Forging process capable of reducing reverse forging coarse grains of 6061 aluminum alloy

Abstract

The invention relates to the technical field of aluminum alloy forging, in particular to a forging process capable of reducing reverse forging coarse grains of 6061 aluminum alloy, which comprises the following steps: acquiring a 6061 aluminum alloy ingot, homogenizing and annealing the 6061 aluminum alloy ingot at 480-520 DEG C for 12-16 hours, cooling to room temperature by water, performing ultrasonic flaw detection, performing turning surface treatment, and alternately forging and pressing in three directions, thereby obtaining the 6061 aluminum alloy. The method comprises the following steps: placing a fine-grain 6061 aluminum alloy forge piece in a graded heating furnace, completing sub-dynamic recrystallization, applying directional pressure stress of 50-80MPa to the 6061 aluminum alloy forge piece, analyzing grain boundary characteristic distribution by adopting an electron back scattering diffraction technology, and obtaining the grain boundary optimized 6061 aluminum alloy forge piece with a discontinuous coarse-grain structure through laser shock strengthening and stress relief annealing. According to the method, the problems that reverse forging coarse grains are caused by uneven strain distribution during forging and pressing, and fine grains and high-density nanoprecipitation cannot be effectively obtained and a grain boundary structure cannot be optimized due to the fact that follow-up forging, heat treatment and stress treatment parameters are difficult to accurately control can be solved.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy forging technology, and specifically relates to a forging process that can reduce the coarse grains in reverse forging of 6061 aluminum alloy. Background Technology

[0002] In the field of 6061 aluminum alloy forging, existing technologies have many shortcomings, especially in reducing coarse grains during reverse forging. Traditional forging processes for 6061 aluminum alloy ingots suffer from imprecise homogenization annealing parameters and a wide range of annealing temperatures and times, resulting in poor internal microstructure uniformity and affecting subsequent forging quality. Although ultrasonic testing is performed after water cooling, the surface treatment during turning lacks comprehensive consideration of optimizing the overall performance of the billet. In the forging stage, the preheating temperature control of cylindrical billets is not precise enough. During three-dimensional alternating forging, there is a lack of systematic research on optimizing deformation, temperature, and path, making it difficult to ensure uniform strain in the forged billet and easily leading to localized coarse grains. In subsequent forging processes, the temperature range, strain rate, and temperature difference control in stepped cooling forging are not precise enough, and the application of overpressure lacks scientific basis, resulting in unsatisfactory grain refinement in the forgings. In terms of heat treatment, the parameter control of the subdynamic recrystallization process in the staged heating furnace is not precise enough, and the temperature and deformation control during solution treatment are difficult to achieve optimal matching. The quenching process also fails to fully consider the uniform distribution of internal stress in the forgings. In the stress treatment stage, the parameter selection for applying directional compressive stress to 6061 aluminum alloy forgings is rather arbitrary, the two-stage aging regime lacks effective monitoring methods for adjusting the stress direction, the residual stress distribution is uneven, and it is difficult to obtain aluminum forgings with high density nano-precipitation.

[0003] Existing technologies suffer from problems such as imprecise pretreatment in homogenization annealing, uneven strain distribution during forging leading to coarse grains, and poor control of subsequent forging, heat treatment, and stress treatment parameters, making it difficult to obtain fine grains, high-density nano-grain, and optimize grain boundary structure. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a forging process that reduces coarse grains in 6061 aluminum alloy during reverse forging. This process solves the problems of insufficient fineness in the initial homogenization annealing affecting the basic properties of the ingot, uneven strain distribution during forging leading to coarse grains, and difficulty in precisely controlling subsequent forging, heat treatment, and stress treatment parameters, thus hindering the effective acquisition of fine grains, high-density nanograin, and optimized grain boundary structure. To achieve the above objectives, this invention adopts the following technical solution:

[0005] The one can reduce 6061 aluminum alloy reverse forging coarse crystal forging process, including the following steps: obtaining 6061 aluminum alloy ingot, homogenizing annealing 6061 aluminum alloy ingot at 480-520 DEG C for 12-16 hours, water cooling to room temperature, by ultrasonic flaw detection, turning surface treatment, get cylindrical blank; obtain cylindrical blank, preheat the cylindrical blank to 420-450 DEG C, by three-way alternative forging, control deformation and temperature, optimize path, get strain uniform 6061 aluminum alloy forging blank; obtain 6061 aluminum alloy forging blank, by 380-400 DEG C step cooling process forging, control strain rate and temperature difference, apply overpressure, get fine grain 6061 aluminum alloy forging; the fine grain 6061 aluminum alloy forging is placed in the staged heating furnace, the sub-dynamic recrystallization is completed, the solid solution treatment is adopted, the temperature and deformation are controlled, the quenching is carried out, and the 6061 aluminum alloy forging is obtained; install hydraulic loading device, apply 50-80 MPa directional compressive stress to 6061 aluminum alloy forging, adopt double-stage aging system, adjust stress direction, monitor residual stress distribution, get high density nanometer 6061 aluminum forging; obtain high density nanometer 6061 aluminum forging, adopt electron backscatter diffraction technique to analyze grain boundary characteristic distribution, through laser shock peening, stress relief annealing, get non-continuous coarse grain structure of optimized grain boundary 6061 aluminum alloy forging.

[0006] Further, the obtaining 6061 aluminum alloy ingot, homogenizing annealing 6061 aluminum alloy ingot at 480-520 DEG C for 12-16 hours, water cooling to room temperature, by ultrasonic flaw detection, turning surface treatment, get cylindrical blank, including the following steps: obtaining 6061 aluminum alloy ingot, homogenizing annealing 6061 aluminum alloy ingot at 480-520 DEG C for 12-16 hours; the 6061 aluminum alloy ingot is rapidly cooled to room temperature by water cooling, the internal defects of the blank are detected by using an ultrasonic flaw detector, and the fatal defects such as shrinkage cavity and crack are ensured; the surface of the 6061 aluminum alloy ingot is turned to remove the oxide skin and the surface defect layer, and the cylindrical blank is obtained.

[0007] Further, the obtaining cylindrical blank, preheating the cylindrical blank to 420-450 DEG C, by three-way alternative forging, control deformation and temperature, optimize path, get strain uniform 6061 aluminum alloy forging blank, including the following steps: obtaining cylindrical blank, preheating the cylindrical blank to 420-450 DEG C into the forging die, adopting three-way alternative forging process to compress 30% height along the axial direction, rotating 90 DEG to carry out radial forging, and completing closed forging along the third direction; the deformation amount of each pass is controlled to be 15-20%, and the temperature fluctuation between passes is controlled to be not more than 20 DEG C; the temperature difference between the die temperature and the blank is kept within ±10 DEG C by using isothermal forging technology; the forging path is optimized by three-dimensional finite element simulation, so that the strain distribution is uniform, and the strain uniform 6061 aluminum alloy forging blank is obtained.

[0008] Further, the 6061 aluminum alloy forging blank is obtained, and the fine-grained 6061 aluminum alloy forging is obtained through 380-400 DEG C step-down temperature process forging, control of strain rate and temperature difference, and application of overpressure, and the fine-grained 6061 aluminum alloy forging comprises the following steps: obtaining a 6061 aluminum alloy forging blank, controlling the temperature at 380-400 DEG C, and performing step-down temperature forging; triggering dynamic recovery by using a medium strain rate of 0.1-0.3 s-1, switching to a low strain rate of 0.01-0.05 s-1 when the cumulative strain reaches 1.2; monitoring the core-surface temperature difference of the blank in real time through an infrared thermometer, adjusting the forging frequency so that the temperature difference is less than or equal to 15 DEG C; and applying an overpressure of 5-8% in the deformation stage, promoting static recrystallization by using residual stress, to obtain a fine-grained 6061 aluminum alloy forging.

[0009] Further, the fine-grained 6061 aluminum alloy forging is placed in a staged heating furnace, sub-dynamic recrystallization is completed, solid solution treatment is adopted, the temperature and deformation are controlled, quenching is performed, and the 6061 aluminum alloy forging is obtained, and the 6061 aluminum alloy forging comprises the following steps: placing the fine-grained 6061 aluminum alloy forging in a staged heating furnace, completing sub-dynamic recrystallization at 350 DEG C for 2 hours, and increasing the temperature to 530 DEG C at a rate of 5 DEG C / min for solid solution treatment; using nitrogen protection to prevent surface oxidation, and controlling the furnace temperature fluctuation in the solid solution stage to be ±3 DEG C; using a clamp to avoid deformation of the fine-grained 6061 aluminum alloy forging, and installing a heat shielding device at a thin-walled part to prevent overburning; through a quenching medium temperature control system, the water temperature is maintained in the range of 20-25 DEG C, and the 6061 aluminum alloy forging is obtained.

[0010] Further, the hydraulic loading device is installed, a directional compressive stress of 50-80 MPa is applied to the 6061 aluminum alloy forging, a two-stage aging system is adopted, the stress direction is adjusted, the residual stress distribution is monitored, and the high-density nanometer 6061 aluminum forging is obtained, and the high-density nanometer 6061 aluminum forging comprises the following steps: installing a hydraulic loading device in an aging furnace, and applying a directional compressive stress of 50-80 MPa to the 6061 aluminum alloy forging; adopting a two-stage aging system to treat the forging: maintaining at a temperature of 120 DEG C for 8 hours to promote the formation of GP zones; increasing the temperature to 180 DEG C for 12 hours for artificial aging, keeping the stress direction consistent with the main load-bearing direction of the forging during the artificial aging process, and adjusting the stress direction every 2 hours; using an X-ray stress analyzer to monitor the residual stress distribution, and obtaining the high-density nanometer 6061 aluminum forging.

[0011] Further, the high-density nanoscale 6061 aluminum forgings are obtained, and the grain boundary characteristic distribution is analyzed by electron backscatter diffraction technology, and the non-continuous coarse grain structure of the optimized grain boundary 6061 aluminum alloy forgings is obtained by laser shock peening and stress relief annealing, including the following steps: obtaining high-density nanoscale 6061 aluminum forgings, and analyzing the grain boundary characteristic distribution by electron backscatter diffraction technology; for the area where the proportion of Σ3-29 special grain boundaries is insufficient, a pulsed laser with a wavelength of 1064nm and a power density of 3-5GW / cm 2 , the impact times are 3-5 times per point, and the local laser shock peening is carried out in an inert gas environment; a stress relief annealing process of 200 degrees Celsius for 2 hours is implemented; through electrolytic polishing, the surface roughness Ra is less than or equal to 0.2μm, and the non-continuous coarse grain structure of the optimized grain boundary 6061 aluminum alloy forgings is obtained.

[0012] Further, the 6061 aluminum alloy ingot surface is turned to remove the oxide skin and surface defect layer, and a cylindrical blank is obtained, including the following steps: setting the turning processing parameters, selecting YT15 hard alloy cutter, extracting and eliminating the undesirable surface material; the 6061 aluminum alloy ingot is fixed on the lathe, and the cutter is moved according to the set trajectory for cutting; through continuous and stable turning processing, the required cylindrical blank is finally obtained.

[0013] Further, the residual stress distribution is monitored by using an X-ray stress analyzer, including the following steps: by adjusting the instrument parameters, ensure that it is in the best detection state, then the 6061 aluminum alloy forgings are accurately placed on the surface of the forgings to be measured area; start the instrument, with the help of X-ray penetration characteristics, extract the characteristic information of the residual stress inside the forgings; the collected data are transmitted to the analysis system, and after professional algorithm processing, the residual stress distribution of each part of the 6061 aluminum alloy forgings is obtained.

[0014] In the technical solution provided by this invention, a 6061 aluminum alloy ingot is obtained, and then homogenized and annealed at 480 to 520°C for 12 to 16 hours. After water cooling to room temperature, the ingot is subjected to ultrasonic testing and surface treatment by turning to obtain a cylindrical billet. The cylindrical billet is then preheated to 420 to 450°C and subjected to triaxial alternating forging, controlling the deformation and temperature, and optimizing the forging path to obtain a 6061 aluminum alloy forging billet with uniform strain. Finally, the 6061 aluminum alloy forging billet is forged using a stepped cooling process from 380 to 400°C, controlling the strain rate and temperature difference, and applying overpressure to obtain a fine-grained 6061 aluminum alloy forging billet. The invention involves placing a fine-grained 6061 aluminum alloy forging in a staged heating furnace to achieve subdynamic recrystallization, followed by solution treatment, temperature and deformation control, and quenching to obtain a high-density nano-precipitate 6061 aluminum alloy forging. A hydraulic loading device is then installed to apply directional compressive stress of 50 to 80 MPa to the 6061 aluminum alloy forging. A two-stage aging process is employed, and by adjusting the stress direction and monitoring the residual stress distribution, a high-density nano-precipitate 6061 aluminum alloy forging is obtained. The high-density nano-precipitate 6061 aluminum alloy forging is then analyzed using electron backscatter diffraction (EBS) technology to determine the grain boundary characteristics. Laser shock annealing and stress-relief annealing are then used to obtain a 6061 aluminum alloy forging with optimized grain boundaries and a discontinuous coarse-grained structure. This invention addresses the problems of insufficient fineness in the initial homogenization annealing process affecting the basic performance of the ingot, uneven strain distribution during forging leading to reverse forging and coarse grains, and difficulty in accurately controlling subsequent forging, heat treatment, and stress treatment parameters, thus hindering the effective acquisition of fine grains, high-density nano-precipitates, and optimized grain boundary structures. Attached Figure Description

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention.

[0016] Figure 1 This is a schematic diagram of a first embodiment of a forging process that can reduce the coarse grains of 6061 aluminum alloy in reverse forging, according to an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of a second embodiment of a forging process that can reduce the coarse grains of 6061 aluminum alloy in reverse forging, according to an embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram of a third embodiment of a forging process that can reduce the coarse grains of 6061 aluminum alloy in reverse forging according to an embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram of the fourth embodiment of a forging process that can reduce the coarse grains of 6061 aluminum alloy in reverse forging according to the present invention.

[0020] Figure 5 This is a schematic diagram of the fifth embodiment of a forging process that can reduce the coarse grains of 6061 aluminum alloy in reverse forging according to the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0023] A forging process that can reduce coarse grains in reverse forging of 6061 aluminum alloy, such as Figure 1 As shown, it includes the following steps:

[0024] In this embodiment, a 6061 aluminum alloy ingot is obtained, and then homogenized and annealed at 480 to 520°C for 12 to 16 hours. After water cooling to room temperature, ultrasonic flaw detection is performed, followed by surface machining to obtain a cylindrical billet. The cylindrical billet is then preheated to 420 to 450°C and subjected to triaxial alternating forging, controlling the deformation and temperature, and optimizing the forging path to obtain a 6061 aluminum alloy forging with uniform strain. This 6061 aluminum alloy forging is then forged using a stepped cooling process from 380 to 400°C, controlling the strain rate and temperature difference, and applying overpressure to obtain a fine-grained 6061 aluminum alloy forging. Fine-grained 6061 aluminum alloy forgings are placed in a staged heating furnace to complete subdynamic recrystallization. Solution treatment is then performed, with temperature and deformation controlled. After quenching, 6061 aluminum alloy forgings are obtained. A hydraulic loading device is installed to apply directional compressive stress of 50 to 80 MPa to the 6061 aluminum alloy forgings. A two-stage aging process is adopted, and the stress direction is adjusted while monitoring the residual stress distribution to obtain high-density nano-grained 6061 aluminum alloy forgings. The high-density nano-grained 6061 aluminum alloy forgings are then analyzed using electron backscatter diffraction (EBS) technology to determine grain boundary characteristics. Laser shock annealing and stress-relief annealing are then performed to obtain 6061 aluminum alloy forgings with optimized grain boundaries and a discontinuous coarse-grained structure.

[0025] 6061 aluminum alloy is a heat-treatable wrought alloy with main alloying elements of aluminum, magnesium and silicon, forming Mg2Si strengthening phase, giving medium strength, good corrosion resistance and weldability. The material can significantly improve the strength and hardness through heat treatment (such as T6, T651 state), and the T651 state is more suitable for precision machining after pre-stretching process to eliminate internal stress. Its typical application fields are widely used in aerospace (aircraft skin, rocket forging ring), transportation (automobile body, hub), electronics (electrical components, cables) and building decoration (doors and windows, curtain wall) and other fields.

[0026] As shown in Figure 2 In this embodiment, 6061 aluminum alloy ingot is obtained, and the 6061 aluminum alloy ingot is homogenized annealed at 480-520°C for 12-16 hours. The 6061 aluminum alloy ingot is rapidly cooled to room temperature by water cooling, and the internal defects of the blank are detected by using an ultrasonic flaw detector to ensure that there are no fatal defects such as shrinkage holes and cracks. The surface of the 6061 aluminum alloy ingot is turned to remove the oxide skin and the surface defect layer, and a cylindrical blank is obtained.

[0027] Homogenizing annealing the 6061 aluminum alloy ingot at 480-520°C for 12-16 hours can eliminate the internal composition segregation of the ingot and improve the uniformity of the structure, laying a good foundation for subsequent processing. Rapid cooling to room temperature by water cooling can effectively fix the structure state after homogenizing annealing. Ultrasonic flaw detection can accurately find fatal defects such as shrinkage holes and cracks in the blank, ensuring the quality of the blank. Surface turning removes the oxide skin and the defect layer, so that the surface quality of the cylindrical blank meets the standard, reduces the hidden danger of subsequent processing, and ensures the smooth development of the forging process.

[0028] As shown in Figure 3 In this embodiment, a cylindrical blank is obtained, and the cylindrical blank is preheated to 420-450°C and put into a forging die. A three-way alternating forging process is used to compress 30% of the height in the axial direction, rotate 90° to perform radial forging, and complete the closed forging in the third direction. The deformation amount of each pass is controlled to be 15-20%, and the temperature fluctuation between passes is kept within 20°C. The isothermal forging technology is used to keep the temperature difference between the die and the blank within ±10°C. The forging path is optimized by three-dimensional finite element simulation to ensure uniform strain distribution, and a 6061 aluminum alloy forging blank with uniform strain is obtained.

[0029] Preheating the cylindrical blank to 420-450°C and using a three-way alternating forging process can shape the blank in all directions and improve the material density through multi-directional compression. Controlling the deformation amount and temperature fluctuation of each pass can avoid defects such as cracks caused by excessive deformation or uneven temperature. The isothermal forging technology makes the temperature difference between the die and the blank small, reducing the influence of thermal stress. The three-dimensional finite element simulation optimizes the forging path, which can accurately plan the forging process and ensure uniform strain distribution.

[0030] As Figure 4 shown in the embodiment, the 6061 aluminum alloy forging blank is obtained, the temperature is controlled at 380-400 DEG C, and the step-down temperature forging is performed; the medium strain rate of 0.1-0.3 s-1 is adopted to trigger dynamic recovery, and when the cumulative strain reaches 1.2, the low strain rate of 0.01-0.05 s-1 is switched; the core-surface temperature difference of the blank is monitored in real time by an infrared thermometer, the forging frequency is adjusted to make the temperature difference less than or equal to 15 DEG C; the overpressure of 5-8% is applied in the deformation stage, the residual stress is utilized to promote static recrystallization, and the fine-grained 6061 aluminum alloy forging is obtained.

[0031] The 6061 aluminum alloy forging blank is subjected to step-down temperature forging at 380-400 DEG C, which can accurately control the material organization evolution. The medium and low strain rates are switched, the dynamic recovery is triggered first, and then the rate is reduced to promote grain refinement. The core-surface temperature difference is monitored in real time by an infrared thermometer and the forging frequency is adjusted to ensure uniform temperature and avoid uneven organization caused by temperature difference. The overpressure of 5-8% is applied, the residual stress is effectively utilized to promote static recrystallization, and the fine-grained 6061 aluminum alloy forging is obtained, which significantly improves the strength and toughness of the material.

[0032] As Figure 5 shown in the embodiment, the fine-grained 6061 aluminum alloy forging is placed in a staged heating furnace, isothermal treated at 350 DEG C for 2 hours to complete the sub-dynamic recrystallization, and is heated to 530 DEG C at a rate of 5 DEG C / min for solid solution treatment; nitrogen protection is adopted to prevent surface oxidation, and the furnace temperature fluctuation in the solid solution stage is controlled within ±3 DEG C; a clamp is used to avoid deformation of the fine-grained 6061 aluminum alloy forging, and a heat shielding device is installed at the thin wall part to prevent overburning; the water temperature is maintained in the range of 20-25 DEG C by a quenching medium temperature control system, and the 6061 aluminum alloy forging is obtained.

[0033] In the embodiment, a hydraulic loading device is installed in the aging furnace to apply a directional compressive stress of 50-80 MPa to the 6061 aluminum alloy forging; a two-stage aging system is adopted to treat the forging: maintaining at 120 DEG C for 8 hours to promote the formation of GP zone; the temperature is increased to 180 DEG C for 12 hours for artificial aging, and the stress direction is kept consistent with the main load direction of the forging during the artificial aging process; the residual stress distribution is monitored by an X-ray stress analyzer, and the high-density 6061 aluminum forging is obtained.

[0034] A hydraulic loading device is installed in the aging furnace to apply a directional compressive stress to the 6061 aluminum alloy forging, which can effectively control the nucleation and growth of precipitates. A two-stage aging system is adopted, the GP zone is first generated at 120 DEG C to lay a foundation for the formation of subsequent strengthening phase, and then the temperature is increased to 180 DEG C for artificial aging to promote the precipitation of strengthening phase. The stress direction is kept consistent with the main load direction and is adjusted regularly during artificial aging, which can optimize the distribution of precipitates.

[0035] In this embodiment, high-density nanocrystalline 6061 aluminum forgings are obtained, and electron backscatter diffraction technology is used to analyze the grain boundary characteristic distribution; for the area where the proportion of Σ3-29 special grain boundaries is insufficient, a pulsed laser with a wavelength of 1064 nm and a power density of 3-5 GW / cm 2 , impact 3-5 times per point, and local laser shock peening is carried out in an inert gas environment; a stress relief annealing process of 200 degrees Celsius for 2 hours is implemented; through electrolytic polishing, the surface roughness Ra is less than or equal to 0.2 μm, and an optimized grain boundary 6061 aluminum alloy forging with a non-continuous coarse grain structure is obtained.

[0036] First, the grain boundary characteristic distribution of high-density nanocrystalline 6061 aluminum forgings is precisely analyzed using electron backscatter diffraction technology, and the area where the proportion of Σ

[0037] 3-29 special grain boundaries is insufficient is found out. Local impact strengthening of a specific parameter pulsed laser in an inert gas environment can effectively improve the proportion of special grain boundaries in this area and enhance the material performance. Then, a stress relief annealing process is carried out to eliminate internal residual stress and avoid cracking caused by stress. Finally, electrolytic polishing is used to reduce surface roughness and obtain a non-continuous coarse grain structure, resulting in an optimized grain boundary 6061 aluminum alloy forging

[0038] In this embodiment, the turning processing parameters are set, YT15 hard alloy tool is selected, and the undesirable surface substances are extracted and eliminated; the 6061 aluminum alloy ingot is fixed on the lathe, and the tool is moved according to the set trajectory for cutting; through continuous and stable turning processing, the required cylindrical blank is finally obtained.

[0039] In this embodiment, the instrument parameters are adjusted to ensure that they are in the best detection state, and then the 6061 aluminum alloy forging is precisely placed on the surface of the forging to be measured. Start the instrument and use the X-ray penetration characteristics to extract the characteristic information of the internal residual stress of the forging. The collected data are transmitted to the analysis system, and after professional algorithm processing, the residual stress distribution of each part of the 6061 aluminum alloy forging is obtained.

[0040] Selecting YT15 hard alloy tool and reasonably setting turning processing parameters can effectively extract and eliminate undesirable substances on the surface of 6061 aluminum alloy ingot, such as oxidation layer and impurities, and improve the surface quality of the blank. Fix the ingot on the lathe and let the tool move accurately according to the set trajectory for cutting, which can ensure the accuracy of the processing size and make the final cylindrical blank meet the design requirements. Continuous and stable turning processing can reduce processing errors and improve production efficiency.

[0041] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A forging process that can reduce 6061 aluminum alloy reverse forging coarse grains, characterized in that, The forging process capable of reducing coarse grains of 6061 aluminum alloy reverse forging includes the following steps: Obtain a 6061 aluminum alloy ingot, homogenize the 6061 aluminum alloy ingot at 480-520 DEG C for 12-16 hours, water cool to room temperature, detect internal defects of the ingot by ultrasonic flaw detection, and perform turning surface treatment to obtain a cylindrical blank; Obtain the cylindrical blank, preheat the cylindrical blank to 420-450 DEG C, control deformation and temperature by three-way alternate forging, and optimize the path to obtain a 6061 aluminum alloy forged blank with uniform strain; Obtain the 6061 aluminum alloy forged blank, forge by a 380-400 DEG C step-down temperature process, control strain rate and temperature difference, and apply overpressure to obtain a fine-grained 6061 aluminum alloy forging; Place the fine-grained 6061 aluminum alloy forging in a staged heating furnace, complete sub-dynamic recrystallization, control temperature and deformation by solid solution treatment, and quench to obtain a 6061 aluminum alloy forging; Install a hydraulic loading device, apply a directional compressive stress of 50-80 MPa to the 6061 aluminum alloy forging, adjust the stress direction by using a two-stage aging system, and monitor residual stress distribution to obtain a high-density nano-precipitated 6061 aluminum forging; Obtain the high-density nano-precipitated 6061 aluminum forging, analyze grain boundary characteristic distribution by electron backscatter diffraction technology, and obtain an optimized grain boundary 6061 aluminum alloy forging with a non-continuous coarse grain structure by laser shock peening and stress relief annealing.

2. The forging process that can reduce the coarse grain of 6061 aluminum alloy reverse forging according to claim 1, characterized in that, The obtaining of the 6061 aluminum alloy ingot, the homogenization of the 6061 aluminum alloy ingot at 480-520 DEG C for 12-16 hours, the water cooling to room temperature, the ultrasonic flaw detection, and the turning surface treatment to obtain the cylindrical blank include the following steps: Obtain a 6061 aluminum alloy ingot, homogenize the 6061 aluminum alloy ingot at 480-520 DEG C for 12-16 hours, water cool to room temperature, detect internal defects of the ingot by ultrasonic flaw detection, and perform turning surface treatment to obtain a cylindrical blank; Use water cooling to rapidly cool the 6061 aluminum alloy ingot to room temperature, use an ultrasonic flaw detector to detect internal defects of the blank, and ensure that there are no fatal defects such as shrinkage holes and cracks; Perform turning processing on the surface of the 6061 aluminum alloy ingot to remove the oxide scale and the surface defect layer to obtain a cylindrical blank.

3. The forging process that can reduce the coarse grain of 6061 aluminum alloy reverse forging according to claim 1, characterized in that, The obtaining of the cylindrical blank, the preheating of the cylindrical blank to 420-450 DEG C, the three-way alternate forging, the control of deformation and temperature, and the optimization of the path to obtain a 6061 aluminum alloy forged blank with uniform strain include the following steps: Obtain the cylindrical blank, preheat the cylindrical blank to 420-450 DEG C, and put it into a forging die, compress 30% of the height along the axial direction by using a three-way alternate forging process, rotate 90 DEG to perform radial forging, and complete closed forging along the third direction; Control the deformation of each pass to be 15-20%, and keep the temperature fluctuation between passes to be no more than 20 DEG C; Use isothermal forging technology to keep the temperature difference between the die and the blank within ±10 DEG C; Optimize the forging path by three-dimensional finite element simulation to ensure uniform strain distribution, and obtain a 6061 aluminum alloy forged blank with uniform strain.

4. The forging process that can reduce the coarse grain of 6061 aluminum alloy reverse forging according to claim 1, characterized in that, The obtaining of the 6061 aluminum alloy forged blank, the forging by a 380-400 DEG C step-down temperature process, the control of strain rate and temperature difference, and the application of overpressure to obtain a fine-grained 6061 aluminum alloy forging include the following steps: Obtaining 6061 aluminum alloy forging blank, controlling temperature at 380-400℃, forging by step-down temperature; Triggering dynamic recovery by medium strain rate of 0.1-0.3s-1, switching to low strain rate of 0.01-0.05s-1 when cumulative strain reaches 1.2; Monitoring the temperature difference between the core and the surface of the blank in real time by infrared thermometer, adjusting the forging frequency to make the temperature difference less than or equal to 15℃; Applying overpressure of 5-8% during deformation stage, promoting static recrystallization by residual stress, obtaining fine-grained 6061 aluminum alloy forgings.

5. The forging process that can reduce the coarse grain of 6061 aluminum alloy reverse forging according to claim 1, characterized in that, Placing the fine-grained 6061 aluminum alloy forgings in a staged heating furnace, completing sub-dynamic recrystallization, adopting solution treatment, controlling temperature and deformation, and obtaining 6061 aluminum alloy forgings by quenching, including the following steps: Placing the fine-grained 6061 aluminum alloy forgings in a staged heating furnace, completing sub-dynamic recrystallization at 350℃ for 2 hours, and solid solution treatment at a rate of 5℃ / min to 530℃; Using nitrogen protection to prevent surface oxidation, controlling the furnace temperature fluctuation of the solid solution stage within ±3℃; Using clamps to avoid deformation of the fine-grained 6061 aluminum alloy forgings, and installing heat shielding devices at thin-walled parts to prevent overburning; Through the quenching medium temperature control system, keeping the water temperature in the range of 20-25℃, obtaining 6061 aluminum alloy forgings.

6. The forging process that can reduce the coarse grain of 6061 aluminum alloy reverse forging according to claim 1, characterized in that, Installing hydraulic loading devices to apply directional compressive stress of 50-80MPa to the 6061 aluminum alloy forgings, adopting double-stage aging system, adjusting stress direction, monitoring residual stress distribution, and obtaining high-density nano-annealed 6061 aluminum forgings, including the following steps: Installing hydraulic loading devices in the aging furnace to apply directional compressive stress of 50-80MPa to the 6061 aluminum alloy forgings; Using double-stage aging system to treat the forgings: keeping at 120℃ for 8 hours to promote GP zone formation; Increasing the temperature to 180℃ for 12 hours of artificial aging, keeping the stress direction consistent with the main load-bearing direction of the forgings during the artificial aging process, and adjusting the stress direction every 2 hours; Using X-ray stress analyzer to monitor residual stress distribution, obtaining high-density nano-annealed 6061 aluminum forgings.

7. The forging process that can reduce the coarse grain of 6061 aluminum alloy reverse forging according to claim 1, characterized in that, Obtaining high-density nano-annealed 6061 aluminum forgings, analyzing grain boundary characteristic distribution by electron backscatter diffraction technology, and obtaining optimized grain boundary 6061 aluminum alloy forgings with non-continuous coarse grain structure through laser shock peening and stress relief annealing, including the following steps: Obtaining high-density nano-annealed 6061 aluminum forgings, analyzing grain boundary characteristic distribution by electron backscatter diffraction technology; For the area where the proportion of Σ3-29 special grain boundaries is insufficient, pulse laser with a wavelength of 1064 nm and a power density of 3-5 GW / cm 2 is used to perform local laser shock peening in an inert gas environment, with 3-5 impacts per point. Implementing stress relief annealing process at 200℃ for 2 hours; Obtaining optimized grain boundary 6061 aluminum alloy forgings with non-continuous coarse grain structure by electrolytic polishing to obtain surface roughness Ra less than or equal to 0.2μm.

8. The forging process that can reduce the coarse grain of 6061 aluminum alloy reverse forging according to claim 2, characterized in that, Turning the surface of the 6061 aluminum alloy ingot to remove the oxide scale and surface defect layer, obtaining cylindrical blank, including the following steps: Setting turning parameters, selecting YT15 carbide tool, and extracting and eliminating undesirable surface substances; Fixing the 6061 aluminum alloy ingot on the lathe, and making the tool move according to the set trajectory for cutting; Through continuous and stable turning, a cylindrical blank meeting the requirements is finally obtained.

9. The forging process that can reduce the coarse grain of 6061 aluminum alloy reverse forging according to claim 6, characterized in that, The monitoring of the residual stress distribution by the X-ray stress analyzer comprises the following steps: adjusting the instrument parameters to ensure that it is in the best detection state, and then accurately placing the 6061 aluminum alloy forge piece on the surface of the forge piece to be measured; Starting the instrument, extracting the characteristic information of the residual stress in the forge piece by means of the X-ray penetration characteristics; The collected data are transmitted to the analysis system, and the residual stress distribution of each part of the 6061 aluminum alloy forge piece is obtained through professional algorithm processing.

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