CN110894580A

CN110894580A - A heat treatment method for improving the strength and toughness of an annealed aluminum-copper alloy sheet

Info

Publication number: CN110894580A
Application number: CN201811059703.6A
Authority: CN
Inventors: 蔺永诚; 朱旭昊; 姜玉强; 吴瞧
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2018-09-12
Filing date: 2018-09-12
Publication date: 2020-03-20

Abstract

本发明公开了一种提高退火态铝铜合金板材强度和韧性的热处理方法。其方法包括以下步骤：(1)将退火态的铝铜合金板材进行固溶处理，然后水淬；(2)对固溶后的铝铜合金板材进行自然时效，自然时效时间50小时～80小时；(3)对自然时效后的铝铜合金板材进行预拉伸变形，预拉伸变形过程包括两个阶段，第一阶段的预变形量为5％～15％，第二阶段的预变形量为1％～5％；(4)对预变形处理后的铝铜合金板材进行人工时效。本发明提出的方法可以有效地提高铝铜合金板材的强度和韧性。The invention discloses a heat treatment method for improving the strength and toughness of an annealed aluminum-copper alloy plate. The method includes the following steps: (1) carrying out solution treatment on the annealed aluminum-copper alloy plate, and then water quenching; (2) performing natural aging on the solid-solution aluminum-copper alloy plate, and the natural aging time is 50 hours to 80 hours (3) Pre-stretching and deforming the aluminum-copper alloy sheet after natural aging. The pre-stretching deformation process includes two stages. The pre-deformation in the first stage is 5% to 15%, and the pre-deformation in the second stage is 1% to 5%; (4) artificial aging is performed on the pre-deformed aluminum-copper alloy sheet. The method proposed by the invention can effectively improve the strength and toughness of the aluminum-copper alloy sheet.

Description

Heat treatment method for improving strength and toughness of annealed aluminum-copper alloy plate

Technical Field

The invention belongs to the technical field of heat treatment of aluminum alloy materials, and relates to a heat treatment method for improving the strength and toughness of an annealed aluminum-copper alloy plate.

Background

The aluminum-copper alloy is widely applied to the aerospace and rail transit industries due to the excellent comprehensive performance of the aluminum-copper alloy. The alloy has small density and good ductility, and is convenient for mechanical processing and plastic forming. The alloy matrix is

The second phase is mainlyAl₂A Cu phase.

At present, aluminum-copper alloy plates produced in China are mostly formed by rolling. The rolled aluminum-copper alloy plate can generate residual stress, and the residual stress generated in the rolling process needs to be eliminated through an annealing process. Although the annealed aluminum-copper alloy plate has better room-temperature tensile toughness, the tensile strength is less than 200 MPa, the yield strength is less than 100 MPa, and the service requirement of the aluminum-copper alloy plate is far lower than that of an aerospace aluminum-copper alloy plate. Therefore, a reasonable heat treatment process is urgently needed to comprehensively improve the strength and toughness of the annealed aluminum-copper alloy plate.

Disclosure of Invention

The invention aims to provide a heat treatment method for improving the strength and toughness of an annealed aluminum-copper alloy plate.

The scheme for solving the problems is as follows:

step 1: carrying out solution treatment on the annealed aluminum-copper alloy plate, wherein the solution temperature is 520-560 ℃, the solution time is 25-55 minutes, then quenching, the quenching medium is room temperature water, and the quenching transfer time is less than 5 seconds;

step 2: naturally aging the aluminum-copper alloy plate after solid solution for 50-80 hours;

and step 3: performing pre-stretching deformation on the naturally aged aluminum-copper alloy plate, wherein the pre-stretching deformation process comprises two stages, the pre-deformation amount of the first stage is 5% -15%, and the pre-deformation amount of the second stage is 1% -5%;

and 4, step 4: and carrying out artificial aging on the pre-deformed aluminum-copper alloy plate, wherein the artificial aging temperature is 130-190 ℃, and the artificial aging time is 6-18 hours.

The invention has the beneficial effects that: first, coarse Al2Cu phase in the starting structure of the aluminum-copper alloy sheet material is dissolved in the aluminum alloy matrix by solution treatment. Secondly, the quenching stress in the solid solution quenching process is reduced through natural aging, and the residual deformation of the plate is reduced. Then, the dislocation density and deformation energy storage in the aluminum-copper alloy plate are improved through pre-deformation. Finally, regulating and controlling the size and distribution of the precipitated phase through artificial aging, thereby obtaining the aluminum-copper alloy plate with high strength and good toughness.

Drawings

FIG. 1 shows an initial structure of an aluminum-copper alloy plate;

FIG. 2 is a room temperature uniaxial tensile stress-strain curve of an annealed aluminum-copper alloy sheet;

FIG. 3 is a room temperature uniaxial tensile stress-strain curve of the aluminum-copper alloy sheet obtained in example 1;

FIG. 4 is a room temperature uniaxial tensile stress-strain curve of the aluminum-copper alloy sheet obtained by comparative experiment 1;

FIG. 5 is a room temperature uniaxial tensile stress strain curve of the aluminum-copper alloy sheet obtained by comparative experiment 2.

Detailed Description

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

The invention relates to a heat treatment method for improving the strength and toughness of an annealed aluminum-copper alloy plate, wherein the initial components of the annealed aluminum-copper alloy plate used in the embodiment 1 are shown in table 1, and the initial microstructure is shown in fig. 1. The aluminum alloy matrix has a uniform distribution of casting phases distributed therein, the volume fraction of the casting phases being about 7.83%. As shown in FIG. 2, the room temperature uniaxial tensile property of the annealed aluminum-copper alloy sheet is that the tensile strength perpendicular to the rolling direction is only 173.96 MPa, the yield strength is only 71.44MPa, and the sheet strength is seriously insufficient.

Table 1 composition (wt.%) of aluminum-copper alloy sheet used in example 1 of the present invention

Cu

Zr

V

Mn

Si

Fe

Ti

Al

5.00~7.00

0.08~0.15

<0.1

0.25~0.45

<0.08

0.12~0.25

Bal.

85.00~90.00

Example 1

Step 1: carrying out solid solution treatment on the aluminum-copper alloy plate, wherein the solid solution temperature is 535 ℃, the solid solution time is 35 minutes, then quenching is carried out, the quenching medium is room temperature water, and the quenching transfer time is not more than 5 seconds;

step 2: naturally aging the aluminum-copper alloy plate after solid solution for 50 hours;

and step 3: performing pre-stretching deformation on the naturally aged aluminum-copper alloy plate, wherein the pre-stretching deformation process comprises two stages, the pre-deformation amount of the first stage is 9%, and the pre-deformation amount of the second stage is 1%;

and 4, step 4: and (3) carrying out artificial aging on the pre-deformed aluminum-copper alloy plate, wherein the artificial aging temperature is 145 ℃, and the artificial aging time is 12 hours.

The room temperature uniaxial tensile stress strain curve of the aluminum-copper alloy sheet obtained by the process of example 1 is shown in fig. 3. The tensile strength of the aluminum-copper alloy plate reaches 536.59 MPa, the yield strength reaches 347.96 MPa, and the elongation is 9.46%. The strength and toughness of the alloy all meet the service requirements of aerospace aluminum-copper alloy. To further demonstrate the superiority of the method of the invention, comparative experiments 1 and 2 were carried out. Comparative experiment 1 only performed step 3 of example 1, and comparative experiment 2 only performed steps 1, 2 and 4 of example 1.

The room temperature uniaxial tensile stress strain curve of the aluminum-copper alloy sheet obtained by carrying out the comparative experiment 1 is shown in fig. 4. As can be seen from fig. 3 and 4, the aluminum-copper alloy sheet obtained in example 1 has a 2.94-fold increase in tensile strength and a 2.15-fold increase in yield strength, as compared to comparative experiment 1. Therefore, the strength of the aluminum-copper alloy plate can be obviously improved by the processes such as solution aging and the like.

The room temperature uniaxial tensile stress strain curve of the aluminum-copper alloy sheet obtained by carrying out the comparative experiment 2 is shown in fig. 5. As can be seen from fig. 3 and 5, the aluminum alloy sheet obtained in example 1 has high strength and good toughness. Therefore, the pre-deformation process can effectively improve the toughness of the aluminum-copper alloy plate.

While the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments, which are exemplary, not restrictive, and any invention that does not exceed the scope of the claims is intended to be protected.

Claims

1. a heat treatment method improving the strength and toughness of annealed aluminum-copper alloy sheet, is characterized in that: the content range of Al element in the chemical composition of described annealed aluminum-copper alloy sheet is 85.00%～90.00%, the content of Cu element The range is 5.00%~7.00%, the content range of Mn element is 0.25%~0.45%, the content range of Fe element is 0.12%~0.25%, the content range of Zr element is 0.08%~0.15%, and the content of V element is less than 0.1 %, the content of Si element is less than 0.08%, and the rest is Ti element. This method can improve the strength and toughness of the aluminum-copper alloy sheet by adjusting the heat treatment process parameters and the amount of pre-stretching deformation, including the following steps:

Step 1: Perform solution treatment on the annealed aluminum-copper alloy sheet, the solution temperature is 520~560°C, the solution time is 25 minutes to 55 minutes, and then quenched, the quenching medium is room temperature water, and the quenching transfer time is less than 5 seconds ;

Step 2: Perform natural aging on the aluminum-copper alloy sheet after solid solution, and the natural aging time is 50 hours to 80 hours;

Step 3: Pre-stretching and deforming the aluminum-copper alloy sheet after natural aging. The pre-stretching deformation process includes two stages. The pre-deformation in the first stage is 5% to 15%, and the pre-deformation in the second stage is 1%~5%;

Step 4: Perform artificial aging on the pre-deformed aluminum-copper alloy sheet, the artificial aging temperature is 130~190°C, and the artificial aging time is 6 hours~18 hours.