CN106834988B - A kind of aluminium-cooper-maganesium alloy obtains the thermo-mechanical treatment process of high combination property - Google Patents

Abstract

The invention discloses a novel thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy, which belongs to the technical field of aluminum alloy thermomechanical treatment. The method includes the following processes: continuous solution hot rolling treatment, cryogenic deformation and aging treatment. This process changes the solid solution, aging, deformation, solid solution, artificial aging and other systems of traditional thermomechanical treatment, making the process simple and easy to implement, and combined with cryogenic deformation and aging treatment, the aluminum alloy can maintain good plasticity and toughness. Under this condition, its strength is improved, and the fatigue resistance of Al-Cu-Mg alloy is improved. Suitable for industrial applications.

Description

A thermomechanical treatment process for obtaining high comprehensive performance of Al-Cu-Mg alloy

Technical field:

The invention relates to a thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy, which can effectively improve the comprehensive performance of the aluminum-copper-magnesium alloy; it belongs to the technical field of aluminum alloy thermomechanical treatment.

technical background:

With the development of the global social economy, in order to meet the needs of human development, the industry has higher and higher requirements for the performance of the materials used. As a metal material with high specific strength, high specific stiffness, good plasticity and toughness, and good processing performance, aluminum alloy is widely used in aerospace, automobile and other fields.

my country's aluminum alloy output is huge, but there are many quality problems. At present, in my country's industry, more and more aluminum alloy materials are required to have good comprehensive properties. However, due to the lack of domestic technology, many aluminum alloy materials used in the aerospace field still rely on imports. Therefore, improving the performance of aluminum alloys has become a hot spot of concern.

Common methods to improve the performance of aluminum alloys include: regulating alloying elements, powder metallurgy, spray forming, regression reaging, thermomechanical treatment, etc. In recent years, in order to improve the comprehensive performance of aluminum alloys, some relatively new methods have emerged, such as: equal channel angular pressing (ECAP, equal channel angular pressing), high pressure torsion (HPT, high pressure torsion), cumulative rolling (ARB, accumulative roll bonding), etc., these methods have a significant effect on refining the alloy structure, thereby improving the overall performance of the alloy. However, in comparison, thermomechanical treatment has the advantages of higher productivity, easier operation, lower cost, and is suitable for continuous production. Therefore, it has greater practical significance to improve the comprehensive properties of aluminum alloys by using thermomechanical treatment. .

In the traditional process, the thermomechanical treatment process of aluminum alloy is usually after solid solution, first overaging to precipitate large-size phases, and then deforming, and then performing solution quenching again in order to refine the grains and eliminate the second phase, and then aging deal with. Through the above process, the strength of aluminum alloy can be effectively improved, but it is difficult to achieve the balance between the strength and ductility of aluminum alloy, especially for the large-size precipitates obtained by overaging for grain refinement in traditional thermomechanical treatment. It is eliminated by secondary solid solution, and the secondary solid solution will completely restore and disappear the microstructure such as dislocations generated by deformation, which is not conducive to the formation of dislocation substructures during subsequent aging treatment, and is not conducive to the improvement of its damage resistance , resulting in damage to the aluminum alloy due to external forces during use, causing its performance to decline or even fail. In addition, the traditional thermomechanical treatment process is often long and complicated, and the process cost is high.

Therefore, optimizing the existing thermomechanical treatment process of aluminum alloys to improve the comprehensive performance of aluminum alloys, effectively improving the plastic toughness and improving the damage resistance of aluminum alloys on the basis of taking into account the strength of aluminum alloys has become an urgent problem in this field. technical challenge.

Invention content:

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a thermomechanical treatment process for Al-Cu-Mg alloys to obtain high comprehensive performance. The process method of the present invention can effectively improve the comprehensive properties of Al-Cu-Mg alloys, and has a short process and convenient operation.

A thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy of the present invention is to heat the aluminum-copper-magnesium alloy sample to the solid solution temperature for heat preservation, and then cool it in the furnace or air-cool it to the rolling temperature for hot rolling. After water quenching, followed by cryogenic deformation treatment, and aging treatment after cryogenic deformation.

A thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy of the present invention comprises the following steps:

The first step: solution hot rolling continuous treatment

After the aluminum-copper-magnesium alloy sample is kept in solid solution above the hot-rolling temperature, it is cooled with the furnace or air-cooled to the hot-rolling temperature for hot-rolling deformation treatment. After hot-rolling deformation, it is quenched in water, and the final rolling temperature is controlled to be ≥ 440°C;

The second step: cryogenic deformation treatment

The aluminum-copper-magnesium alloy sample obtained in the first step is subjected to cryogenic deformation treatment; the cryogenic deformation treatment temperature is lower than -120°C, and the cryogenic deformation amount is ≥ 40%;

The third step: aging treatment

Perform aging treatment on samples after cryogenic deformation treatment;

The present invention is a thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy. In the first step, the solid solution heat preservation temperature is 480°C-510°C, and the solid solution heat preservation time is 30min-3h; after solid solution heat preservation, it is cooled with the furnace or Air cooling out of the furnace to the hot rolling start temperature; the hot rolling start temperature is 450°C-480°C, the final rolling temperature is 440°C-470°C; the hot rolling deformation is 20%-80%;

The preferred solid solution holding temperature is 495°C-505°C, and the solid solution holding time is 1h-1.5h;

The preferred starting rolling temperature is 470°C-480°C, the finishing rolling temperature is 440°C-450°C, and the hot rolling deformation is 40%-60%;

In the present invention, an aluminum-copper-magnesium alloy obtains a thermomechanical treatment process with high comprehensive performance. In the second step, the cryogenic deformation treatment temperature is -190°C to -120°C, and the cryogenic heat preservation time is 5min-15min; The amount is 40% to 80%;

The preferred cryogenic deformation treatment temperature is -160°C to -170°C, and the cryogenic holding time is 10min-15min; the cryogenic deformation is 55%-70%;

The present invention is a thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy. In the third step, the aging treatment is artificial aging, the aging treatment temperature is 120°C-210°C, and the aging time is 1h-48h;

The preferred aging treatment temperature is 180°C-200°C, and the aging time is 10h-20h;

The present invention is a thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy. The aluminum-copper-magnesium alloy includes the following components, which are composed by mass percentage:

Cu1.5%-5.5%

Mg0.2%-2%

The balance is Al.

The present invention is a thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy. The aluminum-copper-magnesium alloy includes the following components, which are composed by mass percentage:

Cu2%-5%

Mg0.5%-1.8%

The balance is Al.

The invention relates to a thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy. The aluminum-copper-magnesium alloy comprises the following components in mass percentage: Al-4.45Cu-1.5Mg.

In the present invention, the continuous treatment of solution hot rolling means that after the solution temperature is kept warm, it is cooled to the required temperature for hot rolling deformation treatment, and then water quenching is carried out immediately; after the sample is hot rolled, its state is Supersaturated state, and solid solution can no longer be carried out before the subsequent aging treatment. In this process, the solid solution holding temperature is 480°C to 510°C, the solution holding time is 30min to 3h, the starting rolling temperature required for hot rolling deformation treatment is 450°C to 480°C, and the final rolling temperature is 440°C to 470°C. ℃, the deformation amount of hot rolling deformation treatment is 20% to 80%. The cryogenic deformation after the continuous treatment of solution hot rolling refers to cooling the aluminum alloy sample with liquid nitrogen to reduce the temperature of the sample to -190°C to -120°C, and then carry out rolling deformation, cryogenic deformation The amount of deformation is 40% to 80%. The samples after cryogenic deformation are then subjected to aging treatment, the aging treatment is artificial aging, the temperature is 120°C to 210°C, and the time is 1h to 48h.

Compared with traditional techniques, the advantages of the present invention are:

1. The present invention organically combines the two independent processes of solid solution and hot rolling in the traditional process, adopts continuous solution hot rolling, that is, first keeps the sample at the solution temperature to make it fully solid solution to reach the Saturated state, then cool with the furnace or air cool to the hot rolling temperature for hot rolling, and then quench immediately. Wherein the hot-rolling temperature 440 ℃ to 480 ℃ in the present invention is higher than the commonly used hot-rolling temperature (400 ℃ to 440 ℃) of aluminum-copper-magnesium-aluminum alloy; After treatment, it still maintains a supersaturated state, inhibits the precipitation of solute atoms, avoids the secondary solid solution treatment in the traditional process, makes the process more continuous and simplifies the process, especially in the state of the aluminum alloy sample after hot rolling It is a supersaturated state, which inhibits the precipitation of solute atoms, and prepares a good matrix structure for subsequent cryogenic and aging strengthening treatments.

2. The present invention does not perform secondary solution treatment, and only performs dynamic recrystallization and dynamic recovery during deformation in solution hot rolling continuous treatment. Compared with traditional thermomechanical treatment, recrystallization will occur when secondary solution treatment is performed. Crystallization, the final product of the present invention has a lower proportion of recrystallized grains. Aluminum alloys generally undergo recrystallization nucleation through subgrain merging. Since the grain boundaries of larger subgrains formed after merging absorb more dislocations, which gradually transform into high-angle grain boundaries, Al-Cu-Mg alloys are The recrystallized grains after secondary solid solution after traditional thermomechanical treatment usually have a higher proportion of high-angle grain boundaries. Due to the high proportion of high-angle grain boundaries in recrystallized grains, larger-sized precipitates tend to precipitate on high-angle grain boundaries during the aging process, which will reduce the grain boundary strength of Al-Cu-Mg alloys, resulting in Al-Cu-Mg The alloy is prone to intergranular fracture under the applied load state, which reduces the toughness of the aluminum alloy. The aluminum-copper-magnesium alloy obtained by the technology of the present invention has a lower proportion of recrystallized grains, so the proportion of high-angle grain boundaries is lower than that of the aluminum-copper-magnesium alloy obtained by traditional thermomechanical treatment, thereby reducing the high-angle grain boundary during the aging process. The possibility of large-scale phase precipitation on the grain boundary, compared with the aluminum-copper-magnesium alloy after traditional thermomechanical treatment, reduces the large-scale phase at the grain boundary, avoids the reduction of grain boundary strength, and makes cracks grow along the grain. The resistance is greater, and the damage resistance is significantly improved compared with the aluminum alloy under traditional thermomechanical treatment.

3. The present invention combines the solid solution and hot rolling processes. On the one hand, it retains the deformation texture produced during hot rolling and effectively strengthens the aluminum alloy; on the other hand, it retains the dislocations produced during hot rolling. It can retain a large dislocation density and form a dislocation substructure in the subsequent aging treatment. When the aluminum alloy is subjected to external force, the dislocation substructure will hinder the dislocation movement and significantly improve the strength and toughness of the aluminum-copper-magnesium alloy. ; It avoids the transformation of the deformed texture into a recrystallized texture during the secondary solution treatment in the traditional process, and the dislocations completely recover and disappear during the solution process, resulting in a strengthened texture in the Al-Cu-Mg alloy matrix And the number of dislocation substructures is reduced, which makes it difficult to achieve a good matching of the strength and toughness of the Al-Cu-Mg alloy.

4. The present invention helps to refine the grains during dynamic recrystallization by combining the two processes of solid solution and hot rolling, and promotes nano-scale precipitation during aging by introducing a large number of dislocations and other defects through subsequent cryogenic deformation The precipitation of phases makes multiple strengthening mechanisms work at the same time, which changes the previous single strengthening mechanism of thermomechanical treatment, so as to better improve the comprehensive properties of aluminum-copper-magnesium alloys, and improve the plasticity, toughness and strength at the same time. The yield strength of the aluminum-copper-magnesium alloy processed by the present invention reaches more than 420Mpa, the tensile strength reaches more than 560Mpa, the elongation reaches more than 11%, and the fracture toughness reaches more than 65MPa·m ^1/2 ; In the case of good elongation, the yield strength increased by 27%; the tensile strength increased by 22%; the fracture toughness increased by 9.8%;

5. Using the method of the present invention, controlling the process parameters of hot rolling continuous treatment, cryogenic deformation and artificial aging treatment can produce ultra-fine grains, increase the grain boundary density to increase the external load required for the formation of dislocation plugging , while increasing the grain boundary area can inhibit the movement and extension of cracks, thereby improving the damage resistance of Al-Cu-Mg alloys.

Description of drawings

Accompanying drawing 1 is process flow chart of the present invention.

In the picture:

T _S ------------- solid solution heat preservation temperature;

T _C ------------- hot rolling deformation treatment temperature;

T _a ------------- aging temperature.

Detailed ways:

The present invention will be further described below in conjunction with embodiment and traditional process comparative example.

Example 1:

An aluminum-copper-magnesium alloy cold-rolled plate with a sample thickness of 12 mm is used, and its alloy composition is Al-4.45Cu-1.5Mg-0.54Mn (mass fraction %). First, put the sample in an air furnace at 493°C for 1 hour; then take the sample out of the air furnace and cool it to the starting temperature of 470°C in the air for hot rolling deformation treatment, and the final rolling temperature is 450°C, the deformation amount is 30%; water quenching is carried out immediately after hot rolling; the sample after water quenching is subjected to cryogenic deformation treatment, and the sample is soaked in liquid nitrogen for 15 minutes to make the temperature drop to -185°C before rolling , the deformation amount is 80%; artificial aging is carried out after the cryogenic deformation treatment, the aging temperature is 120 ℃, and the time is 45h. The yield strength, tensile strength, elongation, and fracture toughness (K _q ) parameters of the Al-Cu-Mg alloy treated in this embodiment are shown in Table 1.

Example 2:

An aluminum-copper-magnesium alloy cold-rolled plate with a sample thickness of 12 mm is used, and its alloy composition is Al-4.45Cu-1.5Mg-0.54Mn (mass fraction %). First, put the sample in an air furnace at 485°C for 1 hour; then take the sample out of the air furnace and cool it to the starting temperature of 455°C in the air for hot rolling deformation treatment, and the final rolling temperature is 440°C, the deformation is 50%; water quenching is carried out immediately after hot rolling; the sample after water quenching is subjected to cryogenic deformation treatment, and the sample is soaked in liquid nitrogen for 10 minutes to make the temperature drop to -155°C before rolling , the deformation amount is 60%; artificial aging is carried out after the room temperature rolling treatment, the aging temperature is 170 ℃, and the time is 16h. The yield strength, tensile strength, elongation, and fracture toughness (K _q ) parameters of the Al-Cu-Mg alloy treated in this embodiment are shown in Table 1.

Example 3:

An aluminum-copper-magnesium alloy cold-rolled plate with a sample thickness of 12 mm is used, and its alloy composition is Al-4.45Cu-1.5Mg-0.54Mn (mass fraction %). First, put the sample into an air furnace at 500 °C for 1 h; then take the sample out of the air furnace and cool it to the starting temperature of 480 °C in the air for hot rolling deformation treatment, and the final rolling temperature is 465°C, the deformation is 70%; water quenching is carried out immediately after hot rolling; the sample after water quenching is subjected to cryogenic deformation treatment, and the sample is soaked in liquid nitrogen for 5 minutes to make the temperature drop to -120°C before rolling , the deformation amount is 40%; artificial aging is carried out after the room temperature rolling treatment, the aging temperature is 200 ℃, and the time is 6h. The yield strength, tensile strength, elongation, and fracture toughness (K _q ) parameters of the Al-Cu-Mg alloy treated in this embodiment are shown in Table 1.

Comparative example 1:

An aluminum-copper-magnesium alloy cold-rolled plate with a sample thickness of 12 mm is used, and its alloy composition is Al-4.45Cu-1.5Mg-0.54Mn (mass fraction %). First carry out solid solution treatment, put the sample in an air furnace with a temperature of 490°C for 1 hour, and then quench it; then keep it in an air furnace with a temperature of 430°C for 20 minutes, and then carry out hot rolling deformation, and the deformation amount is 50%. , Quenching immediately after the deformation is completed; then rolling at room temperature, the deformation amount is 60%; after rolling at room temperature, solution treatment is carried out again, and the sample is placed in an air furnace with a temperature of 490 ° C for 1 hour, and then quenched; Finally, the T3 system treatment is carried out, and the room temperature rolling treatment with a deformation amount of 6% is firstly carried out, and then the natural aging is carried out for 100 hours. The yield strength, tensile strength, elongation, and fracture toughness (K _q ) parameters of the Al-Cu-Mg alloy treated in this comparative example are shown in Table 1.

Comparative example 2:

An aluminum-copper-magnesium alloy cold-rolled plate with a sample thickness of 12 mm is used, and its alloy composition is Al-4.45Cu-1.5Mg-0.54Mn (mass fraction %). First carry out solid solution treatment, put the sample in an air furnace with a temperature of 490°C for 1 hour, and then quench it; then keep it in an air furnace with a temperature of 430°C for 20 minutes, and then carry out hot rolling deformation, and the deformation amount is 50%. , Quenching immediately after the deformation is completed; then rolling at room temperature, the deformation amount is 60%; after rolling at room temperature, solution treatment is carried out again, and the sample is placed in an air furnace with a temperature of 490 ° C for 1 hour, and then quenched; Finally, T6 peak aging is carried out, the aging temperature is 120°C, and the aging time is 24h. The yield strength, tensile strength, elongation, and fracture toughness (K _q ) parameters of the Al-Cu-Mg alloy treated in this comparative example are shown in Table 1.

Comparative example 3:

An aluminum-copper-magnesium alloy cold-rolled plate with a sample thickness of 12 mm is used, and its alloy composition is Al-4.45Cu-1.5Mg-0.54Mn (mass fraction %). First carry out solid solution treatment, put the sample in an air furnace with a temperature of 490°C for 1 hour, and then quench it; then keep it in an air furnace with a temperature of 430°C for 20 minutes, and then carry out hot rolling deformation, and the deformation amount is 50%. , Quenching immediately after the deformation is completed; then rolling at room temperature, the deformation amount is 60%; after rolling at room temperature, solution treatment is carried out again, and the sample is placed in an air furnace with a temperature of 490 ° C for 1 hour, and then quenched; Finally, the T8 system treatment is carried out. First, the sample is subjected to room temperature rolling treatment with a deformation amount of 6%, and then an aging treatment at a temperature of 190°C for 12 hours. The yield strength, tensile strength, elongation, and fracture toughness (K _q ) parameters of the Al-Cu-Mg alloy treated in this comparative example are shown in Table 1.

Table 1:

Example Yield strength (MPa) Tensile strength (MPa) Elongation (%) K _q (MPa·m ^1/2 ) 1 421.6 560.4 13.4 72.91 2 433.5 571.8 12.2 70.26 3 450.1 568.5 11.2 67.82 comparative example Yield strength (MPa) Tensile strength (MPa) Elongation (%) K _q (MPa·m ^1/2 ) 1 354.2 467.2 16.8 66.36 2 375.3 495.6 10.7 55.06 3 481.2 508.0 4.8 40.83

Through the comparison of the performance of the above examples and comparative examples, it can be seen that the tensile strength and yield strength of the aluminum-copper-magnesium alloy obtained by the process of the present invention are significantly improved compared with the traditional thermomechanical treatment process, and the increase rate reaches more than 20%. , and maintain a good elongation rate, in addition, the toughness has also been significantly improved, achieving both plasticity, toughness and strength of the aluminum alloy, and the process technology is more streamlined and effective than before, and it is easier to improve the comprehensive performance of the aluminum alloy.

Claims (8)

1. A thermomechanical treatment process for aluminum-copper-magnesium alloy to obtain high comprehensive performance. After heating the aluminum-copper-magnesium alloy sample to the solid solution temperature for heat preservation, it is cooled with the furnace or air-cooled to the rolling temperature for hot rolling. After water quenching, then undergo cryogenic deformation treatment, and then perform aging treatment after cryogenic deformation; The solid solution holding temperature is 480°C-510°C, and the solid solution holding time is 30min-3h; The starting temperature of hot rolling is 450-480°C, and the finishing temperature is 440-470°C. 2. A thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy according to claim 1, comprising the following steps: The first step: solution hot rolling continuous treatment After the aluminum-copper-magnesium alloy sample is kept in solid solution above the hot-rolling temperature, it is cooled with the furnace or air-cooled to the hot-rolling temperature for hot-rolling deformation treatment. After hot-rolling deformation, it is quenched in water, and the final rolling temperature is controlled to be ≥ 440°C; The second step: cryogenic deformation treatment The aluminum-copper-magnesium alloy sample obtained in the first step is subjected to cryogenic deformation treatment; the cryogenic deformation treatment temperature is lower than -120°C, and the cryogenic deformation amount is ≥ 40%; The third step: aging treatment The samples after cryogenic deformation treatment were subjected to aging treatment. 3. A thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy according to claim 2, characterized in that: After solid solution heat preservation, it is cooled with the furnace or air-cooled to the starting temperature of hot rolling. 4. The thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy according to claim 2, characterized in that: the hot rolling deformation is 20%-80%. 5. A thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy according to claim 2, characterized in that: the cryogenic deformation treatment temperature is -190°C-120°C, and the cryogenic holding time is ≤15min. 6. The thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy according to claim 5, characterized in that: the deformation amount of cryogenic deformation is 40%-80%. 7. A thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy according to claim 2, characterized in that: the aging treatment is artificial aging, the aging treatment temperature is 120°C-210°C, and the aging time is 1h- 48h. 8. A thermomechanical treatment process for obtaining high comprehensive performance of an aluminum-copper-magnesium alloy according to any one of claims 1-7, said aluminum-copper-magnesium alloy comprising the following components, composed by mass percentage: Cu1.5%-5.5% Mg0.2%-2% The balance is Al.