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A kind of ultrahigh-strength low-stress aluminum alloy pipe and its preparation method

An ultra-high-strength, aluminum alloy tube technology, applied in the field of aluminum alloy preparation, can solve problems such as performance loss, achieve residual stress elimination, improve mechanical properties, and achieve significant effects

Active Publication Date: 2020-04-17
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing cryogenic treatment method is ideal for residual stress relief of aluminum alloys, but it will cause performance loss
Therefore, at present, there is no process that has the characteristics of high efficiency, practicality, low loss and easy promotion in the process of reducing the residual stress of aluminum alloy.

Method used

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  • A kind of ultrahigh-strength low-stress aluminum alloy pipe and its preparation method
  • A kind of ultrahigh-strength low-stress aluminum alloy pipe and its preparation method
  • A kind of ultrahigh-strength low-stress aluminum alloy pipe and its preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] A method for preparing an ultra-high-strength and low-stress aluminum alloy pipe, comprising the steps of:

[0039] (1) Insulate the extruded pipe at a solid solution holding temperature of 475°C for 4 hours, and immediately transfer it to room temperature water for quenching and cooling to room temperature.

[0040](2) Put the extruded pipe obtained in step (1) into a cryogenic treatment device, cool it to -200°C at a rate of 25°C / s, keep it warm for 40 minutes, and quickly transfer it to an oil tank after taking it out. The oil temperature is 160°C. The time is 20 minutes, and the heating rate is 35°C / min; after taking it out, put it into the cryogenic treatment device quickly, cool it to -200°C at a speed of 25°C / s, keep it for 20 minutes, and pre-stretch after taking it out, the stretching amount is 1.0% ; After stretching, put it into the cryogenic treatment device, cool it to -200°C at a rate of 25°C / s, keep it warm for 30 minutes, and quickly transfer it to an oi...

Embodiment 2

[0044] A method for preparing an ultra-high-strength and low-stress aluminum alloy pipe, comprising the steps of:

[0045] (1) Heat the extruded pipe at a solid solution holding temperature of 475°C for 4 hours, and then perform step-by-step quenching, wherein: the first stage of PAG quenching: the temperature of the extruded pipe is cooled from 475°C to 420°C, and the temperature of the PAG solution is 30°C. The rate is 15°C / s; the second stage water quenching: cool the extruded pipe after the first stage quenching to 230°C, the water temperature is 10-60°C, and the cooling rate is 80°C / s; the third stage water quenching: the second stage The extruded pipe after quenching is cooled to 60°C, the water temperature is 80°C, and the cooling rate is 10°C / s; this step ensures that the residual stress of the extruded pipe reaches the minimum after quenching and does not bend;

[0046] (2) After 1h, pre-stretch the extruded pipe obtained in step (1) until the material yields, then st...

Embodiment 3

[0050] A method for preparing an ultra-high-strength and low-stress aluminum alloy pipe, comprising the steps of:

[0051] (1) is identical with the step (1) of embodiment 2;

[0052] (2) is identical with the step (2) of embodiment 2;

[0053] (3) Put the extruded pipe obtained in step (2) into a cryogenic treatment device, cool it to -200°C at a rate of 25°C / s, keep it warm for 40 minutes, and quickly transfer it to an oil tank after taking it out. 30min, the heating rate is 35°C / min; after taking it out, put it into the cryogenic treatment device quickly, cool it to -200°C at a speed of 25°C / s, keep it warm for 20min, and pre-stretch after taking it out, the stretching amount is 1.0%; After stretching, put it into a cryogenic treatment device, cool it to -200°C at a rate of 25°C / s, keep it warm for 30 minutes, and quickly transfer it to an oil tank after taking it out. The oil temperature is 80°C, and the storage time is 1200 minutes. min; take it out and carry out pre-st...

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Abstract

The invention particularly relates to an ultra-high strength and low stress aluminum alloy pipe and a preparation method thereof. The ultra-high strength and low stress aluminum alloy pipe is a 7xxx series aluminum alloy pipe, and a grain is in a long strip shape and has the characteristics that the length is 30 to 50mu m, the tensile strength is 618 to 748MPa, the yield strength is 568 to 702MPaand the ellipticity is 0.02 to 0.15mm. The preparation method comprises multistage quenching, slow stretching and multi-time cryogenic treatment. The mechanical properties of the aluminum alloy pipe obtained by the invention are significantly improved; compared with a conventional 7xxx aluminum alloy pipe, the aluminum alloy pipe obtained by the invention has the advantage that the tensile strength can be improved by about 12 percent at most. In addition, residual stress in a product prepared by the invention can be effectively eliminated and the deformation degree can be reduced to 1 / 25 thatof a conventional pipe at most, which show that the reduction effect of the residual stress is obvious; besides, the grain size of the product disclosed by the invention is effectively refined and thegrain length is only about half that of a conventional product.

Description

technical field [0001] The invention belongs to the technical field of aluminum alloy preparation, and in particular relates to an ultra-high-strength and low-stress aluminum alloy pipe and a preparation method thereof. Background technique [0002] Aluminum and aluminum alloys have excellent properties such as low density, high specific strength, and corrosion resistance, and are easy to process and have abundant reserves. They have been widely used in aerospace, machinery, and automobile manufacturing industries. However, aluminum alloy components obtain high strength and high toughness during the rapid quenching process. It causes a huge temperature difference between the surface and the interior, resulting in a large residual stress inside the component. During the heat treatment process of high-strength aluminum alloy, especially the quenching process, it is inevitable to cause a large residual stress inside the structure. Sometimes in order to reduce the residual str...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C21/10C22F1/053
CPCC22C21/10C22F1/002C22F1/053
Inventor 李承波周旺李建湘邓运来张新明
Owner CENT SOUTH UNIV
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