CN115961189B

CN115961189B - Al-Mg-Zn-Cu aluminum alloy test piece and preparation method and application thereof

Info

Publication number: CN115961189B
Application number: CN202111177565.3A
Authority: CN
Inventors: 徐鹏; 喻川; 胡中文; 李江山; 崔强; 西达思·苏哈斯·帕维尔
Original assignee: Guizhou Hansikai Intelligent Technology Co ltd
Current assignee: Guizhou Hansikai Intelligent Technology Co ltd
Priority date: 2021-10-09
Filing date: 2021-10-09
Publication date: 2024-04-26
Anticipated expiration: 2041-10-09
Also published as: CN115961189A

Abstract

The invention discloses an Al-Mg-Zn-Cu aluminum alloy test piece and a preparation method and application thereof, and belongs to the technical field of aluminum alloys. The Al-Mg-Zn-Cu aluminum alloy test piece is prepared by depositing Al-Mg-Zn-Cu aluminum alloy raw materials on the surface of a substrate in an arc fuse mode; the chemical components of the Al-Mg-Zn-Cu aluminum alloy raw material comprise 5-6wt% of Zn, 2-3wt% of Mg, 1-2wt% of Cu, 0.1-0.3wt% of Cr, no more than 0.9wt% of impurity elements and the balance of Al. The aluminum alloy test piece has higher hardness and wear resistance in the deposition direction, and the whole test piece has higher self-corrosion potential, lower corrosion current density and higher mechanical tensile property, and can be used as a structural member in aerospace, transportation, automobile manufacturing, military equipment or a fixture.

Description

Al-Mg-Zn-Cu aluminum alloy test piece and preparation method and application thereof

Technical Field

The invention relates to the technical field of aluminum alloy, in particular to an Al-Mg-Zn-Cu aluminum alloy test piece and a preparation method and application thereof.

Background

The Al-Zn-Mg-Cu alloy is widely applied to the fields of aerospace, transportation, automobile manufacturing, military and the like due to the characteristics of low density, high specific strength, good toughness, corrosion resistance and the like, the traditional aluminum alloy processing technology mainly adopts smelting, casting, forging and other means, and the aluminum alloy component prepared by adopting the traditional smelting, casting, forging and other means is more and more difficult to meet the requirements of aluminum alloy products with large sizes and complex structures at present in terms of tissue structures and mechanical properties.

The additive manufacturing technology directly manufactures solid parts from the three-dimensional digital model, so that the parts are light in structure and composite in performance, and the additive manufacturing technology has the advantages of saving materials, short manufacturing period, low cost and the like. Therefore, the additive manufacturing of the Al-Zn-Mg-Cu alloy has important research significance and good application prospect.

Additive manufacturing is currently focused on laser selective melting (SLM), electron selective beam melting (EBSM), and arc fuse manufacturing (WAAM), depending on the heat source.

Among them, SLM technology rapidly melts metal powder using a high-energy laser beam, obtaining high-precision metal devices of almost any size and shape. Its main advantages are high energy stability, near-net shape, high output and high utilization of raw materials. However, the molding efficiency is low, the temperature gradient caused by the local heat source is high, and large residual stress can be caused, so that the material is easy to deform and crack. In addition, SLM technology is difficult to meet the requirements for rapid fabrication of large parts due to the low deposition rate and limited form factor. EBSM the technique uses electron beam as heat source to heat the powder and layer by layer to form solid. The electron beam has higher power, can provide heat input which cannot be achieved by laser, improves the production efficiency to a certain extent, and is beneficial to manufacturing of structural members with larger sizes. However, the working conditions are severe, the working conditions are necessarily in a vacuum environment, the equipment cost and the production cost are high, the precision is improved, and the size of the formed part is limited by a vacuum chamber. WAAM takes the electric arc as a heat source, has the advantages of simple production equipment, high material utilization rate, capability of producing large-scale components, high efficiency and the like, but the mechanical property and the corrosion resistance of the Al-Mg-Zn-Cu aluminum alloy test piece manufactured by the electric arc fuse at present cannot be considered.

In view of this, the present invention has been made.

Disclosure of Invention

The invention aims to provide an Al-Mg-Zn-Cu aluminum alloy test piece which has higher mechanical property and better corrosion resistance.

The second purpose of the invention is to provide a preparation method of the Al-Mg-Zn-Cu aluminum alloy test piece.

The invention further aims to provide an application of the Al-Mg-Zn-Cu aluminum alloy test piece.

The application can be realized as follows:

in a first aspect, the present application provides an Al-Mg-Zn-Cu aluminum alloy test piece, which is obtained by depositing an Al-Mg-Zn-Cu aluminum alloy raw material on a surface of a substrate in an arc fuse manner; the chemical components of the Al-Mg-Zn-Cu aluminum alloy raw material comprise 5-6wt% of Zn, 2-3wt% of Mg, 1-2wt% of Cu, 0.1-0.3wt% of Cr, no more than 0.9wt% of impurity elements and the balance of Al.

In a preferred embodiment, the chemical composition of the Al-Mg-Zn-Cu aluminum alloy stock comprises 5.2-5.8wt% Zn, 2.2-2.8wt% Mg, 1.5-1.8wt% Cu, 0.15-0.25wt% Cr, and no more than 0.8wt% impurity elements, the balance being Al.

In a more preferred embodiment, the chemical composition of the Al-Mg-Zn-Cu aluminum alloy stock includes 5.52 wt.% Zn, 2.56 wt.% Mg, 1.62 wt.% Cu, 0.20 wt.% Cr, and no more than 0.5 wt.% impurity elements, with the balance being Al.

In an alternative embodiment, the Al-Mg-Zn-Cu aluminum alloy raw material is 7075 aluminum alloy welding wire with the diameter of 0.8-1.5 mm; preferably 7075 aluminum alloy welding wire with the diameter of 1.2 mm.

In an alternative embodiment, the chemical composition of the substrate comprises 5-6wt% Zn, 2-3wt% Mg, 1-2wt% Cu, 0.15-0.35wt% Fe, 0.05-0.15wt% Si, 0.15-0.3wt% Cr, and no more than 0.5wt% impurity elements, the balance being Al.

In a preferred embodiment, the chemical composition of the substrate comprises 5.5-5.8wt% Zn, 2.5-2.8wt% Mg, 1.2-1.8wt% Cu, 0.2-0.25wt% Cr, and no more than 0.4wt% impurity elements, the balance being Al.

In a more preferred embodiment, the chemical composition of the substrate comprises 5.65wt% Zn, 2.61wt% Mg, 1.46wt% Cu, 0.22wt% Cr, and no more than 0.3wt% impurity elements, the balance being Al.

In an alternative embodiment, the substrate is a 7075 aluminum alloy rolled sheet in the T6 temper.

In an alternative embodiment, the Al-Mg-Zn-Cu aluminum alloy test piece is a single pass multi-layer Al-Mg-Zn-Cu aluminum alloy test piece.

In an alternative embodiment, the Al-Mg-Zn-Cu aluminum alloy test piece has a structure which is layered with dendrites, equiaxed crystals and a small number of columnar crystals in the horizontal direction, and the deposition direction consists of the equiaxed crystals and a small number of slender columnar crystals.

In an alternative embodiment, the second phase contained in the Al-Mg-Zn-Cu aluminum alloy test piece consists essentially of a Mg ₂ Si phase and a Mg (Zn, cu, al) ₂ phase.

In an alternative embodiment, the hardness of the Al-Mg-Zn-Cu aluminum alloy test piece in the horizontal direction is 70-75HV _0.1, and the hardness in the deposition direction is 82-90HV _0.1.

In an alternative embodiment, the average coefficient of friction of the Al-Mg-Zn-Cu aluminum alloy test piece in the horizontal direction is not more than 0.511, the average wear amount is not more than 1.093mm ³, the average coefficient of wear in the deposition direction is not more than 0.356, and the average wear amount is not more than 0.8462mm ³.

In an alternative embodiment, the self-corrosion potential of the Al-Mg-Zn-Cu aluminum alloy test piece in the horizontal direction is not lower than-0.9575V, and the self-corrosion current is not more than-3.0794A/cm ²; the self-corrosion potential in the deposition direction is not lower than-0.9745V, and the self-corrosion current is not more than-2.9362A/cm ².

In an alternative embodiment, the average tensile strength of the Al-Mg-Zn-Cu aluminum alloy test piece in the horizontal direction is not lower than 358.64MPa, the average yield strength is not lower than 196.15MPa, and the average elongation is not lower than 37.9%; the average tensile strength in the deposition direction is not lower than 269.29MPa, the yield strength is not lower than 140.65MPa, and the elongation is not lower than 32.52%.

In an alternative embodiment, the fracture mode of the Al-Mg-Zn-Cu aluminum alloy test piece is ductile fracture.

In a second aspect, the present application provides a method for preparing an Al-Mg-Zn-Cu aluminum alloy test piece according to any one of the preceding embodiments, comprising the steps of: and depositing Al-Mg-Zn-Cu aluminum alloy raw materials on the surface of the substrate in an arc fuse mode.

In an alternative embodiment, the process conditions of the arc fuse include: the welding current is 80-120A, the welding voltage is 10-15V, the wire feeding speed is 7-10m/min, the advancing speed is 5-8m/min and the air flow is 18-22L/min.

In a preferred embodiment, the process conditions of the arc fuse include: the welding current was 100A, the welding voltage was 12V, the wire feed speed was 8.5m/min, the travel speed was 6.5m/min, and the air flow was 20L/min.

In an alternative embodiment, the method further comprises removing oxide skin and organic matters on the surface of the substrate before depositing the Al-Mg-Zn-Cu aluminum alloy raw material, and preheating to 75-85 ℃ after drying.

In a third aspect, the present application provides the use of an Al-Mg-Zn-Cu aluminum alloy test piece as in any of the preceding embodiments, for example as a large-size aluminum alloy member.

In alternative embodiments, the Al-Mg-Zn-Cu aluminum alloy test pieces are used as structural members in aerospace, transportation, automotive manufacturing, military equipment, or tool fixtures.

In an alternative embodiment, the Al-Mg-Zn-Cu aluminum alloy test piece is used as an automobile chassis.

The beneficial effects of the application include:

According to the application, specific raw materials and manufacturing process parameters are combined, so that an arc fuse method is adopted to manufacture an Al-Mg-Zn-Cu aluminum alloy test piece with higher mechanical property and corrosion resistance, the manufactured Al-Mg-Zn-Cu aluminum alloy test piece has higher hardness and wear resistance in a deposition direction, and the whole test piece has higher self-corrosion potential, lower corrosion current density and higher mechanical tensile property, meets the high-performance requirements of aluminum alloy products with large size and complex structure at present, and can be used as a structural member in aerospace, transportation, automobile manufacturing, military equipment or a fixture.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a macroscopic topography map and a surface roughness three-dimensional surface topography map of a deposited sample in a macroscopic shaping topography analysis of a test example;

FIG. 2 is a microstructure morphology diagram and a metallographic structure diagram of a test piece in a test example microstructure analysis;

FIG. 3 is a graph of the EDS element distribution of a test piece in a test example microstructure analysis;

FIG. 4 is a graph showing the results of SEM EDS analysis of a test piece in a test example microstructure analysis;

FIG. 5 is a graph showing XRD analysis results of a test piece in phase structure analysis of a test example;

FIG. 6 is a microhardness distribution diagram of a test piece in mechanical property analysis of a test example;

FIG. 7 is a graph showing the abrasion resistance of a test piece in the mechanical property analysis of a test example;

FIG. 8 is a graph showing the tensile properties of a test piece in the mechanical properties analysis of a test example;

FIG. 9 is an SEM image of fracture morphology of a test piece after a tensile test is completed in mechanical property analysis of a test example;

FIG. 10 is a graph showing the results of corrosion resistance of test pieces among the corrosion resistance of test examples.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

The Al-Mg-Zn-Cu aluminum alloy test piece provided by the application and a preparation method and application thereof are specifically described below.

The inventor proposes that the reason why the mechanical property and the corrosion resistance of the Al-Mg-Zn-Cu aluminum alloy test piece manufactured by the arc fuse at present cannot be considered is mainly that: firstly, hydrogen content is easy to exceed the surface in the manufacturing process of aluminum alloy arc additive, and air holes are generated; secondly, the residual stress is generated by remelting due to multiple deposition, and the tissue is segregated after solidification, so that the mechanical strength of the sample is lower.

In view of the above, the inventor creatively provides an effective and feasible additive manufacturing method of an Al-Mg-Zn-Cu aluminum alloy test piece, which effectively solves the problem that the Al-Mg-Zn-Cu aluminum alloy test piece manufactured by an arc fuse in the prior art cannot achieve both mechanical property and corrosion resistance by adopting specific raw materials and combining manufacturing process parameters.

The application provides an Al-Mg-Zn-Cu aluminum alloy test piece, which is prepared by depositing an Al-Mg-Zn-Cu aluminum alloy raw material on the surface of a substrate in an arc fuse manner; the chemical components of the Al-Mg-Zn-Cu aluminum alloy raw material comprise 5-6wt% of Zn, 2-3wt% of Mg, 1-2wt% of Cu, 0.1-0.3wt% of Cr, no more than 0.9wt% of impurity elements and the balance of Al.

The Zn content may be 5wt%, 5.2wt%, 5.5wt%, 5.8wt%, 6wt%, etc., or any other value within the range of 5 to 6 wt%.

The content of Mg may be 2wt%, 2.2wt%, 2.5wt%, 2.8wt% or 3wt%, etc., or may be any other value within the range of 2 to 3 wt%.

The Cu content may be 1wt%, 1.2wt%, 1.5wt%, 1.8wt% or 2wt%, etc., or may be any other value within the range of 1 to 2 wt%.

The Cr content may be 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, etc., or may be any other value within the range of 0.1 to 0.3 wt%.

The impurity elements include Si, fe, and the like, as follows.

It is worth to say that the chemical components Zn, mg, cu and Cr of the Al-Mg-Zn-Cu aluminum alloy raw material in the application can be freely combined in the above range, and the balance is Al.

In some preferred embodiments, the chemical composition of the Al-Mg-Zn-Cu aluminum alloy feedstock illustratively may include 5.2-5.8 wt.% Zn, 2.2-2.8 wt.% Mg, 1.5-1.8 wt.% Cu, 0.15-0.25 wt.% Cr, and no more than 0.8 wt.% impurity elements, with the balance being Al.

In some preferred embodiments, the chemical composition of the Al-Mg-Zn-Cu aluminum alloy feedstock illustratively may include 5.52 wt.% Zn, 2.56 wt.% Mg, 1.62 wt.% Cu, 0.20 wt.% Cr, and no more than 0.5 wt.% impurity elements, with the balance being Al.

Among the above chemical components, mgZn ₂ formed by Zn in Mg mainly plays a role of second phase strengthening. When the Zn content is less than 4wt%, the strengthening effect tends to be insignificant, and when it is more than 7wt%, the stress corrosion cracking tendency tends to be increased.

Mg mainly plays a role in increasing weldability and corrosion resistance, while improving alloy strength. When the content of Mg is less than 1.5% by weight, weldability, corrosion resistance and strengthening effect are easily caused to be insignificant, and when it is more than 3% by weight, mg ₂ Si phase is easily formed to embrittle the alloy.

Cu mainly has a solid solution strengthening effect, and in addition, the aged CuAl ₂ has an obvious ageing strengthening effect. When the Cu content is less than 1wt%, the strengthening effect tends to be insignificant, and when it exceeds 2.5wt%, the solid solution tends to be insufficient.

Cr mainly forms intermetallic compounds with other elements to block nucleation and growth processes of recrystallization, thereby playing a role in strengthening. When the Cr content is less than 0.1wt%, the strengthening effect is easily insignificant, and when it is more than 0.3wt%, segregation is easily caused.

In an alternative embodiment, the Al-Mg-Zn-Cu aluminum alloy stock is 7075 aluminum alloy welding wire with a diameter of 0.8-1.5mm (such as 0.8mm, 1mm, 1.2mm, 1.5mm, etc.); preferably 7075 aluminum alloy welding wire with the diameter of 1.2 mm. The welding wire with the diameter can obtain better fuse effect under the arc fuse process condition adopted by the application, thereby obtaining better product performance.

In alternative embodiments, the chemical composition of the substrate employed in the present application may illustratively include 5-6wt% Zn, 2-3wt% Mg, 1-2wt% Cu, 0.15-0.3wt% Cr, and no more than 0.5wt% impurity elements, with the balance being Al.

For reference, the substrate may be exemplified by a 7075 aluminum alloy rolled sheet in the T6 state, and the dimensions may be exemplified by 300mm×100mm×6mm (length×width×height).

In the application, the Al-Mg-Zn-Cu aluminum alloy test piece is preferably a single-pass multi-layer Al-Mg-Zn-Cu aluminum alloy test piece.

Correspondingly, the application also provides a preparation method of the Al-Mg-Zn-Cu aluminum alloy test piece, which comprises the following steps: and depositing Al-Mg-Zn-Cu aluminum alloy raw materials on the surface of the substrate in an arc fuse mode.

In alternative embodiments, the process conditions of the arc fuse may illustratively include: the welding current is 80-120A, the welding voltage is 10-15V, the wire feeding speed is 7-10m/min, the advancing speed is 5-8m/min and the air flow is 18-22L/min.

For reference, the welding current may be 80-120A, such as 80A, 85A, 90A, 95A, 100A, 105A, 110A, 115A, or 120A, or any other value in the range of 80-120A.

The welding voltage may be 10V, 11V, 12V, 13V, 14V, 15V, or the like, or any other value in the range of 10 to 15V.

The wire feeding speed can be 7m/min, 7.5m/min, 8m/min, 8.5m/min, 9m/min, 9.5m/min or 10m/min, etc., and can be any other value in the range of 7-10 m/min.

The travel speed may be 5m/min, 5.5m/min, 6m/min, 6.5m/min, 7m/min, 7.5m/min, 8m/min, etc., or any other value within the range of 5-8 m/min.

The air flow rate may be 18L/min, 18.5L/min, 19L/min, 19.5L/min, 20L/min, 20.5L/min, 21L/min, 21.5L/min or 22L/min, etc., or may be any other value within the range of 18-22L/min.

Wherein welding current is the main process parameter affecting the quality of the work piece. When the welding current is lower than 80A, the arc is easy to be unstable, and defects such as air holes, inclusions and the like are generated; defects such as undercut and weld flash are easy to occur when the temperature is higher than 120A, and meanwhile deformation of a workpiece is increased.

Welding voltage is also an important process parameter affecting the quality of the workpiece. When the welding voltage is lower than 10V, welding rods are easy to adhere, and when the welding voltage is higher than 15V, arc burning is unstable, splash is large, defects such as undercut and air holes are easy to generate.

Wire feed speed primarily affects workpiece forming quality. When the wire feeding speed is lower than 7m/min, defects such as air holes, inclusions and the like are easy to generate, and when the wire feeding speed is higher than 10m/min, defects such as undercut, weld flash and the like are easy to generate.

The travel speed also affects the workpiece forming quality. When the travelling speed is lower than 5m/min, the welding seam is easy to widen, the residual height is increased, and the power is reduced; if the thickness is higher than 8m/min, the weld joint is easy to narrow and uneven, and undercut and weld joint waveform sharpening are easy to generate.

The air flow mainly protects the electric arc and the liquid metal in the welding pool from being polluted by oxygen, nitrogen, hydrogen and the like in the atmosphere, so as to achieve the aim of improving the welding quality. When the air flow is lower than 18L/min, the isolation effect of air and molten metal in a welding area is not obvious easily, and when the air flow is higher than 22L/min, the air is wasted, and the production cost is increased.

In some preferred embodiments, the process conditions of the arc fuse illustratively include: the welding current was 100A, the welding voltage was 12V, the wire feed speed was 8.5m/min, the travel speed was 6.5m/min, and the air flow was 20L/min.

Preferably, before depositing the Al-Mg-Zn-Cu aluminum alloy raw material, the method further comprises the steps of removing oxide skin (for example, polishing) and organic matters (for example, cleaning by acetone) on the surface of the substrate, and preheating to 75-85 ℃ (preferably 80 ℃), after drying.

After the pretreatment, the Al-Mg-Zn-Cu aluminum alloy raw material is deposited on the surface of the base material in a unidirectional movement manner.

The cooling rate of the arc fuse process is lower than that of the laser additive manufacturing method, and solidification cracks can be avoided to a great extent. In the structure of the Al-Mg-Zn-Cu aluminum alloy test piece prepared by the method, dendrites, equiaxed crystals and a small amount of columnar crystals are layered in the horizontal direction, and the deposition direction consists of the equiaxed crystals and a small amount of slender columnar crystals, so that the characteristic of epitaxial growth is shown. The second phase of the Al-Mg-Zn-Cu aluminum alloy test piece mainly comprises a Mg ₂ Si phase and a Mg (Zn, cu, al) ₂ phase.

The hardness of the Al-Mg-Zn-Cu aluminum alloy test piece in the horizontal direction is 70-75HV _0.1, and the hardness in the deposition direction is 82-90HV _0.1; the average friction coefficient in the horizontal direction is not more than 0.511, and the average abrasion loss is not more than 1.093mm ³; the average wear coefficient in the deposition direction is not more than 0.356, and the average wear amount is not more than 0.8462mm ³; the self-corrosion potential in the horizontal direction is not lower than-0.9575V, and the self-corrosion current is not higher than-3.0794A/cm ²; the self-corrosion potential in the deposition direction is not lower than-0.9745V, and the self-corrosion current is not more than-2.9362A/cm ²; the average tensile strength in the horizontal direction is not lower than 358.64MPa, the average yield strength is not lower than 196.15MPa, and the average elongation is not lower than 37.9%; the average tensile strength in the deposition direction is not lower than 269.29MPa, the yield strength is not lower than 140.65MPa, and the elongation is not lower than 32.52%; the fracture mode of the Al-Mg-Zn-Cu aluminum alloy test piece is ductile fracture.

It should be emphasized that the preparation process of the present application may further include adding auxiliary fields (such as an ultrasonic field and a magnetic field) during the preparation process to perform composite preparation, and performing appropriate subsequent treatment (such as heat treatment) on the obtained product to further improve performance.

In addition, the application also provides application of the Al-Mg-Zn-Cu aluminum alloy test piece, for example, the Al-Mg-Zn-Cu aluminum alloy test piece is used as a large-size aluminum alloy component. In addition, the Al-Mg-Zn-Cu aluminum alloy test piece can be used as a structural member in aerospace, transportation, automobile manufacturing, military equipment or tool fixtures, for example, as an automobile chassis (such as an unmanned automobile aluminum alloy chassis).

The features and capabilities of the present invention are described in further detail below in connection with the examples.

Example 1

The embodiment provides an Al-Mg-Zn-Cu aluminum alloy test piece, which is obtained by depositing an Al-Mg-Zn-Cu aluminum alloy raw material on the surface of a substrate in an arc fuse mode.

The chemical components of the Al-Mg-Zn-Cu aluminum alloy raw material comprise 5.52wt% of Zn, 2.56wt% of Mg, 1.62wt% of Cu, 0.20wt% of Cr and 0.57wt% of impurity elements, and the balance of Al.

The chemical composition of the base material comprises 5.65wt% of Zn, 2.61wt% of Mg, 1.46wt% of Cu, 0.22wt% of Cr and 0.36wt% of impurity element, and the balance of Al.

The Al-Mg-Zn-Cu aluminum alloy raw material is 7075 aluminum alloy welding wire with the diameter of 1.2 mm. The base material is a 7075 aluminum alloy rolled plate in a T6 state with the dimensions of 300mm multiplied by 100mm multiplied by 6 mm.

The preparation method of the Al-Mg-Zn-Cu aluminum alloy test piece comprises the following steps:

Pretreatment of the substrate: polishing the surface of the substrate by a polisher to remove oxide scale, then cleaning with acetone to remove organic matters, drying, preheating the substrate to 80 ℃ by flame, and then carrying out unidirectional mobile deposition.

Depositing Al-Mg-Zn-Cu aluminum alloy raw materials on the surface of the substrate, wherein the arc fuse deposition process conditions comprise: the welding current was 100A, the welding voltage was 12V, the wire feed speed was 8.5m/min, the travel speed was 6.5m/min, and the air flow was 20L/min.

The deposition system used in the above process consisted of a Fronius CMT ADVANCED R arc power supply with wire feeder, a CMT gun mounted on KR 150R2700KUKA robot, and an argon gas delivery system and work platform. Prior to deposition, a standard reference frame was established using Rhino3D NURBS software, with the X axis defined as the direction of travel of the torch, the Z axis defined as the direction of thin wall formation, and the Y axis defined as the transverse direction.

Example 2

This embodiment differs from embodiment 1 in that: the chemical components of the Al-Mg-Zn-Cu aluminum alloy raw material comprise 5.2wt% of Zn, 2.8wt% of Mg, 1.5wt% of Cu, 0.25wt% of Cr and 0.6wt% of impurity elements, and the balance of Al.

Example 3

This embodiment differs from embodiment 1 in that: the chemical components of the Al-Mg-Zn-Cu aluminum alloy raw material comprise 5.8wt% of Zn, 2.2wt% of Mg, 1.8wt% of Cu, 0.15wt% of Cr and the balance of Al.

Example 4

This embodiment differs from embodiment 1 in that: the chemical components of the Al-Mg-Zn-Cu aluminum alloy raw material comprise 5wt% of Zn, 2wt% of Mg, 1wt% of Cu, 0.1wt% of Cr, 0.4wt% of impurity elements and the balance of Al.

Example 5

This embodiment differs from embodiment 1 in that: the chemical components of the Al-Mg-Zn-Cu aluminum alloy raw material comprise 6wt% of Zn, 3wt% of Mg, 2wt% of Cu, 0.3wt% of Cr, not more than 0.8wt% of impurity elements and the balance of Al.

Example 6

This embodiment differs from embodiment 1 in that: the process conditions of the arc fuse include: the welding current was 80A, the welding voltage was 10V, the wire feed speed was 7m/min, the travel speed was 5m/min, and the air flow was 18L/min.

Example 7

This embodiment differs from embodiment 1 in that: the process conditions of the arc fuse include: the welding current was 120A, the welding voltage was 15V, the wire feed speed was 10m/min, the travel speed was 8m/min, and the air flow was 22L/min.

Comparative example 1

The comparative example differs from example 1 in that the chemical composition of the Al-Mg-Zn-Cu aluminum alloy raw material used was: 8wt% Zn, 5wt% Mg, 1wt% Cu, 0.35wt% Fe, 0.03wt% Si, and 0.1wt% Cr, the balance being Al. The hardness of the obtained aluminum alloy arc additive manufactured part in the horizontal direction is 68HV _0.1, and the hardness in the deposition direction is 79HV _0.1; the average tensile strength in the horizontal direction is 326MPa, the average yield strength is 168MPa, and the average elongation is 28%; the average tensile strength in the deposition direction is 230MPa, the yield strength is 116MPa, and the elongation is 26%; the self-corrosion potential in the horizontal direction is lower than-0.9575V, and the self-corrosion current exceeds-3.0794A/cm ²; the self-etching potential in the deposition direction was lower than-0.9745V, the self-etching current exceeded-2.9362A/cm ², and the corrosion resistance was lower than in example 1.

Comparative example 2

The present comparative example differs from example 1 in that the process conditions of the arc fuse are: the welding current was 50A, the welding voltage was 8V, the wire feed speed was 6m/min, the travel speed was 4m/min, and the air flow was 15L/min. The hardness of the obtained aluminum alloy arc additive manufactured part in the horizontal direction is 51HV _0.1, and the hardness in the deposition direction is 65HV _0.1; the average tensile strength in the horizontal direction is 280MPa, the average yield strength is 140MPa, and the average elongation is 18%; the average tensile strength in the deposition direction is 198MPa, the yield strength is 96MPa, and the elongation is 16%; the self-corrosion potential in the horizontal direction is lower than-0.9575V, and the self-corrosion current exceeds-3.0794A/cm ²; the self-etching potential in the deposition direction was lower than-0.9745V, the self-etching current exceeded-2.9362A/cm ², and the corrosion resistance was lower than in example 1.

Comparative example 3

The present comparative example differs from example 1 in that the process conditions of the arc fuse are: the welding current was 150A, the welding voltage was 18V, the wire feed speed was 12m/min, the travel speed was 10m/min, and the air flow was 25L/min. The hardness of the obtained aluminum alloy arc additive manufactured part in the horizontal direction is 63HV _0.1, and the hardness in the deposition direction is 75HV _0.1; the average tensile strength in the horizontal direction is 310MPa, the average yield strength is 160MPa, and the average elongation is 26%; the average tensile strength in the deposition direction is 225MPa, the yield strength is 112MPa, and the elongation is 24%; the self-corrosion potential in the horizontal direction is lower than-0.9575V, and the self-corrosion current exceeds-3.0794A/cm ²; the self-etching potential in the deposition direction was lower than-0.9745V, the self-etching current exceeded-2.9362A/cm ², and the corrosion resistance was lower than in example 1.

Test examples

The Al-Mg-Zn-Cu aluminum alloy test piece obtained in example 1 was subjected to macro morphology analysis, microstructure analysis, phase analysis, mechanical property analysis (microhardness, wear resistance, tensile properties) and corrosion resistance analysis.

The analysis and test methods and results are specifically as follows:

① Macroscopic profiling morphology analysis

The surface roughness is an important characterization parameter for measuring the surface molding quality of a part, and directly influences the service performance and the service life of a molded part.

In the test, a surface roughness test was performed on the molded sample using an olympus LEXT OLS5000 laser confocal scanning microscope (3D MEASURING LASER MICROSCOPE OLS5000).

The results are as follows:

The macroscopic morphology of the Al-Mg-Zn-Cu aluminum alloy test piece (hereinafter may be simply referred to as "deposition sample") obtained in example 1 is as shown in fig. 1 (a) of fig. 1, and the surface of the deposition sample is smooth and bright overall, and shows periodic concave-convex lines, so that each independent deposition layer can be distinguished, the lap joint area between the weld bead and the weld bead is flat and tight, no offset phenomenon exists along the forming direction, and defects such as undercut and weld flash are avoided. Fig. 1 (b) shows the three-dimensional surface morphology of the surface roughness of a small sample of the deposit, fig. 1 (c) shows the scan line, and fig. 1 (d) shows the corresponding coordinate curve, from which it can be derived: the maximum height Rz of the profile of this sample was 112.567 μm and the arithmetic mean deviation of the Ra profile was 5.95. Mu.m.

The side surface of the multilayer single-channel deposition sample has no obvious fluctuation, has good interlayer interface lap joint characteristic, and has good forming characteristic, which is probably due to the following main reasons: the former layer is deposited under the action of the subsequent arc, the upper region is melted for the second time, but the remelting process is uniform and stable, so that the molten drops are stably transited to a molten pool.

② Microscopic tissue analysis

The method comprises the following steps: the microstructure and elemental composition distribution of the powder, deposit samples were analyzed using a JEOLJSM-7500 model field Scanning Electron Microscope (SEM).

The results are shown in FIG. 2:

Fig. 2 (a) and 2 (b) show the microstructure morphology of the deposit sample in the horizontal direction, the former being a 100-fold magnification, the latter being a 500-fold magnification. FIGS. 2 (c) and 2 (d) show the microstructure morphology of the deposit in the deposition direction, the former being a 100-fold magnification, and the latter being a 500-fold magnification.

In fig. 2 (a) and 2 (b), the microstructure of the sample region mainly contains a small amount of fine columnar crystal structure and a large amount of equiaxed crystal structure having irregular characteristics, probably because fine crystal grains are easily obtained at a higher cooling rate in the center of the molten pool, forming fine crystal regions. The cooling speed of the edge of the molten pool is low, and the edge area is melted for the second time when the second layer is welded after the previous layer is completely deposited, so that the edge of the molten pool bears a large amount of welding heat input, partial remelting occurs, crystal grains coarsen, and a coarse grain area is formed. The remelting process is uniform and stable, so that molten drops are stably transited to a molten pool, and an equiaxed crystal structure with irregular characteristics appears in the horizontal direction.

In fig. 2 (c) and 2 (d), most of the grains of the intra-layer region exhibit coarse equiaxed features, while a small number of elongated columnar grain structures are distributed along the inter-layer boundary lines, and heat accumulation in the top layer in the deposition direction is greater, which means that the temperature gradient of the top molten pool is smaller, resulting in an early change in the direction of the temperature gradient. The solidification process is performed from the bottom to the top of the bath, depending on the heat transfer characteristics of the bath, during which the liquid metal remains in contact with the solid substrate. The degree of nucleation supercooling of the melt pool and solid substrate interface is typically minimal compared to nucleation within the melt pool, which means that a good nucleation point is provided. Thus, the subsequent bath solidification process exhibits typical epitaxial growth characteristics.

Compared with the metallographic structure (fig. 2 (f)) of the as-cast 7075 aluminum alloy, the metallographic structure (fig. 2 (e)) of the Al-Mg-Zn-Cu aluminum alloy test piece provided by the embodiment 1 of the application has finer grain size and more uniform distribution. This is mainly because the solidification speed of the liquid phase metal of the arc fuse is high, and the arc has an agitating effect on the molten pool, and the solidification process is dynamic solidification, a large amount of precipitated phases are not accumulated, and the precipitated phases are distributed in a dispersion manner.

In order to characterize the microstructure of the Al-Mg-Zn-Cu aluminum alloy test piece of example 1 and the distribution of elements in the aluminum alloy in dendrites, scanning electron microscopy and spectroscopy analysis were performed, as shown in fig. 3, fig. 3 (a) shows EDS element distribution diagram in the horizontal direction, fig. 3 (b) shows EDS element distribution diagram in the deposition direction, and the results of fig. 3 show that: there is some segregation in the main alloying element distribution. During non-equilibrium crystallization they are enriched at grain boundaries and dendrite boundaries, forming precipitated second phases.

Table 1 EDS spectroscopy of different regions (at.)

These second phases are continuously distributed on the grain boundaries to form a complex grid, as shown in fig. 4, fig. 4 (a) shows SEM EDS analysis result diagram in the horizontal direction, fig. 4 (b) shows SEM EDS analysis result diagram in the deposition direction, and fig. 4 shows: a small amount of grey phase is surrounded by white phase. The chemical composition was determined by spectroscopic analysis at 4 points and the results are shown in table 1, wherein the chemical composition of the white phase was similar, the aluminum content was higher, the magnesium content was higher relative to the other alloying elements, and the copper content was lower. The zinc content is significantly reduced. In the arc manufacturing process, the repeated heating of the upper layer by the lower layer leads to partial melting of the upper layer, and because Zn is a volatile metal with a low melting point and a low boiling point, the high temperature reached in the molten pool leads to vaporization of Zn, so that burning loss of Zn element leads to the existence of a small amount of pores. In addition, the melting point of the alloy elements such as Fe, si and the like is higher, so that the formed second phase is not dissolved in the repeated heating process, and when the alloy elements are dissolved in the unbalanced solidification process, if no evidence of a crystal structure exists, the type of the phase which is difficult to determine from the chemical components to be tested can be primarily judged as the precipitated second phase, and the precipitated second phase is distributed along grain boundaries in a certain way, and is distributed at the boundary of the grain boundaries or in the grain boundaries in a certain way in a dispersing way.

③ Phase structure

Cutting into square blocks with the size of 10 multiplied by 6mm along the deposition travelling direction by using a linear cutting machine, polishing, flattening and smoothing by using sand paper, analyzing the phase composition by using an X-ray diffraction (XRD) instrument of the Panac family of the Netherlands, adopting a Cu target with the wavelength of 1.54060, and scanning the Cu target at the scanning speed (2 theta) of 5deg/min and the scanning range; 20 deg-90 deg, step size 0.02deg.

The phase structure test results are as follows:

The XRD analysis results of the Al-Mg-Zn-Cu aluminum alloy test piece of example 1 in the horizontal direction and the deposition direction and of the as-cast 7075 aluminum alloy (supplied by Shenzhen Huiyu metal materials Co., ltd., hereinafter the same) are shown in FIG. 5. The matrix phase of the 7075 aluminum alloy is alpha-Al, the main alloying elements are zinc, magnesium and copper, and the phases in the horizontal direction and the deposition direction of the Al-Mg-Zn-Cu aluminum alloy test piece of the embodiment 1 mainly consist of alpha-Al, a small amount of Al ₉ Si and Mg (Fe, mn, al). Due to the high cooling rate, eutectic reactions occur in small amounts of the liquid phase and the formation of eutectic phases (α -Al and Mg (Fe, mn, al), al ₉ Si phases) remain because there is not enough time to switch under high cooling rate conditions. The formation of second phase particles in ultra-high strength aluminum alloys belongs to diffusion phase transformation, and the size of atomic diffusion rate is mainly controlled by temperature, so the size of the second phase particles is sensitive to temperature. After solution treatment and artificial aging, the as-cast 7075 aluminum alloy is dissolved in the coarse second phase, and the grains are re-nucleated and grow into fine equiaxed grains, so that the main peak is higher than the peak of additive manufacturing, and the second phase is obviously reduced.

④ Analysis of mechanical Properties

A. Microhardness

The method comprises the following steps: the microhardness analysis is carried out on the sample by using an HV-50 small-load Vickers hardness tester, the loading force is 1.98N, and the distance between each two measuring points is 5mm. Each hardness value was tested in triplicate and averaged.

Results: as shown in FIG. 6, the graph shows the microhardness distribution diagram of the Al-Mg-Zn-Cu aluminum alloy test piece of example 1 in the horizontal direction and in the deposition direction. From the graph, the average hardness of the Al-Mg-Zn-Cu aluminum alloy test piece in the horizontal direction is 73.15HV _0.1, the average hardness of the Al-Mg-Zn-Cu aluminum alloy test piece in the deposition direction is 86.06HV _0.1, the grain size of a heat affected zone is large under the action of arc cyclic heat, and the larger the grain size is, the smaller the microhardness value is according to a Hall-Petch equation; the structure is coarser in the horizontal direction than the crystal grains in the deposition direction, the equiaxed crystal structure with irregular characteristics is more, the structure layering is more obvious, and the precipitated second phase is coarser, so the hardness is slightly lower.

B. Wear resistance

The method comprises the following steps: the abrasion resistance is detected by adopting an HSR-2M type high-speed reciprocating friction tester, the grinding ball is made of GCr15, the load is 50N, the reciprocating stroke is 6mm, and the test time is 15min.

Results: as shown in fig. 7, it shows the abrasion resistance of the Al-Mg-Zn-Cu aluminum alloy test piece of example 1 in the horizontal direction and the deposition direction. As can be seen from FIG. 7 (a), the average friction coefficients in the horizontal direction and the deposition direction of the Al-Mg-Zn-Cu aluminum alloy test piece of example 1 were 0.511 and 0.356, as can be seen from FIG. 7 (b), the average wear amounts in the horizontal direction and the deposition direction of the Al-Mg-Zn-Cu aluminum alloy test piece of example 1 were 1.093mm ³ and 0.8462mm ³, respectively. Fig. 7 (c) shows the three-dimensional profile of the wear scar for two samples, the results of which show: the width of the grinding mark is narrowed, the depth is shallower, and the groove is smoother.

C. Tensile Properties

The method comprises the following steps: the microcomputer controlled electronic universal tester model number MTS810 (250 KN) was selected for strain (elongation) measurements in combination with a laser extensometer. The initial strain rate of the stretching was set to 1mm/min and the tensile force was 50N.

Results: as shown in fig. 8, tensile tests in the deposition direction and the horizontal direction were performed on the Al-Mg-Zn-Cu aluminum alloy test piece and the 7075 aluminum alloy casting of example 1 to evaluate macroscopic mechanical properties thereof. Fig. 8 (a) shows a tensile curve of the sample, and fig. 8 (b) shows strength and elongation obtained from the tensile curve. The Al-Mg-Zn-Cu aluminum alloy test piece of example 1 had an average tensile strength of 358.64MPa in the horizontal direction, an average yield strength of 196.15MPa, and an average elongation of 37.9%; the Al-Mg-Zn-Cu aluminum alloy test piece of example 1 had an average tensile strength in the deposition direction of 269.29MPa, a yield strength of 140.65MPa, and an elongation of 32.52%. The average yield strength and ultimate strength in the horizontal direction were 24.91% and 26.03% higher, respectively, than in the deposition direction, and the anisotropy of mechanical properties could be attributed to the change in microstructure. With reference to fig. 2, the test specimen has dendrites that are strongly elongated upward. The horizontal samples have more dendrite boundaries or inter-dendrite regions in the loading direction than the vertical samples, so that the crack nucleation of this region can accommodate more dislocations as the load increases before fracture occurs.

Further, fracture analysis was performed on the above deposited samples using a JEOLJSM-7500 type field Scanning Electron Microscope (SEM), and the fracture morphology of the tensile samples is shown in fig. 9, in which fig. 9 (a) and 9 (b) are horizontal directions and fig. 9 (c) and 9 (d) are deposition directions. The surface of the fracture has a small amount of pores, and Zn pores are mainly formed by the fact that Zn is evaporated due to the fact that the arc temperature is high in the arc fuse process, but steam is left to form pores in the solidification process of aluminum liquid. The horizontal direction and the deposition direction of the fracture of the sample are provided with a large number of ductile pits, which indicates that the 7075 aluminum alloy prepared by the arc fuse process has good plasticity, and the fracture mode is typical ductile fracture. Compared with the sample in the deposition direction, the dendrite boundaries or inter-dendrite regions in the horizontal direction are more, and more dislocation can be accommodated in the crack nucleation process, so that the plasticity is better.

⑤ Corrosion resistance

The method comprises the following steps: and (3) carrying out an electrochemical corrosion experiment by adopting an IM-6 type electrochemical workstation to acquire a polarization curve. By adopting a three-electrode method, the sample electrode is a working electrode, the saturated calomel electrode and the platinum electrode are respectively used as a reference electrode and an auxiliary electrode, and the corrosion environment is 3.5% NaCl solution.

As a result, as shown in fig. 10, fig. 10 (a) shows polarization curves of the cast 7075 aluminum alloy and the Al-Mg-Zn-Cu aluminum alloy test piece of example 1 in the horizontal direction and the deposition direction. Table 2 shows the main electrochemical parameters obtained by Tafel extrapolation.

TABLE 2 electrochemical corrosion results of deposition samples in the down-product, horizontal and as cast 7075 aluminum alloys

The results showed that the self-corrosion potential of the cast 7075 aluminum alloy was-1.0076V and the self-corrosion current was-2.6876A/cm ². The Al-Mg-Zn-Cu aluminum alloy test piece of example 1 had a self-corrosion potential of-0.9575V in the horizontal direction and a self-corrosion current of-3.0794A/cm ². The self-etching potential in the deposition direction was-0.9745V, and the self-etching current was-2.9362A/cm ². As the potential changes from negative to positive, the corrosion current density gradually decreases; during cathodic polarization, hydrogen evolution reactions mainly occur. When the self-corrosion potential is reached, the self-corrosion current density is minimum, the charge transfer resistance is larger, and the polarization reaction rate is the lowest. As the potential increases further, the corrosion current density gradually decreases from negative to positive with the potential.

Compared with the as-cast 7075 aluminum alloy, the deposited sample provided by the application has higher self-corrosion potential, smaller self-corrosion current and a passivation area with wider horizontal direction and deposition direction, so that the deposited sample has better corrosion resistance. Furthermore, the difference in corrosion resistance in the horizontal direction and the deposition direction is not large. This is because corrosion resistance is related to grain size and precipitated phases. The grain size produced by the additive manufacturing is smaller, the distribution is more uniform, and the precipitated phase is later and can not be aggregated due to the faster solidification speed, so that the corrosion resistance is better.

Fig. 10 (b) shows a 3D profile of the corrosion profile of three samples. As can be seen from the figure, the cast 7075 aluminum alloy has a greater surface roughness after corrosion, and the degree of corrosion is more severe. The more concentrated the surface pitting, the larger the pit.

In summary, the application combines specific raw materials and manufacturing process parameters, so that the manufacturing of the Al-Mg-Zn-Cu aluminum alloy test piece with higher mechanical property and corrosion resistance by adopting an arc fuse method becomes possible, the manufactured Al-Mg-Zn-Cu aluminum alloy test piece has higher hardness and wear resistance in the deposition direction, and the whole test piece has higher self-corrosion potential, lower corrosion current density and higher mechanical tensile property, meets the high performance requirement of the aluminum alloy product with large size and complex structure at present, and can be used as a structural member in aerospace, transportation, automobile manufacturing, military equipment or tool fixtures.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The Al-Mg-Zn-Cu aluminum alloy test piece is characterized in that the Al-Mg-Zn-Cu aluminum alloy test piece is obtained by depositing Al-Mg-Zn-Cu aluminum alloy raw materials on the surface of a base material in an arc fuse mode; the chemical components of the Al-Mg-Zn-Cu aluminum alloy raw material comprise 5-6wt% of Zn, 2-3wt% of Mg, 1-2wt% of Cu, 0.1-0.3wt% of Cr, no more than 0.9wt% of impurity elements and the balance of Al;

the Al-Mg-Zn-Cu aluminum alloy test piece is a single-pass multi-layer Al-Mg-Zn-Cu aluminum alloy test piece;

In the structure of the Al-Mg-Zn-Cu aluminum alloy test piece, dendrites, equiaxed crystals and a small amount of columnar crystals are layered in the horizontal direction, and the deposition direction consists of the equiaxed crystals and a small amount of slender columnar crystals;

The average tensile strength of the Al-Mg-Zn-Cu aluminum alloy test piece in the horizontal direction is not lower than 358.64MPa, the average yield strength is not lower than 196.15MPa, and the average elongation is not lower than 37.9%; the average tensile strength in the deposition direction is not lower than 269.29MPa, the yield strength is not lower than 140.65MPa, and the elongation is not lower than 32.52%;

The chemical components of the base material comprise 5-6wt% of Zn, 2-3wt% of Mg, 1-2wt% of Cu, 0.15-0.3wt% of Cr, no more than 0.5wt% of impurity elements and the balance of Al.

2. The Al-Mg-Zn-Cu aluminum alloy specimen according to claim 1, wherein the chemical composition of the Al-Mg-Zn-Cu aluminum alloy raw material includes 5.2 to 5.8wt% Zn, 2.2 to 2.8wt% Mg, 1.5 to 1.8wt% Cu, 0.15 to 0.25wt% Cr, and not more than 0.8wt% impurity element, the balance being Al.

3. The Al-Mg-Zn-Cu aluminum alloy specimen according to claim 2, wherein the chemical composition of the Al-Mg-Zn-Cu aluminum alloy raw material includes 5.52 wt.% Zn, 2.56 wt.% Mg, 1.62 wt.% Cu, 0.20 wt.% Cr, and not more than 0.5 wt.% impurity element, the balance being Al.

4. The Al-Mg-Zn-Cu aluminum alloy test piece according to any one of claims 1 to 3, wherein the Al-Mg-Zn-Cu aluminum alloy raw material is 7075 aluminum alloy welding wire having a diameter of 0.8 to 1.5 mm.

5. The Al-Mg-Zn-Cu aluminum alloy test piece according to claim 4, wherein said Al-Mg-Zn-Cu aluminum alloy raw material is 7075 aluminum alloy wire having a diameter of 1.2 mm.

6. The Al-Mg-Zn-Cu aluminum alloy test piece according to claim 1, wherein the chemical composition of the base material includes 5.5 to 5.8wt% Zn, 2.5 to 2.8wt% Mg, 1.2 to 1.8wt% Cu, 0.2 to 0.25wt% Cr, and not more than 0.4wt% of an impurity element, the balance being Al.

7. The Al-Mg-Zn-Cu aluminum alloy test piece according to claim 6, wherein the chemical composition of said base material includes 5.65 wt.% Zn, 2.61 wt.% Mg, 1.46 wt.% Cu, 0.22 wt.% Cr, and not more than 0.3 wt.% impurity element, with the remainder being Al.

8. The Al-Mg-Zn-Cu aluminum alloy test piece according to claim 7, wherein said base material is a T6 state 7075 aluminum alloy rolled sheet.

9. The Al-Mg-Zn-Cu aluminum alloy specimen according to claim 1, wherein the second phase contained in the Al-Mg-Zn-Cu aluminum alloy specimen mainly includes Mg ₂ Si phase and Mg (Zn, cu, al) ₂ phase.

10. The Al-Mg-Zn-Cu aluminum alloy specimen according to claim 1, wherein the hardness in the horizontal direction of the Al-Mg-Zn-Cu aluminum alloy specimen is 70 to 75HV _0.1, and the hardness in the deposition direction is 82 to 90HV _0.1.

11. The Al-Mg-Zn-Cu aluminum alloy test piece according to claim 1, wherein an average friction coefficient in a horizontal direction of the Al-Mg-Zn-Cu aluminum alloy test piece is not more than 0.511, an average wear amount is not more than 1.093mm ³, an average wear coefficient in a deposition direction is not more than 0.356, and an average wear amount is not more than 0.8462mm ³.

12. The Al-Mg-Zn-Cu aluminum alloy test piece according to claim 1, wherein the self-corrosion potential in the horizontal direction of the Al-Mg-Zn-Cu aluminum alloy test piece is not lower than-0.9575V, and the self-corrosion current is not more than-3.0794 a/cm ²; the self-corrosion potential in the deposition direction is not lower than-0.9745V, and the self-corrosion current is not more than-2.9362A/cm ².

13. The Al-Mg-Zn-Cu aluminum alloy specimen according to claim 1, wherein the fracture mode of the Al-Mg-Zn-Cu aluminum alloy specimen is ductile fracture.

14. The method for producing an Al-Mg-Zn-Cu aluminum alloy test piece according to any one of claims 1 to 13, comprising the steps of: and depositing Al-Mg-Zn-Cu aluminum alloy raw materials on the surface of the substrate in an arc fuse mode.

15. The method of manufacturing of claim 14, wherein the process conditions of the arc fuse include: the welding current is 80-120A, the welding voltage is 10-15V, the wire feeding speed is 7-10m/min, the advancing speed is 5-8m/min and the air flow is 18-22L/min.

16. The method of manufacturing of claim 15, wherein the process conditions of the arc fuse include: the welding current was 100A, the welding voltage was 12V, the wire feed speed was 8.5m/min, the travel speed was 6.5m/min, and the air flow was 20L/min.

17. The method of claim 15 or 16, further comprising removing oxide scale and organics from the surface of the substrate prior to depositing the Al-Mg-Zn-Cu aluminum alloy feedstock, and preheating to 75-85 ℃ after drying.

18. Use of the Al-Mg-Zn-Cu aluminum alloy specimen according to any one of claims 1 to 13, characterized in that the Al-Mg-Zn-Cu aluminum alloy specimen is used as a large-sized aluminum alloy member.

19. The use according to claim 18, wherein the Al-Mg-Zn-Cu aluminum alloy test piece is used as a structural member in aerospace, transportation, automotive manufacturing, military equipment or tool jigs.

20. The use according to claim 19, wherein the Al-Mg-Zn-Cu aluminum alloy test piece is used for manufacturing an automotive chassis.