阅读说明：本技术 基于高熵合金中间层铝/钢异种金属双光束激光焊接方法 (Aluminum/steel dissimilar metal double-beam laser welding method based on high-entropy alloy intermediate layer ) 是由 谷晓鹏 周贺 徐国成 董娟 于 2021-08-05 设计创作，主要内容包括：本发明涉及一种基于高熵合金中间层铝/钢异种金属双光束激光焊接方法,属于材料焊接技术领域。以Fe/Al基高熵合金金属片为中间层材料,精确调节两并排激光束的功率比,使主光束光斑位于钢板侧,辅助光束光斑位于铝合金板侧。通过控制温度场分布,当高功率激光束的温度达到Fe/Al基高熵合金金属片与钢板的液相线温度以上,在钢板侧,形成熔化焊缝。在铝合金板侧,由于铝熔点较低形成钎焊焊缝。两束激光束的光斑之间预留一段距离,焊接结束后,高熵合金层中间未被激光辐射部分仍为固体状态,避免了Fe,Al元素的相互扩散,减少Fe-Al金属间化合物的生成,从而改善焊件的抗拉强度。(The invention relates to a high-entropy alloy interlayer aluminum/steel dissimilar metal based double-beam laser welding method, and belongs to the technical field of material welding. The Fe/Al-based high-entropy alloy metal sheet is used as an intermediate layer material, and the power ratio of two parallel laser beams is accurately adjusted, so that a main beam spot is positioned on the side of a steel plate, and an auxiliary beam spot is positioned on the side of an aluminum alloy plate. By controlling the temperature field distribution, when the temperature of the high-power laser beam reaches above the liquidus temperature of the Fe/Al-based high-entropy alloy metal sheet and the steel plate, a fusion welding seam is formed on the side of the steel plate. On the aluminum alloy plate side, a brazing weld is formed due to the lower melting point of aluminum. A distance is reserved between light spots of the two laser beams, and after welding is finished, the part, which is not irradiated by the laser, in the middle of the high-entropy alloy layer is still in a solid state, so that mutual diffusion of Fe and Al elements is avoided, and generation of Fe-Al intermetallic compounds is reduced, thereby improving tensile strength of a welded part.)

1. A high-entropy alloy interlayer aluminum/steel dissimilar metal based double-beam laser welding method is characterized by comprising the following steps: the high-entropy alloy metal sheet (3) is used as an intermediate layer for welding dissimilar metals of the aluminum alloy plate (2) and the steel plate (1), and double-beam laser welding is respectively adopted on the interfaces of the high-entropy alloy metal sheet (3), the aluminum alloy plate (2) and the steel plate (1) to form a composite welding joint combining a side fusion welding seam of the steel plate (1) and a side brazing welding seam of the aluminum alloy plate (2);

the high-entropy alloy metal sheet (3) is an Al/Fe-based high-entropy alloy metal sheet, and the width range of the high-entropy alloy metal sheet is 0.3-2 mm; in the welding process, the high entropy effect and the slow diffusion effect are utilized: inhibiting intermetallic compounds from being formed in the welding seam by the high entropy effect; the slow diffusion effect prevents elements in the parent metal from diffusing to the weld joint in a large amount, and further inhibits the generation of intermetallic compounds;

the double-beam laser welding is to adopt light spots of two laser beams at the interface of the steel plate (1) and the high-entropy alloy metal sheet (3) andheating the welding seam in a selected area at the interface of the aluminum alloy plate (2); the light spots of the two laser beams respectively adopt high-power/low-power lasers: a laser beam emitted by the high-power laser is used as a main beam (6), and a main beam spot (4) of the main beam is arranged at the interface of the steel plate (1) and the high-entropy alloy metal sheet (3); a laser beam emitted by a low-power laser is used as an auxiliary beam (7), and an auxiliary beam spot (5) of the auxiliary beam is arranged at the interface of the high-entropy alloy metal sheet (3) and the aluminum alloy plate (2) and is deviated to the side of the aluminum alloy plate (2); adjusting the power ratio of the main beam (6) to the auxiliary beam (7) to be 5: 1-1: 1, and adjusting the spot radius ratio R of the main beam (6) to the auxiliary beam (7)₁/R₂3: 1-1: 1, the heat input of the main beam (6) is higher than that of the auxiliary beam (7); in the welding process, the heat input of the main beam (6) is adjusted, the liquidus temperature of the high-entropy alloy metal sheet (3) and the liquidus temperature of the steel plate (1) are simultaneously reached, and the high-entropy alloy metal sheet (3) and the steel plate (1) are melted in the radiation range of the main beam (6) to form a melting welding seam; adjusting the power of an auxiliary light beam (7) of the laser beam to ensure that the heat input of the auxiliary light beam (7) reaches above the liquidus temperature of the aluminum alloy plate (2) but does not reach the liquidus temperature of the high-entropy alloy metal sheet (3); in the radiation range of the auxiliary beam (7), the aluminum alloy plate (2) is melted, the high-entropy alloy metal sheet (3) is still in a solid state, and molten aluminum liquid wets and spreads the high-entropy alloy metal sheet to form a brazing weld.

2. The high-entropy alloy interlayer aluminum/steel dissimilar metal-based two-beam laser welding method according to claim 1, characterized in that: the double-beam laser welding is double-beam simultaneous laser welding or double-beam time-sharing laser welding; the double-beam simultaneous laser welding is characterized in that a main beam (6) and an auxiliary beam (7) are welded at the interface of the steel plate (1) and the high-entropy alloy metal sheet (3) and the interface of the high-entropy alloy metal sheet (3) and the aluminum alloy plate (2) simultaneously, and a reserved distance d is reserved between two light spots of the main beam (6) and the auxiliary beam (7) at the moment₁Adjusting the distance d between two light spots₁0 mm-0.8 mm, so that the high-entropy alloy metal sheet(3) The middle part which is not radiated by the laser is still in a solid state, so that the mutual diffusion between Fe and Al atoms is avoided to form a brittle Fe-Al intermetallic compound; the width range of the high-entropy alloy metal sheet (3) adopting the middle layer is 1 mm-2 mm; the double-beam time-sharing laser welding is characterized in that an auxiliary beam (7) is firstly adopted to weld the interface of the high-entropy alloy metal sheet (3) and the aluminum alloy plate (2), a main beam (6) is then welded at the interface of the steel plate (1) and the high-entropy alloy metal sheet (3), and at the moment, a reserved distance d does not need to be reserved between light spots of the main beam (6) and the auxiliary beam (7)₁And the width range of the middle-layer high-entropy alloy metal sheet is 0.3-1 mm.

3. The high-entropy alloy interlayer aluminum/steel dissimilar metal-based two-beam laser welding method according to claim 1, characterized in that: the aluminum alloy plate (2) and the steel plate (1) can be equal in thickness or different in thickness; when the aluminum alloy plate (2) and the steel plate (1) have the same thickness, the middle layer is a Fe/Al-based high-entropy alloy metal sheet, the thickness of the middle layer is equal to that of the base metal, and the width d of the middle layer is equal to that of the base metal₂1 mm-2 mm; when the aluminum alloy plate (2) and the steel plate (1) are not of the same thickness, the middle layer Fe/Al-based high-entropy alloy metal sheet is of the same thickness as the steel plate (1) and has the width d₂Is 0.3mm to 1 mm.

4. The high-entropy alloy interlayer aluminum/steel dissimilar metal-based two-beam laser welding method according to claim 1, characterized in that: the high-power laser and the low-power laser both adopt continuous fiber lasers; wherein the light beam radiated by the high-power laser is a main light beam (6), the power range of the main light beam (6) is 800W-2000W, and the spot radius R of the main light beam₁0.5 mm-1.5 mm, the light beam radiated by the low-power laser is an auxiliary light beam (7), the power range of the auxiliary light beam (7) is 400W-1000W, and the spot radius R of the auxiliary light beam₂Is 0mm to 1.0 mm.

5. The high-entropy alloy interlayer aluminum/steel dissimilar metal-based two-beam laser welding method according to claim 1, characterized in that: the auxiliary light beam (7) is in the aluminum alloyThe offset distance of the side of the gold plate (2) is the spot radius R of the auxiliary beam₂0-50% of the aluminum alloy plate, and the offset of the aluminum alloy plate is 0-0.5 mm, so that a brazing welding seam is formed on the side of the aluminum alloy plate (2).

6. The high-entropy alloy interlayer aluminum/steel dissimilar metal two-beam laser welding method according to any one of claims 1 to 5, wherein: the method comprises the following steps:

firstly, an I-shaped groove butt joint mode is adopted between an aluminum alloy plate (2) and a steel plate (1), the aluminum alloy plate (2) and the steel plate (1) are respectively fixed on a clamp by a pressing plate, a Fe/Al-based high-entropy alloy sheet is arranged in the middle of a base metal, a fixing screw on a clamp platform is adjusted, the applied pretightening force is 10N-20N, and good contact of interfaces between the aluminum alloy plate (2) -the high-entropy alloy sheet metal (3) -the steel plate (1) is ensured;

step two, adjusting the power ratio of the two lasers, and setting the positions of the light spots of the two laser beams: the radius of the main beam spot (4) is R₁Placing a main light beam spot (4) at the interface of the steel plate (1) and the high-entropy alloy metal sheet (3); the auxiliary beam spot (5) has a radius of R₂Auxiliary light beam spots (5) are arranged at the interface of the aluminum alloy plate (2) and the high-entropy alloy metal sheet (3) and are deviated to the side of the aluminum alloy plate (2); meanwhile, the power ratio of the main light beam (6) to the auxiliary light beam (7) is adjusted to be 5: 1-1: 1; adjusting two light spot radiuses R₁、R₂So that R is₁/R₂Is 3:1 to 1:1, and a distance d is reserved between the two light spots₁；

Step three, setting welding technological parameters: the laser welding speed is 2 mm/min-10 mm/min; the defocusing amount is-5 mm to +5 mm; welding protective gas is high-purity argon with the purity of 99.99 percent, and is applied to the upper surface and the lower surface of a welding seam, wherein the gas flow range of the protective gas on the upper surface is 5L/min-15L/min, and the gas flow range of the protective gas on the lower surface is 5L/min-20L/min; the air flow of the lower surface is larger than that of the upper surface in the welding process;

and step four, completing welding.

Technical Field

The invention relates to the technical field of dissimilar material welding, in particular to a laser welding method for dissimilar metals of an aluminum alloy plate/steel plate, and particularly relates to a double-beam laser welding method for the dissimilar metals of aluminum/steel based on a high-entropy alloy interlayer. The method is applied to the fields of automobile and rail vehicle manufacturing and the like.

Background

The aluminum steel composite structure has the advantages of low density, good corrosion resistance and plastic processing performance of aluminum alloy, high steel strength, good impact resistance and the like. The welding structure of the dissimilar alloy plays an important role in reducing the weight of the vehicle, reducing the energy consumption and reducing the environmental pollution. However, because the difference between the melting point, the linear expansion coefficient, the specific heat capacity, the thermal conductivity, the density and other physical properties and chemical properties of the aluminum alloy and the steel is large, a large amount of brittle Fe-Al intermetallic compounds can be formed in a welding seam by the aluminum alloy and the steel in the welding process, and how to avoid the generation of excessive intermetallic compounds is the key for ensuring that the joint meets the requirements of the mechanical properties of practical application.

Lightweight requires light materials such as aluminum and magnesium to be widely applied to automobile bodies. However, the copper electrode used in the conventional resistance spot welding is easy to generate a metal bond compound with aluminum magnesium, and the service life of the electrode is shortened. Resistance spot welding applications are limited in connection with lightweight materials. Laser welding is one of the main welding methods in automobile manufacturing because of its high welding speed, high welding efficiency and few welding defects. However, during the welding process of the single-beam laser, the energy is concentrated, the heat affected zone is small, and the temperature gradient is large.

With the progress of science and technology, new materials are continuously emerged, the high-entropy alloy is composed of five or more elements with equal atomic ratio or near equal atomic ratio, the high-entropy alloy has good shaping and toughness, and some properties are far superior to those of the traditional alloy. The high-entropy alloy with the multi-principal element has higher high-entropy effect, so that the inter-atom diffusion is not easy to occur, and an intermetallic compound is not easy to form. The high-entropy alloy has excellent mechanical properties and has a very wide application prospect in the future. However, so far, high-entropy alloys have been rarely studied in laser welding dissimilar materials.

Disclosure of Invention

The invention aims to provide a high-entropy alloy interlayer aluminum/steel dissimilar metal based double-beam laser welding method, which solves the problems in the prior art. According to the invention, the high-entropy alloy metal sheet is taken as the intermediate layer, the width of the intermediate layer and welding process parameters are adjusted, the high-entropy effect of the high-entropy alloy in the welding line inhibits the generation of Fe-Al intermetallic compounds, the brittleness of the joint is reduced, and the mechanical property of the joint is improved. Thereby realizing the effective welding of the aluminum alloy and the steel.

The invention takes Fe/Al-based high-entropy alloy metal sheet as an intermediate layer, and the welded workpiece can be made of the same material, steel, aluminum-based alloy, nickel-based alloy, titanium alloy, or dissimilar material, steel and aluminum alloy, titanium alloy and aluminum alloy, steel and nickel-based alloy, steel and copper alloy, nickel alloy and aluminum alloy.

The above object of the present invention is achieved by the following technical solutions:

based on a high-entropy alloy interlayer aluminum/steel dissimilar metal double-beam laser welding method, a high-entropy alloy metal sheet is used as an interlayer for welding aluminum alloy plates 2 and steel plates 1 dissimilar metals, and double-beam laser welding is respectively adopted on interfaces of the high-entropy alloy metal sheet 3, the aluminum alloy plates 2 and the steel plates 1 to form a composite welding joint combining a melting welding seam on the side of the steel plate 1 and a brazing welding seam on the side of the aluminum alloy plates 2;

the high-entropy alloy metal sheet is an Al/Fe-based high-entropy alloy metal sheet, and the width range of the high-entropy alloy metal sheet is 0.3-2 mm; in the welding process, the high entropy effect and the slow diffusion effect are utilized: inhibiting intermetallic compounds from being formed in the welding seam by the high entropy effect; the slow diffusion effect prevents elements in the parent metal from diffusing to the weld joint in a large amount, and further inhibits the generation of intermetallic compounds;

the double-beam laser welding is characterized in that two laser spots are adopted to selectively heat the welding seams at the interface of the steel plate 1 and the high-entropy alloy metal sheet 3 and the interface of the high-entropy alloy metal sheet 3 and the aluminum alloy plate 2; the light spots of the two laser beams respectively adopt high-power/low-power lasers: the laser beam emitted by the high-power laser is used as a main beam 6, and a main beam spot 4 of the main beam is arranged on the steel plate 1 and the high-entropy alloy goldAt the interface of the sheet 3; a laser beam emitted by a low-power laser is used as an auxiliary beam 7, and an auxiliary beam spot 5 of the auxiliary beam is arranged at the interface of the high-entropy alloy metal sheet 3 and the aluminum alloy plate 2 and is deviated to the side of the aluminum alloy plate 2; adjusting the power ratio of the main beam 6 to the auxiliary beam 7 to be 5: 1-1: 1, and adjusting the spot radius ratio R of the main beam 6 to the auxiliary beam 7₁/R₂3: 1-1: 1, the heat input of the main beam 6 is higher than that of the auxiliary beam 7; in the welding process, the heat input of the main beam 6 is adjusted, meanwhile, the liquidus temperature of the high-entropy alloy metal sheet 3 and the liquidus temperature of the steel plate 1 are reached, and the high-entropy alloy metal sheet 3 and the steel plate 1 are melted in the radiation range of the main beam 6 to form a melting welding seam; adjusting the power of the auxiliary beam 7 of the laser beam to ensure that the heat input of the auxiliary beam 7 reaches above the liquidus temperature of the aluminum alloy plate 2 but does not reach the liquidus temperature of the high-entropy alloy metal sheet 3; in the radiation range of the auxiliary beam 7, the aluminum alloy plate 2 is melted, the high-entropy alloy metal sheet 3 is still in a solid state, and molten aluminum liquid wets and spreads the high-entropy alloy metal sheet to form a brazing weld.

The double-beam laser welding can be double-beam simultaneous laser welding or double-beam time-sharing laser welding; the double-beam simultaneous laser welding is that the main beam 6 and the auxiliary beam 7 are welded at the interface of the steel plate 1 and the high-entropy alloy metal sheet 3 and the interface of the high-entropy alloy metal sheet 3 and the aluminum alloy plate 2 at the same time, and a distance d needs to be reserved between two light spots of the main beam 6 and the auxiliary beam 7₁Adjusting the distance d between the two circular light spots₁The thickness is 0 mm-0.8 mm, so that the part, which is not irradiated by laser, in the middle of the high-entropy alloy metal sheet 3 is still in a solid state, and the mutual diffusion between Fe and Al atoms is avoided to form a brittle Fe-Al intermetallic compound; the width range of the high-entropy alloy metal sheet 3 of the middle layer is 1 mm-2 mm; the double-beam time-sharing laser welding is characterized in that the auxiliary beam 7 is firstly adopted to weld the interface of the high-entropy alloy metal sheet 3 and the aluminum alloy plate 2, the main beam 6 is then welded at the interface of the steel plate 1 and the high-entropy alloy metal sheet 3, and at the moment, a reserved distance d does not need to be reserved between light spots of the main beam 6 and the auxiliary beam 7₁And the width range of the middle-layer high-entropy alloy metal sheet is 0.3-1 mm.

The above-mentionedThe aluminum alloy plate 2 and the steel plate 1 can be equal in thickness or different in thickness; when the aluminum alloy plate 2 and the steel plate 1 are equal in thickness, the intermediate layer is a Fe/Al-based high-entropy alloy metal sheet, the thickness of the intermediate layer is equal to that of the base metal (the aluminum alloy plate 2 and the steel plate 1), and the width d of the intermediate layer is equal to that of the base metal₂1 mm-2 mm; when the aluminum alloy plate 2 and the steel plate 1 are not equal in thickness, the Fe/Al-based high-entropy alloy metal sheet in the middle layer is equal in thickness to the steel plate 1, and the width d₂Is 0.3mm to 1 mm.

The high-power laser and the low-power laser both adopt continuous fiber lasers; wherein the light beam radiated by the high-power laser is a main light beam 6, the power range of the main light beam 6 is 800W-2000W, and the spot radius R of the main light beam₁0.5 mm-1.5 mm, the light beam radiated by the low-power laser is an auxiliary light beam 7, the power range of the auxiliary light beam 7 is 400W-1000W, and the spot radius R of the auxiliary light beam₂Is 0mm to 1.0 mm.

The offset distance of the auxiliary beam 7 at the side of the aluminum alloy plate 2 is the spot radius R of the auxiliary beam₂0-50% of the aluminum alloy plate, and the offset of the aluminum alloy plate is 0-0.5 mm, so that a brazing welding seam is formed on the side of the aluminum alloy plate 2.

The invention relates to a high-entropy alloy interlayer aluminum/steel dissimilar metal based double-beam laser welding method, which comprises the following process steps of:

firstly, an I-shaped groove butt joint mode is adopted between an aluminum alloy plate 2 and a steel plate 1, the aluminum alloy plate 2 and the steel plate 1 are respectively fixed on a clamp by a pressing plate, a Fe/Al-based high-entropy alloy sheet is arranged in the middle of a base material, a fixing screw on a clamp platform is adjusted, and the applied pretightening force is 10N-20N, so that good contact of each interface between the aluminum alloy plate 2-the high-entropy alloy sheet metal (3) -the steel plate 1 is ensured;

step two, adjusting the power ratio of the two lasers, and setting the positions of the two light spots: the main beam spot 4 has a radius of R₁Placing a main light beam spot 4 at the interface of the steel plate 1 and the high-entropy alloy metal sheet 3; auxiliary beam spot 5 having radius R₂Placing an auxiliary light beam spot 5 at the interface of the aluminum alloy plate 2 and the high-entropy alloy metal sheet 3 and deflecting to the side of the aluminum alloy plate 2; meanwhile, the power ratio of the main beam 6 to the auxiliary beam 7 is adjusted to be 5: 1-1: 1; adjusting two light spot radiuses R₁、R₂So that R is₁/R₂3:1 to 1:1, and two light spots are formedA distance d is reserved between₁；

Step three, setting welding technological parameters: the laser welding speed is 2 mm/min-10 mm/min; the defocusing amount is-5 mm to +5 mm; welding protective gas is high-purity argon with the purity of 99.99 percent, and is applied to the upper surface and the lower surface of a welding seam, wherein the gas flow range of the protective gas on the upper surface is 5L/min-15L/min, and the gas flow range of the protective gas on the lower surface is 5L/min-20L/min; the air flow of the lower surface is larger than that of the upper surface in the welding process;

and step four, completing welding.

The invention has the beneficial effects that:

1. and forming a fusion welding seam on the steel plate side and forming a brazing welding seam on the aluminum alloy plate side by adopting double-beam laser welding. The main beam and the auxiliary beam are controlled to have a distance, and the high-entropy alloy still in a solid state after welding prevents mutual diffusion of Fe and Al elements and inhibits the generation of intermetallic compounds in a welding seam.

2. The Fe/Al-based high-entropy alloy metal sheet is used as the intermediate layer, so that elements in the base material are prevented from being diffused into a weld joint in a large amount, and the generation of Fe-Al intermetallic compounds is inhibited. In the welding process, because part of elements in the parent metal are diffused into the welding seam, the elements in the welding seam are subjected to high entropy change, and the generation of intermetallic compounds is further inhibited. The high-entropy alloy high-entropy effect and the slow diffusion effect in the welding seam are beneficial to improving the mechanical property of the weldment.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention.

FIG. 1 is a schematic view of a welding process using side-by-side dual-beam lasers according to the present invention;

FIG. 2 is a three-dimensional view of a specific application of laser welding during simultaneous dual-beam laser welding;

FIG. 3 is a top view of the aluminum alloy plate/steel plate welding by laser welding with dual beams simultaneously when the offset of the auxiliary beam is 0.25 mm;

FIG. 4 is a plan view showing the welding of aluminum alloy sheet/steel sheet in the double beam time-sharing laser welding in accordance with the present invention with an offset of auxiliary beam of 0.25 mm.

In the figure: 1. a steel plate; 2. aluminum alloy plate; 3. a high entropy alloy metal sheet; 4. a main beam spot; 5. an auxiliary beam spot; 6. a main light beam; 7. an auxiliary light beam.

Detailed Description

The details of the present invention and its embodiments are further described below with reference to the accompanying drawings.

Referring to fig. 1 to 4, in the high-entropy alloy interlayer aluminum/steel dissimilar metal-based dual-beam laser welding method, a Fe/Al-based high-entropy alloy metal sheet is used as an interlayer material, and the power ratio of two parallel laser beams is accurately adjusted, so that a circular main beam spot is located on the side of a steel plate, and a circular auxiliary beam spot is located on the side of an aluminum alloy plate. By controlling the temperature field distribution, when the temperature of the high-power laser beam reaches above the liquidus temperature of the Fe/Al-based high-entropy alloy metal sheet and the steel plate, a fusion welding seam is formed on the side of the steel plate. On the aluminum alloy plate side, a brazing weld is formed due to the lower melting point of aluminum. A distance is reserved between the two light spots, and after welding is finished, the part, which is not irradiated by laser, in the high-entropy alloy layer is still in a solid state, so that mutual diffusion of Fe and Al elements is avoided, and generation of Fe-Al intermetallic compounds is reduced, so that the tensile strength of a weldment is improved. The specific process steps are as follows:

1) before welding, respectively polishing the aluminum alloy plate and the steel plate with equal thickness by using 500-mesh, 800-mesh, 1000-mesh, 1500-mesh and 2000-mesh abrasive paper, removing an oxide film on the surface of the metal plate, cleaning by using acetone to remove oil stains on the surface of the metal plate, and then drying;

2) and an I-shaped groove butt joint mode is adopted between the aluminum alloy plate and the steel plate, the two metal plates are respectively arranged on the clamp, and a high-entropy alloy metal sheet is arranged between the two metal plates. A certain pre-tightening force is required to be applied before welding so as to ensure good interface contact among the aluminum alloy plate, the high-entropy alloy sheet and the steel plate;

3) adjusting the power ratio of the two lasers, and setting the positions of the two light spots: the high-power laser and the low-power laser both adopt continuous fiber lasers. Using both high and low power lasers as heat sourcesThe laser emitted by the high-power laser is used as a main beam with the radius of R₁The main beam light spot is arranged at the interface of the steel plate and the high-entropy alloy sheet metal, and the high-entropy alloy sheet and the steel plate are melted in the radiation range of the main beam to form a melting welding seam. Using laser emitted by low-power laser as auxiliary beam with radius of R₂The auxiliary light beam spot is arranged at the interface of the aluminum alloy plate and the high-entropy alloy metal sheet and is deviated to the side of the aluminum alloy plate. In the radiation range of the auxiliary beam, the aluminum alloy plate is melted, the high-entropy alloy metal sheet is still in a solid state, and the molten aluminum liquid wets and spreads the high-entropy alloy metal sheet to form a brazing weld. Adjusting two light spot radiuses R₁、R₂And a distance d is reserved between the two light spots₁；

4) And setting welding process parameters to finish welding.

Further, the thickness of the aluminum alloy plate and the base metal of the steel plate is 1 mm-4 mm, when the thickness of the steel plate and the aluminum alloy plate is equal, the thickness of the middle layer Fe/Al-based high-entropy alloy metal sheet is equal to that of the base metal, and the width d of the middle layer Fe/Al-based high-entropy alloy metal sheet is equal to that of the base metal₂Is 1 mm-2 mm. And (3) adopting double-beam simultaneous laser welding, and respectively placing two light spots at the interface of the steel plate/the high-entropy alloy metal sheet and the interface of the high-entropy alloy metal sheet/the aluminum alloy plate to simultaneously heat the welding seam. When the thickness of the steel plate is different from that of the aluminum alloy plate, the thickness of the Fe/Al-based high-entropy alloy metal sheet in the middle layer is equal to that of the steel plate, and the width d of the Fe/Al-based high-entropy alloy metal sheet is equal to that of the steel plate₂Is 0.3mm to 1 mm. And (3) adopting double-beam time-sharing laser welding, firstly placing auxiliary beam spots at the interface of the high-entropy alloy metal sheet/aluminum alloy plate, and after welding is finished, placing main beam spots at the interface of the steel plate/the high-entropy alloy metal sheet.

Further, before welding, the aluminum alloy plate and the steel plate are respectively fixed on a clamp through a pressing plate, the high-entropy alloy metal sheet is arranged in the middle of the base metal, the fixing screw on the platform of the clamp is adjusted, the applied pretightening force is 10N-20N, and good contact of each interface is ensured.

Further, the high power laser and the low power laser both adopt continuous fiber lasers. Wherein the power of the main beam is 800W-2000W, and the radius R₁0.5mm to 1.5mm, an auxiliary beam power of 400W to 1000W, and a radius R₂Is 0.5mm to 1.0 mm.

Further, adjusting the offset of the auxiliary beam, deflecting the auxiliary beam to the aluminum alloy plate side, increasing the heat input of the auxiliary beam, and adjusting the offset distance of the laser beam to be the spot radius R of the auxiliary beam₂0-50% of the total weight of the aluminum alloy plate, and the offset of the aluminum alloy plate is 0-0.5 mm, so that a brazing welding seam is formed on the side of the aluminum alloy plate.

Further, the power ratio of the main beam to the auxiliary beam is adjusted to be 5: 1-1: 1, the laser welding speed is adjusted to be 2 mm/min-10 mm/min, and the radius ratio R of the main beam spot to the auxiliary beam spot is₁/R₂Is 3:1 to 1: 1. The heat input of the laser is accurately controlled, so that the heat input of the laser beam simultaneously reaches above the liquidus temperature of the high-entropy alloy metal sheet and the steel plate, and the high-entropy alloy metal sheet and the steel plate are melted in the radiation range of the main beam to form a melting welding seam. And adjusting the power of the auxiliary beam of the laser beam to ensure that the heat input of the auxiliary beam is above the liquidus temperature of the aluminum alloy plate but not the liquidus temperature of the high-entropy alloy metal sheet. In the radiation range of the auxiliary beam, the aluminum alloy plate is melted, the high-entropy alloy metal sheet is still in a solid state, and the molten aluminum liquid wets and spreads the high-entropy alloy metal sheet to form a brazing weld. After welding, on the side of the aluminum alloy plate, aluminum atoms are diffused into the welding seam, so that the high entropy effect and the lattice distortion effect of the high entropy alloy are increased, and the tensile strength of the welding seam is further influenced. On the steel sheet side, a fusion weld is formed.

Furthermore, the defocusing amount of the laser beam is adjusted to be-5 mm to +5mm, so that the phenomenon that the joint is not welded through or burnt through is avoided.

Further, the distance d between the two circular light spots is adjusted₁The thickness of the high-entropy alloy metal sheet is 0 mm-0.8 mm, the middle part of the high-entropy alloy metal sheet is not radiated by laser, the middle of the high-entropy alloy metal sheet is still in a solid state, and the phenomenon that mutual diffusion between Fe and Al atoms forms a brittle Fe-Al intermetallic compound is avoided.

Further, the used gas is high-purity argon gas during welding, and the argon gas with the purity of 99.99% is introduced into the upper surface and the lower surface of the welding seam for protection. The gas flow of the upper surface protective gas is adjusted to be 5L/min-15L/min, and the gas flow of the lower surface protective gas is adjusted to be 5L/min-20L/min. The upper surface air flow is not easily too large to affect the heat input of the laser beam. The air flow of the lower surface can be slightly larger, so that the air can be smoothly overflowed from the air holes on the lower surface of the clamp.

Example (b):

a high-entropy alloy interlayer aluminum/steel dissimilar metal based double-beam laser welding method comprises the following specific steps:

(1) A6082-T6 aluminum alloy plate having a size of 50X 70X 2mm was laser welded to a 301L stainless steel plate having a size of 50X 70X 2 mm. Before welding, the aluminum alloy plate and the steel plate with equal thickness are respectively polished by 500-mesh, 800-mesh, 1000-mesh, 1500-mesh and 2000-mesh abrasive paper, an oxidation film on the surface of the metal plate is removed, the surface of the metal plate is cleaned by acetone to remove oil stains on the surface of the metal plate, and then the metal plate is dried by a vacuum drying oven.

(2) An I-shaped groove butt joint mode is adopted between the aluminum alloy plate and the stainless steel plate, the two metal plates are fixed on a platform of the clamp by using a pressing plate before welding, a high-entropy alloy metal sheet is placed between the aluminum alloy plate and the stainless steel plate, and the width d of the metal sheet is larger than the width d of the metal sheet₂At 1mm, laser welding with double beams or width d₂And double-beam time-sharing laser welding is adopted for the thickness of 0.3 mm. And adjusting the fixed screw, and applying a certain pre-tightening force of 10N-20N before welding to ensure that the interface contact between the aluminum alloy plate and the high-entropy alloy metal sheet and the steel plate is good.

(3) Adjusting the power ratio of the two lasers, and setting the positions of the two light spots: the high-power laser and the low-power laser both adopt continuous fiber lasers. High-power and low-power lasers are simultaneously used as heat sources, wherein the power of a main beam is 800W-2000W, and the radius R₁Is 0.5 mm-1.5 mm, preferably, the main beam power is set to be 1500W, and the radius R₁Is 1.0 mm. The main beam light spot is arranged at the interface of the steel plate and the high-entropy alloy metal sheet, and the heat input of the laser is accurately controlled, so that the heat input of the main beam of the laser reaches above the liquidus temperature of the high-entropy alloy metal sheet and the steel plate. In the radiation range of the main light beam, the high-entropy alloy metal sheet and the steel plate are melted to form a melting welding seam. The laser emitted by the low-power laser is used as an auxiliary beam, the power of the auxiliary beam is 400W-1000W, and the radius R₂Is 0.5mm to 1.0 mm. PreferablyThe auxiliary beam power is set to 1000W, radius R₂Is 0.5 mm. The auxiliary light beam light spot is arranged at the interface of the aluminum alloy plate and the high-entropy alloy metal sheet and is deviated to the side of the aluminum alloy plate. Adjusting the laser beam offset distance to assist beam spot radius R₂50% of (A), the amount of the offset is 0.25 mm. The heat input of the laser is accurately controlled, so that the heat input of the laser auxiliary beam reaches above the liquidus temperature of the aluminum alloy plate but does not reach the liquidus temperature of the high-entropy alloy metal sheet. In the radiation range of the auxiliary beam, the aluminum alloy plate is melted, the high-entropy alloy metal sheet is still in a solid state, and the molten aluminum liquid wets and spreads the high-entropy alloy metal sheet to form a brazing weld. The power ratio of the main beam to the auxiliary beam is 3: 2. simultaneously adjusting the radius ratio R of two light spots₁/R₂Is that 2: 1, width d of high-entropy alloy metal sheet₂1mm, adopting double-beam simultaneous laser welding to reserve a distance d between two light spots₁，d₁Is 0.25 mm. Width d of high-entropy alloy sheet metal₂When the thickness is 0.3mm, double-beam time-sharing laser welding is adopted, and a distance d does not need to be reserved between two light spots₁，d₁0mm, but ensuring that the round main beam spot is in a state of being separated from the interface of the aluminum alloy plate/the high-entropy alloy metal sheet.

(4) Setting welding process parameters: adjusting the defocusing amount of the laser beam to be-5 mm to +5mm, and preferably setting the defocusing amount of the laser beam to be-3 mm. The phenomenon that the joint is not welded through or burnt through is avoided as much as possible. Adjusting the welding speed to be 2 mm/min-10 mm/min, and preferably setting the welding speed at 10 mm/min. The used gas is high-purity argon during welding, and argon with the purity of 99.99 percent is introduced to the upper surface and the lower surface of the welding seam for protection. And adjusting the flow of argon, adjusting the flow of the upper surface protective gas to be 5-15L/min, and preferably setting the flow of the upper surface argon at 10L/min. The upper surface air flow is not easily too large to affect the heat input of the laser beam. The gas flow of the surface protective gas is adjusted to be 5L/min-20L/min. Preferably, the flow rate of argon gas for the lower surface is set at 15L/min. The air flow of the lower surface can be slightly larger, so that the air can be smoothly overflowed from the air holes in the clamp.

The invention adopts a double-beam laser welding method to effectively control the temperature field distribution; the Fe/Al-based high-entropy alloy metal sheet is taken as the intermediate layer, so that the formation of Fe-Al intermetallic compounds can be inhibited: during welding, the elements in the welding seam are diffused mutually, so that the high entropy effect of the welding seam is increased. The high entropy effect can effectively inhibit the generation of a large amount of brittle Fe-Al intermetallic compounds. The Fe-Al-based high-entropy alloy metal sheet is used as the intermediate layer, and elements in the base metal are prevented from being diffused into a weld joint in a large amount, so that the generation of intermetallic compounds is further controlled. Meanwhile, the high-entropy alloy has a slow diffusion effect, further inhibits the diffusion of elements in the base metal, reduces the generation amount of intermetallic compounds, and further influences the mechanical property of the weldment.

The above description is only a preferred example of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like of the present invention shall be included in the protection scope of the present invention.