阅读说明：本技术 一种提高铝合金厚板及锻件综合性能的制备工艺 (Preparation process for improving comprehensive performance of aluminum alloy thick plate and forging ) 是由 李国爱 郝时嘉 陆政 吴秀亮 王建国 高艳丽 于 2021-09-08 设计创作，主要内容包括：本发明涉及一种提高铝合金厚板及锻件综合性能的制备工艺,将经过热初轧的板材/热初锻的锻件在260℃～300℃的温度下进行加热,然后通过锻造/轧制的方式进行一定的变形量的变形,变形后的板材/锻件在470℃～530℃温度下加热保温一段时间,随后降低至特定温度通过热终轧/热终锻处理到规定尺寸,最后对板材/锻件进行固溶淬火+拉伸/压缩+时效处理,达到最终所需的热处理状态及尺寸；所述工艺在正常的热初轧/热初锻后,采取合适的中低温锻造/轧制,可以在保障材料不发生开裂的同时,进一步碎化合金中的化合物及大尺寸析出相,通过上述方式,可以有效消除大尺寸化合物/析出相的影响,改善合金的综合性能。(The invention relates to a preparation process for improving the comprehensive performance of an aluminum alloy thick plate and a forged piece, which comprises the steps of heating a plate subjected to hot initial rolling/a forged piece subjected to hot initial rolling at the temperature of 260-300 ℃, then deforming by a certain deformation amount in a forging/rolling mode, heating and preserving heat of the deformed plate/forged piece at the temperature of 470-530 ℃ for a period of time, then reducing the temperature to a specific temperature, carrying out hot finish rolling/hot finish forging treatment to a specified size, and finally carrying out solid solution quenching, stretching/compressing and aging treatment on the plate/forged piece to achieve the final required heat treatment state and size; according to the process, after normal hot initial rolling/hot initial forging, proper medium-low temperature forging/rolling is adopted, so that the compound and large-size precipitated phases in the alloy can be further crushed while the material is prevented from cracking, and by the mode, the influence of the large-size compound/precipitated phase can be effectively eliminated, and the comprehensive performance of the alloy is improved.)

1. A preparation process for improving the comprehensive performance of an aluminum alloy thick plate and a forged piece is characterized in that a plate subjected to hot initial rolling/a forged piece subjected to hot initial rolling is heated at the temperature of 260-300 ℃, then deformation with a certain deformation amount is carried out in a forging/rolling mode, the deformed plate/forged piece is heated at the temperature of 470-530 ℃ for heat preservation for a period of time, then the temperature is reduced to a specific temperature, the plate/forged piece is subjected to hot finish rolling/hot finish forging treatment to reach a specified size, and finally the plate/forged piece is subjected to solid solution quenching, stretching/compressing and aging treatment to reach a finally required heat treatment state and size.

2. The process according to claim 1, wherein the process comprises the steps of:

step one, medium-temperature rolling/forging: placing the plate or the forge piece subjected to hot primary rolling/hot primary forging into a heating furnace for heating at the temperature of 260-290 ℃, taking out the plate or the forge piece after the plate or the forge piece is completely hot for rolling/forging, and controlling the deformation within the range of 15-30%;

step two, high-temperature heating and heat preservation: performing high-temperature heating and heat preservation treatment on the plate or the forge piece treated in the first step, and performing heat preservation for 2-4 hours at the heating temperature of 470-520 ℃ in a furnace;

step three, hot finish rolling/hot finish forging: cooling the plate and the forge piece treated in the step two to 380-470 ℃, then rolling/forging, controlling the rolling or forging deformation within the range of 20-35%, and air-cooling to room temperature;

step four, solution quenching treatment: carrying out solution quenching treatment on the plate or the forging after the treatment in the third step, wherein the solution temperature is 472-540 ℃, and the room temperature water is quenched to room temperature;

step five, cold deformation treatment: the quenched plate and the quenched forged piece are subjected to cold stretching or cold compression within 4 hours;

step six, artificial aging treatment: the cold-deformed plate or forging is subjected to single-stage or double-stage artificial aging treatment.

3. The process according to claim 2, characterized in that: and the cooling mode of the third step adopts air cooling, air cooling or water cooling.

4. The process according to claim 2, characterized in that: and step four, the heat preservation time is 3 multiplied by tmin, and t is the maximum section thickness of the plate or the forge piece, and the thickness unit is mm.

5. The process according to claim 2, characterized in that: and fifthly, the cold deformation is 1.0-5.0%.

6. The process according to claim 2, characterized in that: step six, single-stage aging temperature is 120-175 ℃.

7. The process according to claim 2, characterized in that: and in the six-stage and two-stage aging process, the primary aging temperature is 115-125 ℃, and the secondary aging temperature is 155-165 ℃.

8. The process according to claim 2, characterized in that: the alloy applicable to the process comprises the following components in percentage by weight: 1.5-4.5% of Cu, 0.2-3.0% of Mg, 0.4-12.0% of Zn, 0.25-2.3% of Li, 0.05-0.8% of Mn, 0.02-0.25% of Zr, 0.01-0.10% of Ti, 0.05-0.25% of Sc, 0.2-0.6% of Ag, 0.10-0.25% of Er, no more than 0.15% of impurity element Si, no more than 0.15% of Fe, no more than 0.05% of other single impurities, no more than 0.15% of total amount, and the balance of Al.

Technical Field

The invention relates to a preparation method for improving the comprehensive performance of an aluminum alloy plate and a forging, belonging to the aluminum alloy hot working and heat treatment process.

Background

The adoption of the aluminum alloy with higher ratio and high strength and excellent comprehensive performance is an important measure for reducing the structural weight and effectively improving the carrying capacity of equipment in the fields of aviation and aerospace. In order to further improve the strength, the mode of increasing the content of main alloy elements and adopting multi-element micro-alloying has become an important development trend of ultrahigh-strength aluminum alloy. In the current stage, the content of alloy elements in the 700 MPa-level strength 7 xxx-series ultrahigh-strength aluminum alloy is about 15-18 wt%, the types of the alloy elements in the 600 MPa-level aluminum-lithium alloy are 7-8, the total content is close to 9%, and the main alloy elements in the alloys are close to or exceed the solid solution limit of the aluminum alloy. This results in the alloying elements combining with the micro-alloying elements and the Fe, Si impurities during solidification of the ingot to form large amounts of coarse compounds, which are localized near the grain boundaries. Meanwhile, during homogenization and slow cooling, a cast ingot can also precipitate a large number of needle-like precipitated phases in crystal boundaries and crystal interiors, and the traditional thermal deformation and thermal treatment process is difficult to eliminate the structures, so that the structures are inherited to the crystal boundaries and sub-crystal boundaries of final products, so that the alloy has low stress corrosion resistance, fracture toughness and high plasticity, and the application of the alloy is directly influenced.

With the increase of the content of the alloy, the number and the size of large-size compounds in the aluminum alloy and large-size precipitated phases precipitated in the homogenization process are increased, the large-size compounds and the precipitated phases are difficult to completely eliminate by adopting the conventional hot working and solid solution process, and large-size residual phases remain in positions of grain boundaries and subgrain boundaries, thus seriously affecting the plasticity and fracture toughness of the alloy.

The patent with the application number of 201910693641.2 solves the problem that a large-size widmannstatten is inherited at grain boundaries and subboundary by a mode of medium-temperature heat preservation and rolling after primary solution quenching. On one hand, however, the process steps are complex, and the material needs multiple solid solution cooling, so that the production cost is high and the period is long. On the other hand, the alloy prepared by the process has the problem of reduced fracture toughness caused by a recrystallized structure, and the fracture toughness and high plasticity of the alloy are still not ideal.

Disclosure of Invention

The purpose of the invention is: the preparation process for improving the comprehensive properties of the thick aluminum alloy plate and the forging has the advantage that the comprehensive properties such as plasticity, fracture toughness, corrosion performance, fatigue performance and the like of the alloy plate can be greatly improved under the condition of not reducing the strength.

In order to solve the technical problem, the technical scheme of the invention is as follows:

a preparation process for improving the comprehensive performance of an aluminum alloy thick plate and a forge piece comprises the steps of heating a plate subjected to hot initial rolling/a forge piece subjected to hot initial forging at the temperature of 260-300 ℃, then deforming by a certain deformation amount in a forging/rolling mode, heating and preserving heat of the deformed plate/forge piece at the temperature of 470-530 ℃ for a period of time, then reducing the temperature to a specific temperature, carrying out hot finish rolling/hot finish forging treatment to a specified size, and finally carrying out solution quenching, stretching/compressing and aging treatment on the plate/forge piece to achieve the final required heat treatment state and size.

The preparation process comprises the following steps:

step one, medium-temperature rolling/forging: placing the plate or the forge piece subjected to hot primary rolling/hot primary forging into a heating furnace for heating at the temperature of 260-290 ℃, taking out the plate or the forge piece after the plate or the forge piece is completely hot for rolling/forging, and controlling the deformation within the range of 15-30%;

step two, high-temperature heating and heat preservation: performing high-temperature heating and heat preservation treatment on the plate or the forge piece treated in the first step, and performing heat preservation for 2-4 hours at the heating temperature of 470-520 ℃ in a furnace;

step three, hot finish rolling/hot finish forging: cooling the plate and the forge piece treated in the step two to 380-470 ℃, then rolling/forging, controlling the rolling or forging deformation within the range of 20-35%, and air-cooling to room temperature;

step four, solution quenching treatment: carrying out solution quenching treatment on the plate or the forging after the treatment in the third step, wherein the solution temperature is 472-540 ℃, and the room temperature water is quenched to room temperature;

step five, cold deformation treatment: the quenched plate and the quenched forged piece are subjected to cold stretching or cold compression within 4 hours;

step six, artificial aging treatment: the cold-deformed plate or forging is subjected to single-stage or double-stage artificial aging treatment.

And the cooling mode of the third step adopts air cooling, air cooling or water cooling.

And fourthly, keeping the temperature for 3 Xt min (t is the maximum section thickness of the plate or the forge piece, and mm).

And fifthly, the cold deformation is 1.0-5.0%.

In the sixth step, the single-stage ageing temperature is 120-175 ℃, the two-stage ageing temperature is 115-125 ℃ and the two-stage ageing temperature is 155-165 ℃.

The alloy applicable to the process comprises the following components in percentage by weight: 1.5-4.5% of Cu, 0.2-3.0% of Mg, 0.4-12.0% of Zn, 0.25-2.3% of Li, 0.05-0.8% of Mn, 0.02-0.25% of Zr, 0.01-0.10% of Ti, 0.05-0.25% of Sc, 0.2-0.6% of Ag, 0.10-0.25% of Er, no more than 0.15% of impurity element Si, no more than 0.15% of Fe, no more than 0.05% of other single impurities, no more than 0.15% of total amount, and the balance of Al.

According to the process, after normal hot initial rolling/hot initial forging, proper medium-low temperature (260-300 ℃) forging/rolling is adopted, so that compounds and large-size precipitated phases in the alloy can be further crushed while the material is prevented from cracking, and meanwhile, more deformation energy storage is accumulated near the phases; in the high-temperature heating process, a compound and a large-size precipitated phase are taken as cores to be recrystallized, and the compound and the large-size precipitated phase are transferred into the crystal from the position of a crystal boundary/a subcrystal boundary; in the subsequent thermal deformation, the recrystallized structure is deformed in the rolling/forging direction and becomes a deformed structure again, thereby making up for the problem of reduction in fracture toughness due to recrystallization. By the mode, the influence of large-size compounds/precipitated phases can be effectively eliminated, and the comprehensive performance of the alloy is improved.

The invention has the beneficial effects that:

aiming at the problem that the large-size compounds and flaky Weishi structures existing on grain boundaries and sub-grain boundaries in high-alloy-content aluminum alloy plates and forgings influence the comprehensive performance of the alloy, particularly cause the deterioration of fracture toughness and high-directional plasticity, the rolling plate/forging is subjected to medium-temperature thermal deformation with a certain deformation amount, and the subsequent high-temperature heating and final thermal deformation process is combined, so that on one hand, coarse compounds and Weishi structures can be further crushed by deformation at a relatively low temperature, and meanwhile, partial deformation energy storage is introduced; on the other hand, the deformed structure takes a coarse compound or a widmannstatten as a core through high-temperature heating to form partial recrystallization, and the subsequent final thermal deformation can deform the recrystallized structure to become the deformed structure again, so that the fracture toughness, the plasticity (particularly the high-directional plasticity) and the corrosion resistance of the alloy are improved while the strength of the alloy is not reduced, and a product with excellent comprehensive performance is obtained.

According to the invention, through a mode of medium-temperature deformation, high-temperature heating and heat preservation and final thermal deformation, the problem that the comprehensive performance of the alloy is deteriorated due to the fact that large-size compounds and large-size widmans in the high-alloy-content aluminum alloy are inherited in crystal boundaries and sub-crystal boundaries is solved, the defect that other properties cannot meet the requirements easily while the alloy strength is increased is avoided, and the industrial preparation and engineering application of the ultrahigh-strength and high-comprehensive-performance aluminum alloy plate and forge piece become feasible.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings used in the embodiment of the present invention will be briefly explained. It is obvious that the drawings described below are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be obtained from these drawings without inventive effort.

FIG. 1 shows the high power texture of a plate prepared by different processes;

in the figure, a) and b) are high-power structures of the longitudinal section of a 80mm plate treated by the traditional process (hot rolling, solution quenching, pre-stretching and aging), and a large number of large-size compounds and widmans structures can be observed;

c) and d) is a longitudinal section high-power structure after the hot initial rolling, warm rolling, high-temperature heating, final rolling, solid solution, pre-stretching and aging treatment, and residual phases can be observed to basically disappear, and the Weishi bodies are changed into fine particle phases.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all 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.

Features of various aspects of embodiments of the invention will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. The following description of the embodiments is merely intended to better understand the present invention by illustrating examples thereof. The present invention is not limited to any particular arrangement or method provided below, but rather covers all product structures, any modifications, alterations, etc. of the method covered without departing from the spirit of the invention.

Example one method of verifying the present invention using an Al-Cu-Li-based alloy and a 2-based aluminum alloy is as follows:

by adopting the method for improving the comprehensive performance of the aluminum alloy thick plate and the forging, the corresponding alloy components and weight percentages are as follows: 4.1% of Cu, 1.56% of Li, 1.18% of Mg, 0.42% of Zn, 0.41% of Mn, 0.33% of Ag, 0.08% of Zr, 0.02% of Ti, 0.06% of Si, 0.11% of Fe and the balance of Al, a flat ingot with the thickness of 400mm is heated at the temperature of 505 +/-10 ℃, then is taken out of a furnace for hot rolling, is rapidly rolled to 130mm, then is transferred into a medium-temperature furnace for heating and heat preservation, is subjected to heat preservation at the temperature of 290 +/-10 ℃ for 8 hours, is taken out of the furnace for rolling, is stopped after being rolled to 105mm, and is placed to the room temperature. And (3) transferring the plate into a high-temperature furnace for heating, wherein the heating temperature is 525 +/-10 ℃, preserving heat for 6h, then cooling to 460 ℃, and finally carrying out hot rolling, wherein the plate is rolled to 83 mm. The rolled plate was subjected to solution quenching (530 ℃/4h, room temperature water quenching) + pre-stretching treatment (pre-stretching deformation 4.7% -5.3%) + artificial aging treatment (aging process 120 ℃/12h +145 ℃/13h) and the plate after the above-mentioned process was sampled, and the high-magnification structure was observed and compared with the plate normally rolled, and the results are shown in fig. 1. Subsequently, the elongation and fracture toughness (K) of the aged plate in different directions were measured_IC) And stress corrosion resistance (C ring), the results are shown in Table 1. In addition, 80mm thick plates were also prepared using the process described in comparative patent process application No. 201910693641.2, and the specific properties are shown in table 1.

The alloy components of the 80mm thick plate prepared by the traditional process are as follows: 3.6 percent of Cu, 1.42 percent of Li, 0.48 percent of Mg, 0.49 percent of Zn, 0.30 percent of Mn, 0.33 percent of Ag, 0.09 percent of Zr, 0.03 percent of Ti, 0.04 percent of Si, 0.09 percent of Fe and the balance of Al.

Alloy composition of 80mm thick plate prepared by comparative patent: 3.6% of Cu, 1.43% of Li, 0.5% of Mg, 0.48% of Zn, 0.30% of Mn, 0.33% of Ag, 0.09% of Zr, 0.02% of Ti, 0.04% of Si, 0.09% of Fe and the balance of Al.

After the treatment by the method, the number of large-size compounds is obviously reduced, the large-size compounds are distributed and transferred into crystals from a crystal boundary, and large-size Weishi bodies are completely converted into fine fragments, so that the plasticity, the fracture toughness and the corrosion resistance of the thick plate are obviously improved while the high strength of the thick plate is ensured, and the comprehensive performance is obviously improved.

TABLE 1 comparison of Performance before and after treatment by the method of the invention

In the second embodiment, the method of the present invention is verified by using Al-Zn-Mg series alloy and 7 series aluminum alloy, and the method comprises the following steps:

by adopting the method for improving the comprehensive performance of the aluminum alloy plate and the forging, the alloy comprises the following components in percentage by weight: 12.0% of Zn, 2.8% of Mg, 1.8% of Cu, 0.26% of Li, 0.10% of Zr, 0.15% of Mn, 0.08% of Sc, 0.03% of Ti, 0.08% of Si, 0.12% of Fe and the balance of Al, wherein a round ingot with the diameter of 430mm subjected to homogenization treatment is heated at the temperature of 400 +/-10 ℃, taken out of a furnace and subjected to hot forging, and a forging blank is obtained after two-pier one-pull treatment. Air-cooling the forging blank to room temperature, then placing the forging blank into an air furnace for heating, wherein the heating temperature is 280 +/-10 ℃, and discharging the forging blank from the furnace for forging deformation with the deformation of 23%; and then placing the mixture into an air circulation furnace for high-temperature heating, wherein a heating-in-furnace mode is adopted during heating, the heating temperature is 470 ℃, the temperature is kept for 2 hours, then the mixture is cooled to 410 +/-10 ℃, then the mixture is discharged from the furnace for forging, the forging deformation is 28%, and the mixture is cooled to room temperature. And finally, carrying out solution treatment on the forged piece, wherein the solution temperature is 473 +/-5 ℃/4h, carrying out water quenching at room temperature, carrying out cold pressing deformation of 1.5-3.0% after quenching, and measuring the tensile property, fracture toughness, stripping property and stress corrosion resistance (C ring) of the forged piece after artificial aging of 120 +/-3 ℃/8h +145 +/-3 ℃/8-12 h, wherein the results are shown in table 2.

The method can obviously improve the strength, the plasticity, particularly the high directional plasticity, the fracture toughness and the corrosion resistance of the forging after the treatment, and obviously improve the comprehensive performance.

TABLE 2 comparison of Performance before and after treatment by the method of the invention

Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.