Anti-exfoliation corrosion high-strength aluminum-zinc-magnesium-copper alloy and heat treatment process

A technology of exfoliation corrosion and aluminum-zinc-magnesium, which is applied in the fields of exfoliation corrosion-resistant high-strength aluminum-zinc-magnesium-copper alloy and heat treatment process, aluminum alloy and heat treatment process, and can solve problems such as unfavorable industrial production applications, low stress corrosion resistance, complex aging process, etc. problems, to achieve the effect of short aging time, high production efficiency and simple aging process

Active Publication Date: 2014-03-05
CENT SOUTH UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the three-stage aging system also has fatal shortcomings. One is that the electrical conductivity is lower than that of T73 and T76 states, and low electrical conductivity means lower stress corrosion resistance; the second is that the aging process is too complicated, which is not conducive to large-scale industrial production. application
[0005] In order to overcome the three-stage aging system (RRA) and the low electrical conductivity after T76 treatment and the low strength after T73 treatment, and at the same time considering the applicability of industrial production, it is urgent to develop a new aging treatment process to ensure the conductivity of the alloy. Improve the tensile strength and toughness of the alloy under the premise that the rate and exfoliation corrosion resistance do not decrease or the decrease is small

Method used

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  • Anti-exfoliation corrosion high-strength aluminum-zinc-magnesium-copper alloy and heat treatment process
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  • Anti-exfoliation corrosion high-strength aluminum-zinc-magnesium-copper alloy and heat treatment process

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Experimental program
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Embodiment 1

[0040] The composition of alloy 1 is (weight percent): Zn: 6.1%, Mg: 2.49%, Cu: 1.9%, Cr: 0.25%, Ti: 0.04%, and the balance is Al. The weight ratio of Zn / Mg in this alloy is 2.45; 1.5h solution treatment at 470°C, 3% pre-deformation after water quenching, then aging at 122°C for 3 hours, followed by aging at 165°C for 12 hours. Various performance indicators obtained after this treatment: tensile strength 520MPa, yield strength 468Mpa, elongation 12.8%, electrical conductivity 39.9%IACS. According to the ASTM G34-01 standard, the corrosion grade for exfoliation corrosion evaluation is P, that is, pitting corrosion. There are discontinuous corrosion points on the surface of the sample, see Figure 2.

Embodiment 2

[0042] The composition of alloy 2 is (weight percent): Zn: 5.5%, Mg: 2.3%, Cu: 1.5%, Cr: 0.21%, Ti: 0.03%, and the balance is Al. The weight ratio of Zn / Mg in this alloy is 2.39; solution treatment is carried out at 470°C for 1h, and 2% pre-deformation is carried out immediately after water quenching, then aged at 122°C for 3 hours, followed by aging at 170°C for 10 hours. Various performance indicators obtained after this treatment: tensile strength 509Mpa, yield strength 441Mpa, elongation 12.1%, electrical conductivity 40.1%IACS, corrosion grade P.

Embodiment 3

[0044] Alloy 2 was solution treated at 465°C for 2 hours, pre-deformed by 3% immediately after water quenching, and then aged at 122°C for 4 hours, followed by aging at 165°C for 12 hours. Various performance indicators obtained after this treatment: tensile strength 501Mpa, yield strength 429Mpa, elongation 12.2%, electrical conductivity 42%IACS, corrosion grade P.

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Abstract

The invention discloses an anti-exfoliation corrosion high-strength aluminum-zinc-magnesium-copper alloy and a heat treatment process. The heat treatment process comprises the steps of controlling the Zn content and Zn/Mg weight ratio in the alloy; performing solution treatment and water quenching on the alloy, and performing pre-deformation; then performing first-level low-temperature aging at 122-132 DEG C and second-level aging at 163-180 DEG C. The alloy has relatively high strength and toughness, the self-corrosion current of the alloy in a corrosive medium is reduced, and the corrosion resistance of the alloy is improved. In the alloy disclosed by the invention, the ratio of the components is reasonable, the process is simple, the production period is short, and the operation is convenient; the total aging time is shortened to 10-15 hours from the traditional two-level aging time 25-30 hours, and the production efficiency is high; the alloy has the performance characteristics of high strength, good toughness and exfoliation corrosion resistance, and is suitable for the industrial application of the fields of aerospace and the like.

Description

technical field [0001] The invention relates to an aluminum alloy and a heat treatment process, in particular to an exfoliation corrosion-resistant high-strength aluminum-zinc-magnesium-copper alloy and a heat treatment process, and belongs to the technical field of nonferrous metal materials. Background technique [0002] Al-Zn-Mg-Cu alloy is one of the important structural materials in the field of aviation and aerospace. This alloy has a tendency to exfoliate and corrode during long-term use, which will cause great damage to the strength, plasticity, and fatigue properties of the alloy. Serious Shorten the service life of aluminum alloy. [0003] Exfoliation corrosion has the characteristics of intergranular corrosion and stress corrosion, and its corrosion rate is controlled by alloy composition and grain boundary equilibrium phase distribution. In Al-Zn-Mg-Cu alloy, the higher copper content in the grain boundary equilibrium phase is beneficial to the improvement of th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C21/10C22F1/053
Inventor 刘志义林亮华杨荣先陈来陈旭
Owner CENT SOUTH UNIV
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