CN114713964A - Magnetic field and current-assisted ultrasonic solid-phase connection method of aluminum and magnesium - Google Patents

Abstract

The invention relates to the technical field of welding dissimilar metal materials, in particular to a magnetic field and current-assisted aluminum-magnesium ultrasonic solid-phase connection method capable of effectively improving the welding performance of aluminum-magnesium dissimilar metals. After the magnesium-based material is assembled and fixed, the ultrasonic seam welding connection is completed with the assistance of current and magnetic field, wherein the current is applied to the material to be welded by the positive electrode roller and the negative electrode roller located on the same side of the ultrasonic seam welding mold. The magnetic field is a constant magnetic field with an intensity range of 2-50mt. The present invention affects the diffusion or reaction process of interface atoms through the action of current and magnetic field, and finally realizes the regulation of heterogeneous interface structure and improves the welding mechanical properties of aluminum/magnesium dissimilar metal joints.

Description

Magnetic field and current-assisted ultrasonic solid-phase connection method of aluminum and magnesium

Technical field:

The invention relates to the technical field of dissimilar metal material welding, in particular to a magnetic field and current-assisted aluminum-magnesium ultrasonic solid-phase connection method capable of effectively improving the welding performance of aluminum-magnesium dissimilar metals.

Background technique:

With the increasingly prominent global environmental problems, energy conservation and emission reduction has become a hot issue that countries all over the world are concerned about. According to statistics, vehicles, trains, ships and other means of transportation are the main sources of global greenhouse gas emissions. Taking a car as an example, every 100kg reduction in the overall weight of the vehicle can reduce fuel consumption by 0.6L and CO2 emissions by 500g per 100 kilometers. At the same time, reducing the weight of the car can significantly improve the handling, acceleration and braking performance of the car. Therefore, all countries in the world regard the lightweight design and manufacture of vehicles as the key direction of the development of the automobile industry, and the use of lightweight metal materials to replace the traditional steel structure has become one of the most effective ways to reduce the weight of automobiles.

Because the density of aluminum is only one-third of that of steel, and has good corrosion resistance; while the density of magnesium is two-thirds of that of aluminum, and it has the characteristics of low density, high specific strength, and good shock absorption performance. The lightest metal engineering structural material available. Therefore, the use of aluminum and magnesium alloy conforming components can further realize the lightweight of the automobile structure, and make full use of the respective advantages of aluminum and magnesium alloys. According to the forecast of the US Department of Energy, by 2035, the consumption of aluminum/magnesium alloys and composite materials in automobile body materials will account for more than 50%. However, due to the large differences in the mutual solubility, melting point and linear expansion coefficient of magnesium and aluminum, both of them are prone to form dense oxide films. The conventional fusion welding method is easy to form defects such as cracks and pores at the joints, and at the same time generate a large number of brittle Mg-Al intermetallic compounds, which makes the welding between the two difficult to achieve. In addition, due to the low shear strength of aluminum and magnesium brazed diffusion welded joints and the need for a vacuum environment, they cannot meet the needs of large-scale industrial production.

Due to the low temperature of the welding process, solid-phase joining technologies such as ultrasonic welding and friction stir welding can effectively inhibit the formation of brittle intermetallic compounds between dissimilar materials of aluminum and magnesium, thereby significantly improving the mechanical connection strength of aluminum/magnesium welded joints. / Research hotspots of magnesium welding. However, the friction stir welding method has high requirements on material specifications and assembly conditions, and is greatly limited by the welding space; in addition, the ultrasonic welding method is limited by the performance of power devices such as piezoelectric ceramics, and the current ultrasonic output power is generally difficult to exceed 10kW. , and the price of high-power ultrasonic equipment increases, the above reasons greatly limit the industrial-scale production and application of the above two methods.

Invention content:

Aiming at the shortcomings and deficiencies in the prior art, the present invention proposes a magnetic field and current-assisted ultrasonic solid-phase connection method for aluminum and magnesium, which can effectively improve the welding performance of aluminum and magnesium dissimilar metals.

The present invention achieves through the following measures:

A magnetic field and current assisted aluminum-magnesium ultrasonic solid-phase connection method, characterized in that, after the aluminum-based material to be welded and the magnesium-based material are assembled and fixed, ultrasonic seam welding is completed under the assistance of current and magnetic field. The current is applied to the material to be welded by the positive electrode roller and the negative electrode roller located on the same side of the ultrasonic seam welding die, and the magnetic field is a constant magnetic field with an intensity range of 2-50mt.

In the present invention, the ultrasonic energy field, the resistance thermal field under the action of the current, and the constant magnetic field all act on the welding interface between the aluminum material and the magnesium material from the side of the aluminum material. The material is magnesium or magnesium alloy.

The present invention also includes arranging a coating layer on the surface layer of the magnesium-based material to be welded to effectively suppress the direct reaction of the aluminum-magnesium interface, and the coating layer adopts a zinc-plated layer or a tin-plated layer.

The thickness of the aluminum-based material and the magnesium-based material in the present invention is not more than 2 mm.

In the present invention, while the aluminum and magnesium dissimilar metals are ultrasonically connected in solid phase, the positive and negative electrode guide wheels are used to apply current on the aluminum side to generate internal Joule heat, and the plastic deformation ability of the aluminum side is enhanced under the action of heat, which is beneficial to the ultrasonic energy from upward. while reducing the need for ultrasonic energy during aluminum/magnesium welding. In addition, the direct reaction of the aluminum-magnesium interface can be effectively suppressed by prefabricating the coating on the magnesium side (the third metal with low melting point), and the formation of intermetallic compounds at the interface can be significantly reduced; The interaction of the magnetic field and the interfacial atoms affects the diffusion or reaction process of the interface atoms, and finally realizes the regulation of the heterogeneous interface structure and improves the welding mechanical properties of the aluminum/magnesium dissimilar metal joint.

Description of drawings:

FIG. 1 is a schematic diagram of an embodiment of the present invention.

Accompanying drawing 2 is the test result graph of aluminum/magnesium tensile test in the present invention.

Reference numerals: positive electrode roller 1 , ultrasonic seam welding die 2 , magnetic field 3 , negative electrode roller 4 , aluminum alloy plate 5 , magnesium alloy plate 6 , welding platform 7 , coating 8 .

Detailed ways:

The invention proposes a magnetic field and current-assisted aluminum-magnesium ultrasonic solid-phase connection method. During the ultrasonic solid-phase connection of aluminum-magnesium dissimilar metals, positive and negative electrode guide wheels are used to apply current on the aluminum side to generate internal resistance heat, thereby generating internal resistance heat. Under the action of heat, the plastic deformation ability of the aluminum side is enhanced, which is conducive to the conduction of ultrasonic energy from top to bottom. In addition, the direct reaction of the aluminum-magnesium interface can be effectively suppressed by prefabricating the coating on the magnesium side (the third metal with low melting point), and the formation of intermetallic compounds at the interface can be significantly reduced; The effect affects the diffusion or reaction process of the interface atoms, and finally achieves the purpose of regulating the structure of the heterogeneous interface; among them, the ultrasonic energy field, the current resistance thermal field and the magnetic field are cooperatively coupled during the connection process of the aluminum-magnesium dissimilar metals, and work together with the aluminum-magnesium interface; The set temperature range of the aluminum side material is 50-300 ℃; the prefabricated coating is zinc, tin and other low melting point metals;

The transverse magnetic field is a constant magnetic field, and its set strength range is 2-50mt.

The positive and negative electrode guide wheels are made of brass, the width of the guide wheels is 20mm, and the diameter of the guide wheels is not more than 50mm.

The aluminum side material is pure aluminum and aluminum alloy, and the thickness of the aluminum and magnesium materials is not more than 2mm.

Example 1

First, the aluminum alloy plate 5 and the magnesium alloy plate 6 are fixed and assembled on the welding platform 7 according to the structure of the drawings; wherein the magnesium alloy plate surface coating 8 is prepared by surface modification methods such as electrochemical and cold spraying; The positive electrode roller 1 and the negative electrode roller 3 of the negative end are placed on the upper surface of the aluminum alloy plate 5, and the ultrasonic seam welding die 2 is placed between the positive electrode roller 1 and the negative electrode roller 3 and rolls in the direction shown in the figure; The seam welding die 2, the positive electrode roller 1 and the negative electrode roller 3 apply constant pressure to ensure the effective transmission of current and ultrasonic energy; the flat magnetic field 3 and the current action area coincide with the ultrasonic energy action area to realize the coupling of multi-energy fields. Through the above technical features, the high-efficiency and high-quality connection of aluminum-magnesium dissimilar metal materials can be realized. After the tensile test, the aluminum/magnesium welded joint is broken in the base metal area on the magnesium side.

In the present invention, while the aluminum and magnesium dissimilar metals are ultrasonically connected in solid phase, the positive and negative electrode guide wheels are used to apply current on the aluminum side to generate internal Joule heat, and the plastic deformation ability of the aluminum side is enhanced under the action of heat, which is beneficial to the ultrasonic energy from upward. while reducing the need for ultrasonic energy during aluminum/magnesium welding. In addition, the direct reaction of the aluminum-magnesium interface can be effectively suppressed by prefabricating the coating on the magnesium side (the third metal with low melting point), and the formation of intermetallic compounds at the interface can be significantly reduced; The interaction of the magnetic field and the interfacial atoms affects the diffusion or reaction process of the interface atoms, and finally realizes the regulation of the heterogeneous interface structure and improves the welding mechanical properties of the aluminum/magnesium dissimilar metal joint.

Claims (4)

1. a magnetic field and current-assisted aluminum-magnesium ultrasonic solid-phase connection method, it is characterized in that, after the aluminum-based material to be welded and the magnesium-based material are assembled and fixed, the ultrasonic seam welding is completed under the assistance of current and magnetic field to be connected as a whole, wherein The current is applied to the material to be welded by the positive electrode roller and the negative electrode roller located on the same side of the ultrasonic seam welding die, and the magnetic field is a constant magnetic field with an intensity range of 2-50mt. 2. a kind of magnetic field and current-assisted aluminum-magnesium ultrasonic solid-phase connection method according to claim 1, is characterized in that, the resistance thermal field under the action of ultrasonic energy field, electric current and constant magnetic field are all acted on by aluminum material side to On the welding interface between the aluminum-based material and the magnesium-based material, the aluminum-based material is aluminum or an aluminum alloy, and the magnesium-based material is magnesium or a magnesium alloy. 3. a kind of magnetic field and current-assisted aluminum-magnesium ultrasonic solid-phase connection method according to claim 1, is characterized in that, also comprises in the to-be-welded surface layer of magnesium-based material that coating is arranged to effectively suppress the direct reaction of aluminum-magnesium interface, The plating layer adopts zinc plating layer or tin plating layer. 4. A magnetic field and current-assisted aluminum-magnesium ultrasonic solid-phase connection method according to claim 1, wherein the thickness of the aluminum-based material and the magnesium-based material is not greater than 2 mm.

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