welded according to a predetermined welding speed. The process parameters include the welding speed and the power of the three laser beams.
[0043] In some embodiments of the present application, the process parameters for welding are as follows: the power of the blue laser is 100-500 W, the power of the point infrared laser is 500-1000 W, and the power of the ring infrared laser is 500-1000 W; the amplitude of the oscillating swing is 0.5-2 mm, and the frequency is 50-200 Hz; the welding speed is 10-100 mm / s, and the defocusing amount is 0-0.5 mm.
[0044] In some embodiments of the present application, in S3, an inert medium is used to protect the welding area during the welding process; optionally, the flow rate of the inert medium is 5-20 L / min.
[0045] In addition, the present application provides an aluminum-titanium welded joint, which is prepared by the aluminum-titanium dissimilar metal composite laser welding method provided above, and comprises an aluminum metal plate and a titanium metal plate which are stacked and welded together. The weld is well shaped, the porosity in the weld is <0.5 vol.%, the shear strength can meet 80-95% of the strength of the aluminum metal plate, the shear strength is 95-120 MPa, and the elongation is 5%-15%.
[0046] The features and performances of the present application are further described in detail below in combination with embodiments.
[0047] The present embodiment provides an aluminum-titanium dissimilar metal composite laser welding method, which comprises the following steps: S1, titanium metal plate film plating: the surface of the titanium metal plate (TA1, produced by Baoji Hongyan Titanium Nickel Metal Co., Ltd.) is subjected to sand blasting polishing, ultrasonic cleaning and drying treatment, and then is clamped in a vacuum chamber, vacuumized to a base pressure ≤5*10 -4 Pa, the surface is etched by Ar plasma for 5 min, CrAl target material (Cr-70Al, at.%, purity ≥99.7%, Xi'an Fangke New Material Technology Co., Ltd.) and appropriate process parameters (physical vapor deposition nanohard coating system manufactured by Ningbo Dunge Coating Technology Co., Ltd., model DG1200, plating time 200 min, plating temperature 450 ℃) are used for sputter deposition plating, and a target thickness of 2 μm of CrAl ceramic film is obtained.
[0048] S2, the to-be-welded plate: the aluminum metal plate is polished with sandpaper, cleaned with acetone and dried by ultrasonic cleaning, and fixed with a welding clamp, wherein the aluminum metal plate is overlapped above the plated titanium metal plate, and the 2 μm thick CrAl ceramic film layer is the interface layer for aluminum-titanium metal contact (see Figure 2 ).
[0049] S3, a semiconductor blue laser and an infrared point ring laser beam adjustable mode laser emit blue laser, point infrared laser (central infrared beam) and ring infrared laser (ring-shaped infrared beam), and the multiple laser beams are focused on the upper surface of the aluminum metal plate through the welding head to form a composite laser beam.
[0050] S4, control the welding head to keep the light beam oscillating swing for welding, the laser swing mode is "o" type, and the process parameters consist of: the blue light laser power is 100 W, the center infrared laser power is 600 W, the outer ring infrared laser power is 700 W, the amplitude is 0.5 mm, the oscillation frequency is 150 Hz, the welding speed is 30 mm / s, the defocusing amount is 0 mm, the flow of the inert medium is 15 L / min, and the aluminum-titanium dissimilar metal connection is realized by using the process parameters, and an aluminum-titanium welded joint is obtained.
[0051] The macrostructure and shear performance of the aluminum-titanium welded joint at the weld are as shown in Figure 3 and Figure 4 It is shown that the porosity of the weld is calculated by using the Image-ProPlus software (the ratio of the pore area to the weld area in the metallographic photo). The porosity of the weld of the aluminum-titanium welded joint obtained in this embodiment is low (<0.5 vol.%), the grain structure is fine, the brittle layer of the aluminum-titanium interface layer is thin, the brittle phase content is small, the shear strength is 85% of the base material strength, the highest shear strength is 110 MPa, and the elongation is 12%.
[0052] Embodiment 2 This embodiment provides an aluminum-titanium dissimilar metal composite laser welding method, which comprises the following steps: S1, film plating of the titanium metal plate: the surface of the titanium metal plate (TA1, produced by Baoji Hongyan Titanium Nickel Metal Co., Ltd.) is subjected to sand blasting polishing, ultrasonic cleaning and drying treatment, and then is clamped in a vacuum chamber, vacuumized to a base pressure of ≤5*10 -4 Pa, the surface is etched by Ar plasma for 10 min, CrAl target material (Cr-70Al, at.%, purity ≥99.7%, Xi'an Fangke New Material Technology Co., Ltd.) and appropriate process parameters (physical vapor deposition nanohard coating system manufactured by Ningbo Dunge Coating Technology Co., Ltd., model DG1200, film plating time 300 min, film plating temperature 500 ℃) are used for sputtering deposition film plating, and a CrAl ceramic film with a target thickness of 4 μm is obtained.
[0053] S2, the to-be-welded plate: the aluminum metal plate is polished with sandpaper, cleaned with acetone and dried by ultrasonic cleaning, and fixed by a welding clamp, wherein the aluminum metal plate is overlapped above the film-plated titanium metal plate, and the 4 μm thick CrAl ceramic film layer is the interface layer for the contact between the aluminum and titanium metal.
[0054] S3, the semiconductor blue light laser and the infrared point ring light beam adjustable mode laser emit blue light laser, point infrared laser (center infrared light beam) and ring infrared laser (ring-shaped infrared light beam), and the multiple laser beams are focused on the upper surface of the aluminum metal plate through the welding head to form a composite laser beam.
[0055] S4, control the welding head to keep the light beam oscillating swing welding, the laser swing mode is "∞" type, and the process parameters consist of: the blue light laser power is 200 W, the central infrared laser power is 700 W, the outer ring infrared laser power is 800 W, the amplitude is 1.0 mm, the oscillation frequency is 100 Hz, the welding speed is 50 mm / s, the defocusing amount is 0.2 mm, the flow of inert medium is 10 L / min, and the aluminum-titanium welding joint is prepared.
[0056] The macrostructure and shear performance of the aluminum-titanium welding joint at the weld are as shown in Figure 5 and Figure 6 It is shown that the porosity of the weld is calculated by using the Image-ProPlus software (the ratio of the pore area to the weld area in the metallographic photo). The porosity of the weld of the aluminum-titanium welding joint obtained in the embodiment is low (<0.5 vol.%), the grain structure is fine, the brittle layer of the aluminum-titanium interface layer is thin, the brittle phase content is less, the shear strength is 90% of the base material strength, the highest shear strength is 118 MPa, and the elongation is 8%.
[0057] Embodiment 3 The embodiment provides an aluminum-titanium dissimilar metal composite laser welding method, which comprises the following steps: S1, film plating of the titanium metal plate: the surface of the titanium metal plate (TA1, produced by Baoji Hongyan Titanium Nickel Metal Co., Ltd.) is subjected to sand blasting polishing, ultrasonic cleaning and drying treatment, and then is clamped in a vacuum chamber, vacuumized to a base pressure ≤5*10 -4 Pa, the surface is etched by using Ar plasma for 10 min, Cr-Al target material (Cr-70Al, at.%, purity ≥99.7%, Xi'an Fangke New Material Technology Co., Ltd.) and appropriate process parameters (a physical vapor deposition nanohard coating system manufactured by Ningbo Dunge Coating Technology Co., Ltd., model number is DG1200, film plating time is 200 min, film plating temperature is 450℃) are used for sputtering deposition film plating, and a CrAl ceramic film with a target thickness of 2 μm is obtained.
[0058] S2, the to-be-welded plate: the aluminum metal plate is polished by using sandpaper, cleaned by using acetone and dried by ultrasonic cleaning, and fixed by using a welding clamp, wherein the aluminum metal plate is overlapped above the film-plated titanium metal plate, and the 2 μm thick CrAl ceramic film layer is an interface layer for the contact between the aluminum and titanium metal.
[0059] S3, the semiconductor blue light laser and the infrared point ring light beam adjustable mode laser emit blue light laser, point infrared laser (central infrared light beam) and ring infrared laser (ring-shaped infrared light beam), the multiple light beams are focused on the upper surface of the aluminum metal plate through the welding head to form a composite laser beam.
[0060] S4, control the welding head to keep the light beam oscillating swing welding, the laser swing mode is "∞" type, and the process parameters consist of: the blue light laser power is 200 W, the center infrared laser power is 700 W, the outer ring infrared laser power is 800 W, the amplitude is 1.0 mm, the oscillation frequency is 100 Hz, the welding speed is 50 mm / s, the defocusing amount is 0.2 mm, the flow of inert medium is 10 L / min, and the aluminum-titanium welding joint is prepared.
[0061] The macrostructure and shear performance of the aluminum-titanium welding joint at the weld are as shown in Figure 7 and Figure 8 It is shown that the porosity of the weld is calculated by using Image-ProPlus software (the ratio of the pore area to the weld area in the metallographic photo). The porosity of the weld of the aluminum-titanium welding joint obtained in this embodiment is low (<0.5 vol.%), the grain structure is fine, the brittle layer of the aluminum-titanium interface layer is thin, the brittle phase content is small, the shear strength is 92% of the base material strength, the highest shear strength is 120 MPa, and the elongation is 6%.
[0062] Example 4 This embodiment provides an aluminum-titanium dissimilar metal composite laser welding method, and the steps are as follows: S1, aluminum metal plate film coating: the surface of the aluminum metal (6061-T4, Henan Mingtai Aluminum Co., Ltd.) is subjected to sand blasting polishing, ultrasonic cleaning and drying treatment, and then is clamped in a vacuum chamber, vacuumized to a base pressure ≤5*10 -4 Pa, the surface is etched by Ar plasma for 10 min, CrAl target material (Cr-70Al, at.%, purity ≥99.7%, Xi'an Fangke New Material Technology Co., Ltd.) and appropriate process parameters (physical vapor deposition nanohard coating system manufactured by Ningbo Dunge Coating Technology Co., Ltd., model DG1200, film coating time 200 min, film coating temperature 450°C) are used for sputtering deposition film coating, and a CrAl ceramic film with a target thickness of 2 μm is obtained.
[0063] S2, the plate to be welded: the titanium metal plate is polished with sandpaper, cleaned with acetone and dried by ultrasonic cleaning, and fixed with a welding clamp, wherein the titanium metal plate is overlapped above the coated aluminum metal plate, and the 2 μm thick CrAl ceramic film layer is the interface layer for aluminum-titanium metal contact.
[0064] S3, the semiconductor blue light laser and the infrared point ring light beam adjustable mode laser emit blue light laser, point infrared laser (center infrared light beam) and ring infrared laser (ring infrared light beam), and the multiple laser beams are focused on the upper surface of the titanium metal plate through the welding head to form a composite laser beam.
[0065] S4, the welding head is controlled to keep the light beam oscillating and welding, the laser oscillation mode is "∞" type, and the process parameters consist of: the blue light laser power is 200 W, the central infrared laser power is 700 W, the outer ring infrared laser power is 800 W, the amplitude is 1.0 mm, the oscillation frequency is 100 Hz, the welding speed is 50 mm / s, the defocusing amount is 0.2 mm, and the flow of the inert medium is 10 L / min, so that the aluminum-titanium welded joint is prepared.
[0066] The macrostructure and shear performance of the aluminum-titanium welded joint at the weld are as shown in Figure 9 and Figure 10 The porosity of the weld is calculated by using Image-ProPlus software (the ratio of the pore area to the weld area in the metallographic photo). The aluminum-titanium welded joint obtained in this embodiment has a low porosity (<0.5 vol.%) in the weld, a small grain structure, a large amount of brittle phase in the aluminum-titanium interface layer, a shear strength of 72% of the base material strength, a maximum shear strength of 95 MPa, and an elongation of 5.4%.
[0067] Comparative Example 1 The same as in Example 1, except that the CrAl ceramic film is not included and the blue light laser is not included.
[0068] The macrostructure and shear performance of the aluminum-titanium welded joint at the weld obtained in this comparative example are as shown in Figure 11 and Figure 12 The aluminum-titanium welded joint obtained in this comparative example has cracks in the weld, a porosity of 7.5 vol.%, a maximum shear strength of 40 MPa, and an elongation of 2%.
[0069] Comparative Example 2 The same as in Example 1, except that the CrAl ceramic film is not included and the point infrared laser (central infrared light beam) is not included.
[0070] The macrostructure and shear performance of the aluminum-titanium welded joint at the weld obtained in this comparative example are as shown in Figure 13 and Figure 14 The aluminum-titanium welded joint obtained in this comparative example has cracks in the weld, a porosity of 3.5 vol.%, a maximum shear strength of 65 MPa, and an elongation of 3%.
[0071] Comparative Example 3 The same as in Example 1, except that the CrAl ceramic film is not included and the ring infrared laser (annular infrared light beam) is not included.
[0072] The macrostructure and shear performance of the aluminum-titanium welded joint at the weld obtained in this comparative example are as shown in Figure 15 and Figure 16As shown, the obtained aluminum-titanium welded joint has cracks in the weld, a porosity of 4.5 vol.%, a maximum shear strength of 50 MPa, and an elongation of 4%.
[0073] Comparative Example 4 The same as in Example 1, except that the CrAl ceramic film is not included.
[0074] The macrostructure and shear performance of the aluminum-titanium welded joint obtained in this comparative example 4 at the weld are as follows: Figure 17 and Figure 18 As shown, the obtained aluminum-titanium welded joint has cracks in the weld, a porosity of 5.5 vol.%, a maximum shear strength of 55 MPa, and an elongation of 3%.
[0075] In summary: 1. The physical barrier effect of the ceramic film on Ti dissolution must be coordinated with the effect of the blue light on the improvement of the absorption rate of the high-reflectivity metal surface, so as to effectively control the interface reaction rate in the initial stage of welding. Only with the ceramic coating film and without the blue light preheating, although the Ti dissolution can be partially blocked, the initial energy absorption is unstable due to the high reflectivity, and the coating film is easy to fail locally; only with the blue light and without the ceramic coating film, the energy absorption is improved, but Ti directly interacts with the Al molten pool and the laser, the Ti dissolution rate is fast, and the content of the interface brittle phase is high.
[0076] 2. With the progress of the welding process, part of the ceramic film peels off into the molten pool under the action of thermal shock, which can serve as a heterogeneous nucleation core to promote the grain refinement in the weld zone. Without the red and blue laser and the oscillation mode, the peeled particles are easy to agglomerate and difficult to uniformly refine the weld grains; if there is no ceramic coating film, there is a lack of effective nucleation centers in the molten pool, and the change of the molten pool flow mode has limited effect on the grain refinement.
[0077] 3. If only a point infrared laser is used, although a high energy density can form a spoon hole, the surface temperature gradient is too large, and the stability of the spoon hole is poor; if only a blue light or a blue light + point infrared light is used, the size of the molten pool is limited, and it is difficult to form a stable deep penetration welding; the introduction of the ring infrared light redistributes the energy in the radial direction, significantly improves the stability of the spoon hole, and reduces the overall heat input under the premise of ensuring weld penetration. The beam oscillation of the composite laser can provide stirring force for the molten pool, which is beneficial to the floating of the bubbles in the spoon hole, so as to achieve the purpose of reducing the porosity.
[0078] That is, the present application can reduce the cracking tendency and porosity in the weld, and improve the mechanical properties and ductility of the weld, which meets the urgent needs of high-quality aluminum-titanium welded joints.
[0079] The above merely provides an example of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims
1. A method for laser welding aluminum-titanium dissimilar metal composites, characterized in that, Includes the following steps: S1. Deposit a ceramic thin film on the surface of a titanium or aluminum metal component; S2. Stack and fix the aluminum and titanium metal parts together to obtain the parts to be welded; S3. Combine and focus the blue laser, point infrared laser and ring infrared laser onto the welding point on the surface of the workpiece to be welded to form a composite laser beam; S4. The composite laser beam is kept oscillating and swinging to weld the workpiece.
2. The method for laser welding aluminum-titanium dissimilar metal composites according to claim 1, characterized in that, The aluminum metal component includes aluminum or an aluminum alloy, and the titanium metal component includes titanium or a titanium alloy.
3. The aluminum-titanium dissimilar metal composite welding method according to claim 1, characterized in that, In S1, the thickness of the ceramic film is 1-5 μm.
4. The aluminum-titanium dissimilar metal composite welding method according to claim 1, characterized in that, In S2, when a ceramic thin film is deposited on the surface of a titanium metal component, its aluminum metal component is stacked on top of the titanium metal component; when a ceramic thin film is deposited on the surface of an aluminum metal component, its titanium metal component is stacked on top of the aluminum metal component.
5. The aluminum-titanium dissimilar metal composite welding method according to claim 1, characterized in that, In S3, blue laser and infrared tunable mode laser are used to emit blue laser, point infrared laser and ring infrared laser. The laser beams are combined by the welding head so that the waist of each laser beam is located at the welding point to form the composite laser beam.
6. The method for laser welding aluminum-titanium dissimilar metal composites according to claim 1, characterized in that, The blue laser has a radius of 0.8-1 mm, the point infrared laser has a diameter of 0.01-0.05 mm, the ring infrared laser has a diameter of 0.1-0.3 mm, and the central energy density is >10. 6 W / mm 2 .
7. The aluminum-titanium dissimilar metal composite welding method according to claim 1, characterized in that, The oscillation mode of the composite laser beam includes at least one of the following: ∞-type, 8-type, o-type, and linear type.
8. A method for aluminum-titanium dissimilar metal composite welding according to claim 1 or 6, characterized in that, The power of the blue laser is 100-500 W, the power of the point infrared laser is 500-1000 W, and the power of the ring infrared laser is 500-1000 W; the amplitude of the oscillation is 0.5-2 mm, the frequency is 50-200 Hz, the welding speed is 10-100 mm / s, and the defocusing amount is 0-0.5 mm.
9. The aluminum-titanium dissimilar metal composite welding method according to claim 1, characterized in that, In S2, an inert medium is used to protect the welding area during the welding process, and the flow rate of the inert medium is 5-20 L / min.
10. An aluminum-titanium welding joint, characterized in that, It is prepared by an aluminum-titanium dissimilar metal composite welding method as described in any one of claims 1 to 9. The aluminum-titanium welded joint comprises aluminum metal parts and titanium metal parts stacked and welded together. The porosity of the weld is <0.5 vol.%, the shear strength is 95-120 MPa, and the elongation is 5%-15%.