Method for homogenizing reinforced phase of inserted ultrasonic vibration-assisted laser welding aluminum-based composite material

Abstract

The invention discloses a plug-in ultrasonic vibration assisted laser welding aluminum-based composite reinforcement phase homogenization method which is characterized by comprising the following steps: carrying out mechanical assembly and laser spot welding fixation on a workpiece to be welded; and formal welding operation is conducted on the to-be-welded workpiece, when welding is started to form a keyhole, a variable-amplitude tungsten needle capable of conducting ultrasonic vibration extends into a molten pool to conduct stirring, and welding is completed. Ultrasonic vibration directly acts on a laser welding pool through the variable-amplitude tungsten needle, and the aggregation phenomenon of a reinforcing phase in the welding process is effectively improved. Compared with a traditional method only by optimizing welding parameters or adding filling materials, the method has the advantages that highly uniform distribution of the reinforcement phase in the welding joint area can be achieved, the contour morphology of the welding seam is improved, and the quality of the welding seam is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of material processing engineering, and particularly relates to an insertion-type ultrasonic vibration-assisted laser welding method for homogenizing an aluminum-based composite material reinforcement phase. Background Art

[0002] With the widespread application of aluminum matrix composites (Al-MMCs) in aerospace, automotive industry and high-performance structural materials, improving the quality of their welded joints has become a research focus. The reinforcing phases in Al-MMCs usually contain SiC, BC, TiC, CNTs, etc. The presence of these reinforcing phases can significantly improve the strength, heat resistance and wear resistance of the material. However, during its laser welding process, the reinforcing phases often aggregate or distribute unevenly in the welding area, resulting in unstable performance of the welded joints and prone to defects such as cracks and pores, which greatly limits its application in scenarios with high service requirements.

[0003] In the laser connection of Al-MMCs structural parts, the reaction of the reinforcement phase and its uneven distribution are usually suppressed by optimizing the laser welding mode, welding parameters or in-situ fillers. Although the joint performance is improved, this method cannot completely homogenize the distribution of the reinforcement phase particles and may even lead to the segregation of alloy elements in the welded joint area, resulting in a sharp decline in joint performance. In addition, the heat input and material fluidity control in the welding process are difficult, which further increases the complexity of the homogenization of the reinforcement phase. Although the existing technology has been improved to a certain extent by optimizing welding parameters and adding filler materials, it has not been able to completely solve the problem of homogenization of the reinforcement phase. Summary of the invention

[0004] In view of the problem in the prior art that the distribution of reinforcing phase particles in aluminum-based composite materials cannot be completely homogenized, the purpose of the present invention is to provide a method for homogenizing the reinforcing phase of aluminum-based composite materials by inserting ultrasonic vibration-assisted laser welding. This method introduces ultrasonic vibration during the laser welding process of the workpiece to be welded. The variable amplitude tungsten needle of the ultrasonic vibration system is directly extended into the molten pool for stirring, and moves synchronously with the laser to obtain a welding joint of the workpiece to be welded with good forming, uniform distribution of reinforcing phase and excellent joint mechanical properties.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for inserting ultrasonic vibration-assisted laser welding of aluminum-based composite reinforcement phase homogenization, comprising the following steps: Mechanically assemble and fix the workpieces to be welded by laser spot welding; The workpiece to be welded is formally welded. When the keyhole is formed, a variable amplitude tungsten needle capable of ultrasonic vibration is inserted into the molten pool for stirring to complete the welding.

[0006] Furthermore, the workpiece to be welded is mechanically assembled and fixed by laser spot welding, including the following steps: the workpiece to be welded is mechanically assembled using copper pads, the copper pads use two pairs of upper and lower copper pads with the lower pad having a groove to position the workpiece to be welded, and then both ends are fixed by laser spot welding.

[0007] Furthermore, the workpiece to be welded is an aluminum-based composite material reinforced with silicon carbide particles.

[0008] Furthermore, the size of the workpiece to be welded is 5-40 μm, and the volume fraction of the silicon carbide particle reinforcement phase is 5-25%.

[0009] Furthermore, the process parameters of laser spot welding are: Laser power: 800W~1500W; Welding speed: 0.5m / min~1.0m / min; Defocus: -3mm~3mm; Protective gas: 99.99% Ar; Protective gas flow rate: 15L / min~25L / min for both front and back sides; Welding position: both ends of the butt weld of the workpiece to be welded.

[0010] Furthermore, the process parameters of laser formal welding are: Laser power: 1000W~8000W; Welding speed: 1.0m / min~7.0m / min; Defocus: -5mm~5mm; Ultrasonic power: 240W~840W; Protective gas: 99.99% Ar; Protective gas flow rate: 15L / min~25L / min.

[0011] Furthermore, the method for inserting ultrasonic vibration-assisted laser welding of aluminum-based composite reinforced phase homogenization is carried out using a digital welding system, which includes a laser welding system, an ultrasonic vibration system and a PLC controller. The laser welding system and the ultrasonic vibration system are synchronized through the PLC controller; the ultrasonic vibration system includes a variable amplitude tungsten needle.

[0012] Further, the tip of the variable amplitude tungsten needle is aligned with the center of the laser spot of the laser welding system.

[0013] Furthermore, the workpiece to be welded is pretreated before being mechanically assembled and fixed by laser spot welding. Furthermore, when welding to form the keyhole, a variable amplitude tungsten needle capable of ultrasonic vibration is inserted into the molten pool for stirring, and then a cooling step is included.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses a tungsten needle to allow ultrasonic vibration to directly act on the laser welding molten pool, effectively improving the aggregation phenomenon of the reinforcing phase during the welding process. Compared with the traditional method of only optimizing welding parameters or adding filler materials, the present invention can achieve a highly uniform distribution of the reinforcing phase in the welding joint area, improve the weld profile morphology, and significantly improve the weld quality. The present invention ensures uniform stirring of materials in the molten pool through a tungsten needle, promotes fusion effect, reduces the occurrence of welding defects such as pores and cracks, and thus improves the quality of the weld. The present invention can adjust the insertion depth and vibration parameters of the tungsten needle in real time according to the welding process, thereby improving the flexibility of the process and being suitable for metal-based composite materials of different thicknesses and types.

[0015] Furthermore, the present invention uses a PLC controller to integrate a laser welding system and an ultrasonic vibration system, thereby simplifying the multiple process steps required for traditional welding, improving welding efficiency, and reducing production costs.

[0016] Furthermore, the present invention can be widely used in various metal matrix composite materials containing particle reinforcement phases to obtain the effect of homogenizing the reinforcement phase particles of the welded joint, which is not limited to a specific material system. By regulating the material behavior in the molten pool through ultrasonic vibration, the flexibility and stability of the welding process under different materials and different welding environments are ensured, which significantly broadens the scope of industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, objects and advantages of the present invention will become more apparent from a reading of the detailed description of non-limiting embodiments made with reference to the following drawings; Figure 1 A schematic diagram of the Al-MMCs laser-ultrasonic welding method for enhanced phase homogenization provided by the present invention; In the figure, 1 is the ultrasonic vibration system, 2 is the laser head, 3 is the laser beam, 4 is the variable amplitude tungsten needle, and 5 is the copper pad; Figure 2 Figure 15% SiCp / 2A14 Al butt weld joint obtained by direct laser welding without applying ultrasonic vibration; Figure 3 Figure 1 shows the ultrasonic-assisted 15%SiCp / 2A14 Al laser butt welding joint. Figure 4 for Figure 2 The microstructure of the central area A of the middle weld; Figure 5 for Figure 3 The microstructure of the central area B of the middle weld; Figure 6 This is the welding result diagram of Comparative Example 2. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0019] The present invention proposes a method for inserting ultrasonic vibration-assisted laser welding of aluminum-based composite reinforcement phase homogenization, comprising the following steps: See also Figure 1 The method of inserting ultrasonic vibration assisted laser welding aluminum-based composite reinforcement phase homogenization adopts a digital welding system. The digital welding system includes: a laser welding system, an ultrasonic vibration system 1 and a PLC controller. The laser welding system and the ultrasonic vibration system are synchronized through the PLC controller. The laser welding system includes a laser head 2, which can emit a laser beam 3. The ultrasonic vibration system includes a variable amplitude tungsten needle 4 located at the end. During formal welding, the variable amplitude tungsten needle 4 contacts the molten pool to achieve a specific insertion and withdrawal operation.

[0020] Welding preparation steps: selecting the size, volume fraction and material thickness specifications of the Al-MMCs reinforcement phase particles of the material to be welded, such as an aluminum-based composite material (SiCp / Al composite material) reinforced with silicon carbide particles of size 5-40 μm and volume fraction 5-25%, and pre-treating the material to be welded; wherein the pre-treatment includes: any one or more combinations of cleaning, alkali cleaning, pickling and drying; Fixing step: Mechanically assemble the Al-MMCs to be welded and fix the two ends by laser spot welding, and ensure the stability of the workpiece during welding; wherein, the copper pad 5 is used for mechanical assembly of the material to be welded, and the copper pad 4 is composed of two pairs of upper and lower copper pads with grooves on the lower pad to position the Al-MMCs to be welded through the back shielding gas. The process parameters of laser spot welding are: Laser power: 800W~1500W; Welding speed: 0.5m / min~1.0m / min; Defocus: -3mm~3mm; Protective gas: 99.99% Ar; Protective gas flow rate: 15L / min~25L / min for both front and back sides; Welding position: both ends of the butt weld of the assembled workpieces to be welded; Preferably, in the welding step, the process parameters of the laser formal welding are: Laser power: 1000W~8000W; Welding speed: 1.0m / min~7.0m / min; Defocus: -5mm~5mm; Ultrasonic power: 240W~840W; Protective gas: 99.99% Ar; Shielding gas flow rate: 15L / min~25L / min; Preparation steps for the ultrasonic vibration system: installing the variable amplitude tungsten needle of the ultrasonic vibration system on the laser welding system; wherein the variable amplitude tungsten needle can move synchronously with the laser beam and the tip of the variable amplitude tungsten needle is directly aligned with the center of the laser spot; Welding steps: Butt welding is performed using a fiber laser and a digital welding system; when a keyhole is formed, a variable amplitude tungsten needle is quickly inserted into the molten pool for stirring. When a keyhole is formed, a variable amplitude tungsten needle is quickly inserted into the molten pool for stirring.

[0021] Ultrasonic retraction step: At the end of welding, the variable amplitude tungsten needle is quickly pulled out of the molten pool through the PLC controller to avoid unnecessary interference in the cooling process of the weld joint.

[0022] In the fixing step and the welding step, the welded parts of the Al-MMCs to be welded are all in a clean and weldable state, and the formal welding is performed by optical fiber laser welding, which is synchronized with the ultrasonic vibration system.

[0023] Preferably, the power and amplitude variation of the ultrasonic vibration system can be adjusted according to material properties and welding conditions.

[0024] Preferably, the method for homogenizing the enhanced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding provided by the present invention further includes: Cooling step: After the welding step is completed, the positive protection cover remains at the end point, and the positive and back protection gases are maintained for 10s~50s until they are cooled below the phase change temperature of the material.

[0025] Example 1 A method for inserting ultrasonic vibration-assisted laser welding of aluminum-based composite reinforcement phase homogenization, using 2 mm thick 15% SiCp / 2A14Al as a workpiece to be welded, comprising the following steps: Welding preparation steps: 15%SiCp / 2A14Al was selected as the Al-MMCs to be welded and pretreated; Fixing steps: mechanically assemble and fix the two 15%SiCp / 2A14Al workpieces to be welded by laser spot welding; Preparation steps for the ultrasonic vibration system: Install the ultrasonic vibration system on the laser welding system to ensure that it can move synchronously with the laser and is accurately positioned.

[0026] Welding steps: Formal welding operation is carried out through fiber laser and digital welding system, and 15% SiCp / 2A14Al composite material is butt-welded; when the keyhole is formed, the variable amplitude tungsten needle is quickly extended into the molten pool for stirring.

[0027] Ultrasonic retraction steps: At the end of welding, quickly pull out the ultrasonic amplitude variable tungsten needle from the molten pool to avoid interference with the cooling process of the joint.

[0028] Wherein, the pretreatment includes: the pretreatment includes mechanical grinding, alkali cleaning, pickling and drying to ensure that the surface to be welded is clean and free of oxides or oil stains.

[0029] In the fixing step and the welding step, the parts to be welded of the 15%SiCp / 2A14Al composite material are all in a clean and weldable state, and the formal welding is performed using a fiber laser.

[0030] Preferably, the spot welding fixation in the fixing step is laser spot welding fixation. After assembly, both sides of the 15%SiCp / 2A14Al composite material are in a weldable state, and the formal welding material is assembled tightly using two pairs of upper and lower copper pads, and the spot welding positions are located at both ends of the weld to be welded.

[0031] Preferably, in the welding step, while the laser beam is irradiated to the butt joint position to form a keyhole, an ultrasonic variable amplitude tungsten needle is inserted into the molten pool to perform homogenizing stirring.

[0032] Specifically: In the fixed step, the process parameters of laser spot welding are: Laser power: 1000W; Welding speed: 1.0m / min; Defocus: 1mm; Protective gas: 99.99% Ar; Shielding gas flow rate: 15L / min on both sides of the material to be welded; Welding position: both ends of the weld of the assembled 15%SiCp / 2A14Al composite material to be welded; In the welding steps, the process parameters of laser formal welding are: Laser power: 3000W; Welding speed: 4.0m / min; Defocus: -1mm; Ultrasonic power: 500W; Protective gas: 99.99% Ar; Protective gas flow rate: 20L / min; Cooling step: After the welding step, the front protection cover of the 15%SiCp / 2A14Al composite material is still stopped at the end point, and the gas is maintained for 15s until it is cooled to below 200°C.

[0033] Furthermore, the present invention provides an insert-type ultrasonic vibration-assisted laser welding method for homogenizing the reinforced phase of aluminum-based composites, and its manufacturing process is similar to conventional laser welding, and also includes surface oil cleaning, alkali cleaning, pickling, drying, assembly, spot welding and formal welding steps. At the same time, new solutions are proposed for the assembly method, spot welding method, formal welding method and cooling method. In the preferred example mentioned in the present invention, in terms of the assembly method, the 15%SiCp / 2A14Al composite material is clamped up and down with four copper pads, and positioned horizontally on the left and right; in terms of the spot welding method and the formal welding method, optical fiber laser is used for welding; in terms of the cooling method, cooling is carried out after the welding is completed, and the positive protection cover of the 15%SiCp / 2A14Al composite material is still stopped at the end point, and the positive and back protection gases are continuously output for 15s until it is cooled to below 200°C. The inserted ultrasonic-assisted laser welding of the 15%SiCp / 2A14Al composite material of Example 1 of the present invention can address the problems of low quality, low efficiency, uneven distribution of reinforcing phases, and inconvenience in achieving widespread industrial applications of the current laser welding joints of Al-MMCs. A new assembly, welding, and cooling scheme is proposed. By adopting an assembly method of copper pad clamping, the heat dissipation of the material to be welded is accelerated, thermal deformation is avoided, a large number of operating procedures are omitted, the production process is greatly simplified, and the welding efficiency is improved. By coupling the inserted ultrasonic vibration system with the laser system, the molten pool of Al-MMCs at the weld is directly stirred to make the reinforcing phase distribution uniform. Through the precise design of the ultrasonic composite laser welding system, the reinforcing phase is perfectly homogenized and the joint quality is improved.

[0034] Example 2 A method for inserting ultrasonic vibration assisted laser welding of aluminum-based composite reinforcement phase homogenization is used, and the welding method of 3 mm 10% SiCp / 2009Al composite material is adopted, and the steps are as follows: (1) After the type and thickness of Al-MMCs were selected as 3 mm 10% SiCp / 2009Al, the insertion amount of the ultrasonic variable amplitude tungsten needle was changed to 2.8 mm according to the material thickness; (2) The 10%SiCp / 2009Al composite material is manufactured by machine milling, especially the side to be welded is smoothed; (3) The 10% SiCp / 2009Al composite material is cleaned of oil, alkali, pickled, neutralized and dried to remove surface impurities and keep the position to be welded clean; (4) The two 10%SiCp / 2009Al workpieces to be welded were mechanically assembled and fixed by laser spot welding to ensure the stability of the welding process. The main process parameters of spot welding were: laser power 1200W, welding speed 1.0m / min, defocusing amount -1mm, shielding gas 99.99%Ar, and shielding gas flow rate 15L / min; (5) Install the ultrasonic vibration system on the laser welding system to ensure that it can be accurately inserted into the molten pool and move synchronously with the laser; (6) The formal welding operation was carried out by using a fiber laser and ultrasonic vibration coupled digital welding system to butt weld 10% SiCp / 2009Al composite materials. While laser welding was started, an ultrasonic variable amplitude tungsten needle was inserted into the molten pool for stirring. The formal welding process parameters were: laser power 5000W, welding speed 4.0m / min, defocusing amount -1mm, ultrasonic power 600W, shielding gas 99.99% Ar, and the front and back shielding gas flow rates were both 20L / min.

[0035] (7) When welding is finished, the ultrasonic amplitude variable tungsten needle is quickly withdrawn; (8) After welding, the front and back shielding gases will continue to output shielding gas flow for 30 seconds until the weld joint cools to a lower temperature.

[0036] Example 3 A method for inserting ultrasonic vibration-assisted laser welding of aluminum-based composite reinforcement phase homogenization, using 2 mm thick 15% SiCp / 2A14Al as a workpiece to be welded, comprising the following steps: Welding preparation steps: 5%SiCp / 2A14Al was selected as the Al-MMCs to be welded and pretreated; Fixing steps: mechanically assemble and fix the two 5%SiCp / 2A14Al workpieces to be welded by laser spot welding; Preparation steps for the ultrasonic vibration system: Install the ultrasonic vibration system on the laser welding system to ensure that it can move synchronously with the laser and is accurately positioned.

[0037] Welding steps: Formal welding operation is performed through fiber laser and digital welding system, butt welding of 5%SiCp / 2A14Al composite material; Ultrasonic retraction steps: At the end of welding, quickly pull out the ultrasonic amplitude variable tungsten needle from the molten pool to avoid interference with the cooling process of the joint.

[0038] Wherein, the pretreatment includes: the pretreatment includes mechanical grinding, alkali cleaning, pickling and drying to ensure that the surface to be welded is clean and free of oxides or oil stains.

[0039] In the fixing step and the welding step, the parts to be welded of the 5%SiCp / 2A14Al composite material are all in a clean and weldable state, and the formal welding is performed using a fiber laser.

[0040] Preferably, the spot welding fixation in the fixing step is laser spot welding fixation. After assembly, both sides of the 5%SiCp / 2A14Al composite material are in a weldable state, and the formal welding material is assembled tightly using two pairs of upper and lower copper pads, and the spot welding positions are located at both ends of the weld to be welded.

[0041] Preferably, in the welding step, while the laser beam is irradiated to the butt joint position to form a keyhole, an ultrasonic variable amplitude tungsten needle is inserted into the molten pool to perform homogenizing stirring.

[0042] Specifically: In the fixed step, the process parameters of laser spot welding are: Laser power: 800W; Welding speed: 1.0m / min; Defocus: -3mm; Protective gas: 99.99% Ar; Shielding gas flow rate: 20L / min on both sides of the material to be welded; Welding position: both ends of the weld of the assembled 5%SiCp / 2A14Al composite material to be welded; In the welding steps, the process parameters of laser formal welding are: Laser power: 1000W; Welding speed: 1.0m / min; Defocus: -4mm; Ultrasonic power: 240W; Protective gas: 99.99% Ar; Protective gas flow: 25L / min; Cooling step: After the welding step, the 5%SiCp / 2A14Al composite front protection cover is still stopped at the end point, and the gas is maintained for 10 seconds until it is cooled to below 200°C.

[0043] Example 4 A method for inserting ultrasonic vibration-assisted laser welding of aluminum-based composite reinforcement phase homogenization, using 2 mm thick 25% SiCp / 2A14Al as a workpiece to be welded, comprising the following steps: Welding preparation steps: 25%SiCp / 2A14Al was selected as the Al-MMCs to be welded and pretreated; Fixing steps: mechanically assemble and fix the two 25%SiCp / 2A14Al workpieces to be welded by laser spot welding; Preparation steps for the ultrasonic vibration system: Install the ultrasonic vibration system on the laser welding system to ensure that it can move synchronously with the laser and is accurately positioned.

[0044] Welding steps: Formal welding operation is carried out through fiber laser and digital welding system, butt welding of 25% SiCp / 2A14Al composite material; Ultrasonic retraction steps: At the end of welding, quickly pull out the ultrasonic amplitude variable tungsten needle from the molten pool to avoid interference with the cooling process of the joint.

[0045] Wherein, the pretreatment includes: the pretreatment includes mechanical grinding, alkali cleaning, pickling and drying to ensure that the surface to be welded is clean and free of oxides or oil stains.

[0046] In the fixing step and the welding step, the parts to be welded of the 25%SiCp / 2A14Al composite material are all in a clean and weldable state, and the formal welding is performed using a fiber laser.

[0047] Preferably, the spot welding fixation in the fixing step is laser spot welding fixation. After assembly, both sides of the 25%SiCp / 2A14Al composite material are in a weldable state, and the formal welding material is assembled tightly using two pairs of upper and lower copper pads, and the spot welding positions are located at both ends of the weld to be welded.

[0048] Preferably, in the welding step, while the laser beam is irradiated to the butt joint position to form a keyhole, an ultrasonic variable amplitude tungsten needle is inserted into the molten pool to perform homogenizing stirring.

[0049] Specifically: In the fixed step, the process parameters of laser spot welding are: Laser power: 1500W; Welding speed: 0.5m / min; Defocus: 2mm; Protective gas: 99.99% Ar; Shielding gas flow rate: 25L / min on both sides of the material to be welded; Welding position: both ends of the weld of the assembled 25%SiCp / 2A14Al composite material to be welded; In the welding steps, the process parameters of laser formal welding are: Laser power: 8000W; Welding speed: 5.0m / min; Defocus: 5mm; Ultrasonic power: 800W; Protective gas: 99.99% Ar; Protective gas flow rate: 15L / min; Cooling step: After the welding step, the front protection cover of the 25%SiCp / 2A14Al composite material is still stopped at the end point, and the gas is maintained for 30 seconds until it is cooled to below 200°C.

[0050] Example 5 A method for inserting ultrasonic vibration assisted laser welding of aluminum-based composite reinforcement phase homogenization is used, and the welding method of 3 mm 10% SiCp / 2009Al composite material is adopted, and the steps are as follows: (1) After the type and thickness of Al-MMCs were selected as 3 mm 10% SiCp / 2009Al, the insertion amount of the ultrasonic variable amplitude tungsten needle was changed to 2.8 mm according to the material thickness; (2) The 10%SiCp / 2009Al composite material is manufactured by machine milling, especially the side to be welded is smoothed; (3) The 10% SiCp / 2009Al composite material is cleaned of oil, alkali, pickled, neutralized and dried to remove surface impurities and keep the position to be welded clean; (4) The two 10%SiCp / 2009Al workpieces to be welded were mechanically assembled and fixed by laser spot welding to ensure the stability of the welding process. The main process parameters of spot welding were: laser power 1300W, welding speed 0.7m / min, defocusing amount 3mm, shielding gas 99.99%Ar, and shielding gas flow rate 15L / min; (5) Install the ultrasonic vibration system on the laser welding system to ensure that it can be accurately inserted into the molten pool and move synchronously with the laser; (6) The formal welding operation was carried out by using a fiber laser and ultrasonic vibration coupled digital welding system to butt weld 10% SiCp / 2009Al composite materials. While laser welding was started, an ultrasonic variable amplitude tungsten needle was inserted into the molten pool for stirring. The formal welding process parameters were: laser power 5000W, welding speed 7.0m / min, defocusing amount -5mm, ultrasonic power 500W, shielding gas 99.99%Ar, and the front and back shielding gas flow rates were both 20L / min.

[0051] (7) When welding is finished, the ultrasonic amplitude variable tungsten needle is quickly withdrawn; (8) After welding, the front and back shielding gases will continue to output shielding gas flow for 30 seconds until the weld joint cools to a lower temperature.

[0052] Comparative Example 1 The same as Example 1, except that the laser welding is performed directly without applying ultrasonic vibration. The microstructure of the obtained 15% SiCp / 2A14 Al butt weld joint is as follows: Figure 2 shown.

[0053] The microstructure of the welded joint of the 15%SiCp / 2A14Al composite material prepared in Example 1 is as follows: Figure 3 and Figure 5 As shown, it can be seen that compared Figure 2 and Figure 4 Laser welding joint without ultrasonic application, from Figure 3 and Figure 5 It can be clearly seen that after applying ultrasonic assistance, the weld profile is improved, the pores are reduced, and the reinforcement phase particles in the joint are not obviously segregated and grown. The reinforcement phase is evenly distributed, the matrix grains are refined to a certain extent, and the welding quality is better.

[0054] Comparative Example 2 A method for inserting ultrasonic vibration assisted laser welding of aluminum-based composite reinforcement phase homogenization is provided, using an ultrasonic vibration coupled laser welding method of a 2 mm 15% SiCp / 2A14Al composite material, the steps are as follows: After welding, remove the workpiece and observe the weld. Figure 6 It was found that when the ultrasonic power was too large, the inappropriate vibration parameters completely vibrated and cracked the weld and the heat-affected zone of the 15%SiCp / 2A14Al composite material, causing the weld to fall off as a whole and unable to be formed and connected. It can be seen that it is necessary to adopt the ultrasonic power range in the present invention.

[0055] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. A method for homogenizing the enhanced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding, characterized in that: The following steps are involved: Mechanically assemble and fix the workpieces to be welded by laser spot welding; The workpiece to be welded is formally welded. When the keyhole is formed, a variable amplitude tungsten needle capable of ultrasonic vibration is inserted into the molten pool for stirring to complete the welding.

2. The method for homogenizing the reinforced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding according to claim 1 is characterized in that: The method comprises the following steps: mechanically assembling the workpiece to be welded and fixing it with laser spot welding, wherein the workpiece to be welded is mechanically assembled with a copper pad, wherein the copper pad adopts two pairs of upper and lower copper pads and the lower pad has a groove, the workpiece to be welded is positioned, and then both ends are fixed with laser spot welding.

3. The method for homogenizing the reinforced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding according to claim 1 is characterized in that: The workpiece to be welded is an aluminum-based composite material reinforced with silicon carbide particles.

4. The method for homogenizing the reinforced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding according to claim 3 is characterized in that: The size of the workpiece to be welded is 5~40μm, and the volume fraction of the silicon carbide particle reinforcement phase is 5~25%.

5. The method for homogenizing the reinforced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding according to claim 1, characterized in that: The process parameters of laser spot welding are: Laser power: 800W~1500W; Welding speed: 0.5m / min~1.0m / min; Defocus: -3mm~3mm; Protective gas: 99.99% Ar; Protective gas flow rate: 15L / min~25L / min for both front and back sides; Welding position: both ends of the butt weld of the workpiece to be welded.

6. The method for homogenizing the reinforced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding according to claim 1, characterized in that: The process parameters of laser welding are: Laser power: 1000W~8000W; Welding speed: 1.0m / min~7.0m / min; Defocus: -5mm~5mm; Ultrasonic power: 240W~840W; Protective gas: 99.99% Ar; Protective gas flow rate: 15L / min~25L / min.

7. The method for homogenizing the reinforced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding according to claim 1, characterized in that: The method for inserting ultrasonic vibration-assisted laser welding of aluminum-based composite reinforcement phase homogenization is carried out using a digital welding system, which includes a laser welding system, an ultrasonic vibration system and a PLC controller. The laser welding system and the ultrasonic vibration system are synchronized through the PLC controller; the ultrasonic vibration system includes a variable amplitude tungsten needle.

8. The method for homogenizing the reinforced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding according to claim 7, characterized in that: The tip of the variable amplitude tungsten needle is centered on the laser spot of the laser welding system.

9. The method for homogenizing the reinforced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding according to claim 1, characterized in that: The workpiece to be welded is pretreated before mechanical assembly and laser spot welding.

10. The method for homogenizing the reinforced phase of aluminum-based composites by inserting ultrasonic vibration-assisted laser welding according to claim 1, characterized in that: When welding to form a keyhole, a variable amplitude tungsten needle capable of ultrasonic vibration is inserted into the molten pool for stirring, and a cooling step is also included.

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