An additive friction stir welding device and method for steel and aluminum dissimilar metals

Abstract

This invention relates to an additive friction stir welding device and method for steel-aluminum dissimilar metals, belonging to the field of steel-aluminum dissimilar metal welding technology. It addresses the problem that significant inhomogeneity in microstructure and properties still exists in friction stir welding of steel-aluminum dissimilar metals, making them prone to unexpected failures under complex loads. The device includes a non-rotating component and a rotating component. The rotating component is coaxially arranged inside the non-rotating component. The non-rotating component includes a conveying section with a wire feeding groove on its side and an axial hollow channel. The inner wall of the hollow channel is machined with local guide grooves. The rotating component includes a screw section and a stirring pin section. The stirring pin section is coaxially arranged at the lower end of the screw section. The screw section is machined with a feeding thread, and the stirring pin section is machined with a threaded structure. This invention ensures uniform microstructure and properties in the steel-aluminum joint, making it extremely difficult for unexpected failures to occur under complex loads.

Description

Technical Field

[0001] This invention relates to an additive friction stir welding device and method, belonging to the field of steel-aluminum dissimilar metal welding technology. Background Technology

[0002] New energy vehicles have become a major direction for the transformation and development of the global automotive industry and an important engine for promoting sustained global economic growth, leading to breakthroughs in common energy-saving technologies for lightweight vehicles. A 1.0% reduction in overall vehicle weight reduces harmful gas emissions by 1.0%, and lowers electricity / fuel consumption by 0.6-0.8%. Most automotive brands utilize steel-aluminum dissimilar metal composite structures, achieving weight reductions of over 40% compared to steel bodies, while also ensuring high-strength safety design and significantly improving electric range / fuel efficiency. However, the welding technology of steel and aluminum dissimilar metals, a key aspect of lightweight structural performance, remains unresolved. The significant differences in their thermophysical properties and poor chemical compatibility result in common key challenges in steel-aluminum welded joints, including weak interfacial bonding, poor load-bearing capacity, and low yield.

[0003] Friction stir welding (FSW), a solid-state joining method, utilizes the high-speed rotation of the welding tool to generate heat through friction with the workpiece, forming a thermoplastic material layer. As the welding tool and workpiece move relative to each other, the thermoplastic metal continuously forming in front is transferred to the rear of the welding tool, filling the cavity there, and forming a dense weld under the pressure of the shoulder. This technology features low heat input, short high-temperature dwell time, and minimal welding deformation. It effectively avoids defects such as cracks and porosity caused by the melting-solidification process and is largely unaffected by the material's physical and chemical properties and structure. It has significant advantages in overcoming the welding difficulties caused by the differences in the physical and chemical properties of dissimilar materials and has become a hot research direction in dissimilar metal welding. However, when using FSW to weld steel and aluminum dissimilar metals, significant inhomogeneity in microstructure and properties still exists, making them prone to unexpected failures under complex loads.

[0004] Therefore, there is an urgent need to propose an additive friction stir welding device and method for steel and aluminum dissimilar metals to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to address the significant inhomogeneity of microstructure and properties that still exists when welding dissimilar metals like steel and aluminum using friction stir welding, leading to unpredictable failures under complex loads. This invention provides an additive friction stir welding apparatus and method for steel and aluminum dissimilar metals. A brief overview of the invention is given below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0006] The technical solution of the present invention:

[0007] A steel-aluminum dissimilar metal additive friction stir riveting device includes a non-rotating component and a rotating component. The rotating component is coaxially arranged inside the non-rotating component. The non-rotating component includes a conveying section with a wire feeding groove on its side and an axial hollow channel. The inner wall of the hollow channel is machined with a partial guide groove. The rotating component includes a screw section and a stirring pin section. The stirring pin section is coaxially arranged at the lower end of the screw section. The screw section is machined with a feeding thread, and the stirring pin section is machined with a threaded structure.

[0008] Preferably, the local guide grooves are large-pitch spiral grooves, with a quantity of 3-10, and the angle difference between each groove is 60° divided by the number of spiral grooves.

[0009] Preferably, the non-rotating component further includes a clamping part, and the upper outer side of the conveying part is provided with a clamping part, and a plurality of positioning through holes arranged in a circumferential array are machined on the clamping part. The clamping part is used to connect with the non-rotating stator part of the spindle of the machining equipment, and the positioning through holes are used for positioning and clamping. The lower outer side of the conveying part has a symmetrical mounting plane, and a local guide groove is machined on the plane. The bottom end of the conveying part has a shoulder.

[0010] Preferably, the rotating component further includes a clamping part and a transition part, the clamping part, the transition part, and the screw part are arranged in sequence, the clamping part is located outside the hollow channel, the outer side of the clamping part has a milled surface, the clamping part is used to connect with the rotating spindle rotor part of the machining equipment, and the milled surface is used for side-fixed clamping; the transition part is provided with a disassembly groove for installation and disassembly; the stirring pin part is provided with several milled surface structures arranged in a circumferential array, and the stirring pin part is located outside the hollow channel.

[0011] Preferably, the bottom end of the screw section and the shoulder section are located on the same plane.

[0012] Preferably, the number of milled plane structures is 2-6, and the pitch of the thread structure is 0.5-2.5mm.

[0013] A method for additive friction stir riveting of dissimilar metals such as steel and aluminum includes the following steps:

[0014] Step 1: Pre-welding preparation

[0015] Equally spaced blind rivet holes are machined on one side of the steel plate to be welded, and the mating surface is machined into a bevel with the same angle as the generatrix angle of the stirring pin. At the same time, the aluminum plate to be welded is machined into an inverted bevel on one side to ensure that the mating interface between the steel plate and the aluminum plate to be welded can be in complete contact.

[0016] Step Two: Welding process, including the following steps:

[0017] Step 2.1: The non-rotating part and the rotating part are installed coaxially. The shoulder of the non-rotating part should be flush with the end face of the screw part of the rotating part. The rotating part rotates at high speed.

[0018] Step 2.2: The stirring needle is inserted into the junction of the steel plate and the aluminum plate to be welded. At this time, the additive raw material wire is continuously fed from the wire feeding slot of the non-rotating part and converges towards the steel plate to be welded. Under the strong plastic deformation of the stirring needle, it fills the steel side riveting hole and forms the weld seam residual layer.

[0019] Step 2.3: The non-rotating and rotating parts move synchronously along the weld seam of the steel-aluminum butt joint interface. While realizing the metallurgical connection of the steel-aluminum dissimilar metal interface, they continuously fill the steel side riveting holes to achieve the riveting mechanical connection, and finally form a complete steel-aluminum dissimilar metal additive friction stir riveting joint.

[0020] Step 3: Post-weld treatment

[0021] Milling the remaining high layer of weld seam.

[0022] Preferred: In step one, after machining the bevel, a portion of the blind rivet hole side can be exposed, but not more than half; the stirring pin is frustum-shaped, and the generatrix angle of the stirring pin is 5-20°;

[0023] In step two, in step 2.1, the rotation direction of the rotating component is opposite to the rotation direction of the feeding thread; in step 2.2, when inserting, it should be ensured that the side wall of the stirring needle coincides with the bevel of the steel-aluminum butt joint interface or the distance is not greater than 0.1mm, and the shoulder of the non-rotating component is 0.1 to 0.8mm away from the surface of the steel plate or aluminum plate to be welded; the additive raw material wire is an aluminum alloy welding wire with a diameter of 1.2 to 3.0mm.

[0024] The present invention has the following beneficial effects:

[0025] 1. By setting blind rivet holes on the workpiece to be welded and using the device of this invention, the present invention takes into account both the welding metallurgy and riveting mechanical connection dual load-bearing modes of steel-aluminum dissimilar metal joints, realizes the reliable connection of steel-aluminum dissimilar metal joints, effectively solves the common key problems of weak interface bonding, poor load-bearing performance, uneven microstructure and properties and low yield in steel-aluminum dissimilar metal welding, and is extremely difficult to cause unexpected failures under complex loads.

[0026] 2. This invention achieves a high aluminum superstructure on the weld surface (weld superstructure) through synchronous deposition additive manufacturing, thereby avoiding direct contact friction and wear between the rotating parts of the welding tool and the steel being welded. This enables steel welding tools to complete butt joints between dissimilar metals such as steel and aluminum, reduces the cost of using welding tools, and increases the service life of welding tools. Attached Figure Description

[0027] Figure 1This is a schematic diagram of an additive friction stir riveting device for dissimilar steel and aluminum metals as described in this invention.

[0028] Figure 2 This is a schematic diagram of the non-rotating component structure described in this invention;

[0029] Figure 3 This is a schematic diagram of the rotating component structure described in this invention;

[0030] Figure 4 This is a schematic diagram of a basic method for additive friction stir welding of dissimilar metals such as steel and aluminum, as described in this invention.

[0031] In the diagram: 1-Non-rotating component, 101-Clamping part, 10101-Positioning through hole, 102-Conveying part, 10201-Wire feeding slot, 10202-Hollow channel, 10203-Partial guide channel, 10204-Mounting plane, 103-Shoulder part, 2-Rotating component, 201-Clamping part, 20101-Side milling plane, 202-Transition part, 20201-Disassembly slot, 203-Screw part, 20301-Feeding screw, 204-Stirring needle part, 20401-Uniformly distributed circumferential milling plane, 20402-Threaded structure, 3-Welded steel plate, 301-Blind riveting hole, 302-Bevel, 4-Welded aluminum plate, 5-Additive raw material wire, 6-Weld seam excess layer. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0033] Specific implementation method one: Combining Figure 1-3 This embodiment describes a steel-aluminum dissimilar metal additive friction stir riveting device, comprising a non-rotating component 1 and a rotating component 2. The rotating component 2 is coaxially arranged inside the non-rotating component 1. The non-rotating component 1 includes a conveying section 102, which has a wire feeding groove 10201 on its side. The conveying section 102 has an axial hollow channel 10202 communicating with the wire feeding groove 10201. The inner wall is machined with inclined local guide grooves 10203. The rotating component 2 includes a screw part 203 and a stirring needle part 204. The stirring needle part 204 is coaxially arranged at the lower end of the screw part 203. The screw part 203 is machined with a feeding thread 20301, and the stirring needle part 204 is machined with a thread structure 20402. The inclination direction of the local guide grooves 10203 is the same as the rotation direction of the feeding thread 20301. The present invention is reasonably designed, easy to operate, and easy to observe intuitively.

[0034] Specific Implementation Method Two: Combining Figure 1-3 This embodiment describes a steel-aluminum dissimilar metal additive friction stir riveting device. The local guide grooves 10203 are large-pitch spiral grooves, numbered 3-10, with an angle difference of 60° between each groove divided by the number of spiral grooves. In the non-rotating component 1, the local guide grooves 10203 are located on one side of the steel plate 3 to facilitate additive friction stir riveting, forcing the thermoplasticized additive raw material filaments 5 towards the steel-side riveting holes 301, thus increasing the filling rate of the riveting holes 301. During rotation, the thermoplasticized additive raw material filaments are diverted, ensuring sufficient contact and stirring between the thermoplasticized additive raw material filaments and the stirring needle 204. The local guide grooves 10203 are evenly distributed at equal angles on one side of the wall of the hollow channel 10202 inside the conveying section.

[0035] Specific implementation method three: Combining Figure 1-3 This embodiment describes a steel-aluminum dissimilar metal additive friction stir welding device. The non-rotating component 1 further includes a clamping part 101. The clamping part 101 is located on the upper outer side of the conveying part 102. The clamping part 101 has a plurality of circumferentially arranged positioning through holes 10101 machined on it. The clamping part 101 is used to connect to the non-rotating stator part of the spindle of machining equipment including, but not limited to, friction stir welding machines, CNC milling machines, and CNC machining centers. The positioning through holes 10101 are used for positioning and clamping. The lower outer side of the conveying part 102 has symmetrical mounting planes 10204. Local guide grooves 10203 are machined on one or both sides of the mounting planes 10204. The outlet of the local guide grooves 10203 is located at the weld... The upper side of the steel plate 3; the bottom end of the conveying part 102 has a shoulder 103; the conveying part 102 has three functions: feeding the additive raw material filament 6, providing the screw extrusion conveying channel, and realizing steel side flow guidance. The feeding of the additive raw material filament 5 is completed by the filament feeding slot 10201 on the side of the non-rotating part 1. The screw extrusion conveying channel is provided by the hollow channel 10202 inside the conveying part. The steel side flow guidance is realized by the local flow guidance groove 10203 set on the side wall of the hollow channel. In addition, the conveying part is provided with two mounting planes 10204 for easy disassembly and installation. The shoulder 103 plays a role in compacting and smoothing the small granular additive raw material of the thermoplastic stirring needle part 204 of the rotating part, so as to achieve full filling of the steel side riveting hole 301 and densification of the weld excess layer 6.

[0036] Specific implementation method four: Combination Figure 1-3This embodiment describes a steel-aluminum dissimilar metal additive friction stir welding device. The rotating component 2 further includes a clamping part 201 and a transition part 202. The clamping part 201, transition part 202, and screw part 203 are arranged sequentially and are integrally formed. The clamping part 201 is located outside the hollow channel 10202, and its outer side has a milled surface 20101. The clamping part 201 is used to connect to the rotating spindle rotor part of machining equipment, including but not limited to friction stir welding machines, CNC milling machines, and CNC machining centers. Plane 20101 is used for side-fixed clamping; the transition part 202 is provided with a disassembly groove 20201 for installation and disassembly; the stirring needle part 204 is provided with several milled plane structures 20401 arranged in a circumferential array, and the stirring needle part 204 is located outside the hollow channel 10202; the feeding thread 20301 is used to feed and extrude the additive raw material wire 5 fed from the wire feeding groove 10201 of the non-rotating part towards the stirring needle part 204, and in the process, the additive raw material wire 5 is broken and thermoplasticized, and then filled into the steel side riveting hole 301 and formed the weld excess layer 6 under the strong plastic deformation of the stirring needle 204.

[0037] Specific Implementation Method Five: Combining Figure 1-3 This embodiment describes a steel-aluminum dissimilar metal additive friction stir riveting device, wherein the bottom end of the screw portion 203 and the shoulder portion 103 are located on the same plane.

[0038] Specific Implementation Method Six: Combination Figure 1-3 This embodiment describes a steel-aluminum dissimilar metal additive friction stir riveting device, wherein the number of milled flat structures 20401 is 2-6, and the pitch of the threaded structures 20402 is 0.5-2.5mm.

[0039] Specific implementation method seven: Combination Figure 1-4 This embodiment describes a steel-aluminum dissimilar metal additive friction stir riveting method, employing the aforementioned steel-aluminum dissimilar metal additive friction stir riveting device, and includes the following steps:

[0040] Step 1: Pre-welding preparation

[0041] The additive friction stir welding method is a butt joint, and the welded steel plate 3 and the welded aluminum plate 4 have the same thickness. Blind riveting holes 301 with equal spacing are machined on one side of the welded steel plate 3, and the butt joint surface is machined into a bevel 302 with the same generatrix angle as the stirring pin 204. At the same time, the welded aluminum plate 4 needs to be machined into an inverted bevel to ensure that the butt joint interface of the welded steel plate 3 and the welded aluminum plate 4 can be in complete contact. This invention, through the design of blind riveting holes on the steel side and additive friction stir welding design, and the introduction of a local flow guiding scheme, takes into account both the welding metallurgy and riveting mechanical connection dual load-bearing modes of steel-aluminum dissimilar metal joints, and realizes the reliable connection of steel-aluminum dissimilar metal joints. It effectively solves the common key problems of weak interface bonding, poor load-bearing capacity, uneven microstructure and properties, and low yield in steel-aluminum dissimilar metal welding.

[0042] Step Two: Welding process, including the following steps:

[0043] Step 2.1: Non-rotating component 1 and rotating component 2 are installed coaxially. The shoulder 103 of the non-rotating component and the end face of the screw 203 of the rotating component should be flush. The rotating component 2 rotates at high speed.

[0044] Step 2.2: The stirring needle 204 is inserted into the junction of the steel plate 3 and the aluminum plate 4 to be welded. At this time, the additive raw material wire 5 is continuously fed from the wire feeding slot 10201 of the non-rotating component at a certain rate. Under the squeezing and conveying action of the screw part 203 of the rotating component, it is pushed to the vicinity of the stirring needle 204 of the rotating component. Under the guidance of the local guide groove 10203 of the non-rotating component, it actively converges towards the steel plate 3 to be welded. Under the strong plastic deformation action of the stirring needle 204, it fills the steel side riveting hole 301 to form the weld reinforcement layer 6. The present invention can realize the adjustment of the additive raw material wire composition, further suppress the tendency of steel-aluminum dissimilar metal welding defects, and improve the joint strength and toughness.

[0045] Step 2.3: Non-rotating component 1 and rotating component 2 move synchronously along the direction of the weld seam for steel-aluminum butt joint (butt joint interface). While realizing the metallurgical connection of the steel-aluminum dissimilar metal interface, they continuously fill the steel side riveting hole 301 to achieve the riveting mechanical connection, and finally form a complete steel-aluminum dissimilar metal additive friction stir riveting joint.

[0046] Step 3: Post-weld treatment

[0047] Depending on the actual working conditions, the option may be to remove or not remove the excess weld layer 6 by machining and milling.

[0048] Specific implementation method eight: Combination Figure 1-4This embodiment describes a steel-aluminum dissimilar metal additive friction stir riveting method. In step one, after machining the bevel 302, a portion of the side of the blind riveting hole 301 is exposed, but not exceeding half. The stirring pin 204 is frustum-shaped, used to stir and thermoplasticize the aluminum alloy plate 4 to achieve a metallurgical connection with the steel sidewall 302, while simultaneously driving the thermoplasticized additive raw material wire 5 to fill the steel side riveting hole 301 and form the weld reinforcement layer 6. The generatrix angle of the stirring pin 204 is 5-20°. The weld reinforcement layer 6 serves to prevent direct contact and frictional wear between the steel rotating component 2 and the surface 3 of the steel being welded, so that the steel welding tool can complete the butt joint connection of steel and aluminum dissimilar metals, reducing the cost of welding tool use and increasing the service life of the welding tool.

[0049] In step two, in step 2.1, the rotation direction of the rotating component 2 is opposite to the rotation direction of the feeding thread 20301; in step 2.2, when inserting, it should be ensured that the side wall of the stirring needle 204 basically coincides with the interface (bevel) of the steel-aluminum butt joint or the distance is not greater than 0.1mm, and the shoulder 103 of the non-rotating component is 0.1 to 0.8mm away from the surface of the steel plate 3 or the aluminum plate 4 to be welded; the additive raw material wire 5 is an aluminum alloy welding wire with a diameter of 1.2 to 3.0mm, and in order to improve the welding strength and toughness of the steel-aluminum dissimilar joint, a high silicon content welding wire with a silicon content of >10% can be used.

[0050] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A steel-aluminum dissimilar metal additive friction stir riveting device, characterized in that: The non-rotating component (1) and the rotating component (2) are included. The rotating component (2) is coaxially arranged on the inner side of the non-rotating component (1). The non-rotating component (1) includes a conveying part (102). The side of the conveying part (102) has a wire feeding groove (10201). The conveying part (102) has an axial hollow channel (10202). The inner wall of the hollow channel (10202) is machined with a local guide groove (10203). The rotating component (2) includes a screw part (203) and a stirring needle part (204). The lower end of the screw part (203) is coaxially arranged with the stirring needle part (204). The screw part (203) is machined with a feeding thread (20301). The stirring needle part (204) is machined with a thread structure (20402). The non-rotating component (1) also includes a clamping part A (101). The upper outer side of the conveying part (102) is provided with the clamping part A (101). The clamping part A (101) is machined with a plurality of positioning through holes (10101) arranged in a circumferential array. The clamping part A (101) is used to connect with the non-rotating stator part of the spindle of the machining equipment. The positioning through holes (10101) are used for positioning and clamping. The lower outer side of the conveying part (102) has a symmetrical mounting plane (10204). The mounting plane (10204) is machined with a local guide groove (10203). The bottom end of the conveying part (102) has a shoulder (103). The rotating component (2) also includes a clamping part B (201) and a transition part (202). The clamping part B (201), the transition part (202), and the screw part (203) are arranged in sequence. The clamping part B (201) is located outside the hollow channel (10202). The outer side of the clamping part B (201) has a milled surface (20101). The clamping part B (201) is used to connect with the rotating spindle rotor part of the machining equipment. The milled surface (20101) is used for side-fixed clamping. The transition part (202) is provided with a disassembly groove (20201) for installation and disassembly. The stirring needle part (204) is provided with several milled surface structures (20401) arranged in a circumferential array. The stirring needle part (204) is located outside the hollow channel (10202).

2. The additive friction stir riveting device for steel and aluminum dissimilar metals according to claim 1, characterized in that: The local guide groove (10203) is a large pitch spiral groove, with a quantity of 3-10. The angle difference between each local guide groove (10203) is 60° divided by the number of spiral grooves.

3. The additive friction stir riveting device for steel and aluminum dissimilar metals according to claim 2, characterized in that: The bottom end of the screw part (203) and the shoulder part (103) are located on the same plane.

4. The additive friction stir riveting device for steel and aluminum dissimilar metals according to claim 3, characterized in that: The number of milled flat structures (20401) is 2-6, and the pitch of threaded structures (20402) is 0.5~2.5mm.

5. A method for additive friction stir riveting of dissimilar metals such as steel and aluminum, characterized in that: The steel-aluminum dissimilar metal additive friction stir welding device according to any one of claims 1-4 includes the following steps: Step 1: Pre-welding preparation Equally spaced blind rivet holes (301) are machined on one side of the steel plate (3) to be welded, and the mating surface is machined into a bevel (302) with the same angle as the generatrix of the stirring needle part (204). At the same time, the aluminum plate (4) to be welded is machined into an inverted bevel to ensure that the mating interface between the steel plate (3) to be welded and the aluminum plate (4) to be welded can be fully contacted. Step Two: Welding process, including the following steps: Step 2.1: The non-rotating component (1) and the rotating component (2) are installed coaxially. The shoulder (103) of the non-rotating component and the end face of the screw (203) of the rotating component should be flush. The rotating component (2) rotates at high speed. Step 2.2: The stirring needle (204) is inserted into the junction of the steel plate (3) to be welded and the aluminum plate (4) to be welded. At this time, the additive raw material wire (5) is continuously fed into the wire feeding slot (10201) of the non-rotating part and converges into the steel plate (3) to be welded. Under the strong plastic deformation of the stirring needle (204), it fills the blind riveting hole (301) on the steel side and forms the weld reinforcement layer (6). Step 2.3: The non-rotating component (1) and the rotating component (2) move synchronously along the welding direction of the weld seam. While realizing the metallurgical connection of the steel-aluminum dissimilar metal interface, they continuously fill the steel side riveting hole (301) to realize the riveting mechanical connection function and finally form a complete steel-aluminum dissimilar metal additive friction stir riveting joint. Step 3: Post-weld treatment Milling the remaining high layer of the weld seam (6).

6. The additive friction stir riveting method for steel and aluminum dissimilar metals according to claim 5, characterized in that: In step one, after machining the bevel (302), a portion of the side of the blind rivet hole (301) can be exposed, but not more than half; the stirring pin (204) is frustum-shaped, and the generatrix angle of the stirring pin (204) is 5~20°; In step 2.1 of step two, the rotation direction of the rotating part (2) is opposite to the rotation direction of the feeding thread (20301); in step 2.2, when inserting, it should be ensured that the side wall of the stirring needle (204) coincides with the interface of the steel-aluminum butt joint or the distance is not greater than 0.1mm, and the shoulder (103) of the non-rotating part is 0.1~0.8mm away from the surface of the welded steel plate (3) or welded aluminum plate (4); the additive raw material wire (5) is an aluminum alloy welding wire with a diameter of 1.2~3.0mm.

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