Welding method for welding aluminum/steel dissimilar metal by using three beams of laser

文档序号:1163060 发布日期:2020-09-18 浏览:25次 中文

阅读说明:本技术 一种利用三束激光进行铝/钢异种金属焊接的焊接方法 (Welding method for welding aluminum/steel dissimilar metal by using three beams of laser ) 是由 王文权 杜明 张新戈 毕英超 王岩新 王苏煜 刘亮 曲秋怡 于 2020-06-04 设计创作,主要内容包括:本发明提供了一种利用三束激光进行铝/钢异种金属焊接的焊接方法,它包括如下步骤:(1)对等厚度的待焊接铝板和钢板进行打磨、清洗;(2)将待焊接铝板和钢板以及中间层金属置于焊接夹具上进行装夹固定;(3)调整主光束和辅助光束的位置,设置光束能量:将两个低功率激光器和一个高功率激光器同时作为焊接热源,高功率激光器发出的激光辐照于中间层金属和铝板一侧;两个低功率激光器发出的激光辐照于铝板一侧和钢板一侧,圆形光斑与辐照于铝板一侧的矩形光斑为分离、相切或部分重叠的状态;(4)按照设定的工艺参数进行焊接。该焊接方法可获得界面反应、焊缝成形和焊接应力控制所需的温度场分布,最终实现铝/钢异种金属高质量的焊接。(The invention provides a welding method for welding aluminum/steel dissimilar metals by using three beams of laser, which comprises the following steps: (1) polishing and cleaning the aluminum plate and the steel plate to be welded with equal thickness; (2) placing an aluminum plate to be welded, a steel plate and a middle layer metal on a welding fixture for clamping and fixing; (3) adjusting the positions of the main beam and the auxiliary beam, and setting the beam energy: two low-power lasers and one high-power laser are simultaneously used as welding heat sources, and laser emitted by the high-power laser irradiates one side of the intermediate layer metal and the aluminum plate; the laser emitted by the two low-power lasers irradiates one side of the aluminum plate and one side of the steel plate, and the circular light spots and the rectangular light spots irradiated on one side of the aluminum plate are in a separated, tangent or partially overlapped state; (4) and welding according to the set process parameters. The welding method can obtain the temperature field distribution required by interface reaction, weld joint formation and welding stress control, and finally realizes the high-quality welding of the aluminum/steel dissimilar metals.)

1. A welding method for welding aluminum/steel dissimilar metals by using three beams of laser is characterized in that: it comprises the following steps:

(1) polishing and cleaning the aluminum plate and the steel plate to be welded with equal thickness;

(2) placing an aluminum plate to be welded, a steel plate and a middle layer metal on a welding fixture for clamping and fixing;

(3) adjusting the positions of the main beam and the auxiliary beam, and setting the beam energy: two low-power lasers and one high-power laser are simultaneously used as welding heat sources, wherein laser emitted by the high-power laser is focused into a circular light spot and is used as a main light beam to irradiate one side of the intermediate layer metal and the aluminum plate, so that the intermediate layer metal and the aluminum plate are melted; shaping laser emitted by two low-power lasers into rectangular light spots serving as auxiliary light beams to be respectively irradiated on one side of an aluminum plate and one side of a steel plate, irradiating the rectangular light spot laser beam on one side of the aluminum plate to melt the aluminum plate, and heating the steel plate and molten metal liquid spread on the edge of the steel plate by the rectangular light spot laser beam irradiated on one side of the steel plate to enable molten intermediate layer metal and the aluminum plate to form a metal compound layer; three laser beams are arranged in parallel and are irradiated perpendicular to an aluminum plate, a steel plate and an intermediate layer metal to be welded, wherein a circular light spot of a main beam and a rectangular light spot of an auxiliary beam irradiated on one side of the aluminum plate are in a separated, tangential or partially overlapped state;

(4) and welding according to the set process parameters.

2. The welding method of aluminum/steel dissimilar metal welding using three beams of laser according to claim 1, characterized in that: the long edges of the rectangular light spots are parallel to the butt joint edges of the aluminum plate, the steel plate and the middle layer metal respectively, and when the circular light spot of the main light beam is partially overlapped with the rectangular light spot of the auxiliary light beam irradiated on one side of the aluminum plate, the width d2 of the overlapped part of the light spots is less than or equal to 30% of the diameter of the circular light spot; when the circular spot of the main beam is separated from the rectangular spot of the auxiliary beam irradiated to one side of the aluminum plate, the separation distance d3 between the circular spot and the rectangular spot is less than or equal to 20% of the diameter of the circular spot.

3. The welding method of aluminum/steel dissimilar metal welding using three beams of laser according to claim 2, characterized in that: the rectangular light spot of the auxiliary light beam irradiated on one side of the steel plate has an offset distance from the butt joint edge of the middle layer metal and the steel plate, and the offset distance is 0-10% of the diameter of the circular light spot.

4. The welding method of aluminum/steel dissimilar metal welding using three beams of laser according to claim 3, characterized in that: the high-power laser adopts a continuous fiber laser with the power of 1.0-2.8 KW, and the diameter of a circular light spot is 0.6-1.6 mm.

5. The welding method of aluminum/steel dissimilar metal welding using three beams of laser according to claim 4, characterized in that: the low-power laser adopts a continuous fiber laser with the power of 200-800W, and the width of a rectangular light spot is 0.5mm, and the length of the rectangular light spot is 1.5 mm.

6. The welding method of aluminum/steel dissimilar metal welding using three beams of laser according to claim 5, characterized in that: the intermediate layer metal is AlSi12The diameter of the middle layer metal is d1, the size of d1 is 20% -40% of the thickness of the aluminum plate and the steel plate, and the thickness of the aluminum plate and the steel plate is 0.8-3.0 mm.

7. The welding method of aluminum/steel dissimilar metal welding using three beams of laser according to claim 6, characterized in that: the welding speed of the high-power laser and the low-power laser is 0.1-1 m/min.

8. The welding method of aluminum/steel dissimilar metal welding using three beams of laser according to claim 7, characterized in that: adopt the mode of gaseous safety cover to carry out the inert gas protection to welding position during the welding, protective gas is the argon gas that the purity is 99.99%, protective gas's gas flow is 15 ~ 20L/min, gaseous safety cover all is equipped with a spherical gaseous safety cover on the welding head of two low power laser instruments and a high power laser instrument, the bonding tool of two low power laser instruments and a high power laser instrument all is located the lower tip of spherical gaseous safety cover, spherical gaseous safety cover upper end is equipped with the intake pipe, the middle part is equipped with the multilayer copper wire netting structure, the multilayer copper wire netting structure will spherical gaseous safety cover divide into upper portion air inlet chamber and lower part gas protection room, the diameter of spherical gaseous safety cover is welding speed vxmolten bath and cools off the time t to the room temperature.

9. The welding method of claim 8, wherein the welding method comprises the steps of: the power of the high-power laser is 2KW, the diameter of a circular light spot is 1mm, and the power of the low-power laser is 600W; the welding speed of the high-power laser and the low-power laser is 0.6 m/min; the width d2 of the spot overlap is 0.2mm and the separation distance d3 between the circular and rectangular spots is 0.15 mm.

10. The welding method of aluminum/steel dissimilar metal welding using three laser beams as set forth in claim 9, wherein: in the step (1), the aluminum plate is 5083 aluminum alloy, the steel plate is TWIP steel, the aluminum plate and the steel plate are 200mm in width, 100mm in length and 2mm in thickness, the surfaces of the aluminum plate and the steel plate are polished by 800-mesh, 1500-mesh and 2000-mesh abrasive paper before welding, the polished aluminum plate is washed by alkali and then by acid, and is wiped by alcohol and then is dried; and wiping the grinded steel plate with acetone, and drying.

Technical Field

The invention relates to a welding method for welding aluminum/steel dissimilar metals by using three beams of laser, belonging to the technical field of dissimilar metal welding.

Background

The aluminum alloy has the advantages of light weight, high strength, higher corrosion resistance, excellent machining performance and the like, and is widely applied to the aerospace industry, the aviation industry and the automobile industry. For a long time, steel is a main material used for automobile bodies, but with the improvement of fuel economy standards, the realization of energy conservation and emission reduction of automobiles through light weight becomes an important means, so that light aluminum alloy materials are popular in the automobile industry, and many automobile manufacturers adopt all-aluminum alloy to manufacture automobiles. For example, the audi automobile company in germany has already introduced automobiles with all-aluminum body frames in the mid 90's of the 20 th century. All aluminum vehicles, while successful in achieving overall vehicle weight savings, still exhibit problems during actual manufacturing and use. In practical use, people find that the safety of all-aluminum frame automobiles is different from that of the traditional steel automobiles, the safety performance is reduced, and in addition, the manufacturing cost and the selling price are higher. The high-strength aluminum alloy plate has higher forming and processing cost than that of the same steel, and the cost for processing the aluminum alloy welding machine is obviously higher than that of the steel, so that the automobile manufactured by adopting the full aluminum has higher selling price. The cost, the performance and the light weight effect are comprehensively considered, and the structural design of the aluminum/steel mixed material becomes the most important light weight means in the future. Aluminum alloy is a light metal, and its use presents a new problem for the method of joining structural members. For the automobile industry, the welding method is still an economic and reasonable mode, and the welding joint has higher strength and can ensure the safety performance of the automobile; the welding joint can also save raw materials, and the automobile is more environment-friendly while the weight of the automobile body is reduced. By comprehensively considering all factors, the connection of dissimilar metals in the automobile industry is mainly welding.

The aluminum alloy and the steel have large difference of material thermophysical properties and low solid solubility, and intermetallic compounds are formed in the welding heating process to influence the performance of a welding joint. Therefore, the welding of aluminum/steel dissimilar metals is one of the difficult problems in the welding field. At present, some researchers adopt a solid-phase welding and brazing method to realize the connection of aluminum/steel joints, but the application range of the aluminum/steel joints is limited to a certain extent, and parts with complex shapes are difficult to weld. The industrial welding method generally adopts methods such as brazing, diffusion welding and the like for connection, but is limited by process limitations, and the methods have the disadvantages of low welding efficiency, poor processing flexibility and difficult manufacture of large-size parts and complex structural members. Some researchers also weld the dissimilar metals of aluminum/steel by using friction stir welding and arc welding, and research results show that the two methods can realize the connection of the dissimilar metals of aluminum/steel, but the joint strength is low and the flexibility is poor, mainly because the two methods cannot realize the precise control of heat input quantity and inhibit the growth of an intermetallic compound layer in the aluminum/steel joint, so the joint strength is low. With the rise of laser welding, laser welding and brazing show great advantages in the connection of dissimilar metals, which is expressed by high energy density, small heat input amount and high welding efficiency of laser welding, and has certain application prospect in the field of aluminum/steel dissimilar metal welding. In the process of welding and soldering aluminum/steel dissimilar metals, one side of an aluminum base metal is melted and one side of a steel base metal is not melted through the adjustment of a welding process and heat input, and the melted aluminum base metal and a solid steel base metal are soldered to realize the welding of the aluminum/steel dissimilar metals. According to the literature report and research report of the prior publication, the aluminum/steel dissimilar metal welding joint with higher strength and better welding quality can be obtained by adopting laser melting-brazing welding. However, in the laser welding process, the heating range is small, the temperature gradient is large, and certain limitation exists on the accurate temperature field regulation and control required by interface reaction, weld forming and welding stress control.

Disclosure of Invention

The invention aims to solve the technical problem that the prior art has defects, and provides a welding method for welding aluminum/steel dissimilar metals by using three beams of laser, wherein the welding method can obtain temperature field distribution required by interface reaction, weld seam forming and welding stress control, finally realizes high-quality welding of the aluminum/steel dissimilar metals, and solves the problems that welding heat input, temperature field distribution and interface reaction are difficult to accurately control in the laser welding-brazing process of the aluminum/steel dissimilar metals in the prior art.

The scheme is realized by the following technical measures: a welding method for welding aluminum/steel dissimilar metals by using three beams of laser comprises the following steps:

(1) polishing and cleaning the aluminum plate and the steel plate to be welded with equal thickness;

(2) placing an aluminum plate to be welded, a steel plate and a middle layer metal on a welding fixture for clamping and fixing;

(3) adjusting the positions of the main beam and the auxiliary beam, and setting the beam energy: two low-power lasers and one high-power laser are simultaneously used as welding heat sources, wherein laser emitted by the high-power laser is focused into a circular light spot and is used as a main light beam to irradiate one side of the intermediate layer metal and the aluminum plate, so that the intermediate layer metal and the aluminum plate are melted; shaping laser emitted by two low-power lasers into rectangular light spots serving as auxiliary light beams to be respectively irradiated on one side of an aluminum plate and one side of a steel plate, irradiating the rectangular light spot laser beam on one side of the aluminum plate to melt the aluminum plate, and heating the steel plate and molten metal liquid spread on the edge of the steel plate by the rectangular light spot laser beam irradiated on one side of the steel plate to enable molten intermediate layer metal and the aluminum plate to form a metal compound layer; three laser beams are arranged in parallel and are irradiated perpendicular to an aluminum plate, a steel plate and an intermediate layer metal to be welded, wherein a circular light spot of a main beam and a rectangular light spot of an auxiliary beam irradiated on one side of the aluminum plate are in a separated, tangential or partially overlapped state;

(4) and welding according to the set process parameters.

Preferably, the long sides of the rectangular light spots are parallel to the butt joint edges of the aluminum plate and the steel plate with the middle layer metal respectively, and when the circular light spot of the main light beam is partially overlapped with the rectangular light spot of the auxiliary light beam irradiated on one side of the aluminum plate, the width d2 of the overlapped part of the light spots is less than or equal to 30% of the diameter of the circular light spot; when the circular spot of the main beam is separated from the rectangular spot of the auxiliary beam irradiated to one side of the aluminum plate, the separation distance d3 between the circular spot and the rectangular spot is less than or equal to 20% of the diameter of the circular spot.

Preferably, the rectangular light spot of the auxiliary light beam irradiated on one side of the steel plate has an offset distance from the butt joint edge of the middle layer metal and the steel plate, and the offset distance is 0-10% of the diameter of the circular light spot.

Preferably, the high-power laser adopts a continuous fiber laser with the power of 1.0-2.8 KW, and the diameter of a circular light spot is 0.6-1.6 mm.

Preferably, the low-power laser adopts a continuous fiber laser with the power of 200-800W, and the width of a rectangular light spot is 0.5mm and the length of the rectangular light spot is 1.5 mm.

Preferably, the intermediate layer metal is AlSi12The diameter of the middle layer metal is d1, the size of d1 is 20% -40% of the thickness of the aluminum plate and the steel plate, and the thickness of the aluminum plate and the steel plate is 0.8-3.0 mm.

Preferably, the welding speed of the high-power laser and the low-power laser is 0.1-1 m/min.

Preferably, the mode that adopts the gaseous safety cover during the welding carries out the inert gas protection to the welding position, protective gas is the argon gas that the purity is 99.99%, protective gas's gas flow is 15 ~ 20L/min, gaseous safety cover all is equipped with a spherical gaseous safety cover on the welding head of two low power laser instruments and a high power laser instrument, the bonding tool of two low power laser instruments and a high power laser instrument all is located the lower tip of spherical gaseous safety cover, spherical gaseous safety cover upper end is equipped with the intake pipe, the middle part is equipped with multilayer copper wire net structure, multilayer copper wire net structure will spherical gaseous safety cover divide into upper portion air inlet chamber and lower part gas protection room, the diameter of spherical gaseous safety cover is welding speed vxmolten bath and cools off to the time t of room temperature.

Preferably, the power of the high-power laser is 2KW, the diameter of the circular light spot is 1mm, and the power of the low-power laser is 600W; the welding speed of the high-power laser and the low-power laser is 0.6 m/min; the width d2 of the spot overlap is 0.2mm and the separation distance d3 between the circular and rectangular spots is 0.15 mm.

Preferably, in the step (1), the aluminum plate is 5083 aluminum alloy, the steel plate is TWIP steel, the aluminum plate and the steel plate are 200mm in width, 100mm in length and 2mm in thickness, the surfaces of the aluminum plate and the steel plate are polished by 800-mesh, 1500-mesh and 2000-mesh abrasive paper before welding, and the polished aluminum plate is subjected to alkali washing, acid washing, alcohol wiping and drying; and wiping the grinded steel plate with acetone, and drying.

According to the scheme, the welding method for welding the dissimilar metals of the aluminum/steel by using the three beams of laser has the advantages that two low-power rectangular light spot laser beams are used as auxiliary beams to be respectively irradiated on one side of the aluminum plate and one side of the steel plate, and the middle main beam provides enough heat to melt part of the aluminum plate and the middle layer metal; the three laser beams all move at the same speed along the welding direction, and the welding heat input is controlled by adjusting the welding process parameters, so that the distribution of temperature fields (namely the phenomena of high-temperature rapid cooling and large temperature gradient) during the welding of aluminum/steel dissimilar metals is improved; the welding interface reaction and the weld joint forming are improved, and the welding stress is reduced, so that a welding joint with better performance is obtained. Therefore, compared with the prior art, the invention has prominent substantive features and remarkable progress, and the beneficial effects of the implementation are also obvious.

Drawings

FIG. 1 is a perspective view of a weld according to an embodiment of the present invention.

Fig. 2 is a schematic top view of a weld according to an embodiment of the present invention when the circular spot of the main beam partially overlaps the rectangular spot of the auxiliary beam irradiated on one side of the aluminum plate.

FIG. 3 is a schematic top view of a weld according to an embodiment of the present invention when the circular spot of the primary beam is separated from the rectangular spot of the secondary beam that is irradiated on one side of the aluminum plate.

In the figure, 1-aluminum plate, 2-steel plate, 3-rectangular spot irradiated on one side of aluminum plate, 4-rectangular spot irradiated on one side of steel plate, 5-circular spot, 6-center line of three laser beams, 7-weld, 8-intermediate layer metal, 9-welding direction, d 1-diameter of intermediate layer metal, d 2-width of overlapping portion of circular spot of main beam and rectangular spot of auxiliary beam irradiated on one side of aluminum plate, d 3-separation distance between circular spot and rectangular spot.

Detailed Description

In order to clearly illustrate the technical features of the present solution, the following explains the present solution by way of specific embodiments and with reference to the accompanying drawings.

A welding method for welding aluminum/steel dissimilar metals by using three beams of laser comprises the following steps.

(1) Before welding, the aluminum plate 1 and the steel plate 2 to be welded with equal thickness are polished and cleaned.

The aluminum plate 1 is a 5083 aluminum alloy, the steel plate 2 is TWIP steel, the thicknesses of the aluminum plate 1 and the steel plate 2 are 0.8-3.0 mm, preferably, the widths of the aluminum plate 1 and the steel plate 2 are both 200mm, the lengths of the aluminum plate 1 and the steel plate 2 are both 100mm, and the thicknesses of the aluminum plate 2 and the steel plate 2 are both 2mm, the surfaces of the aluminum plate 1 and the steel plate 2 are polished by 800-mesh, 1500-mesh and 2000-mesh abrasive paper before welding, the polished aluminum plate 1 is subjected to alkali cleaning and acid cleaning, is wiped by alcohol, and is dried; and wiping the polished steel plate 2 with acetone, and drying.

(2) Placing an aluminum plate 1 to be welded, a steel plate 2 and an intermediate layer metal 8 on a welding fixture for clamping and fixing, wherein the intermediate layer metal 8 is AlSi12In said, inThe diameter of the interlayer metal 8 is d1, the size of d1 is 20% -40% of the thickness of the aluminum plate 1 and the steel plate 2, the diameter of the interlayer metal 8 is preferably 0.8mm, and the welding joint is in the form of a butt joint.

(3) And adjusting the positions of the main beam and the auxiliary beam to set the beam energy.

Two low-power lasers and a high-power laser are simultaneously used as welding heat sources, the high-power laser adopts a continuous fiber laser with the power of 1.0-2.8 KW, the diameter of a circular light spot 5 of the high-power laser is 0.6-1.6 mm, preferably, the power of the high-power laser is 2KW, and the diameter of the circular light spot 5 of the high-power laser is 1 mm. The low-power laser adopts a continuous fiber laser with the power of 200-800W, preferably the power of the low-power laser is 600W, the width of rectangular light spots (a rectangular light spot 3 irradiated on one side of an aluminum plate and a rectangular light spot 4 irradiated on one side of a steel plate) is 0.5mm, and the length of the rectangular light spots is 1.5 mm. The welding speed of the high-power laser and the low-power laser is 0.1-1 m/min, and the welding speed of the high-power laser and the low-power laser is preferably 0.6 m/min.

Three laser beams are arranged in parallel and are irradiated perpendicular to the aluminum plate 1, the steel plate 2 and the intermediate layer metal 8 to be welded, laser emitted by a high-power laser is focused into a circular light spot 5 to be used as a main beam to be irradiated on one side of the intermediate layer metal 8 and one side of the aluminum plate 1, so that the intermediate layer metal 8 and the aluminum plate 1 are melted; laser shaping that sends two low power laser instrument is the rectangle facula and irradiates in aluminum plate 1 one side and steel sheet 2 one side respectively as auxiliary beam, the long limit of rectangle facula (the rectangle facula 3 of irradiation in aluminum plate one side and the rectangle facula 4 of irradiation in steel sheet one side) is parallel with aluminum plate 1 and steel sheet 2 and intermediate level metal 8's butt joint edge respectively, and the rectangle facula laser beam of irradiation in aluminum plate 1 one side makes aluminum plate 1 take place to melt, and the rectangle facula laser beam of irradiation in steel sheet 2 one side heats steel sheet 2 and the molten state metal liquid of spreading at steel sheet 2 edge, makes molten intermediate level metal 8 and aluminum plate 1 form the metallic compound layer.

The space between the auxiliary light beam and the main light beam on one side of the aluminum plate 1 influences the stability of the welding process, and if the space between the two light beams is too small, the welding process is not stable easily like a single light beam welding process; if the distance between the two light beams is too large, the welding penetration and the welding seam quality are influenced. When the circular light spot 5 of the main light beam and the rectangular light spot of the auxiliary light beam irradiated on one side of the aluminum plate 1 are in a separated, tangent or partially overlapped state, the welding process is stable, the formed keyhole has a larger opening, and the evaporation and the escape of magnesium element in the welding process are facilitated. When the circular spot 5 of the main beam overlaps the rectangular spot portion of the subsidiary beam irradiated on the aluminum plate side, the width d2 of the spot overlapping portion is less than or equal to 30% of the diameter of the circular spot 5, and preferably the width d2 of the spot overlapping portion is 0.2 mm. When the circular light spot 5 of the main light beam is separated from the rectangular light spot of the auxiliary light beam irradiated on one side of the aluminum plate 1, the separation distance d3 between the circular light spot 5 of the main light beam and the rectangular light spot of the auxiliary light beam irradiated on one side of the aluminum plate 1 is less than or equal to 20% of the diameter of the circular light spot 5, and preferably, the separation distance d3 between the circular light spot 5 and the rectangular light spot of the auxiliary light beam irradiated on one side of the aluminum plate 1 is 0.15 mm. When the circular light spot 5 and the rectangular light spot of the auxiliary light beam irradiated on one side of the aluminum plate 1 are within the above distance range, the welding process is stable. The rectangular light spot of the auxiliary light beam irradiated on one side of the steel plate 2 has an offset distance from the butt joint edge of the middle layer metal 8 and the steel plate 2, and the offset distance is 0-10% of the diameter of the circular light spot 5.

The three beams of laser are generated by three lasers respectively, the power of the three beams of laser can be adjusted, and the energy of the main beam is determined according to the thickness of the middle layer metal 8, the thickness of the aluminum plate 1 and the welding speed, so that the aluminum plate 1 and the middle layer metal 8 are guaranteed to be melted. The heat input and the temperature field distribution at the joint are regulated and controlled by controlling the power and the irradiation position of the three beams of laser, so that the melting of the intermediate layer metal 8 and one side of the aluminum plate 1 is ensured in the welding process, the non-melting of one side of the steel plate 2 is ensured, and the high-quality aluminum/steel melting brazing joint is finally obtained. Under the condition of ensuring that the steel plate 2 is not melted, the heat input of the rectangular light spot laser beam irradiated on the steel plate 2 is moderate, and the size of the intermetallic compound newly formed at the interface is larger due to overlarge heat input amount, so that the brittleness of a welding joint is increased, and the performance is reduced; if the heat input is too small, a large welding stress is easily generated, cracking occurs at the interface, and the welding performance is difficult to ensure.

(4) Welding according to set process parameters, performing inert gas protection on a welding part in a mode of adopting a gas protection cover during welding, wherein the protection gas is argon with the purity of 99.99 percent, the gas flow of the protection gas is 15-20L/min, the gas protection cover is a spherical gas protection cover which is arranged on welding heads of two low-power lasers and a high-power laser, the welding heads of the two low-power lasers and the high-power laser are both positioned at the lower end part of the spherical gas protection cover, the upper end part of the spherical gas protection cover is provided with a gas inlet pipe, the middle part of the spherical gas protection cover is provided with a multilayer copper wire mesh structure, the multilayer copper wire mesh structure divides the spherical gas protection cover into an upper gas inlet chamber and a lower gas protection chamber, and the diameter of the spherical gas protection cover is equal to the welding speed vxwelding pool time t for cooling the molten, after the structure is adopted, the protection range of the gas protection cover can effectively cover the welding pool of the three beams of laser.

In the welding method for welding the aluminum/steel dissimilar metal by using the three beams of laser, two low-power rectangular facula laser beams are used as auxiliary beams to be respectively irradiated on one side of an aluminum plate 1 and one side of a steel plate 2, and the middle main beam provides enough heat to melt part of the aluminum plate 1 and the middle layer metal 8; the three laser beams all move along the welding direction 9 at the same speed, and the welding heat input is controlled by adjusting the welding process parameters, so that the distribution of temperature fields (namely the phenomena of high-temperature rapid cooling and large temperature gradient) during the welding of aluminum/steel dissimilar metals is improved; the welding interface reaction and the weld joint forming are improved, and the welding stress is reduced, so that a welding joint with better performance is obtained.

Technical features not described in the present invention can be implemented by the prior art, and are not described in detail herein. The present invention is not limited to the above-described embodiments, and variations, modifications, additions and substitutions which are within the spirit of the invention and the scope of the invention may be made by those of ordinary skill in the art are also within the scope of the invention.

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