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Staged homogenization heat treatment method for improving microstructure and performances of Zr-containing 7xxx aluminum alloy

A homogeneous heat treatment and aluminum alloy technology, applied in the homogeneous heat treatment of 7xxx series aluminum alloy structure and properties, the field of heat treatment of 7xxx series (Al-Zn-Mg-Cu) aluminum alloys, can solve the problem that is difficult to control, microstructure Imperfect, uneven distribution, etc.

Active Publication Date: 2014-05-28
GRIMAT ENG INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional homogenization heat treatment method mostly adopts a single-stage homogenization heat treatment process at around 470 °C for 24~72 hours. The structure of the Zr-containing 7xxx series aluminum alloy treated by this method is not ideal, the second phase is not fully dissolved, and the Al 3 Zr particle size is coarse, unevenly distributed, and loses the effect of pinning grain boundaries; if the temperature continues to rise, overburning will easily occur and the material will be scrapped
In recent years, domestic and foreign studies have carried out related double-stage or multi-stage homogenization heat treatment methods, most of which are graded treatment in the range of 440~490°C for 24~72h. The 7xxx series aluminum alloys containing Zr treated by this method The structure is still not very ideal, either the second phase is fully dissolved back, the grains are thick and large, or the Al 3 Zr is uniform and fine, the second phase is not fully dissolved, and some methods are not easy to control and prone to overburning

Method used

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  • Staged homogenization heat treatment method for improving microstructure and performances of Zr-containing 7xxx aluminum alloy
  • Staged homogenization heat treatment method for improving microstructure and performances of Zr-containing 7xxx aluminum alloy
  • Staged homogenization heat treatment method for improving microstructure and performances of Zr-containing 7xxx aluminum alloy

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] This example takes the 7050 / 7150 alloy (Al-6.4Zn-2.3Mg-2.2Cu-0.12Zr (wt%)) 280mm thick flat ingot as the research object. The 7050 / 7150 alloy ingots were prepared by semi-continuous casting under industrial conditions. Block samples were cut from the ingots and subjected to homogenization heat treatment tests of different schemes. The homogenization heat treatment system is shown in Table 1. Immediately after the homogenization treatment is completed, water cooling is performed to obtain the characteristic morphology of the structure reflecting the homogenization effect of the alloy, so as to avoid the influence of a large amount of precipitation of precipitation during the slow cooling process of the alloy and the second relative result analysis. Analytical tests were carried out in accordance with relevant standards, and the samples subjected to different homogenization treatments were subjected to tissue analysis. The results are shown in Table 2.

[0037] Table 1 70...

Embodiment 2

[0044] In this example, a round ingot of 7449 alloy (Al-8.2Zn-2.2Mg-1.8Cu-0.14Zr (wt%)) φ630mm is taken as the research object. The 7449 alloy ingot was prepared by semi-continuous casting under industrial conditions. Block samples were cut from the ingot and subjected to homogenization heat treatment tests of different schemes. The homogenization heat treatment system is shown in Table 3. Immediately after the homogenization treatment is completed, water cooling is performed to obtain the characteristic morphology of the structure reflecting the homogenization effect of the alloy, so as to avoid the influence of a large amount of precipitation of precipitation during the slow cooling process of the alloy and the second relative result analysis. Analytical tests were carried out in accordance with relevant standards, and the samples subjected to different homogenization treatments were subjected to tissue analysis. The results are shown in Table 4.

[0045] Table 3 7449 alloy ...

Embodiment 3

[0053] This example takes 7B85 alloy (Al-7.5Zn-1.7Mg-1.4Cu-0.12Zr (wt%)) 280mm thick slab as the research object. The 7B85 alloy ingot was prepared by semi-continuous casting under industrial conditions. Block samples were cut from the ingot and subjected to homogenization heat treatment tests of different schemes. The homogenization heat treatment system is shown in Table 5. Immediately after the homogenization treatment is completed, water cooling is performed to obtain the characteristic morphology of the structure reflecting the homogenization effect of the alloy, so as to avoid the influence of a large amount of precipitation of precipitation during the slow cooling process of the alloy and the second relative result analysis. Analytical tests were carried out in accordance with relevant standards, and the samples subjected to different homogenization treatments were subjected to tissue analysis, and the results are shown in Table 6.

[0054] Table 5 7B85 alloy homogeniza...

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Abstract

The invention discloses a staged homogenization heat treatment method for improving a microstructure and performances of a Zr-containing 7xxx aluminum alloy. The staged homogenization heat treatment method comprises the following steps of 1, in a stage I, putting an alloy ingot into a heat treatment heating furnace, heating to a temperature of T1 from a room temperature and carrying out heat preservation, wherein treatment time spent in the stage I is t1; T1 is greater than or equal to 300 DEG C and less than or equal to 450 DEG C; and t1 is greater than or equal to 1 hour and less than or equal to 14 hours, 2, in a stage II, heating to a temperature of T2 from the temperature of T1 and carrying out heat preservation, wherein treatment time spent in the stage II is t2; T2 is greater than or equal to 460 DEG C and less than or equal to 480 DEG C; and t2 is greater than or equal to 1 hour and less than or equal to 48 hours, 3, in a stage III, heating to a temperature of T3 from the temperature of T2 and carrying out heat preservation, wherein treatment time spent in the stage III is t3; T3 is greater than or equal to 480 DEG C and less than or equal to 510 DEG C; and t3 is greater than or equal to 1 hour and less than or equal to 16 hours, and cooling the treated alloy ingot to the room temperature from the temperature of T3. According to alloy ingredient characteristics, the staged homogenization heat treatment method can fully promote precipitation of uniform and fine disperse phases and re-dissolution of a soluble second phase in alloy homogenization heat treatment without alloy overburning, and can effectively inhibit growth of a grain structure thereby obviously improving a microstructure and integrated performances of an alloy. The staged homogenization heat treatment method has the characteristics of strong operationality, accurate control and good economical efficiency and feasibility.

Description

technical field [0001] The invention relates to the technical field of heat treatment of aluminum alloys, in particular to a heat treatment method for 7xxx series (Al-Zn-Mg-Cu) aluminum alloys; more particularly, the invention relates to a stage for improving the microstructure and properties of Zr-containing 7xxx series aluminum alloys Homogenization heat treatment method. Background technique [0002] 7xxx series (Al-Zn-Mg-Cu series) aluminum alloys are typical heat-treatable-strengthened deformable aluminum alloys. The homogenization treatment of alloy ingots (or castings) is the key process link to obtain ideal uniform structure and excellent comprehensive properties. one. The alloy ingot needs to undergo deformation processing and solution aging treatment, so that the alloy has a dense structure and an ideal microstructure, so that it has excellent comprehensive properties. However, the aluminum alloy ingots produced by traditional casting and semi-continuous casting ...

Claims

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Application Information

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IPC IPC(8): C22F1/053C22C21/10
Inventor 李锡武熊柏青张永安李志辉刘红伟王锋朱宝宏
Owner GRIMAT ENG INST CO LTD
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