阅读说明：本技术 一种镁/镁合金与铝/铝合金的焊接方法 (Welding method of magnesium/magnesium alloy and aluminum/aluminum alloy ) 是由 潘厚宏 陈刚 郭阳阳 王鸿 谭天宝 于 2021-10-09 设计创作，主要内容包括：本发明提供了一种镁/镁合金与铝/铝合金的焊接方法,其特征在于,将镁/镁合金、铝/铝合金、纯锡和纯锌材料经研磨、抛光、超声清洗后吹干,然后将上述材料依次按照镁/镁合金、纯锌、纯锡和铝/铝合金的顺序进行装配固定,然后分阶段升温进行真空扩散焊接,制得。该方法可有效解决现有的焊接方法存在的二次焊接过程操作繁琐、焊接效率低的问题。(The invention provides a welding method of magnesium/magnesium alloy and aluminum/aluminum alloy, which is characterized in that magnesium/magnesium alloy, aluminum/aluminum alloy, pure tin and pure zinc materials are ground, polished, ultrasonically cleaned and dried, then the materials are sequentially assembled and fixed according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, and then the materials are heated by stages for vacuum diffusion welding to obtain the magnesium/magnesium alloy and aluminum/aluminum alloy. The method can effectively solve the problems of complex operation and low welding efficiency of the secondary welding process in the existing welding method.)

1. A welding method of magnesium/magnesium alloy and aluminum/aluminum alloy is characterized in that magnesium alloy, aluminum alloy, pure tin and pure zinc are ground, polished, ultrasonically cleaned and dried in sequence, then the materials are assembled and fixed in sequence according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, and then the materials are heated in stages for vacuum diffusion welding to obtain the magnesium/magnesium alloy and aluminum/aluminum alloy.

2. The method for welding magnesium/magnesium alloy and aluminum/aluminum alloy according to claim 1, wherein the vacuum diffusion welding is performed by the following specific operation process: under the vacuum condition, firstly keeping the temperature for 2-120min under the conditions of 200-225 ℃ and the induction pressure of 3-6MPa, then heating to 330-338 ℃, keeping the temperature for 1-4h under the pressure of 2-6MPa, then cooling to below 150 ℃ along with the furnace, and stopping vacuumizing.

3. A method for welding magnesium alloy and aluminum alloy as recited in claim 2, wherein the temperature is raised to 200 ℃ at a rate of 15-30 ℃/min for the first time and maintained for 2-120 min.

4. The method for bonding Mg/Mg alloy and Al/Al alloy as claimed in claim 2, wherein the temperature is raised to 338 ℃ at a rate of 15-30 ℃/min after the tin-zinc eutectic reaction is induced at 225 ℃ and 200 ℃.

5. The method for welding magnesium/magnesium alloy and aluminum/aluminum alloy as set forth in claim 2, wherein the temperature is raised to 335 ℃ at a rate of 15 ℃/min.

6. The method for welding magnesium/magnesium alloy and aluminum/aluminum alloy as recited in claim 2, wherein the welding pressure is constant and the pressure is maintained at 4MPa during the welding.

7. The method of welding a magnesium/magnesium alloy to an aluminum/aluminum alloy of claim 1, wherein the magnesium alloy is type AZ31 and the aluminum alloy is type 5083.

Technical Field

The invention belongs to the field of metal materials, and particularly relates to a welding method of magnesium/magnesium alloy and aluminum/aluminum alloy.

Background

Currently, friction stir welding, explosion welding, resistance welding, arc welding, brazing, and diffusion welding are commonly used for metallurgical bonding of dissimilar materials of magnesium/aluminum. Magnesium and aluminum have significant differences in physical properties such as lattice structure, thermal expansion coefficient and the like, so that aluminum/magnesium dissimilar materials are easy to generate residual stress and Mg-Al intermetallic compounds with high brittleness and strong crack sensitivity in the direct contact welding process.

The diffusion welding is a method which is easy to accurately control welding parameters, can effectively avoid the defects of cracks, deformation, segregation and the like generated by fusion welding, and has the structure and performance which are more similar to those of welding parent metal, thereby obtaining a good connection interface. In the prior art, the diffusion welding between magnesium/magnesium alloy and aluminum/aluminum alloy is realized, and when pure zinc is adopted as an interlayer material, the specific operation process is as follows: the pure zinc and the aluminum alloy are firstly subjected to diffusion welding at a higher temperature, and then the diffusion welding of the pure zinc and the magnesium alloy is realized at a lower temperature, two welding processes are required in the processes, the operation is more complicated, and the welding efficiency is lower. If only one-time diffusion welding operation is adopted at a higher temperature, eutectic reaction is generated between magnesium and zinc in a high-temperature environment to form a magnesium-zinc eutectic liquid phase, so that a zinc layer disappears, and the aim of isolating the mutual diffusion effect of magnesium atoms and aluminum atoms by a pure zinc intermediate layer cannot be fulfilled.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a diffusion welding method of magnesium/magnesium alloy and aluminum/aluminum alloy, which can effectively solve the problems of complex operation and low welding efficiency of the secondary welding process in the existing diffusion welding method.

In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problems is as follows:

a welding method of magnesium/magnesium alloy and aluminum/aluminum alloy comprises the steps of sequentially grinding, polishing, ultrasonically cleaning and drying magnesium alloy, aluminum alloy, pure tin and pure zinc materials, sequentially assembling and fixing the materials according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, and then heating in stages for vacuum diffusion welding to obtain the magnesium/magnesium alloy and aluminum/aluminum alloy.

In the scheme, pure tin and pure zinc are simultaneously used as the intermediate layers, because the eutectic point of tin and zinc is lower than the eutectic point of zinc, magnesium alloy and aluminum alloy, tin and zinc firstly take eutectic reaction to form a tin-zinc eutectic liquid phase substance, the formed tin-zinc eutectic liquid phase can only keep thinner thickness under the action of induced pressure in the lower-temperature vacuum diffusion process, and the surplus tin-zinc eutectic liquid phase is extruded out of a connecting interface by the induced pressure, therefore, the extrusion quantity of the tin-zinc eutectic liquid phase can be controlled by the duration time of the eutectic reaction, the thickness of a pure zinc isolation layer is adjusted, when the temperature is continuously raised, the surplus pure tin layer is completely melted into liquid extrusion, the pure zinc and the aluminum/aluminum alloy are connected by instant liquid phase diffusion welding by the aid of a mixture of the tin-zinc eutectic liquid phase and the pure tin liquid phase existing in the interface at the same diffusion welding temperature, and the magnesium/magnesium alloy and the pure zinc are connected by solid phase diffusion welding, therefore, the magnesium/magnesium alloy and the aluminum/aluminum alloy are welded into a whole, the process is a one-step welding process, the welding efficiency is greatly improved, and the complexity of operation is reduced.

Further, the specific operation process of the vacuum diffusion welding is as follows: under the vacuum condition, firstly keeping the temperature for 2-120min under the conditions of 200-225 ℃ and the induction pressure of 3-6MPa, then heating to 330-338 ℃, keeping the temperature for 1-4h under the welding pressure of 2-6MPa, then cooling to below 150 ℃ along with the furnace, and stopping vacuumizing.

Further, the temperature is increased to 200 ℃ at the speed of 15-30 ℃/min for the first time, and the temperature is kept for 2-120 min.

Further, after the reaction is induced at 200-225 ℃, the temperature is raised to 335 ℃ at a speed of 15-30 ℃/min.

Further, the induction pressure and the welding pressure in the welding process are constant pressures, and the pressure is kept at 4 MPa.

Further, the magnesium alloy was AZ31 type, and the aluminum alloy was 5083 type.

The beneficial effects produced by the invention are as follows:

in the application, pure zinc and pure tin are used as intermediate layers, because the eutectic point of tin and zinc is lower than the eutectic point of zinc, magnesium alloy and aluminum alloy, tin and zinc firstly generate eutectic reaction in the vacuum diffusion process at lower temperature to form a tin-zinc eutectic liquid phase substance, the formed eutectic liquid phase can only keep thinner thickness due to the action of induced pressure in the induction process, and the redundant eutectic liquid phase is extruded out of a connection interface by the induced pressure, therefore, the extrusion amount of the eutectic liquid phase can be controlled by the duration time of the eutectic reaction, the thickness of a pure zinc isolation layer is adjusted, when the temperature is continuously raised, the residual pure tin layer is completely melted into liquid extrusion, the pure zinc and the aluminum/aluminum alloy are connected by instantaneous liquid phase diffusion welding by means of the mixture of the tin-zinc eutectic liquid phase and the pure tin liquid phase existing in the interface at the diffusion welding temperature, and the magnesium/magnesium alloy and the pure zinc are connected by solid phase diffusion welding, the magnesium/magnesium alloy and the aluminum/aluminum alloy are welded into a whole, the process is a one-step welding process, the welding efficiency is greatly improved, and the complexity of operation is reduced.

In this application, weld under the temperature condition that is less than 338 ℃ whole journey, among the welding process, because there is remaining pure zinc layer, prevented magnalium's direct contact diffusion, consequently, can not produce magnalium intermetallic compound after the welding, can obviously improve the performance of joint.

In the application, the thickness of the pure zinc intermediate layer between the magnesium/magnesium alloy and the aluminum/aluminum alloy can be adjusted by adjusting the heat preservation time at 200-225 ℃ according to the requirement of personalized production so as to meet the requirement of production; the longer the holding time, the thinner the thickness of the pure zinc intermediate layer.

Drawings

FIG. 1 is a diagram of a welding process route and assembly of the present invention;

FIG. 2 is a diagram of a weld joint formation mechanism of the present invention;

FIG. 3 is an SEM and EDS of a weld in example 1;

FIG. 4 is an SEM and EDS of a weld in example 2;

FIG. 5 is an SEM and EDS picture of a weld in example 3;

FIG. 6 is an SEM and EDS picture of a weld in example 4;

FIG. 7 is an SEM and EDS of the weld in example 5.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

Example 1

A welding method of magnesium/magnesium alloy and aluminum/aluminum alloy comprises the steps of sequentially grinding, polishing, ultrasonically cleaning and drying magnesium/magnesium alloy, aluminum/aluminum alloy, pure tin and pure zinc, then sequentially assembling and fixing the materials according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, wherein the model of the aluminum alloy is 5083, the model of the magnesium alloy is AZ31, then raising the temperature by stages to perform vacuum diffusion welding, and the specific operation process of vacuum diffusion is as follows: under the vacuum condition, firstly heating to 200 ℃ at the speed of 15 ℃/min, preserving heat for 2min under the condition of constant pressure with the induction pressure of 4MPa, then heating to 335 ℃ at the speed of 15 ℃/min, preserving heat for 2h under the constant welding pressure of 4MPa, then cooling to below 150 ℃, and stopping vacuumizing to obtain the high-strength high-toughness steel.

Example 2

A welding method of magnesium/magnesium alloy and aluminum/aluminum alloy is characterized in that magnesium/magnesium alloy, aluminum/aluminum alloy, pure tin and pure zinc are ground, polished, ultrasonically cleaned and dried in sequence, then the materials are assembled and fixed in sequence according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, wherein the model of the aluminum alloy is 5083, the model of the magnesium alloy is AZ31, then the temperature is raised in stages for vacuum diffusion welding, and the specific operation process of vacuum diffusion is as follows: under the vacuum condition, firstly heating to 200 ℃ at the speed of 20 ℃/min, preserving heat for 30min under the condition of constant pressure with the induction pressure of 4MPa, then heating to 335 ℃ at the speed of 15 ℃/min, preserving heat for 2h under the constant welding pressure of 4MPa, then cooling to below 150 ℃, and stopping vacuumizing to obtain the high-strength high-toughness steel.

Example 3

A welding method of magnesium/magnesium alloy and aluminum/aluminum alloy comprises the steps of sequentially grinding, polishing, ultrasonically cleaning and drying magnesium/magnesium alloy, aluminum/aluminum alloy, pure tin and pure zinc, then sequentially assembling and fixing the materials according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, wherein the model of the aluminum alloy is 5083, the model of the magnesium alloy is AZ31, then raising the temperature by stages to perform vacuum diffusion welding, and the specific operation process of vacuum diffusion is as follows: under the vacuum condition, firstly heating to 200 ℃ at the speed of 15 ℃/min, preserving heat for 90min under the condition of constant pressure with the induction pressure of 4MPa, then heating to 335 ℃ at the speed of 15 ℃/min, preserving heat for 2h under the constant welding pressure of 4MPa, then cooling to below 150 ℃, and stopping vacuumizing to obtain the high-strength high-toughness steel.

Example 4

A welding method of magnesium/magnesium alloy and aluminum/aluminum alloy comprises the steps of sequentially grinding, polishing, ultrasonically cleaning and drying magnesium/magnesium alloy, aluminum/aluminum alloy, pure tin and pure zinc, then sequentially assembling and fixing the materials according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, wherein the model of the aluminum alloy is 5083, the model of the magnesium alloy is AZ31, then raising the temperature by stages to perform vacuum diffusion welding, and the specific operation process of vacuum diffusion is as follows: under the vacuum condition, firstly heating to 200 ℃ at the speed of 20 ℃/min, preserving heat for 30min under the condition of constant pressure with the induction pressure of 4MPa, then heating to 335 ℃ at the speed of 20 ℃/min, preserving heat for 3h under the welding pressure of 4MPa, then cooling to below 150 ℃, and stopping vacuumizing to obtain the material.

Example 5

A welding method of magnesium/magnesium alloy and aluminum/aluminum alloy comprises the steps of sequentially grinding, polishing, ultrasonically cleaning and drying magnesium/magnesium alloy, aluminum/aluminum alloy, pure tin and pure zinc, then sequentially assembling and fixing the materials according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, wherein the model of the aluminum alloy is 5083, the model of the magnesium alloy is AZ31, then raising the temperature by stages to perform vacuum diffusion welding, and the specific operation process of vacuum diffusion is as follows: under the vacuum condition, firstly heating to 200 ℃ at the speed of 30 ℃/min, preserving heat for 30min under the condition of constant pressure with the induction pressure of 4MPa, then heating to 335 ℃ at the speed of 30 ℃/min, preserving heat for 4h under the constant welding pressure of 4MPa, then cooling to below 150 ℃, and stopping vacuumizing to obtain the high-strength high-toughness steel.

Example 6

A welding method of magnesium/magnesium alloy and aluminum/aluminum alloy comprises the steps of sequentially grinding, polishing, ultrasonically cleaning and drying magnesium/magnesium alloy, aluminum/aluminum alloy, pure tin and pure zinc, then sequentially assembling and fixing the materials according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, wherein the model of the aluminum alloy is 5083, the model of the magnesium alloy is AZ31, then raising the temperature by stages to perform vacuum diffusion welding, and the specific operation process of vacuum diffusion is as follows: under the vacuum condition, firstly heating to 220 ℃ at the speed of 15 ℃/min, preserving heat for 7min under the condition of constant pressure with the induction pressure of 6MPa, then heating to 338 ℃ at the speed of 15 ℃/min, preserving heat for 1h under the constant welding pressure of 4MPa, then cooling to below 150 ℃, and stopping vacuumizing to obtain the high-strength high-toughness steel.

Example 7

A welding method of magnesium/magnesium alloy and aluminum/aluminum alloy comprises the steps of sequentially grinding, polishing, ultrasonically cleaning and drying magnesium/magnesium alloy, aluminum/aluminum alloy, pure tin and pure zinc, then sequentially assembling and fixing the materials according to the sequence of magnesium/magnesium alloy, pure zinc, pure tin and aluminum/aluminum alloy, wherein the model of the aluminum alloy is 5083, the model of the magnesium alloy is AZ31, then raising the temperature by stages to perform vacuum diffusion welding, and the specific operation process of vacuum diffusion is as follows: under the vacuum condition, firstly heating to 210 ℃ at the speed of 15 ℃/min, preserving heat for 120min under the condition of constant pressure with the induction pressure of 3MPa, then heating to 330 ℃ at the speed of 15 ℃/min, preserving heat for 4h under the constant welding pressure of 4MPa, then cooling to below 150 ℃, and stopping vacuumizing to obtain the high-temperature-resistant high-power-point-resistant welding wire.

Comparative example 1

A welding method of magnesium/magnesium alloy and aluminum/aluminum alloy comprises the steps of sequentially grinding, polishing, ultrasonically cleaning and drying magnesium/magnesium alloy, aluminum/aluminum alloy and pure zinc material, sequentially assembling and fixing the materials according to the sequence of the magnesium/magnesium alloy, the pure zinc and the aluminum/aluminum alloy, wherein the model of the aluminum alloy is 5083, the model of the magnesium alloy is AZ31, heating to 335 ℃ at the speed of 15 ℃/min under the vacuum condition, keeping the temperature for 2 hours under the welding pressure of 4MPa, cooling to below 150 ℃, and stopping vacuumizing to obtain the magnesium/magnesium alloy and aluminum/aluminum alloy.

Test examples

Cutting the welded joint prepared in the embodiments 1-5 into a sample along the vertical direction of the joint welding line by using a wire cutting machine, grinding, polishing, ultrasonically cleaning, and then immediately drying, corroding and diffusing the cross section of the welded joint by using a mixed solution of 10ml of acetic acid, 100ml of ethanol, 10ml of distilled water and 4.2g of picric acid, and detecting the composition of a reaction layer, the microstructure and distribution of each main chemical element near the diffusion region of the welded joint and local chemical elements by using a scanning electron microscope under the voltage of 15kV after corroding for 3 s; the maximum shear strength was measured by subjecting the weld parts of examples 1 to 7 and comparative example 1 to a shear strength test at a shear rate of 0.25mm/min using a MTS-CMT5105 universal tester. The specific results of the above experimental tests are shown in the attached drawings and table 1.

Table 1: strength test data of welded parts

	Maximum shear strength
		Example 1	5MPa
Example 2	7MPa
		Example 3	17MPa
Example 4	18MPa
		Example 5	13MPa
Example 6	5MPa
		Example 7	4MPa
Comparative example 1	/

As can be seen from the data in the above table, the weld parts in examples 1 to 7 all achieve effective connection of the weld joint, and in comparative example 1, since the vacuum diffusion welding temperature is much lower than the eutectic temperature of the aluminum zinc side, the aluminum zinc atoms are not sufficiently diffused, so that reliable connection of the aluminum zinc side cannot be achieved.

Figure 2 shows the formation of a diffusion bonded joint of AZ31 magnesium alloy and 5083 aluminum alloy using a pure zinc/pure tin composite interlayer. The eutectic reaction temperature of tin and zinc is lower than that of zinc, magnesium alloy and aluminum alloy, during vacuum diffusion at lower temperature, tin and zinc are subjected to eutectic reaction first to form a tin-zinc eutectic liquid phase substance, when the temperature is continuously raised, the residual pure tin layer is completely melted into a liquid state and then is partially extruded under the action of induced pressure, and the mixed liquid phase of the residual tin-zinc eutectic and the pure tin induces low-temperature diffusion connection of aluminum/aluminum alloy and pure zinc. At the diffusion welding temperature, pure zinc and aluminum/aluminum alloy are connected by instant liquid phase diffusion welding by virtue of a liquid phase mixture of tin-zinc eutectic and pure tin existing in an interface, and magnesium/magnesium alloy and pure zinc are connected by solid phase diffusion welding, so that magnesium/magnesium alloy and aluminum/aluminum alloy are welded into a whole.

The SEM results of figure 3 show that the joint connection is good, the obvious layered structure exists at the welding seam interface, and a bright 'net' structure is found in the aluminum alloy base material. The diffusion reaction layer is divided according to the concentration distribution condition of the elements of magnesium, aluminum, tin and zinc swept by EDS lines on the interface, the joint diffusion interface diffusion layer can be divided into a region I, a region II, a region III and a region IV, and the EDS result at the interface shows that the pure zinc layer effectively blocks the mutual diffusion of aluminum and magnesium atoms.

EDS line scanning and point scanning are carried out on the joint in the embodiment 2, and the results of the point scanning are shown in a table 2;

table 2: dot scan data for joints in example 2

The results in fig. 4 and table 2 show that the diffusion interface can be divided into five regions: combining the results of the areas I, II, III, IV and V in the table 2 and EDS point analysis shows that the areas I and II near the AZ31 magnesium alloy are respectively MgZn generated by eutectic reaction of magnesium alloy and pure zinc₂、Mg₂Zn₁₁. EDS line scans and point 3 show that region iii has a stable composition and that the proportion of zinc atoms is 96.05 at.%, which is determined to be a residual pure zinc layer. In the IV area, the aluminum, magnesium, zinc and tin atom ratios are respectively 0.1 at.%, 54.7 at.%, 45.1 at.% and 0.1 at.%, and the area is possible to be Al-Zn eutectic by combining the phase diagram of the aluminum-zinc binary alloy. The EDS line scan and point 5 results indicate that zone V is primarily Al (Zn) solid solution. The aluminum, magnesium, zinc and tin atom ratios of the EDS point 6 are 1 at.%, 65.2 at.%, 12.2 at.% and 21.6 at.%, respectively, which indicates that a bright "network" structure of Al (Sn, Zn) solid solution is found in the aluminum alloy base material.

The results of fig. 3, 4 and 5 show that when the temperature reaches the tin-zinc eutectic reaction temperature, the tin-zinc eutectic reaction consumes the thickness of the pure zinc layer and extrudes part of the liquid phase zinc-tin eutectic under the induced pressure. With the prolonging of the tin-zinc eutectic reaction time, the residual thickness of the pure zinc layer is obviously reduced, and the thickness of other diffusion layers and reaction products are not changed.

SEM and EDS line scans in figure 6 show that the joint connection is good, the I area, the II area and the V area formed on the magnesium-zinc interface are gradually widened along with the extension of the diffusion time to 3h, the pure zinc layer is consumed by the reaction of the pure zinc layer and magnesium alloy, the III area of the middle layer is gradually thinned, and the IV area has no obvious change.

The comparative analysis of fig. 4, 6 and 7 shows that the diffusion layer thickness of the joint gradually becomes thicker and the pure zinc layer becomes thinner as the diffusion time is longer. In the performance of the joint, the shear strength tends to increase firstly and then decrease, because the pure zinc intermediate layer with low strength is thicker and has lower shear strength value when the welding heat preservation is carried out for 2 hours. When the welding heat preservation is carried out for 3 hours, the thickness of the pure zinc layer and the diffusion thickness of the joint are both proper, and the shearing strength is the maximum. However, when the welding holding time is 4 hours, the magnesium-zinc intermetallic compound layer becomes significantly thick, resulting in deterioration of joint properties.