WO2017215098A1

WO2017215098A1 - Method for designing major components of high-hardenability and high-strength aluminium alloys

Info

Publication number: WO2017215098A1
Application number: PCT/CN2016/094097
Authority: WO
Inventors: 许晓静; 朱金鑫; 丁清; 罗勇; 吴瑶; 谈成; 赵建吉; 张香丽; 杨帆; 张冲
Original assignee: 江苏大学
Priority date: 2016-06-16
Filing date: 2016-08-09
Publication date: 2017-12-21
Also published as: CN105908028B; CN105908028A

Abstract

Disclosed is a method for designing major components of high-hardenability and high-strength Al-Zn-Mg-Cu-series aluminum alloys. In order to obtain the high hardenability, the principle that the radius difference percentage sum of the main alloying element atoms and Al atoms is minimised as much as possible is followed, such that the atom radius difference percentage sum delta meets 0.059% ≤ δ ≤ 0.3044%. In order to obtain the high strength, the principles that the mass percentages of Zn and Mg in the alloy elements should meet Wt_Zn/Wt_Mg ≥ 4, and the mass percentage Wt_Mg of Mg should meet Wt_Mg ≥ 4 should be followed when the components are designed. An ideal method for designing the major components of the high-hardenability and high-strength Al-Zn-Mg-Cu-series aluminium alloys is obtained based on a large quantity of experiments and calculations, where the calculations are simple and convenient, the method is reliable, and the problem that the high-hardenability and high-strength Al-Zn-Mg-Cu-series aluminium alloy component design field lacks a recognised and accurate design method is solved.

Description

Method for designing main components of high-hardenability high-strength aluminum alloy

Technical field

The invention belongs to the field of metal alloys, and in particular relates to a method for designing a main component of a high-hardenability high-strength Al-Zn-Mg-Cu-based aluminum alloy.

Background technique

As the most widely used non-ferrous metal structural material in industrial applications, aluminum alloy has been widely used in aviation, aerospace, automobile, machinery manufacturing, shipbuilding and chemical engineering, and high-strength aluminum alloy is one of the higher strengths of aluminum alloy. Materials, demand is also increasing. The main body of the high-strength aluminum alloy is an Al-Zn-Mg-Cu system (referred to as 7000 series) alloy, which has good plasticity, toughness, stress corrosion resistance and processing property.

However, with the continuous development of aerospace vehicles, the development of the latest generation of aerospace vehicle model equipment, especially large-scale model equipment, has placed higher demands on high-strength aluminum alloys. Large-scale model equipment requires that its load-bearing members must be large and integrated. In order to ensure the core performance of large-scale load-bearing members, high-strength aluminum alloys must have better hardenability (quenching sensitivity). The composition design of 7075, 7050, 7055 alloy can only meet the requirements of the manufacture of structural parts with thickness less than 120mm. The difference in surface performance between the surface and the core of the product with thickness greater than 120mm is difficult to meet the demand of aerospace for ultra-large-section aluminum alloy materials. In order to solve this problem, it has been necessary to develop a low quench-sensitive alloy that can be applied to the production of large, integrated structural parts.

Chinese patent CN104004946A discloses a 690-730 MPa ultra high strength and high hardenability aluminum alloy and a preparation method thereof, and the single end hardening depth of the aluminum alloy can reach 80-100 mm. Chinese patent CN102703782A discloses an ultra-high strength and high hardenability Al-Zn-Mg-Cu alloy which has a hardness of up to 214 HV after quenching and a single-end hardenable depth of about 82 mm. However, both of these patents only give the main components of the alloy and do not provide a method for designing the two aluminum alloy compositions.

In recent years, the United States and Europe have developed the latest generation represented by 7136 (Al-8.9Zn-2.2Mg-2.2Cu-0.15Zr), etc., which has higher strength grade, more comprehensive performance and better hardenability. Aluminum alloys are at the forefront of the world, but so far, in addition to giving alloy composition, other technologies are still blocked in China.

Many research institutes and scholars have proposed their own viewpoints and methods for how to reduce the quenching sensitivity. For example, adjusting the distribution ratio of main alloying elements (Zn, Mg, Cu) and reducing quenching-sensitive alloying elements (Cu, Cr) The content of (etc.) further reduces and controls the content of impurity elements (Fe, Si) and the like. However, these viewpoints and methods have limitations at a certain level. In some cases, they are even contradictory. So far, there has not been a recognized better. The theory has emerged, and there is no method that can be used to guide the design of high-hardenability high-strength Al-Zn-Mg-Cu-based aluminum alloy components, which restricts the aerospace, weaponry and other industries to a certain extent. development of.

Summary of the invention

The object of the present invention is to solve the problem that the design theory and method of the Al-Zn-Mg-Cu high-hardenability high-strength Al-Zn-Mg-Cu-based aluminum alloy component are lacking, and the invention can be used for guiding high quenching. A method for designing a composition of a highly permeable Al-Zn-Mg-Cu aluminum alloy.

The technical solution of the present invention is:

A method for designing a main component of a high-hardenability high-strength Al-Zn-Mg-Cu-based aluminum alloy, characterized in that, when designing a main component of a high-hardenability high-strength Al-Zn-Mg-Cu-based aluminum alloy, Obtaining high hardenability. When designing the mass percentage of the main components of the Al-Zn-Mg-Cu-based aluminum alloy, first calculate the total difference δ of the radius difference of the main alloying element atoms Zn, Mg, Cu and Al atoms, so that the main The alloying element atomic Zn, Mg, Cu and Al atom radius difference sum δ satisfies 0.059% ≤ δ ≤ 0.344%; at the same time, the δ value is as small as possible within the above range, and the main alloying element Zn is found by substituting into the formula. The appropriate mass percentage of each of Mg and Cu in the alloy; in order to obtain high strength, the composition should also follow the following principle: the ratio of the mass percentage of Zn and Mg in the alloying element should satisfy 4 ≤ Wt _Zn / Wt _Mg ≤ 5.5, the mass percentage of _Mg Wt _Mg should satisfy 1.4% ≤ Wt _Mg ≤ 3.5%.

The sum of the atomic radius differences is δ, and the calculation formula is

Wt _Zn is the mass percentage of Zn in the aluminum alloy, Wt _Mg is the mass percentage of Mg in the aluminum alloy, and Wt _Cu is the mass percentage of Cu in the aluminum alloy.

The beneficial effects of the invention:

(1) A method for designing a main component of a high-hardenability high-strength Al-Zn-Mg-Cu-based aluminum alloy proposed by the present invention is a pioneering method at home and abroad, and proposes a new and reliable composition design method. The problem that there is no recognized and accurate design method in the design of high-hardenability high-strength Al-Zn-Mg-Cu-based aluminum alloy composition has been solved.

(2) The invention obtains an ideal method for designing the main components of the high-hardenability high-strength Al-Zn-Mg-Cu alloy by a large number of tests and calculations, and the calculation is simple and convenient, and the method is reliable.

(3) A method for designing a main component of a high-hardenability high-strength Al-Zn-Mg-Cu-based aluminum alloy proposed by the present invention, which greatly simplifies a high-hardenability high-strength Al-Zn-Mg-Cu system The composition of aluminum alloy is reliable and practical, which promotes the development of aerospace, weaponry and other industries to some extent.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a dimensional view of an end-hardened bar of the present invention.

Figure 2 is a photograph of the end quenching scene of the present invention.

Fig. 3 is a schematic view showing the wire cutting of the end-hardened bar of the present invention.

Figure 4 is a dimensional view of a tensile specimen of the present invention.

Fig. 5 is a graph showing the end-hardening of the hardness-distinguish end distance according to the first embodiment of the present invention.

Fig. 6 is a graph showing the end-hardening of the hardness-distinguish end distance of the second embodiment of the present invention.

Figure 7 is a graph showing the end-hardness of the hardness-distinguish end distance of the third embodiment of the present invention.

Figure 8 is a graph showing the end-hardness of the hardness-distinguish end distance of Comparative Example 1 of the present invention.

Figure 9 is a graph showing the end-hardening curves of the hardness-distinguish end distances of the first, second, third and comparative examples of the present invention.

detailed description

The embodiments and comparative examples of the present invention are described in detail below. The present embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation procedures are given, but the scope of protection of the present invention is not limited to the following. The embodiments described.

In order to illustrate a specific embodiment of the present invention, three typical 7000 series aluminum alloy compositions will be designed in accordance with the method provided by the present invention. To demonstrate the reliability and superiority of the method provided by the present invention, a comparative example will be provided. It is a 7075 alloy, and the composition design of the comparative alloy is contrary to the principle in the method provided by the present invention. The materials of all the above examples and comparative examples were subjected to the following material preparation, heat treatment, hardenability and tensile properties tests.

Experimental scheme for material preparation, heat treatment, hardenability and tensile properties:

(1) Material preparation:

1) The alloy is smelted according to the designed alloy composition, and the melting temperature is 850 ° C to 900 ° C.

2) The ingot is subjected to homogenization annealing treatment, the annealing mechanism is 470 ° C × 24 h, and then cooled to 200 ° C with the furnace, and finally air cooling is taken out.

3) The ingot is subjected to hot extrusion processing to obtain an extruded bar having a diameter of Φ30 mm. The extrusion ratio is 20:1.

4) The bar obtained in the previous step is processed into a tensile test bar of Φ 30 mm × 40 mm and an end-hardened bar as shown in (1).

(2) Heat treatment:

1) Strengthening solution treatment: The above-mentioned tensile test bar and end-hardened bar are subjected to enhanced solution treatment, and the solid solution mechanism is 470 ° C × 2 h + 480 ° C × 2 h + 490 ° C × 2 h.

2) quenching treatment: the terminal hardened bar after the above solid solution solidification is immediately quenched at the end, the quenching transfer time is not more than 10 seconds, the quenching medium is 20 ° C water, and the end quenching site is as shown in the figure. (2); the above-mentioned tensile test bar after strengthening solid solution is subjected to water quenching treatment, and the quenching transfer time is not more than 10 seconds, and the bar is directly immersed in clean water at 20 ° C until the bar is completely cooled.

3) Aging treatment: The quenched end quenched bar and the tensile test bar are subjected to aging treatment, wherein the 7085 and 7075 aluminum alloys are subjected to T76 aging treatment, and the aging mechanism is 121 ° C × 5 h + 153 ° C × 16 h, super The high-strength aluminum alloy adopts T6 aging, and the aging mechanism is 121 ° C × 24 h.

(3) Performance test:

1) Hardenability test: Using the method of wire cutting, the end quenched bar is cut according to the method shown in Figure (3), and the cut test piece is polished. Starting from the small end, the hardness is measured at intervals. The hardness is plotted as the end-hardening curve of the hardness-distance from the quenching end, and the hardness is reduced by 10% to the single-end hardening depth.

2) Tensile test: The wire was cut into a tensile test piece as shown in (4) by a wire cutting method, and a tensile test was performed to measure the tensile strength of the sample.

Embodiment 1

According to the method provided by the present invention, a 7085 aluminum alloy is designed, which is composed of Al-7Zn-1.41Mg-1.5Cu and a very small amount of 0.4% Zr and 0.025% Sr, which is called 7085-1 alloy. , substituting the mass percentage of Zn, Mg, and Cu into the formula

Calculated the total atomic radius difference of the alloy is δ=0.059%, Wt _Zn /Wt _Mg =4.96, and Wt _Mg =1.41%, satisfying 0.059%≤δ≤0.344%, 4≤Wt _Zn /Wt _Mg ≤5.5,1.4 %≤Wt _Mg ≤3.5%, the alloy was subjected to the above materials preparation, heat treatment, hardenability and tensile properties test, and the end-hardening curve of hardness-disturbing end distance was shown in Fig. (5), and analyzed by 7085. The single-end hardening depth of the -1 aluminum alloy is greater than 140 mm, so its hardenability is at least 280 mm, the hardenability is very high, and the tensile strength is 518.25 MPa.

Embodiment 2

According to the method provided by the present invention, a 7085 aluminum alloy is designed, which is composed of Al-7.48Zn-1.51Mg-1.42Cu and a very small amount of 0.4% Zr and 0.025% Sr, which is called 7085-2. Alloy, the mass percentage of Zn, Mg, Cu is substituted into the formula

Calculated the total atomic radius difference of the alloy is δ=0.0959%, Wt _Zn /Wt _Mg =4.95, and Wt _Mg =1.51%, satisfying 0.059%≤δ≤0.344%, 4≤Wt _Zn /Wt _Mg ≤5.5,1.4 %≤Wt _Mg ≤3.5%, the alloy was subjected to the above materials preparation, heat treatment, hardenability and tensile properties test, and the end-hardening curve of hardness-disturbing end distance was plotted as shown in Fig. (6). The -2 aluminum alloy has a single-end hardenability of more than 140 mm, so its hardenability is at least 280 mm, the hardenability is very high, and the tensile strength is 517 MPa.

Embodiment 3

According to the method provided by the invention, a 7085 aluminum alloy is designed, which has the composition of Al-7.95Zn-1.8Mg-1.59Cu and a very small amount of 0.4% Zr and 0.025% Sr, which is called 7085-3. Alloy, the mass percentage of Zn, Mg, Cu is substituted into the formula

Calculated the total atomic radius difference of the alloy is δ=0.1833%, Wt _Zn /Wt _Mg =4.4, and Wt _Mg =1.8%, satisfying 0.059%≤δ≤0.344%, 4≤Wt _Zn /Wt _Mg ≤5.5,1.4 %≤Wt _Mg ≤3.5%, the alloy was subjected to the above materials preparation, heat treatment, hardenability and tensile properties test, and the end-hardening curve of hardness-disturbing end distance was plotted as shown in Fig. (7). The -1 aluminum alloy has a single-end hardened depth of more than 140 mm, so its hardenability is at least 280 mm, the hardenability is very high, and the tensile strength is 542.25 MPa.

Comparative example one

A 7075 aluminum alloy was designed, which was made of Al-5.6Zn-2.5Mg-1.6Cu. The alloy was prepared by the above materials and heat-treated to prepare experimental samples. The hardenability and tensile properties of the alloy were tested. Zn, Mg , the mass percentage of Cu is substituted into the formula

Calculated the total atomic radius difference percentage of the alloy δ = 0.00648, Wt _Zn / Wt _Mg = 2.24, and Wt _Mg = 2.5%, does not meet the conditions of 0.059% ≤ δ ≤ 0.344%, according to the results of the hardenability test, draw The end-hardening curve of the hardness-distance from the quenching end is shown in Fig. (8). The single-end hardening depth of the 7075 aluminum alloy is about 36 mm, so the hardenability is 72 mm, and the hardenability is not good. The condition of 4 ≤ Wt _Zn /Wt _Mg ≤ 5.5 is not satisfied, and the tensile strength is 505 MPa, and the tensile strength thereof is not high.

We compare Examples I, II, III and Comparative Example 1. The compositions of the 7085-1, 7085-2, and 7085-3 alloys provided by the three examples are all designed according to the principles and methods provided by the present invention. The hardenability is very high, while the composition of the comparative one 7075 alloy is inconsistent with the principle provided by the present invention, the hardenability is very low, and the strength is also the lowest among the alloys. The hardness of the four alloys - the quenching end The end quenching curve of the distance is plotted in a graph. As shown in Fig. (9), it can be found that the 7805 alloy provided according to the present invention has a hardenability of at least 3.8 times that of the 7075 alloy. The rationality and superiority of the composition design method provided by the present invention can be seen.

Claims

A method for designing a main component of a high-hardenability high-strength aluminum alloy, wherein the high-strength aluminum alloy is an Al-Zn-Mg-Cu-based aluminum alloy, characterized in that in order to obtain high hardenability, Al-Zn is designed. - For the mass percentage of the main component of the -Mg-Cu-based aluminum alloy, first calculate the total difference δ of the radius difference between the main alloying element atoms Zn, Mg, Cu and Al atoms, so that the main alloying element atoms Zn, Mg, Cu and Al The total δ of the radius difference of the atom satisfies 0.059% ≤ δ ≤ 0.344%; at the same time, the smaller the δ value is in the above range, the smaller the δ value is calculated by the formula, the main alloying elements Zn, Mg, and Cu are found in the alloy. The appropriate percentage of mass; in order to obtain high strength, the composition should also follow the following principle. The ratio of the mass percentage of Zn and Mg in the alloying element should satisfy 4 ≤ Wt Zn /Wt Mg ≤ 5.5, and the mass percentage of Mg Wt Mg should satisfy 1.4. % ≤ Wt Mg ≤ 3.5%.
A method for designing a main component of a high-hardenability high-strength aluminum alloy according to claim 1, wherein said main alloying element atom Zn, Mg, Cu and Al atom have a total difference in radius δ, Its calculation formula is
Wt Zn is the mass percentage of Zn in the aluminum alloy, Wt Mg is the mass percentage of Mg in the aluminum alloy, and Wt Cu is the mass percentage of Cu in the aluminum alloy.