阅读说明：本技术 一种抑制铝锂合金再结晶的加工方法 (Processing method for inhibiting recrystallization of aluminum-lithium alloy ) 是由 黄伟九 杨绪盛 祝祥辉 张然 于 2019-11-25 设计创作，主要内容包括：一种抑制铝锂合金后续再结晶的加工方法,依次包括铸锭、均匀化处理、热轧开坯、最终固溶、预拉伸及人工时效,其特征在于：所述热轧开坯和固溶之间还依次有初次固溶、淬火和多道次控温热轧步骤；所述初次固溶是在510~550℃进行0.5~2小时的固溶处理,随后进行淬火；所述多道次控温热轧具体是将上述淬火后的铝锂合金板材在150~350℃下进行多道次轧制,其总压下率在55%~83%。本发明抑制铝锂合金后续再结晶的加工方法,从形核和晶核长大上抑制最终固溶再结晶发生,消除局部应变区,降低铝锂合金的板材的再结晶倾向；使得铝锂合金变形均匀,大幅度降低了基体中晶界两侧的储能差异,从而稳定抑制了再结晶晶核的长大。使得板材具备更好的综合性能。(A processing method for inhibiting subsequent recrystallization of an aluminum-lithium alloy sequentially comprises ingot casting, homogenization treatment, hot rolling cogging, final solid solution, pre-stretching and artificial aging, and is characterized in that: the steps of primary solid solution, quenching and multi-pass temperature-controlled hot rolling are sequentially carried out between the hot rolling cogging and the solid solution; the primary solid solution is performed for 0.5-2 hours at 510-550 ℃, and then quenching is performed; the multi-pass temperature-control hot rolling is to perform multi-pass rolling on the quenched aluminum-lithium alloy plate at 150-350 ℃, and the total reduction rate is 55-83%. The processing method for inhibiting the subsequent recrystallization of the aluminum lithium alloy inhibits the final solid solution recrystallization from nucleation and crystal nucleus growth, eliminates a local strain region and reduces the recrystallization tendency of the plate of the aluminum lithium alloy; the aluminum lithium alloy is uniformly deformed, and the energy storage difference at two sides of the crystal boundary in the matrix is greatly reduced, so that the growth of the recrystallization crystal nucleus is stably inhibited. So that the plate has better comprehensive performance.)

1. A processing method for inhibiting subsequent recrystallization of an aluminum-lithium alloy sequentially comprises ingot casting of the aluminum-lithium alloy, homogenization treatment, hot rolling cogging, final solid solution, pre-stretching and artificial aging, and is characterized in that: the steps of primary solid solution, quenching and multi-pass temperature-controlled hot rolling are sequentially carried out between the hot rolling cogging and the final solid solution; the primary solid solution is performed for 0.5-2 hours at 510-550 ℃, and then quenching is performed; the multi-pass temperature-control hot rolling is to perform multi-pass rolling on the quenched aluminum-lithium alloy plate at 150-350 ℃, and the total reduction rate is 55-83%.

2. The processing method for inhibiting subsequent recrystallization of an aluminum-lithium alloy as claimed in claim 1, wherein: the temperature of the solution treatment in the primary solution treatment is 535-545 ℃, and the solution time is 0.9-1.2 hours.

3. The processing method for suppressing subsequent recrystallization of an aluminum-lithium alloy as claimed in claim 1 or 2, wherein: the rolling speed of the multi-pass temperature-control hot rolling is 4-8 m/min.

4. A processing method for suppressing subsequent recrystallization of an aluminum-lithium alloy as recited in any one of claims 1 to 3, wherein: the rolling passes of the multi-pass temperature-control hot rolling are 5-8 passes, and the reduction rate of each pass is 15-20%.

5. The processing method for suppressing subsequent recrystallization of an aluminum-lithium alloy as recited in any one of claims 1 to 4, wherein: the artificial aging is specifically performed for 20-40 h at 160 ℃, and then the product is cooled to room temperature in an air cooling mode.

6. The processing method for inhibiting subsequent recrystallization of an aluminum-lithium alloy as claimed in claim 1, wherein: the aluminum lithium alloy comprises the following chemical components: 2.7-2.8 wt%; li: 1.7-1.9 wt%; mg: 0.3-0.5 wt%; mn: 0.3-0.5 wt%; zn: 0.5-0.7 wt%; zr: 0.08-0.12 wt%; si: less than or equal to 0.05 wt%; fe is less than or equal to 0.07 wt%; the balance being aluminum.

7. A processing method for inhibiting subsequent recrystallization of an aluminum-lithium alloy is characterized by comprising the following steps:

(1) preparing an aluminum lithium alloy ingot by using a vacuum casting method, wherein the aluminum lithium alloy comprises the following chemical components: 2.7-2.8 wt%; li: 1.7-1.9 wt%; mg: 0.3-0.5 wt%; mn: 0.3-0.5 wt%; zn: 0.5-0.7 wt%; zr: 0.08-0.12 wt%; si: less than or equal to 0.05 wt%; fe is less than or equal to 0.07 wt%; the balance being aluminum;

(2) homogenizing the cast ingot at 510-530 ℃ for 70-80 h;

(3) preheating the homogenized aluminum-lithium alloy cast ingot at 420-460 ℃, preserving heat for 20-40 min, and then rolling and cogging to form a plate;

(4) carrying out solid solution treatment on the cogging aluminum lithium alloy plate at 510-550 ℃ for 0.5-2 hours, and then quenching the aluminum lithium alloy plate by using cold water at 25 ℃;

(5) rolling the quenched aluminum-lithium alloy plate at 150-350 ℃ for 5-8 times, wherein the total rolling reduction rate is 55-83%, and the rolling speed is 4-8 m/min;

(6) carrying out solution treatment on the aluminum lithium alloy plate at 535-550 ℃ for 1-2 h;

(7) pre-stretching the aluminum-lithium alloy plate, wherein the stretching amount is 3-6%;

(8) and (3) carrying out aging treatment on the stretched aluminum-lithium alloy plate, aging at 160 ℃ for 20-40 h, and cooling to room temperature in an air cooling mode.

Technical Field

The invention belongs to the field of aluminum lithium alloy processing, and particularly relates to a processing method for inhibiting recrystallization of an aluminum lithium alloy.

Background

Aluminum lithium alloys are considered ideal structural materials in the aerospace industry due to their high specific strength, high specific stiffness, and excellent low temperature properties. The density of the alloy can be reduced by 3% and the elastic modulus can be increased by 6% for each 1% of the lithium content added to the aluminum-lithium alloy. The aluminum lithium alloy is used for replacing the conventional aluminum alloy, so that the mass of the structural part can be reduced by 15%, and the rigidity can be improved by 15% -20%. Compared with the previous two generations of aluminum-lithium alloys, the third generation of aluminum-lithium alloys has smaller anisotropy, higher thermal stability, corrosion resistance and damage tolerance. Novel aluminum-lithium alloys such as 2196, 2099, 2199 and the like are used for structural components such as skins, wing cross beams, floor beams, seat slide rails, cabins and the like of the airbus 380. The bodies of domestic C919 large passenger aircraft, Boeing next generation B777-X passenger aircraft and Russian next generation narrow passenger aircraft MS-21 are made of a large amount of novel aluminum-lithium alloy.

During the processing of the aluminum lithium alloy, the static recrystallization phenomenon in the solid solution process can cause the structural nonuniformity of the section, and the structural nonuniformity can deteriorate the mechanical properties of the material and also can increase the mechanical anisotropy of the plate or the section. Therefore, it is generally required to suppress the static recrystallization phenomenon of the sheet or the shaped material during the solid solution process and to control the recrystallization volume fraction. Generally, Sc element can be used for inhibiting recrystallization, but metal Sc is very expensive, so that the popularization and the application of the metal Sc are limited. It is common practice in the industry to employ a single recovery anneal between hot deformation and solution treatment to inhibit to some extent the static recrystallization process of the sheet during solution treatment. However, the annealing treatment is time-consuming and labor-consuming, and the effect is not stable. Because the thickness of the aluminum lithium alloy is very large when the aluminum lithium alloy is cast into a ingot, the aluminum lithium alloy can reach at least ten centimeters and several millimeters after cogging, and the final alloy plate finished product is generally kept at the level of several millimeters, and under the condition of high rolling reduction rate, the recovery annealing can not achieve the ideal effect and has no universality.

Disclosure of Invention

The invention aims to provide a processing method for inhibiting subsequent recrystallization of an aluminum lithium alloy. The static recrystallization of the aluminum lithium alloy material is inhibited from the aspect of processing technology.

The purpose of the invention is realized according to the following technical scheme:

a processing method for inhibiting subsequent recrystallization of an aluminum-lithium alloy sequentially comprises ingot casting of the aluminum-lithium alloy, homogenization treatment, hot rolling cogging, final solid solution, pre-stretching and artificial aging, and is characterized in that: the steps of primary solid solution, quenching and multi-pass temperature-controlled hot rolling are sequentially carried out between the hot rolling cogging and the final solid solution; the primary solid solution is performed for 0.5-2 hours at 510-550 ℃, and then quenching is performed; the multi-pass temperature-control hot rolling is to perform multi-pass rolling on the quenched aluminum-lithium alloy plate at 150-350 ℃, and the total reduction rate is 55-83%.

The static recrystallization of the aluminum lithium alloy is mainly carried out by two steps of nucleation and growth. Coarse primary phase particles exist in an alloy matrix, when the alloy deforms, local strain regions can be formed around the particles, and the local strain regions serve as nucleation points for particle-induced recrystallization and are easy to generate recrystallization crystal nuclei; due to the dislocation energy storage difference of the deformation matrix inside and around the crystal nucleus, energy is provided for the growth of the crystal nucleus, and a serious static recrystallization phenomenon is generated during final solid solution.

In the traditional aluminum lithium alloy processing technology, after hot rolling and cogging, recrystallization annealing treatment needs to be carried out on the aluminum lithium alloy plate, so that the aluminum lithium alloy plate achieves the purpose of improving the rolling forming performance, and is beneficial to further deformation processing. The primary solid solution adopted by the invention replaces recrystallization annealing, so that the aim of recrystallization annealing is achieved, meanwhile, the aluminum lithium alloy plate is subjected to primary solid solution and quenching after hot rolling and cogging, precipitated phases in the material are mostly eliminated, and most of alloying elements enter a matrix in a solid solution manner, so that the aluminum lithium alloy forms a supersaturated solid solution state; then carrying out multi-pass temperature-controlled hot rolling, wherein in the rolling process, Cu element and Li element in the aluminum-lithium alloy form Al₂The CuLi phase is preferentially and dynamically precipitated around the primary phase particles at a certain rate, the matrix strength around the primary phase particles is increased, the formation of local strain regions around the primary phase particles is inhibited, and the static recrystallization nucleation points are reduced, so that the static recrystallization tendency of the aluminum-lithium alloy sheet is reduced. The primary solid solution and quenching are combined with multi-pass temperature control hot rolling to eliminate a local strain area, so that the aluminum-lithium alloy plate deforms uniformly,the energy storage difference of two sides of the crystal boundary in the matrix is greatly reduced, so that the growth of the recrystallization crystal nucleus is inhibited.

Preferably, the solid solution temperature in the primary solid solution is 535-545 ℃ and the solid solution time is 0.9-1.2 hours.

Further, the quenching medium is cold water at 25 ℃.

Preferably, the temperature of the multi-pass temperature-controlled hot rolling is 250-300 ℃.

Furthermore, the rolling speed of the multi-pass temperature-controlled hot rolling is 4-8 m/min.

Furthermore, the rolling passes of the multi-pass temperature-control hot rolling are 5-8 passes, and the reduction rate of each pass is 15-20%.

Preferably, the rolling passes are 6 passes, and the total reduction ratio is 62% to 75%.

Further, the artificial aging treatment is specifically aging at 160 ℃ for 20-40 h, and then cooling to room temperature in an air cooling mode.

Further, the aluminum-lithium alloy is a third generation aluminum-lithium alloy.

Preferably, the aluminum lithium alloy has an alloy chemical composition of Cu: 2.7-2.8 wt%; li: 1.7-1.9 wt%; mg: 0.3-0.5 wt%; mn: 0.3-0.5 wt%; zn: 0.5-0.7 wt%; zr: 0.08-0.12 wt%; si: less than or equal to 0.05 wt%; fe is less than or equal to 0.07 wt%; the balance being aluminum.

Specifically, the processing method for inhibiting the subsequent recrystallization of the aluminum lithium alloy is characterized by comprising the following steps of:

(1) preparing an aluminum lithium alloy ingot by using a vacuum casting method, wherein the aluminum lithium alloy comprises the following chemical components: 2.7-2.8 wt%; li: 1.7-1.9 wt%; mg: 0.3-0.5 wt%; mn: 0.3-0.5 wt%; zn: 0.5-0.7 wt%; zr: 0.08-0.12 wt%; si: less than or equal to 0.05 wt%; fe is less than or equal to 0.07 wt%; the balance being aluminum;

(2) homogenizing the cast ingot at 510-530 ℃ for 70-80 h;

(3) preheating the homogenized cast ingot at 420-460 ℃, preserving heat for 20-40 min, and then rolling and cogging to form a plate;

(4) carrying out solid solution treatment on the aluminum lithium alloy plate after cogging at 510-550 ℃ for 0.5-2 h, and then quenching with cold water at 25 ℃;

(5) rolling the quenched aluminum-lithium alloy plate at 150-350 ℃ for 5-8 times, wherein the reduction rate of each time is 15-20%, the total reduction rate is 55-83%, and the rolling speed is 4-8 m/min;

(6) carrying out solution treatment on the aluminum lithium alloy plate at 535-550 ℃ for 1-2 h;

(7) pre-stretching the aluminum-lithium alloy plate, wherein the stretching amount is 3-6%;

(8) and (3) carrying out aging treatment on the stretched aluminum-lithium alloy plate, aging at 160 ℃ for 20-40 h, and cooling to room temperature in an air cooling mode.

In the processing process, the processes of preliminary solution treatment, quenching and temperature-controlled hot rolling can be repeated, and the thickness of the aluminum-lithium alloy is adjusted to meet the actual requirement.

The invention has the following beneficial effects:

the processing method for inhibiting the subsequent recrystallization of the aluminum-lithium alloy does not adopt expensive metal, has low cost, inhibits the final solid solution recrystallization from nucleation and crystal nucleus growth, eliminates a local strain region, and reduces the recrystallization tendency of the aluminum-lithium alloy plate; because the precipitated phase is precipitated at a specific position at a specific rate, the aluminum-lithium alloy deforms uniformly, the energy storage difference at two sides of a crystal boundary in the matrix is greatly reduced, and the growth of a recrystallization crystal nucleus is stably inhibited. The recrystallization volume fraction of the aluminum lithium alloy plate in the final solid solution process is remarkably controlled to be reduced from 99.3 percent to 51.3 percent. So that the plate has better comprehensive performance.

Drawings

FIG. 1: surface microstructure and ODF cross-sectional view of example 1 of the present invention;

FIG. 2: surface microstructure and ODF cross-sectional view of comparative example 1;

FIG. 3: surface microstructure and ODF cross-sectional view of comparative example 2.

Detailed Description

The present invention is described in detail below by way of examples, it should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and those skilled in the art can make some insubstantial modifications and adaptations of the present invention based on the above-mentioned disclosure.