阅读说明：本技术 一种强形变强压力辅助冷焊制备异种金属复合结构的方法 (Method for preparing dissimilar metal composite structure by strong deformation and strong pressure assisted cold welding ) 是由 万龙 刘景麟 黄体方 黄永宪 于 2020-12-31 设计创作，主要内容包括：本发明涉及冷焊制备异种金属复合结构,更具体的说是一种强形变强压力辅助冷焊制备异种金属复合结构的方法,一种强形变强压力辅助冷焊制备异种金属复合结构的方法,该方法包括以下步骤：步骤一：母材Ⅰ加工形成塑性表层Ⅰ；步骤二：母材Ⅱ加工形成塑性表层Ⅱ；步骤三：塑性表层Ⅰ和塑性表层Ⅱ进行冷焊；可以通过母材Ⅰ和母材Ⅱ表面材料在搅拌与剪切作用下会产生塑性表层Ⅰ和塑性表层Ⅱ；塑性变形致使金属内部形成远超过平衡浓度的过饱和空位,变形过程中产生的位错和空位为金属原子的快速扩散提供了通道；同时,形成的大量晶体缺陷,如位错和层错同样可以促进原子扩散,高密度的可动空位、应变势梯度和应力均促进扩散动力学过程。(The invention relates to a method for preparing a dissimilar metal composite structure by cold welding, in particular to a method for preparing a dissimilar metal composite structure by strong deformation and strong pressure assisted cold welding, which comprises the following steps: the method comprises the following steps: processing the base material I to form a plastic surface layer I; step two: processing the base metal II to form a plastic surface layer II; step three: cold welding the plastic surface layer I and the plastic surface layer II; the plastic surface layer I and the plastic surface layer II can be generated by the surface materials of the base material I and the base material II under the stirring and shearing actions; plastic deformation causes supersaturated vacancies far exceeding equilibrium concentration to be formed inside the metal, and dislocation and vacancies generated in the deformation process provide channels for rapid diffusion of metal atoms; meanwhile, a large number of formed crystal defects such as dislocation and stacking fault can promote atomic diffusion, and a diffusion kinetic process is promoted by high-density movable vacancies, strain potential gradient and stress.)

1. A method for preparing a dissimilar metal composite structure by strong deformation and strong pressure auxiliary cold welding is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: processing the surface of the base material I (1) to form a plastic surface layer I (4);

step two: processing the surface of the base material II (2) to form a plastic surface layer II (5);

step three: and (5) performing cold welding on the plastic surface layer I (4) and the plastic surface layer II (5).

2. The method for preparing the dissimilar metal composite structure by the cold welding with the assistance of strong deformation and strong pressure according to claim 1, is characterized in that: the method for processing the base material I (1) to form the plastic surface layer I (4) comprises the following steps:

the method comprises the following steps: polishing the surface of the base material I (1) to remove an oxide layer and oil stains;

step two: the processing tool (3) performs friction stir processing on the base material I (1) to form a plastic surface layer I (4).

3. The method for preparing the dissimilar metal composite structure by the cold welding with the assistance of strong deformation and strong pressure according to claim 2, is characterized in that: the step of processing the base material II (2) to form the plastic surface layer II (5) comprises the following steps:

the method comprises the following steps: polishing the surface of the base material II (2) to remove an oxide layer and oil stains;

step two: the processing tool (3) performs friction stir processing on the base material II (2) to form a plastic surface layer II (5).

4. The method for preparing the dissimilar metal composite structure by the cold welding with the assistance of strong deformation and strong pressure according to claim 3, is characterized in that: the processing tool (3) is a pin-free stirring head, a conical needle with a thread stirring head with a small length of the stirring needle, a three-milling-plane conical needle with a thread stirring head or a cylindrical needle stirring head.

5. The method for preparing the dissimilar metal composite structure by the cold welding with the assistance of strong deformation and strong pressure according to claim 3, is characterized in that: and the surfaces of the base material I (1) and the base material II (2) are polished by manual sand paper or by a grinding machine.

6. The method for preparing the dissimilar metal composite structure by the cold welding with the assistance of strong deformation and strong pressure according to claim 1, is characterized in that: the cold welding of the plastic surface layer I (4) and the plastic surface layer II (5) comprises the following steps:

the method comprises the following steps: the plastic surface layer I (4) and the plastic surface layer II (5) are machined, an oxidation layer, oil stains and a water adsorption layer on the surface are removed, and the surface is smooth and flat;

step two: opening a vacuum diffusion welding furnace, clamping a base material I (1) to be connected and a base material II (2) on a workbench, and contacting the surfaces of the plastic surface layer I (4) and the plastic surface layer II (5);

step three: closing the vacuum chamber, opening the vacuumizing system to form a vacuum environment (6), and starting the pressurizing system (7);

step four: and after the pressure maintaining is finished, unloading the pressure, opening the vacuum chamber, and taking out the dissimilar metal composite structural member.

7. The method for preparing the dissimilar metal composite structure by the cold welding with the strong deformation and the strong pressure assistance as claimed in claim 6, is characterized in that: rigid clamps (9) are adopted around the cold welding process of the base metal I (1) and the base metal II (2).

8. The method for preparing the dissimilar metal composite structure by the cold welding with the assistance of strong deformation and strong pressure according to claim 1, is characterized in that: the processing method for processing the base material I (1) to form the plastic surface layer I (4) comprises friction stir, rolling, shot blasting and magnetic pulse high-speed impact, and the processing method for processing the base material II (2) to form the plastic surface layer II (5) comprises friction stir, rolling, shot blasting and magnetic pulse high-speed impact.

9. The method for preparing the dissimilar metal composite structure by the cold welding with the assistance of strong deformation and strong pressure according to claim 1, is characterized in that: the base material I (1) and the base material II (2) are aluminum, magnesium, titanium, copper, iron, nickel, cobalt or alloys thereof.

Technical Field

The invention relates to a method for preparing a dissimilar metal composite structure by cold welding, in particular to a method for preparing a dissimilar metal composite structure by strong-deformation and strong-pressure auxiliary cold welding.

Background

Light metals such as aluminum alloys, magnesium alloys, and titanium alloys have been widely used in the aerospace field, wherein the connection between multiple metals is unavoidable. The connection of dissimilar metals can give full play to the advantages of the two metals to meet the requirements of different conditions on materials. The lightweight alloy is adopted to replace part of alloy with higher density, so that the lightweight structure design can be realized, the lightweight alloy can be widely applied to the fields of aerospace, transportation and ship manufacturing, and the energy consumption can be greatly reduced due to the lightweight alloy. In addition, on the premise of ensuring the performance of the structure, the material with lower cost can be adopted to replace part of metal with higher cost, so that the production cost can be greatly reduced. At present, the dissimilar metal composite structure is generally prepared by a mechanical connection or welding mode.

Mechanical connection methods such as riveting and bolting require prefabricated holes, destroy structural integrity, cause stress concentration, and greatly reduce fatigue life of the joint. In addition, bolts and rivets add weight to the structure, which is not conducive to lightweight designs.

Welding methods such as arc welding, laser, electron beam, etc. generate a large heat input, resulting in the generation of a large amount of intermetallic compounds in the joint, which seriously deteriorates the mechanical properties of the joint. The brazing connection interface is also easy to generate more intermetallic compounds, which are usually weak links in the joint and are easy to fail in service. Although the friction stir welding technology has the characteristic of low heat input, more intermetallic compounds are easily generated, and defects such as holes and the like are likely to be generated to influence the performance of the joint. In addition, a hook-like structure may occur in the friction stir lap joint, which may have a large influence on the structure of the joint. Due to the limitation of the process, the ultrasonic welding is difficult to realize the connection of the test pieces with large real-time areas and large thicknesses. The diffusion welding is used for preparing a dissimilar metal mixed structure, and the effective connection can be realized only by long heat preservation time due to the poor diffusion capacity of metal atoms at an interface. In addition, the linear expansion coefficients of different materials are different greatly, so that large stress concentration can be generated after connection, and even crack defects can be generated at welding seams; the disadvantages of the prior art are that the connection time cannot be effectively shortened, and the connection efficiency is improved.

Disclosure of Invention

The invention aims to provide a method for preparing a dissimilar metal composite structure by using strong-deformation and strong-pressure auxiliary cold welding, which can effectively shorten the connection time and improve the connection efficiency.

The purpose of the invention is realized by the following technical scheme:

a method for preparing a dissimilar metal composite structure by strong deformation and strong pressure auxiliary cold welding comprises the following steps:

the method comprises the following steps: processing the surface of the base material I to form a plastic surface layer I;

step two: processing the surface of the base metal II to form a plastic surface layer II;

step three: and cold welding the plastic surface layer I and the plastic surface layer II.

As further optimization of the technical scheme, the method for preparing the dissimilar metal composite structure by using the strong deformation and strong pressure assisted cold welding comprises the following steps of:

the method comprises the following steps: polishing the surface of the base material I to remove an oxide layer and oil stains;

step two: and the processing tool performs friction stir processing on the base material I to form a plastic surface layer I.

As further optimization of the technical scheme, the method for preparing the dissimilar metal composite structure by using the strong deformation and strong pressure assisted cold welding comprises the following steps of:

the method comprises the following steps: polishing the surface of the base material II to remove an oxide layer and oil stains;

step two: and the processing tool performs stirring friction processing on the base metal II to form a plastic surface layer II.

According to the method for preparing the dissimilar metal composite structure by using the strong deformation and strong pressure assisted cold welding, the processing tool is a pin-free stirring head, a conical needle threaded stirring head with a small stirring pin length, a three-milling-plane conical needle threaded stirring head or a cylindrical pin stirring head.

According to the method for preparing the dissimilar metal composite structure by using the strong-deformation and strong-pressure auxiliary cold welding, the surfaces of the base metal I and the base metal II are polished by manual sand paper or by a grinding machine.

As further optimization of the technical scheme, the method for preparing the dissimilar metal composite structure by using the strong deformation and strong pressure assisted cold welding comprises the following steps of:

the method comprises the following steps: the plastic surface layer I and the plastic surface layer II are machined, so that an oxide layer, oil stains and a water adsorption layer on the surface are removed, and the surface is smooth;

step two: opening the vacuum diffusion welding furnace, clamping a base material I to be connected and a base material II on a workbench, and contacting the surfaces of the plastic surface layer I and the plastic surface layer II;

step three: closing the vacuum chamber, opening the vacuumizing system to form a vacuum environment, and starting the pressurizing system;

step four: and after the pressure maintaining is finished, unloading the pressure, opening the vacuum chamber, and taking out the dissimilar metal composite structural member.

As further optimization of the technical scheme, the method for preparing the dissimilar metal composite structure by strong deformation and strong pressure assisted cold welding adopts rigid clamps around the cold welding process of the base metal I and the base metal II.

According to the method for preparing the dissimilar metal composite structure by the cold welding assisted by the strong deformation and the strong pressure, the processing method for forming the plastic surface layer I by processing the base metal I comprises the steps of stirring friction, rolling, shot blasting and magnetic pulse high-speed impact, and the processing method for forming the plastic surface layer II by processing the base metal II comprises the steps of stirring friction, rolling, shot blasting and magnetic pulse high-speed impact.

As further optimization of the technical scheme, the method for preparing the dissimilar metal composite structure by strong deformation and strong pressure auxiliary cold welding is characterized in that the base material I and the base material II are aluminum, magnesium, titanium, copper, iron, nickel, cobalt or alloys thereof.

The method for preparing the dissimilar metal composite structure by the cold welding with the assistance of strong deformation and strong pressure has the beneficial effects that:

the invention relates to a method for preparing a dissimilar metal composite structure by strong deformation and strong pressure auxiliary cold welding, which can generate a plastic surface layer I and a plastic surface layer II by surface materials of a base material I and a base material II under the stirring and shearing actions; plastic deformation causes supersaturated vacancies far exceeding equilibrium concentration to be formed inside the metal, and dislocation and vacancies generated in the deformation process provide channels for rapid diffusion of metal atoms; meanwhile, a large number of formed crystal defects such as dislocation and stacking fault can promote atomic diffusion, and a diffusion kinetic process is promoted by high-density movable vacancies, strain potential gradient and stress. Under the submicron grain size, the increase of the number of the grain boundaries and the increase of the volume fraction form a short-distance diffusion channel at the grain boundaries, the high-energy unbalanced deformation-state grain boundaries are favorable for diffusion, the grain boundary diffusion becomes a main diffusion mechanism, the diffusion efficiency is greatly improved, and the connection time is further shortened. The auxiliary action of the super-high pressure can provide enough energy for connection, eliminate the energy consumed by plastic deformation and have enough energy to meet the diffusion of metal atoms. Therefore, the existence of the plastic surface layer I and the plastic surface layer II can not only effectively increase the diffusion capacity of interface atoms, but also improve the production efficiency; in addition, the formation of intermetallic compounds can be effectively inhibited or even avoided by low-temperature welding, a heat affected zone cannot be generated in a cold welding joint, and the uniform structure is favorable for improving the mechanical property of the joint; the size of the metal composite structural part prepared by the method is not limited.

Drawings

The invention is described in further detail below with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a schematic structural view of a base material I of the present invention;

FIG. 2 is a schematic structural view of a base metal II according to the present invention;

FIG. 3 is a schematic diagram of the process of forming a plastic surface layer I by friction stir processing of a base material I according to the present invention;

FIG. 4 is a schematic structural view of a plastic surface layer II formed by stirring friction processing of a base metal II according to the present invention;

FIG. 5 is a schematic view of the cold welding process of the present invention.

In the figure: a base material I1; a base material II 2; a machining tool 3; a plastic surface layer I4; a plastic surface layer II 5; a vacuum environment 6; a strong pressure load 7; a backing plate 8; a rigid clamp 9.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

The first embodiment is as follows:

in the following, referring to fig. 1 to 5, the present embodiment is described, and a method for preparing a dissimilar metal composite structure by cold welding with strong deformation and strong pressure assistance comprises the following steps:

the method comprises the following steps: processing the surface of the base material I1 to form a plastic surface layer I4;

step two: processing the surface of the base metal II 2 to form a plastic surface layer II 5;

step three: and performing cold welding on the plastic surface layer I4 and the plastic surface layer II 5.

The second embodiment is as follows:

in the following description of the present embodiment with reference to fig. 1 to 5, the step of forming the plastic skin layer i 4 by processing the base material i 1 is as follows:

the method comprises the following steps: polishing the surface of the base material I1 to remove an oxide layer and oil stains;

step two: the processing tool 3 carries out stirring friction processing on the base material I1 to form a plastic surface layer I4; the prepared plastic surface layer I4 has stronger plasticity and smaller grain size, and is favorable for eliminating gaps between interfaces under the action of strong pressure so as to promote atomic diffusion. In addition, the diffusion capacity of atoms along grain boundaries is stronger than transgranular diffusion; in the stirring friction, the speed of the processing tool 3 is 5-6000 mm/min, the rotating speed is 50-5000 rpm, the inclination angle alpha of the main shaft is 0-3 degrees, the pressing amount of the shaft shoulder is 0-1 mm, and the length of the stirring pin is 0-3 mm.

The third concrete implementation mode:

the present embodiment will be described with reference to fig. 1 to 5, and the second embodiment will be further described, in which the step of forming the plastic surface layer ii 5 by processing the base material ii 2 is:

the method comprises the following steps: polishing the surface of the base material II 2 to remove an oxide layer and oil stains;

step two: the processing tool 3 performs stirring friction processing on the base metal II 2 to form a plastic surface layer II 5; the prepared plastic surface layer II 5 has stronger plasticity and smaller grain size, and is favorable for eliminating gaps between interfaces under the action of strong pressure so as to promote atomic diffusion. In addition, the diffusion capacity of atoms along grain boundaries is stronger than transgranular diffusion; in the stirring friction, the speed of the processing tool 3 is 5-6000 mm/min, the rotating speed is 50-5000 rpm, the inclination angle alpha of the main shaft is 0-3 degrees, the pressing amount of the shaft shoulder is 0-1 mm, and the length of the stirring pin is 0-3 mm.

The fourth concrete implementation mode:

the third embodiment is further described with reference to fig. 1 to 5, and the thickness of the plastic layer prepared by friction stir processing is small, and the processing tool 3 may be a pin-less pin mixer, a tapered pin threaded pin mixer with a small pin length, a triple-milled flat tapered pin threaded pin mixer, or a pin mixer.

The fifth concrete implementation mode:

the fourth embodiment will be further described with reference to fig. 1 to 5, wherein the surfaces of the base material i 1 and the base material ii 2 are polished by manual sanding or grinding machine; and impurities are prevented from being present in the plastic surface layer I4 and the plastic surface layer II 5.

The sixth specific implementation mode:

in the following description of the present embodiment with reference to fig. 1 to 5, the present embodiment further describes an embodiment five, in which the step of cold welding the plastic skin layer i 4 and the plastic skin layer ii 5 is:

the method comprises the following steps: the plastic surface layer I4 and the plastic surface layer II 5 are machined, so that an oxide layer, oil stains and a water adsorption layer on the surface are removed, and the surface is smooth; the mechanical polishing treatment can be combined by adopting a machining center, laser cutting, water jet cutting or linear cutting and the like, and the roughness reaches more than 3.2 microns;

step two: opening the vacuum diffusion welding furnace, clamping the base metal I1 and the base metal II 2 to be connected on a workbench, and contacting the surfaces of the plastic surface layer I4 and the plastic surface layer II 5;

step three: closing the vacuum chamber, opening the vacuumizing system to form a vacuum environment 6, and starting the pressurizing system 7; the pressure of the pressurizing system 7 is set to be 2-100 MPa, and the pressure maintaining time is 5-120 min; the connection adopts larger pressure, so that the interface can not generate pores after cold welding, and the vacuum pumping is carried out until the pressure is 10^-4-0.1 Pa; the heating system does not need to be started in connection;

step four: and after the pressure maintaining is finished, unloading the pressure, opening the vacuum chamber, and taking out the dissimilar metal composite structural member.

The seventh embodiment:

the present embodiment will be described with reference to fig. 1 to 5, and the sixth embodiment will be further described, in which a rigid jig 9 is used around the base material i 1 and the base material ii 2 during the cold welding process; the test piece is prevented from being deformed laterally as shown in fig. 5.

The specific implementation mode is eight:

the present embodiment will be described with reference to fig. 1 to 5, and a seventh embodiment will be further described, in which the plastic surface layer i 4 is formed by processing the base material i 1 by friction stir, rolling, shot peening, and magnetic pulse high speed impact, and the plastic surface layer ii 5 is formed by processing the base material ii 2 by friction stir, rolling, shot peening, and magnetic pulse high speed impact; the plastic surface layer I4 and the plastic surface layer II 5 prepared by stirring friction are thinner, and other modes can be adopted. For example, crushing, shot blasting, and magnetic pulse high-speed impact.

The specific implementation method nine:

this embodiment will be described with reference to fig. 1 to 5, and this embodiment will further describe an eighth embodiment, in which the base material i 1 and the base material ii 2 are aluminum, magnesium, titanium, copper, iron, nickel, cobalt, or an alloy thereof; and preparing a multi-material metal composite structure, wherein three or more than three materials can be selected as the base material II 2 or the base material I1.

It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and that various changes, modifications, additions and substitutions which are within the spirit and scope of the present invention and which may be made by those skilled in the art are also within the scope of the present invention.