阅读说明：本技术 一种铝锂合金的双级均匀化退火工艺 (Two-stage homogenization annealing process of aluminum-lithium alloy ) 是由 蒋呐 饶茂 王燕 姚勇 高鑫 于 2020-12-28 设计创作，主要内容包括：本发明提供了一种铝锂合金的双级均匀化退火工艺,包括：将铝锂合金铸锭在495～505℃进行一级均匀化退火,然后在515～525℃进行二级均匀化退火。本发明提供的均匀化退火工艺采用双级均热的方法,最大程度消除铝锂合金铸锭中的结晶相残留,使铸锭获得理想的组织和成分的均匀性。(The invention provides a two-stage homogenization annealing process of an aluminum-lithium alloy, which comprises the following steps: and carrying out primary homogenizing annealing on the aluminum-lithium alloy cast ingot at 495-505 ℃, and then carrying out secondary homogenizing annealing at 515-525 ℃. The homogenization annealing process provided by the invention adopts a two-stage soaking method, so that the crystal phase residue in the aluminum-lithium alloy ingot is eliminated to the greatest extent, and the ingot can obtain ideal tissue and component uniformity.)

1. A two-stage homogenization annealing process of an aluminum-lithium alloy comprises the following steps:

and carrying out primary homogenizing annealing on the aluminum-lithium alloy cast ingot at 495-505 ℃, and then carrying out secondary homogenizing annealing at 515-525 ℃.

2. The method according to claim 1, wherein the temperature of the primary homogenizing annealing is 500-505 ℃.

3. The method of claim 1, wherein the primary homogenizing anneal is performed for 16 hours.

4. The method according to claim 1, wherein the temperature of the secondary homogenizing annealing is 520-525 ℃.

5. The method of claim 1, wherein the secondary homogenizing anneal is for a period of 24 hours.

6. The method of claim 1, wherein the aluminum-lithium alloy is 2099 aluminum-lithium alloy, and wherein the 2099 aluminum-lithium alloy comprises the following components:

2.4 to 3.0 wt% of Cu;

1.6-2.0 wt% of Li;

0.4 to 1.0 wt% of Zn;

0.1 to 0.5 wt% of Mg;

0.1 to 0.5 wt% Mn;

0.05 to 0.12 wt% of Zr;

the balance being Al.

Technical Field

The invention relates to the technical field of aluminum alloy heat treatment, in particular to a two-stage homogenization annealing process of an aluminum-lithium alloy.

Background

The aluminum-lithium alloy is an aluminum alloy added with 1-2 wt% of lithium element, has lower density and higher rigidity, and has better market prospect in the fields of aviation and aerospace. 2099 the aluminum lithium alloy section bar has installed application on a C919 large commercial passenger plane independently developed in China. At present, China flies to rely on import of the product from the United states to meet the installation requirement. However, the aluminum lithium alloy belongs to a confidential material, the united states has extremely strict blockade of key process parameters, and the process technology details of united states 2099 aluminum lithium alloy homogenization annealing cannot be obtained at present. In order to successfully produce 2099 aluminum lithium alloy section, firstly, a homogenization annealing process of an ingot casting needs to be overcome, and the process technology belongs to a blank technology in China.

Disclosure of Invention

In view of this, the present invention provides a two-stage homogenization annealing process for 2099 aluminum lithium alloy, which employs a two-stage soaking method to eliminate the crystalline phase residue in the ingot to the maximum extent, so that the ingot obtains ideal structure and component uniformity.

The invention provides a 2099 aluminum lithium alloy two-stage homogenization annealing process, which comprises the following steps:

and carrying out primary homogenizing annealing on the cast ingot at 495-505 ℃, and then carrying out secondary homogenizing annealing at 515-525 ℃.

Preferably, the temperature of the primary homogenizing annealing is 500-505 ℃.

Preferably, the time of the primary homogenizing annealing is 16 h.

Preferably, the temperature of the secondary homogenizing annealing is 520-525 ℃.

Preferably, the time of the secondary homogenizing annealing is 24 hours.

The 2099 aluminum lithium alloy comprises the following components:

2.4 to 3.0 wt% of Cu;

1.6-2.0 wt% of Li;

0.4 to 1.0 wt% of Zn;

0.1 to 0.5 wt% of Mg;

0.1 to 0.5 wt% Mn;

0.05 to 0.12 wt% of Zr;

the balance being Al.

The size of the 2099 aluminum lithium alloy ingot of the invention covers round ingots and square ingots of all specifications with preparation capability.

The homogenization annealing process provided by the invention adopts a two-stage soaking method, so that the crystal phase residue in the ingot is eliminated to the maximum extent, and the ingot can obtain ideal tissue and component uniformity.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is 2099 Al-Li alloy as-cast metallographic structure;

FIG. 2 is an as-cast DSC curve of 2099 aluminum lithium alloy;

FIG. 3 is a 2099 Al-Li alloy as-cast grain boundary non-equilibrium phase and intragranular second phase morphology;

FIG. 4 is a spectrum analysis of the nonequilibrium phase at the as-cast grain boundaries of 2099 aluminum lithium alloy;

FIG. 5 is a spectrum analysis of 2099 second phase of spherical shape in as-cast grain of aluminum lithium alloy;

FIG. 6 is a graph of the energy spectrum of an irregularly shaped second phase within the as-cast grain of 2099 aluminum lithium alloy;

FIG. 7 is an as-cast XRD phase composition analysis of 2099 aluminum lithium alloy;

FIG. 8 is a metallographic structure of an aluminum lithium alloy ingot of 2099 after soaking at 500 deg.C;

FIG. 9 is a scanning electron microscope structure of an aluminum lithium alloy ingot casting after soaking at 500 deg.C;

FIG. 10 is a spectrum analysis of a second phase at a grain boundary after soaking of 2099 Al-Li alloy ingot at 500 deg.C;

FIG. 11 is an energy spectrum analysis of a second phase in the ingot of 2099 aluminum lithium alloy after soaking at 500 deg.C;

FIG. 12 is an energy spectrum analysis of a second phase at a grain boundary after soaking of 2099 aluminum lithium alloy ingot at 500 ℃;

FIG. 13 is an energy spectrum analysis of a second phase in the ingot of 2099 aluminum lithium alloy after soaking at 500 deg.C;

FIG. 14 is a DSC curve of an aluminum lithium alloy ingot of 2099 after soaking at 500 deg.C;

FIG. 15 is a metallographic structure of an aluminum lithium alloy ingot 2099 after soaking at 505 ℃ and heating;

FIG. 16 is a scanning electron microscope structure of an aluminum lithium alloy ingot 2099 after being soaked at 505 ℃ in heat;

FIG. 17 is an energy spectrum analysis of a second phase at a grain boundary of an aluminum lithium alloy ingot 2099 after soaking at 505 ℃;

FIG. 18 is an energy spectrum analysis of a second phase in the ingot of 2099 aluminum lithium alloy after soaking at 505 deg.C;

FIG. 19 is a second phase energy spectrum analysis of the grain boundary of the aluminum lithium alloy ingot 2099 after soaking at 505 deg.C;

FIG. 20 is an energy spectrum analysis of a second phase in the ingot of 2099 aluminum lithium alloy after soaking at 505 deg.C;

FIG. 21 is a DSC curve of an aluminum lithium alloy ingot of 2099 after being soaked at 505 ℃ in heat;

FIG. 22 is a metallographic structure of a 2099 aluminum lithium alloy ingot soaked at 510 deg.C;

FIG. 23 is a scanning electron microscope structure of a 2099 Al-Li alloy ingot soaked at 510 deg.C;

FIG. 24 is a second phase energy spectrum analysis of a 2099 Al-Li alloy ingot after soaking at 510 deg.C;

FIG. 25 is a second phase energy spectrum analysis of a 2099 Al-Li alloy ingot after soaking at 510 deg.C;

FIG. 26 is a DSC curve of an aluminum lithium alloy ingot of 2099 after soaking at 510 deg.C;

FIG. 27 is a metallographic structure of a 2099 aluminum lithium alloy ingot soaked at 515 deg.C;

FIG. 28 is a scanning electron microscope structure of a 2099 Al-Li alloy ingot soaked at 515 deg.C;

FIG. 29 is an energy spectrum analysis of a second phase at a grain boundary after soaking of 2099 Al-Li alloy ingot at 515 deg.C;

FIG. 30 is a second phase energy spectrum analysis of the grain boundary of the aluminum lithium alloy ingot of 2099 after soaking at 515 deg.C;

FIG. 31 is a DSC curve of an aluminum lithium alloy ingot of 2099 after soaking at 515 deg.C;

FIG. 32 is a Vickers hardness curve of an aluminum lithium alloy ingot of 2099 after being soaked at 505 ℃ for first-class soaking for different time;

FIG. 33 is a metallographic structure of an aluminum lithium alloy ingot 2099 which is soaked for different times at the first stage of 505 ℃ (a) is 16h, (b) is 20h, and (c) is 24 h;

FIG. 34 is a DSC curve of an ingot of 2099 aluminum lithium alloy after 505 ℃ first-order soaking;

FIG. 35 is a metallographic structure of a 2099 aluminum lithium alloy ingot after primary soaking at different secondary soaking temperatures, where (a) is 525 ℃/16 h; (b) at 530 ℃/7 h; (c) 535 ℃/7 h; (d) 540 ℃/7 h;

FIG. 36 is a scanning electron microscope structure of 2099 Al-Li alloy ingot after primary soaking at different secondary soaking times, (a)505 ℃/16h +525 ℃/12h, (b)505 ℃/16h +525 ℃/16h, (c)505 ℃/16h +525 ℃/24h, (d)505 ℃/16h +525 ℃/36 h;

FIG. 37 is a scanning view of the surface of a 2099 Al-Li alloy ingot after 505 ℃/16h +525 ℃/24h two-stage soaking;

fig. 38 shows the microstructures of 2099 aluminum lithium alloy ingots after two-stage homogenizing annealing obtained in examples 1 to 4 of the present invention, (a) example 1, (b) example 2, (c) example 3, and (d) example 4;

fig. 39 shows microstructures of 2099 aluminum lithium alloy ingots after two-stage homogenization annealing obtained in examples 5 to 6 of the present invention, (a) example 5, and (b) example 6.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a 2099 aluminum lithium alloy two-stage homogenization annealing process, which comprises the following steps:

carrying out primary homogenizing annealing on the 2099 aluminum lithium alloy cast ingot at 495-505 ℃, and then carrying out secondary homogenizing annealing at 515-525 ℃.

In the present invention, the aluminum-lithium alloy 2099 includes the following components:

2.4 to 3.0 wt% of Cu;

1.6-2.0 wt% of Li;

0.4 to 1.0 wt% of Zn;

0.1 to 0.5 wt% of Mg;

0.1 to 0.5 wt% Mn;

0.05 to 0.12 wt% of Zr;

the balance being Al.

In the invention, the nominal component of the 2099 aluminum lithium alloy ingot is Al-2.7Cu-1.8Li-0.7Zn-0.3Mg-0.3Mn-0.10 Zr.

The source of the 2099 aluminum lithium alloy ingot is not particularly limited, and the aluminum lithium alloy ingot with the components can be obtained by smelting and pouring alloy raw materials by using an aluminum lithium alloy ingot preparation method well known to those skilled in the art.

In the present invention, the size of the 2099 aluminum lithium alloy ingot covers all specifications of round and square ingots for production capability.

In the invention, the as-cast microstructure of the 2099 aluminum lithium alloy is shown in fig. 1, and as can be seen from fig. 1, the as-cast microstructure mostly exists in the form of dendrites, the growth of dendrites is obvious, and the dendrite spacing is about 50 μm; FIG. 2 is an as-cast DSC curve of 2099 Al-Li alloy, which shows that the alloy has an endothermic peak at 526 deg.C, which is caused by the dissolution of a second phase formed at the grain boundaries by dendrite segregation, and the temperature at which the dissolution starts is 514 deg.C and reaches a peak at 526 deg.C; SEM observation showed that the non-equilibrium phase was mainly distributed at the grain boundaries, as shown in fig. 3; EDS analysis results show that the composition (at.%) of the grain boundary nonequilibrium phase is 2.0Al-1.0Cu, and FIG. 4 shows that a second phase containing Zn is also precipitated in the crystal, wherein the Zn content is not more than 2%; in FIG. 5, a hardly soluble phase containing Fe and Mn is observed; in FIG. 6, a poorly soluble phase containing Si is observed.

As-cast XRD analysis of 2099 aluminum lithium alloy was performed at a scan rate of 8 °/min ranging from 10 ° to 80 °, and as can be seen from the X-ray diffraction pattern of fig. 7, the main phase composition of the as-cast was: al (Al)₂Cu、Al₂CuLi、Al₂MgLi, AlLi, and the like.

In the invention, the selected temperatures are respectively 500 ℃, 505 ℃, 510 ℃ and 515 ℃, the homogenization annealing time is 24 hours, and the influence of different homogenization temperatures on the microstructure is researched: 2099 the microstructure of the aluminum lithium alloy ingot after soaking at 500 deg.C is shown in fig. 8, no overburnt structure is observed, SEM observation shows that the overburnt structure is not appeared, and some insoluble second phases are not dissolved into the matrix; EDS (electron-ray diffraction) spectrum analysis shows that after the cast ingot of 2099 aluminum lithium alloy is subjected to homogenizing annealing at 500 ℃, the grain boundary is mainly a refractory phase containing Fe and Mn, as shown in FIGS. 10 and 12, and the grain interior is also mainly a refractory phase containing Fe and Mn, as shown in FIGS. 11 and 13; meanwhile, the Cu content in the grain boundary and the grain interior is higher; in combination with the DSC curve, as shown in fig. 14, it can be seen that the endothermic peak of the as-cast state of the 2099 aluminum lithium alloy ingot disappears after homogenization at 500 ℃, indicating that the non-equilibrium phase has dissolved; from this, it is clear that a homogenization temperature of 500 ℃ is possible.

2099 the microstructure of the aluminum lithium alloy ingot after soaking at 505 ℃ is shown in fig. 15, and the microstructure is relatively clean; SEM observations show that no burned tissue was observed, but some poorly soluble second phase did not dissolve into the matrix, as in FIG. 16; from the EDS spectrum analysis, it is found that after the alloy is subjected to the uniform annealing at 505 ℃, the grain boundary is mainly a poorly soluble phase containing Fe and Mn as shown in fig. 17 and 19, and the grain interior is also mainly a poorly soluble phase containing Fe and Mn as shown in fig. 18 and 20; from DSC analysis (fig. 21), it was found that the endothermic peak of the non-equilibrium phase of the 2099 aluminum lithium alloy ingot after homogenization at 505 ℃ was disappeared and the DSC curve was relatively gentle, and it was found that after soaking at 505 ℃, the dendrite segregation and the non-equilibrium eutectic phase were eliminated and the homogenization was sufficient.

2099 the microstructure of the aluminum lithium alloy ingot after soaking at 510 ℃ is shown in fig. 22, the grain boundary has the tendency of remelting and spheroidizing, and SEM observation shows that the aluminum lithium alloy ingot has the sign of overburning, and as shown by the arrow in fig. 23, the grain boundary second phase is still not dissolved in the matrix; from the EDS energy spectrum analysis in fig. 24 and 25, it is known that, after the ingot of 2099 aluminum lithium alloy is subjected to the homogenization annealing at 510 ℃, the grain boundary is still mainly a poorly soluble impurity phase containing Fe and Mn; FIG. 26 is a DSC curve after homogenization annealing at 510 ℃ in which the endothermic peak of the non-equilibrium phase in the alloy disappears, indicating that this temperature homogenization eliminates dendrite segregation, but it is clear from the microstructure that overburning occurs at this temperature (as shown in FIG. 22).

2099 the microstructure of the al-li alloy ingot after soaking at 515 deg.c is shown in fig. 27, where the remelted balls appear more than 510 deg.c (fig. 22), and SEM observations also show that the alloy has more pronounced overburning, as shown in fig. 28; as can be seen from the EDS energy spectrum analysis results of fig. 29 and fig. 30, significant overburning has occurred; FIG. 31 is a DSC curve of 2099 Al-Li alloy ingot at 515 deg.C, which is flat in front, with the endothermic peak of as-cast non-equilibrium phase disappeared and the grain boundary non-equilibrium phase eliminated.

In the invention, the primary homogenizing annealing temperature of the 2099 aluminum lithium alloy ingot is required to be lower than 510 ℃, preferably 495-505 ℃, more preferably 500-505 ℃, and most preferably 505 ℃.

In the invention, fig. 32 is a vickers hardness curve of the aluminum lithium alloy ingot casting ingot subjected to different soaking and heat preservation times at 505 ℃, and it can be seen that the hardness curve after soaking for 16 hours appears as a platform and drops after 24 hours, so that 16-24 hours are reasonable first-level homogenization annealing time; FIG. 33 is a view showing that the aluminum lithium alloy ingot is soaked for 16h, 20h and 24h at 505 ℃ respectively, and it can be seen that the change of the structure is not obvious along with the prolonging of the soaking time; the primary homogenizing annealing time is within the range of 16-24 h, the homogenizing effect is equivalent, and the primary homogenizing annealing time is preferably 16h in consideration of the production efficiency. Fig. 34 shows a DSC curve of 2099 aluminum lithium alloy ingot after primary homogenizing annealing at 505 ℃, and it can be seen that the endothermic peak of the non-equilibrium phase disappears at this time.

In the present invention, the primary soaking temperature reaches 510 ℃, and a part of the insoluble second phase is not dissolved in the matrix (as shown in fig. 23), and in order to further improve the homogenization effect, the primary soaking treatment is performed in addition to the secondary soaking treatment. FIG. 35 shows the microstructure of the alloy at different soaking temperatures in two stages, and it can be seen that the alloy has suspected over-burning at 530 deg.C (FIG. 35(b)), and that the over-burning phenomenon is more pronounced after the temperature exceeds 530 deg.C (FIGS. 35(c), (d)).

In the invention, the secondary homogenizing annealing temperature of the 2099 aluminum lithium alloy ingot is preferably 515-525 ℃, more preferably 520-525 ℃, and most preferably 525 ℃.

In the invention, the primary soaking process is 505 ℃/16h, the secondary soaking temperature is set to 525 ℃, the homogenization annealing with different soaking and heat-preserving times of 12h, 16h, 24h and 36h is carried out, the SEM appearance is as shown in figure 36, and the soaking structure according to figure 36 shows that when the secondary soaking time reaches 24 h-36 h (525 ℃/24 h-36 h), the residual insoluble phase is relatively less (see figures 36(c) and (d)), and the two times of 24h and 36h are compared, so that the difference is not obvious; therefore, the time of the secondary homogenizing annealing in the invention is preferably 24-36 h, and more preferably 24 h.

Fig. 37 is a SEM surface scanning result of main alloying elements and impurities of the 2099 aluminum lithium alloy ingot after soaking at 505 ℃/16h +525 ℃/24h, and it can be seen that the components are uniformly distributed and the alloy obtains a better homogenization effect. In the invention, the preferred soaking system of the 2099 aluminum lithium alloy ingot is as follows: the primary homogenizing annealing is 505 ℃/16h + the secondary homogenizing annealing is 525 ℃/24 h. The invention adopts a two-stage soaking process, so that the alloy obtains a more sufficient homogenization effect.

2099 aluminum lithium alloy cast ingots used in the following examples of the invention comprise the following components: al-2.63Cu-1.76Li-0.66Zn-0.30Mg-0.32Mn-0.11 Zr; the size is as follows: phi 540X 3500 mm.

Example 1

And carrying out two-stage homogenizing annealing on the 2099 aluminum-lithium alloy cast ingot, wherein the first-stage homogenizing annealing is carried out firstly, and then the second-stage homogenizing annealing is carried out, the temperature of the first-stage homogenizing annealing is 495 ℃ for 16 hours, and the temperature of the second-stage homogenizing annealing is 515 ℃ for 24 hours.

The microstructure of the homogenized alloy (measured according to ASTM E407) is shown in FIG. 38.

Example 2

The ingot of 2099 aluminum lithium alloy was treated by the two-stage homogenization annealing in example 1, which is different from example 1 in that the temperature of the two-stage homogenization annealing was 525 ℃.

The microstructure of the homogenized alloy is shown in FIG. 38.

Example 3

The ingot of 2099 aluminum lithium alloy was treated by the two-stage homogenization annealing in example 1, which is different from example 1 in that the temperature of the one-stage homogenization annealing was 505 ℃.

The microstructure of the homogenized alloy is shown in FIG. 38.

Example 4

The ingot of 2099 aluminum lithium alloy was treated by the two-stage homogenization annealing in example 1, which is different from example 1 in that the temperature of the first-stage homogenization annealing was 505 ℃ and the temperature of the second-stage homogenization annealing was 525 ℃.

The microstructure of the homogenized alloy is shown in FIG. 38.

In examples 1 to 4, it can be seen that coarse nonequilibrium crystal phases in the grain boundaries of the aluminum lithium alloy ingots of 2099 were eliminated, and a good homogenization effect was obtained, and as shown in fig. 38(b) and (d), no overburning phenomenon was observed even when the second-stage soaking temperature was at the upper limit temperature (525 ℃).

Example 5

And (2) carrying out two-stage homogenizing annealing on the 2099 aluminum-lithium alloy round ingot with the diameter of 540X 3500mm, firstly carrying out first-stage homogenizing annealing, and then carrying out second-stage homogenizing annealing, wherein the temperature of the first-stage homogenizing annealing is 500 ℃ for 16h, and the temperature of the second-stage homogenizing annealing is 520 ℃ for 24 h.

The microstructure of the alloy after the homogenization annealing (the detection method is the same as that of example 1) is shown in FIG. 39, and it can be seen that the grain boundary is cleaner and the homogenization effect is better.

Example 6

A 2099 round ingot of Al-Li alloy phi 540 x 3500mm was processed by the two-stage homogenizing annealing process of example 5, which differs from example 5 in the composition of Al-2.63Cu-1.78Li-0.68Zn-0.28Mg-0.31Mn-0.12 Zr.

Comparative example 1

The annealing process of example 1 was followed to treat 2099 aluminum lithium alloy ingot, which is different from example 1 in that only the primary homogenizing annealing was performed, and the secondary homogenizing annealing was not performed, and the temperature of the primary homogenizing annealing was 510 ℃.

The SEM appearance, EDS (electron-ray diffraction) spectrum analysis and DSC curve of the microstructure of the alloy after the first-order homogenization treatment are shown in figures 22-26.

Comparative example 2

The annealing process of example 1 was followed to treat 2099 aluminum lithium alloy ingot, which is different from example 1 in that only the primary homogenizing annealing was performed, and the secondary homogenizing annealing was not performed, and the temperature of the primary homogenizing annealing was 515 ℃.

The microstructure, the SEM appearance, the EDS spectrum analysis and the DSC curve of the alloy after the primary homogenization treatment are shown in FIGS. 27 to 31.

Comparative example 3

The annealing process in example 3 was carried out on 2099 aluminum lithium alloy ingot, which is different from example 3 in that only the primary homogenizing annealing was carried out, and the secondary homogenizing annealing was not carried out, and the time of the primary homogenizing annealing was 8 hours.

The Vickers hardness of the alloy after the first-order homogenization treatment is shown in FIG. 32.

Comparative examples 4 to 7

The annealing process in example 3 was carried out on 2099 aluminum lithium alloy ingot, which is different from example 3 in that only the primary homogenizing annealing was carried out, and the secondary homogenizing annealing was not carried out, and the primary homogenizing annealing time was 16h, 20h, 24h and 36h, respectively.

The Vickers hardness of the alloy after the first-order homogenization treatment is shown in FIG. 32.

Comparative example 8

The aluminum lithium alloy ingot casting ingot is treated by the two-stage homogenizing annealing process in the embodiment 4, which is different from the embodiment 4 in that the temperature of the two-stage homogenizing annealing process is 530 ℃ and the time is 7 hours.

The microstructure of the homogenized annealed alloy is shown in FIG. 35.

Comparative examples 9 to 10

The aluminum lithium alloy ingot of 2099 was processed by the two-stage homogenizing annealing process of comparative example 8, which is different from comparative example 8 in that the temperatures of the two-stage homogenizing annealing process were 535 ℃ and 540 ℃.

The microstructure of the homogenized annealed alloy is shown in FIG. 35.

Comparative examples 11 to 12

The aluminum lithium alloy ingot casting ingot is treated by the two-stage homogenization annealing process in the embodiment 4, and the difference from the embodiment 4 is that the time of the two-stage homogenization annealing process is 12h and 16h respectively.

The SEM morphology of the homogenized annealed alloy is shown in fig. 36.

As can be seen from the above embodiments, the present invention provides a two-stage homogenization annealing process for 2099 aluminum lithium alloy, which includes: carrying out primary homogenizing annealing on the 2099 aluminum lithium alloy cast ingot under the schedule of 495-505 ℃/16h, and then carrying out secondary homogenizing annealing under the schedule of 515-525 ℃/24 h. The homogenization annealing process provided by the invention adopts a two-stage soaking method, so that the crystal phase residue in the ingot is eliminated to the maximum extent, and the ingot can obtain ideal tissue and component uniformity.