Shape control method for aerospace 2195 aluminum alloy frame beam piece and frame beam piece

Abstract

The invention discloses a shape control method for a spaceflight 2195 aluminum alloy frame beam piece. The shape control method comprises the following steps: carrying out vacuum gas quenching on an annular part; performing subzero treatment and uphill quenching treatment on the annular part subjected to vacuum gas quenching; and carrying out harmonic vibration aging treatment on the annular part subjected to liquid helium subzero treatment, and cooling to obtain the frame beam part. The invention further discloses the frame beam piece obtained through the control method. According to the method, the residual stress of the spaceflight 2195 aluminum alloy frame beam piece can be reduced, uniform stress distribution is achieved, quadratic term precipitation and grain refinement are promoted, and the mechanical property of the component is improved.

Description

Technical Field

[0001] The invention belongs to the field of aerospace materials, and in particular is a shape control method for improving the performance of 2195 aluminum alloy thin-walled annular components. Background Art

[0002] Aerospace 2195 aluminum alloy frame beams will produce large residual stresses during the quenching process. These stresses will cause deformation or even structural failure during subsequent processing and manufacturing or under high and low temperature service conditions in the space environment. Although conventional 2195 aluminum alloy solid solution aging can improve material properties, it cannot effectively reduce residual stress and cannot achieve uniform distribution of residual stress. How to further improve the mechanical properties of 2195 aluminum alloy, further reduce the residual stress level of aerospace frame beams, and improve dimensional stability is a problem that needs to be solved at present. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects and provide a method for controlling the shape of aerospace 2195 aluminum alloy frame beams and frame beams. The present invention solves the technical problems that the existing solid solution aging heat treatment method cannot effectively reduce and evenly distribute residual stress, and is difficult to promote the optimization of material microstructure. The present invention can reduce the residual stress of aerospace 2195 aluminum alloy frame beams, achieve uniform stress distribution, promote secondary precipitation and grain refinement, and improve the mechanical properties of components.

[0004] A method for controlling the shape of an aerospace 2195 aluminum alloy frame beam, comprising:

[0005] S1 performs vacuum quenching on the annular parts;

[0006] S2 performs deep cryogenic treatment and uphill quenching treatment on the annular parts after vacuum gas quenching;

[0007] S3 performs harmonic vibration aging treatment on the annular parts after liquid helium cryogenic treatment and cools them down.

[0008] Furthermore, in step S1, the method of vacuum quenching the annular part includes:

[0009] After the annular parts are put into the furnace, heating begins when the vacuum degree is less than 10Pa, and the temperature is raised to 495-505℃ with the furnace at a heating rate of 10-25℃ / min, and kept at this temperature for 1-3 hours;

[0010] After the insulation is completed, nitrogen is filled into the furnace to make the pressure inside the furnace 4-10 bar. The annular parts are gas quenched under this pressure until the furnace temperature drops to 50-70°C and then taken out of the furnace.

[0011] Furthermore, in step S2, the annular part after vacuum quenching is subjected to 3 to 8 times of deep cryogenic treatment and uphill quenching treatment.

[0012] Further, in step S2, the method of performing deep cryogenic treatment and uphill quenching treatment on the annular part after vacuum quenching includes:

[0013] S2.1 Place the vacuum quenched annular parts into liquid helium and keep them warm for 0.5 to 2 hours;

[0014] S2.2 After the heat preservation is completed, take out the annular parts and put them into oil at 60-90℃ for 15-60min;

[0015] S2.3 Repeat steps S2.1 and S2.2 3 to 8 times.

[0016] Furthermore, in step S3, the method of harmonic vibration aging treatment includes:

[0017] S3.1 Place the annular part in a harmonic vibration aging furnace and heat it to the aging temperature;

[0018] S3.2 At the aging temperature, the annular part is subjected to harmonic vibration treatment at the set vibration frequency, amplitude and total harmonic vibration time;

[0019] S3.3 After the harmonic vibration treatment is completed, continue the thermal insulation aging until the aging is completed.

[0020] Furthermore, in step S3.1, the aging temperature is 155-165°C; the heating rate is 5-20°C / min;

[0021] In step S3.2, the vibration frequency is determined according to the natural frequency of the annular part, the amplitude is determined according to the elastic limit of the annular part, and the total harmonic vibration time is determined based on the optimal fatigue load loading principle;

[0022] In step S3.3, the insulation time is 20 to 32 hours.

[0023] Further, in step S3.2, the vibration frequency is 16 to 160 Hz and has 3 to 6 optimal resonance peaks;

[0024] The amplitude is 0.03-0.07 mm;

[0025] The total harmonic vibration time is 0.5 to 3 hours.

[0026] The above-mentioned aerospace 2195 aluminum alloy frame beam shape control method also includes:

[0027] After S4 harmonic vibration aging treatment, the annular parts are cooled to below 60-100°C in the furnace and then taken out of the furnace.

[0028] A frame beam component, characterized in that it is obtained by adopting the above-mentioned aerospace 2195 aluminum alloy frame beam component shape control method.

[0029] Furthermore, the tensile strength of the frame beam is ≥550MPa, the yield strength is ≥500MPa, and the elongation is ≥8%; and the dimensional change after 100 hot and cold cycle tests at 120°C to -196°C is ≤0.01mm.

[0030] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0031] (1) The method of the present invention can effectively reduce and evenly distribute the residual stress of aerospace 2195 aluminum alloy frame beams, promote the precipitation of secondary terms of aluminum alloys, refine grains, and thus significantly improve the comprehensive performance of the material;

[0032] (2) The present invention adopts a method combining vacuum gas quenching and multiple liquid nitrogen cryogenic treatments to control the cooling temperature of the aluminum alloy through vacuum gas quenching, reduce the generation of residual stress, and enhance the mechanical properties of the component and improve the dimensional stability of the component through cryogenic treatment;

[0033] (3) The present invention combines harmonic vibration technology with traditional thermal aging treatment to achieve dynamic stress adjustment, microstructure optimization and mechanical property improvement of the material during the heat treatment process. DETAILED DESCRIPTION

[0034] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0035] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0036] The present invention provides a method for controlling the shape of aerospace 2195 aluminum alloy frame beam parts. The method performs vacuum gas quenching to room temperature after solid solution of annular parts (i.e., frame beam parts or aluminum alloy components), controls the cooling rate by vacuum gas quenching, and reduces the generation of residual stress. Subsequently, the parts are transferred to liquid helium for heat preservation. After the heat preservation is completed, the parts are placed in oil at 60 to 90°C for rapid heating and repeated cryogenic treatment for many times. Liquid helium (about -269°C) has a lower temperature than liquid nitrogen (about -196°C), which is conducive to maintaining the supersaturated state of 2195 aluminum alloy after quenching in cryogenic treatment, and is conducive to grain refinement, increasing dislocation density, and promoting subsequent secondary phase distribution optimization. Through uphill quenching after liquid helium deep cooling, the uphill quenching temperature difference is larger, which is opposite to the quenching temperature history curve, and the residual stress of the workpiece can be further eliminated, and the residual stress effect after quenching is better. Harmonic vibration is performed at the same time as aging, aiming to eliminate residual stress, reduce the residual stress level, and achieve uniform distribution of stress, while promoting the precipitation of secondary terms of aluminum alloy, refining grains, thereby significantly improving the performance of aluminum alloy. The method of the invention is suitable for the shape control of aerospace 2195 aluminum alloy frame beam parts and has broad application prospects.

[0037] The method of the present invention comprises the following key steps: (1) performing multiple liquid helium cryogenic treatments and uphill quenching after vacuum quenching, wherein the uphill quenching reduces the residual stress of the component, and the liquid helium cryogenic treatment reduces the structural defects and grain refinement; (2) adding harmonic vibration treatment during the aging process, and promoting the increase of dislocations and the precipitation of secondary phases through harmonic vibration. For these two processes:

[0038] Preferably, the cryogenic treatment medium is liquid helium.

[0039] Preferably, the cryogenic treatment holding time is 1 hour.

[0040] Preferably, the quenching medium is selected as 60°C quenching oil.

[0041] Preferably, the harmonic vibration amplitude is 0.03 mm.

[0042] Preferably, the harmonic vibration selects 5 best resonance peaks.

[0043] Preferably, the harmonic vibration time is 1 hour.

[0044] Preferably, the harmonic vibration aging time is 28 hours.

[0045] The specific method is:

[0046] 1) After the annular part is put into the furnace, heating begins when the vacuum degree is less than 10Pa, and the temperature is raised to 495-505°C and kept at this temperature for 1-3 hours, with a heating rate of 10-25°C / min; preferably, the vacuum degree is 5Pa and the heating rate is 15°C / min;

[0047] 2) After the heat preservation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 4 to 10 bar for gas quenching until the furnace temperature drops by 50 to 70° C. before being taken out of the furnace; preferably, the pressure is 10 bar;

[0048] 3) quickly placing the aluminum alloy components taken out of the furnace into liquid helium and keeping them warm for 0.5 to 2 hours; the preferred keeping time is 1 hour;

[0049] 4) After the heat preservation in liquid helium is completed, the component is quickly taken out and placed in oil at 60-90°C for 15-60 minutes. Preferably, the oil temperature is 60°C and the heat preservation time is 60 minutes.

[0050] 5) After the insulation in oil is completed, the component is placed in liquid helium again, and steps (3) and (4) are repeated 3 to 8 times; the preferred number of repetitions is 5 times;

[0051] 6) Place the frame beam into a harmonic vibration aging furnace and heat it to an aging temperature of 155-165°C; the heating rate is 5-20°C / min. Preferably, the aging temperature is 165°C and the heating rate is 10°C / min;

[0052] 7) Dynamically adjust the vibration frequency and amplitude according to the response and material properties of the frame beam to achieve the best stress relief and microstructure optimization effect;

[0053] The vibration frequency should refer to the principle of multiple vibration modes and maximum energy absorption, optimize stress distribution and microstructure adjustment, and the vibration frequency should be close to the natural frequency of the frame beam material to achieve resonance effect; the general excitation frequency selection range is between 16 and 160 Hz, and 3 to 6 optimal resonance peaks are generally selected;

[0054] The selection of amplitude is based on the elastic limit of the material to ensure that the vibration will not cause damage to the material; the amplitude is generally selected between 0.03 and 0.07 mm;

[0055] The optimal fatigue load loading principle is used as the criterion to determine the time required for the selected frequency to be processed; for 2 series aluminum alloys, the total harmonic vibration time is 0.5 to 3 hours; too long vibration time is likely to cause a decrease in material fatigue performance;

[0056] The preferred amplitude is 0.03 mm and the vibration time is 1 h.

[0057] 8) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature of 155-165° C., the harmonic vibration is turned on; after the harmonic vibration is completed, the heat preservation and aging are continued for 20-32 hours until the aging is completed; preferably, the total heat preservation time for aging is 28 hours;

[0058] 9) After aging, the steel is cooled to below 60-100°C in the furnace and then taken out of the furnace; preferably, the cooling temperature in the furnace is 60°C.

[0059] The tensile strength of the aerospace 2195 aluminum alloy frame beam component that is shape-controlled according to the method of the present invention is ≥550MPa, the yield strength is ≥500MPa, and the elongation is ≥8%; after 100 times of hot and cold cycles at 120°C to -196°C for aerospace components, the dimensional change is ≤0.01mm.

[0060] Through the combination of vacuum gas quenching and multiple liquid helium cryogenic treatments, the cooling temperature of the aluminum alloy is controlled by vacuum gas quenching to reduce the generation of residual stress. At the same time, through liquid helium cryogenic treatment, due to the volume shrinkage effect after extremely low temperature (about -269℃) liquid helium cryogenic treatment, the crystal structure in the alloy is rapidly cooled in a short time, the atomic spacing in the material becomes smaller, and the original stress balance inside the metal is broken through strong internal stress; due to the existence of strong internal stress, the crystal lattice of the grain is distorted, so a large number of dislocations appear inside the grain, and the grain is refined at the same time, enhancing the mechanical properties of the component. Liquid helium cryogenic treatment is used multiple times to release quenching residual stress and improve the dimensional stability of the component.

[0061] The present invention combines harmonic vibration technology with traditional thermal aging treatment to achieve dynamic stress adjustment, microstructure optimization and mechanical property improvement of materials during heat treatment. Conventional thermal aging is actually under the action of heat, secondary phase is precipitated, thereby improving the mechanical properties of the material, but the improvement effect of residual stress is not great. Adding harmonic vibration during thermal aging, the alternating initial stress and residual stress in harmonic resonance are superimposed, driving the workpiece to produce greater vibration, local yielding, causing micro-slip of internal dislocations and grain boundaries of the crystal, causing micro plastic deformation, and promoting a large number of dislocations, one part of which acts on impurities, another part gathers on grain boundaries, and another part of the dislocation obtains enough energy, which can pass through the grain boundary and enter another grain, so that the residual stress of the workpiece is relaxed or homogenized from the overall. At the same time, a large number of dislocations are promoted, providing a large number of nucleation points for the secondary phase, promoting the precipitation of the secondary phase and the refinement of the grains in the aluminum alloy, and further improving the mechanical properties of the material.

[0062] Example:

[0063] Example 1

[0064] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 10 Pa. The temperature is raised to 505°C and kept at this temperature for 2 hours at a heating rate of 15°C / min.

[0065] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 5 bar for gas quenching until the furnace temperature drops by 60°C before being taken out of the furnace.

[0066] (3) The aluminum alloy components are quickly placed in liquid helium and kept warm for 1 hour.

[0067] (4) After the insulation in liquid helium is completed, the components are quickly taken out and placed in 60°C oil for insulation for 45 minutes.

[0068] (5) After the insulation in oil is completed, the component is placed in liquid helium again and steps (3) and (4) are repeated for three times of deep cryogenic treatment.

[0069] (6) Place the frame beam into a harmonic vibration aging furnace and heat it to an aging temperature of 165°C at a heating rate of 15°C / min.

[0070] (7) The excitation frequency is 76 Hz, and the five best resonance peaks are selected. The amplitude is selected to be 0.03 mm. The total harmonic vibration time is 1 hour.

[0071] (8) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature, the harmonic vibration is turned on. After the harmonic vibration is completed, the heat preservation aging is continued for 30 hours until the aging is completed.

[0072] (9) After aging, cool down to below 60℃ and then take out of the furnace.

[0073] The aerospace 2195 aluminum alloy frame beam of Example 1 has a tensile strength of 551 MPa, a yield strength of 502 MPa, and an elongation of 8.1%. After 100 times of thermal cycling at 120°C to -196°C for aerospace components, the dimensional change is 0.005 mm.

[0074] Example 2

[0075] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 10 Pa. The temperature is raised to 505°C and kept at this temperature for 2.5 hours at a heating rate of 10°C / min.

[0076] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 6 bar for gas quenching until the furnace temperature drops by 70°C before being taken out of the furnace.

[0077] (3) The aluminum alloy components taken out of the furnace are quickly placed into liquid helium and kept warm for 45 minutes.

[0078] (4) After the insulation in liquid helium is completed, quickly remove the component and place it in 70°C oil and keep it warm for 30 minutes.

[0079] (5) After the insulation in oil is completed, the component is placed in liquid helium again and steps (3) and (4) are repeated for five times of deep cryogenic treatment.

[0080] (6) Place the frame beam into a harmonic vibration aging furnace and heat it to an aging temperature of 155°C at a heating rate of 20°C / min.

[0081] (7) The excitation frequency is 76 Hz, and the five best resonance peaks are selected. The amplitude is selected to be 0.03 mm. The total harmonic vibration time is 1 hour.

[0082] (8) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature, the harmonic vibration is turned on. After the harmonic vibration is completed, the heat preservation aging is continued for 28 hours until the aging is completed.

[0083] (9) After aging, cool down to below 90℃ and then take out of the furnace.

[0084] The aerospace 2195 aluminum alloy frame beam of Example 2 has a tensile strength of 561 MPa, a yield strength of 504 MPa, and an elongation of 8.4%. After 100 times of thermal cycling at 120°C to -196°C for aerospace components, the dimensional change is 0.01 mm.

[0085] Example 3

[0086] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 5 Pa. The temperature is raised to 495°C and kept at this temperature for 2.5 hours at a heating rate of 15°C / min.

[0087] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 10 bar for gas quenching until the furnace temperature drops by 50°C before being taken out of the furnace.

[0088] (3) The aluminum alloy components are quickly placed in liquid helium and kept warm for 1 hour.

[0089] (4) After the insulation in liquid helium is completed, the components are quickly taken out and placed in 60°C oil and kept warm for 1 hour.

[0090] (5) After the insulation in oil is completed, the component is placed in liquid helium again and steps (3) and (4) are repeated for five times of deep cryogenic treatment.

[0091] (6) Place the frame beam into a harmonic vibration aging furnace and heat it to an aging temperature of 165°C at a heating rate of 10°C / min.

[0092] (7) The excitation frequency is 76 Hz, and the five best resonance peaks are selected. The amplitude is selected to be 0.03 mm. The total harmonic vibration time is 1 hour.

[0093] (8) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature, the harmonic vibration is turned on. After the harmonic vibration is completed, the heat preservation aging is continued for 28 hours until the aging is completed.

[0094] (9) After aging, cool down to below 60℃ and then take out of the furnace.

[0095] The aerospace 2195 aluminum alloy frame beam of Example 3 has a tensile strength of 567 MPa, a yield strength of 509 MPa, and an elongation of 8.4%. After 100 times of thermal cycling at 120°C to -196°C for aerospace components, the dimensional change is 0.005 mm.

[0096] Comparative Example 1

[0097] Compared with Example 1, this comparative example only changes the gas quenching pressure in step (2), and the specific steps are as follows:

[0098] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 10 Pa. The temperature is raised to 505°C and kept at this temperature for 2 hours at a heating rate of 15°C / min.

[0099] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 20 bar for gas quenching until the furnace temperature drops by 60°C before being taken out of the furnace.

[0100] (3) The aluminum alloy components are quickly placed in liquid helium and kept warm for 1 hour.

[0101] (4) After the insulation in liquid helium is completed, the components are quickly taken out and placed in 60°C oil for insulation for 45 minutes.

[0102] 3 times of deep freezing treatment

[0103] (6) Place the frame beam into a harmonic vibration aging furnace and heat it to an aging temperature of 165°C at a heating rate of 15°C / min.

[0104] (7) The excitation frequency is selected within the range of 76 Hz, and the five best resonance peaks are selected. The amplitude is selected to be 0.03 mm. The total harmonic vibration time is 1 hour.

[0105] (8) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature, the harmonic vibration is turned on. After the harmonic vibration is completed, the heat preservation aging is continued for 30 hours until the aging is completed.

[0106] (9) After aging, cool down to below 90℃ and then take out of the furnace.

[0107] The tensile strength of the aerospace 2195 aluminum alloy frame beam of comparative example 1 is 553MPa, the yield strength is 497MPa, and the elongation is 5.9%. After 100 times of hot and cold cycles at 120℃ to -196℃ for aerospace components, the dimensional change is 0.1mm.

[0108] Compared with Example 1, Comparative Example 1 increases the gas quenching pressure during the quenching process, and the cooling rate increases, resulting in excessive residual stress. After subsequent deep cooling and vibration aging, the residual stress is still large, resulting in subsequent dimensional stability and over-tolerance. The dimensional change is 0.1 mm.

[0109] Comparative Example 2

[0110] Compared with Example 2, this comparative example only changes the gas quenching pressure in step (2), and the specific steps are as follows:

[0111] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 10 Pa. The temperature is raised to 505°C and kept at this temperature for 2.5 hours at a heating rate of 10°C / min.

[0112] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 1 bar for gas quenching until the furnace temperature drops by 70°C before being taken out of the furnace.

[0113] (3) The aluminum alloy components taken out of the furnace are quickly placed into liquid helium and kept warm for 45 minutes.

[0114] (4) After the insulation in liquid helium is completed, quickly remove the component and place it in 70°C oil and keep it warm for 30 minutes.

[0115] 5 times of deep freezing treatment

[0116] (6) Place the frame beam into a harmonic vibration aging furnace and heat it to an aging temperature of 155°C at a heating rate of 20°C / min.

[0117] (7) The excitation frequency is selected within the range of 76 Hz, and the five best resonance peaks are selected. The amplitude is selected to be 0.03 mm. The total harmonic vibration time is 1 hour.

[0118] (8) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature, the harmonic vibration is turned on. After the harmonic vibration is completed, the heat preservation aging is continued for 28 hours until the aging is completed.

[0119] (9) After aging, cool down to below 90℃ and then take out of the furnace.

[0120] The tensile strength of the aerospace 2195 aluminum alloy frame beam of comparative example 2 is 534MPa, the yield strength is 487MPa, and the elongation is 6.7%. After 100 times of hot and cold cycles at 120℃ to -196℃ for aerospace components, the dimensional change is 0.05mm.

[0121] Compared with Example 2, in Comparative Example 2, the gas quenching pressure is reduced during the quenching process, and the cooling rate is reduced, resulting in a decrease in the supersaturation of the material and a decrease in its mechanical properties.

[0122] Comparative Example 3

[0123] Compared with Example 2, this comparative example has too many and too long cryogenic treatment and uphill quenching times, and is kept warm for 3 hours and treated 12 times. The specific steps are as follows:

[0124] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 10 Pa. The temperature is raised to 505°C and kept at this temperature for 2.5 hours at a heating rate of 10°C / min.

[0125] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 6 bar for gas quenching until the furnace temperature drops by 70°C before being taken out of the furnace.

[0126] (3) The aluminum alloy components are quickly placed in liquid helium and kept warm for 3 hours.

[0127] (4) After the insulation in liquid helium is completed, quickly remove the component and place it in 70°C oil for insulation for 1.5 hours.

[0128] (5) After the insulation in oil is completed, the component is placed in liquid helium again and steps (3) and (4) are repeated for 12 times of deep cryogenic treatment.

[0129] (6) Place the frame beam into a harmonic vibration aging furnace and heat it to an aging temperature of 155°C at a heating rate of 20°C / min.

[0130] (7) The excitation frequency is selected within the range of 76 Hz, and the five best resonance peaks are selected. The amplitude is selected to be 0.03 mm. The total harmonic vibration time is 1 hour.

[0131] (8) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature, the harmonic vibration is turned on. After the harmonic vibration is completed, the heat preservation aging is continued for 28 hours until the aging is completed.

[0132] (9) After aging, cool down to below 90℃ and then take out of the furnace.

[0133] The tensile strength of the aerospace 2195 aluminum alloy frame beam of comparative example 3 is 542MPa, the yield strength is 493MPa, and the elongation is 6.4%. After 100 times of hot and cold cycles at 120℃ to -196℃ for aerospace components, the dimensional change is 0.01mm.

[0134] Compared with Example 2, due to the longer time and number of deep cooling and uphill quenching, the dimensional stability of the workpiece is better, but the long-term treatment also causes slow natural precipitation in the workpiece, so that the aging strengthening effect is reduced and the mechanical properties are reduced.

[0135] Comparative Example 4

[0136] Compared with Example 2, this comparative example adopts liquid nitrogen for cryogenic treatment, and the specific steps are as follows:

[0137] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 10 Pa. The temperature is raised to 505°C and kept at this temperature for 2.5 hours at a heating rate of 10°C / min.

[0138] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 6 bar for gas quenching until the furnace temperature drops by 70°C before being taken out of the furnace.

[0139] (3) The aluminum alloy components taken out of the furnace are quickly placed into liquid nitrogen and kept warm for 45 minutes.

[0140] (4) After the insulation in liquid nitrogen is completed, the component is quickly taken out and placed in 70°C oil for insulation for 30 minutes.

[0141] (5) After the insulation in oil is completed, the component is placed in liquid helium again and steps (3) and (4) are repeated for five times of deep cryogenic treatment.

[0142] (6) Place the frame beam into a harmonic vibration aging furnace and heat it to an aging temperature of 155°C at a heating rate of 20°C / min.

[0143] (7) The excitation frequency is selected within the range of 76 Hz, and the five best resonance peaks are selected. The amplitude is selected to be 0.03 mm. The total harmonic vibration time is 1 hour.

[0144] (8) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature, the harmonic vibration is turned on. After the harmonic vibration is completed, the heat preservation aging is continued for 28 hours until the aging is completed.

[0145] (9) After aging, cool down to below 90℃ and then take out of the furnace.

[0146] The tensile strength of the aerospace 2195 aluminum alloy frame beam of comparative example 4 is 532MPa, the yield strength is 501MPa, and the elongation is 7.1%. After 100 times of hot and cold cycles at 120℃ to -196℃ for aerospace components, the dimensional change is 0.02mm.

[0147] Compared with Example 2, since the temperature of liquid helium is -269°C and the temperature of liquid nitrogen is only -196°C, the supersaturated state of 2195 aluminum alloy is better maintained during cryogenic treatment, which is beneficial to improving mechanical properties. At the same time, the uphill quenching temperature difference is larger, the internal stress is stronger, and the residual stress elimination effect is better.

[0148] Comparative Example 5

[0149] Compared with Example 2, this comparative example does not perform cryogenic treatment and uphill quenching, and the specific steps are as follows:

[0150] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 5 Pa. The temperature is raised to 505°C and kept at this temperature for 2.5 hours at a heating rate of 10°C / min.

[0151] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 6 bar for gas quenching until the furnace temperature drops by 70°C before being taken out of the furnace.

[0152] (6) The excitation frequency is selected within the range of 76 Hz, and the five best resonance peaks are selected. The amplitude is selected to be 0.03 mm. The total harmonic vibration time is 1 hour.

[0153] (7) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature, the harmonic vibration is turned on. After the harmonic vibration is completed, the heat preservation aging is continued for 28 hours until the aging is completed.

[0154] (8) After aging, cool down to below 90℃ and then take out of the furnace.

[0155] The tensile strength of the aerospace 2195 aluminum alloy frame beam of comparative example 4 is 539MPa, the yield strength is 501MPa, and the elongation is 7.5%. After 100 times of hot and cold cycles at 120℃ to -196℃ for aerospace components, the dimensional change is 0.04mm.

[0156] Compared with Example 2, the deep cryogenic treatment and uphill quenching treatment are lacking, the residual stress of the workpiece is large, and the dimensional stability is poor.

[0157] Comparative Example 6

[0158] Compared with Example 3, the harmonic vibration parameter selection in this comparative example exceeds the recommended range, and the specific steps are as follows:

[0159] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 10 Pa. The temperature is raised to 495°C and kept at this temperature for 2.5 hours at a heating rate of 15°C / min.

[0160] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 10 bar for gas quenching until the furnace temperature drops by 50°C before being taken out of the furnace.

[0161] (3) The aluminum alloy components are quickly placed in liquid helium and kept warm for 1 hour.

[0162] (4) After the insulation in liquid helium is completed, the components are quickly taken out and placed in 60°C oil and kept warm for 1 hour.

[0163] (5) After the insulation in oil is completed, the component is placed in liquid helium again and steps (3) and (4) are repeated for five times of deep cryogenic treatment.

[0164] (6) Place the frame beam into a harmonic vibration aging furnace and heat it to an aging temperature of 165°C at a heating rate of 10°C / min.

[0165] (7) The excitation frequency is selected within the range of 200 Hz, and the five best resonance peaks are selected. The amplitude is selected to be 0.1 mm. The total harmonic vibration time is 10 hours.

[0166] (8) After the temperature of the 2195 aluminum alloy annular component rises to the set temperature, the harmonic vibration is turned on. After the harmonic vibration is completed, the heat preservation aging is continued for 28 hours until the aging is completed.

[0167] (9) After aging, cool down to below 60℃ and then take out of the furnace.

[0168] The tensile strength of the aerospace 2195 aluminum alloy frame beam of comparative example 5 is 553MPa, the yield strength is 503MPa, and the elongation is 6.1%. After 100 times of hot and cold cycles at 120℃ to -196℃ for aerospace components, the dimensional change is 0.02mm.

[0169] Compared with Example 3, due to inappropriate selection of the excitation frequency and vibration amplitude in the harmonic vibration, after long-term vibration stress relief, although some residual stress is eliminated, the residual stress level of the workpiece is still high and the dimensional stability of the workpiece is poor.

[0170] Comparative Example 7

[0171] Compared with Example 3, this comparative example does not perform harmonic vibration treatment, and the specific steps are as follows:

[0172] (1) After the 2195 aluminum alloy ring part is placed in the furnace, heating begins when the vacuum degree is less than 5 Pa. The temperature is raised to 495°C and kept at this temperature for 2.5 hours at a heating rate of 15°C / min.

[0173] (2) After the insulation is completed, high-pressure high-purity nitrogen is filled in at a pressure of 10 bar for gas quenching until the furnace temperature drops by 50°C before being taken out of the furnace.

[0174] (3) The aluminum alloy components are quickly placed in liquid helium and kept warm for 1 hour.

[0175] (4) After the insulation in liquid helium is completed, the components are quickly taken out and placed in 60°C oil and kept warm for 1 hour.

[0176] (5) After the insulation in oil is completed, the component is placed in liquid helium again and steps (3) and (4) are repeated for five times of deep cryogenic treatment.

[0177] (6) Place the frame beam into a harmonic vibration aging furnace and heat it to 165°C for aging. The heating rate is 20°C / min. The aging is kept for 28 hours.

[0178] (9) After aging, cool down to below 60℃ and then take out of the furnace.

[0179] The tensile strength of the aerospace 2195 aluminum alloy frame beam of comparative example 6 is 542MPa, the yield strength is 486MPa, and the elongation is 5.4%. After 100 times of hot and cold cycles at 120℃ to -196℃ for aerospace components, the dimensional change is 0.03mm.

[0180] Compared with Example 3, since harmonic vibration is not performed to eliminate residual stress, the residual stress of the workpiece is relatively high, resulting in poor dimensional stability of the workpiece.

[0181] Table 1 Comparison of specific implementation effects

[0182] Tensile strength / MPa Yield strength / MPa Elongation / % Dimension change / mm Example 1 551 502 8.1 0.005 Example 2 561 504 8.4 0.01 Example 3 567 509 8.4 0.005 Comparative Example 1 553 497 5.9 0.1 Comparative Example 2 534 487 6.7 0.05 Comparative Example 3 542 493 6.4 0.01 Comparative Example 4 532 501 7.1 0.02 Comparative Example 5 539 501 7.5 0.04 Comparative Example 6 553 503 6.1 0.02 Comparative Example 7 542 486 5.4 0.03

[0183] The test results of Examples 1 to 3 of the present invention and Comparative Examples 1 to 7 are shown in the table. According to the comparison between Comparative Examples 1 to 7 and Examples 1 to 3, it can be seen that the pressure and the furnace temperature in step (2), the liquid helium cryogenic treatment in step (3), the selection of the cryogenic temperature, time and number of cycles, the uphill quenching treatment in step (4), the harmonic vibration aging treatment in steps (7 to 8) and the corresponding parameter selection of the present invention are beneficial to reducing the residual stress of the workpiece, improving the tensile strength, yield strength and elongation of the workpiece, and improving the dimensional stability and other properties of the workpiece.

[0184] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0185] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for controlling the shape of aerospace 2195 aluminum alloy frame beams, characterized in that: include: S1 performs vacuum quenching on the annular parts; S2 performs deep cryogenic treatment and uphill quenching treatment on the annular parts after vacuum gas quenching; S3 performs harmonic vibration aging treatment on the annular parts after liquid helium cryogenic treatment and cools them down.

2. The method for controlling the shape of aerospace 2195 aluminum alloy frame beam according to claim 1, characterized in that: In step S1, the method of vacuum quenching the annular part includes: After the annular parts are put into the furnace, heating begins when the vacuum degree is less than 10Pa, and the temperature is raised to 495-505℃ with the furnace at a heating rate of 10-25℃ / min, and kept at this temperature for 1-3 hours; After the insulation is completed, nitrogen is filled into the furnace to make the pressure inside the furnace 4-10 bar. The annular parts are gas quenched under this pressure until the furnace temperature drops to 50-70°C and then taken out of the furnace.

3. The method for controlling the shape of aerospace 2195 aluminum alloy frame beam according to claim 1, characterized in that: In step S2, the annular part after vacuum quenching is subjected to 3 to 8 times of deep cryogenic treatment and uphill quenching treatment.

4. The method for controlling the shape of aerospace 2195 aluminum alloy frame beam according to claim 1, characterized in that: In step S2, the method of performing deep cryogenic treatment and uphill quenching treatment on the annular part after vacuum gas quenching includes: S2.1 Place the vacuum quenched annular parts into liquid helium and keep them warm for 0.5 to 2 hours; S2.2 After the heat preservation is completed, take out the annular parts and put them into oil at 60-90℃ for 15-60min; S2.3 Repeat steps S2.1 and S2.2 3 to 8 times.

5. The method for controlling the shape of aerospace 2195 aluminum alloy frame beam according to claim 1, characterized in that: In step S3, the method of harmonic vibration aging treatment includes: S3.1 Place the annular part in a harmonic vibration aging furnace and heat it to the aging temperature; S3.2 At the aging temperature, the annular part is subjected to harmonic vibration treatment at the set vibration frequency, amplitude and total harmonic vibration time; S3.3 After the harmonic vibration treatment is completed, continue the thermal insulation aging until the aging is completed.

6. The method for controlling the shape of aerospace 2195 aluminum alloy frame beam according to claim 5, characterized in that: In step S3.1, the aging temperature is 155-165°C; the heating rate is 5-20°C / min; In step S3.2, the vibration frequency is determined according to the natural frequency of the annular part, the amplitude is determined according to the elastic limit of the annular part, and the total harmonic vibration time is determined based on the optimal fatigue load loading principle; In step S3.3, the insulation time is 20 to 32 hours.

7. The method for controlling the shape of aerospace 2195 aluminum alloy frame beam according to claim 5, characterized in that: In step S3.2, the vibration frequency is 16 to 160 Hz and has 3 to 6 optimal resonance peaks; The amplitude is 0.03-0.07 mm; The total time of harmonic vibration is 0.5 to 3 hours.

8. The method for controlling the shape of aerospace 2195 aluminum alloy frame beam according to claim 5, characterized in that: Also includes: After S4 harmonic vibration aging treatment, the annular parts are cooled to below 60-100°C in the furnace and then taken out of the furnace.

9. A frame beam member, characterized in that: The shape control method of aerospace 2195 aluminum alloy frame beam is adopted as described in any one of claims 1 to 8.

10. A frame beam member according to claim 9, characterized in that: The tensile strength of the frame beam is ≥550MPa, the yield strength is ≥500MPa, and the elongation is ≥8%; the dimensional change after 100 hot and cold cycle tests at 120℃~-196℃ is ≤0.01mm.