阅读说明：本技术 一种高强易焊Al-Mg-Zn-Cu合金及其制备方法 (High-strength easy-to-weld Al-Mg-Zn-Cu alloy and preparation method thereof ) 是由 张迪 潘艳林 张济山 庄林忠 于 2019-09-11 设计创作，主要内容包括：一种具有高强度的易焊Al-Mg-Zn-Cu合金及其制备方法,属于铝合金领域。合金质量百分比为：Mg 4.3～7.0％,Zn 2.5～5.0％,Cu 0.4～1.2％,Mn≤0.3％,Cr≤0.1％,Ti≤0.2％,Zr≤0.3％,其余为Al和不可避免杂质,其中Zn/Mg质量比≤1.0。合金板材制备工艺包括:合金成分选择—合金的熔铸—均匀化处理—热轧变形—中间退火—冷轧变形一固溶处理—时效处理。本发明合金通过固溶时效处理调控基体内均匀弥散分布强化相T-Mg<Sub>32</Sub>(Al,Zn,Cu)<Sub>49</Sub>相的尺寸和密度,使合金强度与高强7000系Al-Zn-Mg-Cu合金相当,通过调控晶界析出相的连续性以及无析出带(PFZ)控制其腐蚀性能；降低发明合金结晶温度区间,提高凝固末期液相分数含量,降低合金热裂敏感性。本发明合金焊接性能良好。具有强度高、耐腐蚀性能好、可焊接等特点。(An easily-welded Al-Mg-Zn-Cu alloy with high strength and a preparation method thereof belong to the field of aluminum alloys. The alloy comprises the following components in percentage by mass: 4.3 to 7.0 percent of Mg, 2.5 to 5.0 percent of Zn, 0.4 to 1.2 percent of Cu, less than or equal to 0.3 percent of Mn, less than or equal to 0.1 percent of Cr, less than or equal to 0.2 percent of Ti, less than or equal to 0.3 percent of Zr, and the balance of Al and inevitable impurities, wherein the mass ratio of Zn to Mg is less than or equal to 1.0. The preparation process of the alloy plate comprises the steps of alloy component selection, alloy casting, homogenization treatment, hot rolling deformation, intermediate annealing, cold rolling deformation, solution treatment and aging treatment. The alloy regulates and controls the size and density of a uniform dispersion distribution strengthening phase T-Mg32(Al, Zn, Cu)49 phase in a matrix through solution aging treatment, so that the alloy strength is equivalent to that of a high-strength 7000 series Al-Zn-Mg-Cu alloy, and the corrosion performance of the alloy is controlled through regulating and controlling the continuity of a grain boundary precipitated phase and a non-precipitated zone (PFZ); the crystallization temperature interval of the alloy is reduced, the liquid phase fraction content at the final stage of solidification is improved, and the hot cracking sensitivity of the alloy is reduced. The alloy of the invention has good welding performance. Has the characteristics of high strength, good corrosion resistance, weldability and the like.)

1. The high-strength easy-welding Al-Mg-Zn-Cu alloy is characterized by comprising the following chemical components in percentage by mass:

4.3 to 7.0 percent of Mg, 2.5 to 5.0 percent of Zn, 0.4 to 1.2 percent of Cu, less than or equal to 0.3 percent of Mn, less than or equal to 0.1 percent of Cr, less than or equal to 0.2 percent of Ti, less than or equal to 0.3 percent of Zr, and the balance of Al and inevitable impurities, wherein the mass ratio of Zn to Mg is less than or equal to 1.0.

2. The high-strength weldable Al-Mg-Zn-Cu alloy as claimed in claim 1, wherein the alloy comprises, in mass%, 4.5 to 6.0% of Mg, 3.0 to 4.6% of Zn, 0.5 to 1.0% of Cu, 0 to 0.15% of Mn, 0.03 to 0.06% of Cr, 0.03 to 0.1% of Ti, 0.05 to 0.15% of Zr, and the balance of Al and unavoidable impurities, and Zn/Mg is less than or equal to 1.0.

3. The method for preparing the high-strength easy-to-weld Al-Mg-Zn-Cu alloy as claimed in claim 1 or 2, wherein the alloy plate is prepared by the following process:

Selecting alloy components, casting the alloy, homogenizing, hot rolling deformation, intermediate annealing, cold rolling deformation, solution treatment and aging treatment;

The homogenization treatment process comprises single-stage homogenization and two-stage homogenization, wherein the single-stage homogenization process is 450-475 ℃/20-30 h; the two-stage homogenization process is 420-450 ℃/6-18 h + 465-480 ℃/20-30 h.

4. The method for preparing the high-strength easily weldable Al-Mg-Zn-Cu alloy according to claim 3, wherein the hot rolling deformation process of the aluminum alloy sheet comprises the steps of heating a sample to 420-480 ℃, preserving heat for more than 2 hours, carrying out thermal deformation with the deformation of more than 85%, and enabling the finishing rolling temperature to be more than 330 ℃.

5. The method for preparing the high-strength easily weldable Al-Mg-Zn-Cu alloy as claimed in claim 3, wherein the intermediate annealing process of the aluminum alloy sheet comprises heating a sample to 350-450 ℃, keeping the temperature for 30-120 min, and then cooling in air.

6. The method for preparing the high-strength easily weldable Al-Mg-Zn-Cu alloy as claimed in claim 3, wherein the cold rolling deformation process of the aluminum alloy sheet is specifically that the cold rolling deformation of a sample is 20-85%.

7. The method for preparing the high-strength easily weldable Al-Mg-Zn-Cu alloy according to claim 3, wherein the solution treatment process of the aluminum alloy sheet comprises the steps of preserving heat of a sample in an air furnace at 455-485 ℃ for 15-120 min, and then directly carrying out water quenching.

8. the method for preparing the high-strength easy-welding Al-Mg-Zn-Cu alloy as claimed in claim 3, wherein the aging treatment process of the aluminum alloy plate is specifically as follows: carrying out primary aging treatment for 12-60 h in a heat treatment furnace at 70-120 ℃, and then carrying out secondary aging treatment for 10-30 h at 100-180 ℃.

Technical Field

The invention particularly relates to a high-strength easy-welding Al-Mg-Zn-Cu alloy and a plate prepared from the alloy. The alloy has the characteristics of high strength, good corrosion resistance, weldability and the like, and can be used for materials such as aircraft skins, aircraft body plates, aircraft structural members, automobile structural members, armor plates, ship plates and the like.

Background

The traditional 5xxx series Al-Mg alloy has a series of excellent properties, such as good corrosion resistance, good formability, good weldability and the like, and the excellent properties enable the alloy to be widely applied to ocean, armored vehicle transportation and national defense war industry. However, the traditional Al-Mg alloy belongs to non-heat-treatable strengthening alloy, and the mechanical property of the alloy cannot be further enhanced through aging precipitation, so that the Al-Mg alloy belongs to medium-strength alloy, and the application of the Al-Mg alloy in the aspects of airplane structural parts, automobile structural parts and the like is limited. The high-strength 7 xxx-series Al-Zn-Mg-Cu alloy has high strength, high toughness, corrosion resistance and other performances, and is widely applied to the field of aerospace, such as wing skins, airplane structural members and the like. However, it is insufficient in formability, weldability, and the like.

Some patents have been explored for related work. In patent CN 104313413.A granted by our application, based on the scientific idea of aging strengthening introduced in A1-Zn-Mg (7xxx series) aging precipitation sequence spherical GP zone → T' → T (A12Mg3Zn3), a large amount of Zn is introduced in 5xxx series Al-Mg alloy to reduce the relative solid solution content of Mg, Al-Mg precipitated phase is consumed in a large amount, the component range of the alloy is adjusted reasonably, and a novel aging precipitation strengthening Al-Mg-Zn alloy is successfully developed, wherein the mass percentage (the mass percentage of other alloys is described below) of the Al-Mg-Zn series alloy is respectively 4.0-5.7% of Mg, 2.5-4.0% of Zn, 0-0.4% of Cu, 0.4-1.2% of Mn, 0-0.1% of Cr, 0-0.15% of Ti, 0-0.25% of Zr, 0-0.4% of Fe, 0-0.4% of Si, and the balance of Al; the mechanical property of the alloy is obviously improved, the tensile strength can reach 500MPa at most, the yield strength is 419MPa, and the elongation can reach 14.3%. Although the strength of the Al-Mg-Zn alloy of the invention is improved to a certain extent compared with the strength of the traditional Al-Mg alloy, the invention has a certain difference compared with the high-strength 7000 series alloy, and can not meet the requirements of the aerospace industry. In patent CN106148865.B, Cu and Zn are fully precipitated simultaneously to achieve the effect of synergistic strengthening through reasonable component design and preparation process, and the problem of insufficient baking finish hardenability and dent resistance of 5xxx series aluminum alloy in the application process of automobile plates is solved. The strength of the newly designed plate after the Al-Mg-Cu-Zn baking finish is greatly improved, the increment can reach more than 100MPa, and the problem of formability is solved. Designing alloy components of Mg4.0-6.0%, Cu 0.30-1.0 wt%, Zn 1.0-3.5 wt%, Mn less than or equal to 0.4 wt%; fe is less than or equal to 0.4 wt%, Si is less than or equal to 0.4 wt%, Cr is less than or equal to 0.4 wt%, Ti is less than or equal to 0.1 wt%, and the balance is A1 and inevitable impurities.

Therefore, in order to meet the increasing application requirements of lightweight materials, namely aluminum alloys, a novel Al-Mg-Zn-Cu aluminum alloy with high strength, corrosion resistance and good weldability is developed through further optimizing component design, and the method has great significance in meeting the requirements of the aviation field and the automobile industry.

Disclosure of Invention

In order to meet the increasing application requirements of lightweight materials-aluminum alloys, a novel Al-Mg-Zn-Cu alloy which has the strength of more than 500MPa, Zn/Mg of less than or equal to 1.0 and good corrosion resistance and weldability is developed through further optimizing component design.

The invention firstly selects the component range of the Al-Mg-Zn-Cu alloy through phase diagram component design and optimization, then prepares the designed alloy through processing technologies such as smelting and casting, and researches the mechanical property, the spalling corrosion property and the welding hot cracking sensitivity of the alloy, and finally determines the components of the high-strength corrosion-resistant easy-welding A1-Mg-Zn-Cu alloy.

The invention aims to provide an easily-welded Al-Mg-Zn-Cu alloy with high strength, which is characterized by comprising the following chemical components in percentage by mass:

4.3 to 7.0 percent of Mg, 2.5 to 5.0 percent of Zn, 0.4 to 1.2 percent of Cu, less than or equal to 0.3 percent of Mn, less than or equal to 0.1 percent of Cr, less than or equal to 0.2 percent of Ti, less than or equal to 0.3 percent of Zr, and the balance of Al and inevitable impurities, wherein the mass ratio of Zn to Mg is less than or equal to 1.0.

preferably, the aluminum alloy comprises, by mass, 4.5-6.0% of Mg, 3.0-4.6% of Zn, 0.5-1.0% of Cu, 0-0.15% of Mn, 0.03-0.06% of Cr, 0.03-0.1% of Ti, 0.05-0.15% of Zr, and the balance of Al and unavoidable impurities, wherein Zn/Mg is less than or equal to 1.0.

The second purpose of the invention is to provide a preparation method of the high-strength easy-welding Al-Mg-Zn-Cu alloy. The preparation process of the alloy plate comprises the following steps:

Selecting alloy components, casting the alloy, homogenizing, hot rolling deformation, intermediate annealing, cold rolling deformation, solution treatment and aging treatment.

The homogenization treatment process comprises single-stage homogenization and two-stage homogenization, wherein the single-stage homogenization process is 450-475 ℃/20-30 h; the two-stage homogenization process is 420-450 ℃/6-18 h + 465-480 ℃/20-30 h.

The hot rolling deformation process of the aluminum alloy plate comprises the steps of heating a sample to 420-480 ℃, preserving heat for more than 2 hours, carrying out thermal deformation with the deformation amount of more than 85%, and enabling the final rolling temperature to be more than 330 ℃.

The intermediate annealing process of the aluminum alloy plate is specifically that a sample is heated to 350-450 ℃ and is kept warm for 30-120 min, and then air cooling is carried out.

The cold rolling deformation process of the aluminum alloy plate is characterized in that the cold rolling deformation of a sample is 20-85%.

The solid solution treatment process of the aluminum alloy plate comprises the steps of preserving heat of a sample in an air furnace at 455-485 ℃ for 15-120 min, and then directly carrying out water quenching.

The aging treatment process of the aluminum alloy plate comprises the following specific steps: carrying out primary aging treatment for 12-60 h in a heat treatment furnace at 70-120 ℃, and then carrying out secondary aging treatment for 10-30 h at 100-180 ℃.

compared with the prior art, the invention has the following outstanding advantages and beneficial effects:

The novel high-strength easy-welding Al-Mg-Zn-Cu alloy regulates and controls the size and density of a strengthening phase T-Mg32(Al, Zn, Cu)49 phase which is uniformly dispersed and distributed in a matrix through solution aging treatment, so that the alloy strength is equivalent to that of a high-strength 7000 series Al-Zn-Mg-Cu alloy, and the strength is obviously improved. The corrosion performance of the alloy is controlled by regulating the continuity of a grain boundary precipitated phase and a non-precipitated zone (PFZ).

The invention reduces the crystallization temperature interval of the alloy, improves the liquid phase fraction content at the final stage of solidification, reduces the hot cracking sensitivity of the alloy and has good welding performance of the alloy.

The alloy has the characteristics of high strength, good corrosion resistance, weldability and the like, and is very suitable for further development and production of materials such as aircraft skins, aircraft body plates, aircraft structural members, automobile structural members, armor plates, ship plates and the like.

Drawings

FIG. 1 is a non-equilibrium solidification curve of an alloy welding cooling process.

FIG. 2 is a schematic diagram of the spalling corrosion performance of an alloy.

FIG. 3 is a schematic representation of the hot crack sensitivity of an alloy weld.

Detailed Description

the present invention will be described in further detail with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

the invention is prepared by casting high-purity aluminum, industrial pure Mg, industrial pure Zn, intermediate alloy Al-50 wt% Cu, Al-10 wt% Mn, Al-l 0 wt% Ti, Al-5 wt% Cr and Al-10% Zr as raw materials under laboratory conditions. The specific chemical composition of the designed alloy is shown in Table 1. Wherein 7075 is a comparative alloy, 1#,2#,3#,4#, and 5# are inventive alloys, and the detailed description of the invention will be given with 1#,2#,3#, and 4# as specific embodiments.

TABLE 1 specific chemical composition of the alloy

Comparative example

The 7075 cast ingot which is cast and formed is subjected to single-stage homogenization treatment, and the specific process comprises the following steps: the sample is heated from room temperature to 470 ℃ at the heating rate of 30 ℃/h and is kept warm for 24h, then the temperature is reduced to room temperature along with a furnace at the cooling rate of 30 ℃/h, hot rolling is carried out at 430 ℃ after face milling, the total reduction rate of the hot rolling is more than 85 percent, a hot rolled plate with the thickness of 5mm is obtained, then cold rolling is carried out, the total reduction rate of the cold rolling is 50 percent, first cold rolling is carried out to obtain a cold rolled plate with the thickness of 4mm, then the intermediate annealing process of keeping warm for 90min at 360 ℃ is carried out, and then second cold rolling is carried out to obtain the cold rolled plate with the final thickness. Keeping the cold-rolled sheet in an air furnace at 475 ℃ for 60min, then directly carrying out water quenching, carrying out aging treatment in a heat treatment furnace at 120 ℃ for 24h after water quenching, carrying out room temperature mechanical property test, peeling corrosion test and welding hot cracking sensitivity test on the alloy after aging treatment, wherein the mechanical test results are shown in Table 2, and the peeling corrosion test and the welding hot cracking sensitivity results are respectively shown in figures 2 and 3