Dimension stabilizing treatment method for aluminum-based composite sheet part

Abstract

The invention is suitable for the field of aluminum-based composite material treatment, and particularly relates to a size stabilizing treatment method for aluminum-based composite material sheet parts. High-performance and high-uniformity aluminum-based composite material blanks which are qualified through nondestructive testing are sequentially subjected to high-temperature annealing treatment, rough machining, low-temperature annealing treatment, semi-finish machining and cryogenic circulation size stabilization treatment in the machining process, and finally grinding machining is conducted to obtain the aluminum-based composite material sheet parts with high size stability. After the part is subjected to size stabilization treatment, the residual stress of the aluminum-based composite material can be effectively reduced, and the size stability of the aluminum-based composite material is improved; based on the excellent dimensional stability of the aluminum-based composite material, a structure-function integrated solution under an extreme environment (especially the temperature ranges from-180 DEG C to + 120 DEG C) is provided for precise components such as an aerospace inertial navigation system and optical detection equipment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of size stabilization treatment of aluminum matrix composites, and particularly relates to a size stabilization treatment method for aluminum matrix composite sheet parts. BACKGROUND

[0002] Aluminum matrix composites are composites formed by taking aluminum or its alloy as a matrix and taking ceramics as a reinforcing phase, and have good mechanical and thermal physical properties by virtue of the advantages of both aluminum alloy and ceramics. The emergence of high-performance light-weight high-strength aluminum matrix composites provides a new way to meet the application requirements in the field of aerospace, and gradually replaces traditional aluminum alloy, titanium alloy and other types of composites, and has a broad application prospect in the field of aerospace. The size stability of a material is an important characteristic of a material used for a precision component, and represents the ability of the material to resist deformation after being pretreated and processed under service environmental conditions. Possible reasons for causing the size change of the material under service conditions include elastic and plastic deformation caused by bearing load, size change caused by temperature change, relaxation of internal stress existing in the material, and phase transformation caused by unstable structure in the material.

[0003] At present, there are two commonly used processes for eliminating residual stress and improving size stability; one is to eliminate stress by annealing treatment, which has a certain effect, but the effect is poor at low temperature, and a very long annealing time is required; with the increase of the annealing temperature, the annealing time is shortened, but the tensile strength of the part is greatly reduced, which affects the strength requirement. The other process is cold and hot cycle treatment of heat treatment plus cryogenic treatment, which has obvious effect and small effect on strength, but is suitable for products with simple structure and certain wall thickness. When the deep cryogenic treatment is performed on the sheet structure product, the deformation is more serious, and cracks are also generated.

[0004] In summary, a new processing method is needed to solve the problems of difficulty in eliminating residual stress of existing sheet parts during the machining process and obvious size deformation during long-term use. SUMMARY

[0005] The embodiment of the application provides a size stabilization treatment method for aluminum matrix composite sheet parts, and aims to solve the problems of difficulty in eliminating residual stress of existing sheet parts during the machining process and obvious size deformation during long-term use.

[0006] The embodiment of the application is implemented as follows: A size stabilization treatment method for aluminum matrix composite sheet parts, comprising: Step 1: selecting a to-be-cut blank that meets the processing requirements from a high-performance and high-uniformity particle reinforced aluminum matrix composite blank by nondestructive testing; Step 2: The blank to be cut is subjected to high temperature annealing treatment to reduce the residual stress generated during the material preparation process, and then rough machining is performed to obtain rough-machined parts; Step 3: Perform low-temperature annealing on the rough-machined parts to eliminate stress concentration caused by rough machining, and then perform semi-finishing to obtain semi-finished parts; Step 4: Perform deep cold cycle dimensional stabilization treatment on the semi-finished parts to obtain the parts to be processed; Step 5: Grinding the parts to be processed after the deep cold cycle dimensional stabilization treatment to obtain dimensionally stable aluminum-based composite material thin plate parts.

[0007] Furthermore, the particle volume fraction of the blank to be cut is 25%-60%, the D50 of the particles is 5μm-60μm, and the density fluctuation value is less than ±0.01g / cm 3 , the fluctuation value of elastic modulus is less than ±3GPa, and the fluctuation value of thermal expansion coefficient is less than ±0.5×10 -6 / K.

[0008] Furthermore, the non-destructive testing determines that there are no point or linear defects larger than φ0.8 mm in the blank to be cut, and the bottom reflection loss is less than 6 dB.

[0009] Furthermore, the process of high temperature annealing of the blank to be cut is: Place the blank to be cut on a marble platform and heat it at 420℃-480℃ for 4-16h to eliminate the initial residual stress; the marble platform used for annealing requires a flatness of 0.01-0.03mm.

[0010] Furthermore, the process of performing low temperature annealing treatment on the rough-machined parts is: Place the parts on a marble platform and keep it at 150℃-220℃ for 10-16 hours to eliminate the stress concentration caused by rough machining; the marble platform used for annealing is required to have a flatness of 0.01-0.03mm.

[0011] Furthermore, the deep cold cycle dimensional stabilization treatment process for the semi-finished parts is: Step 1: During the heating phase, the semi-finished parts are placed in a deep cooling furnace in a hanging manner and heated and cooled at a rate of 5-10°C per minute. The heating phase is from room temperature (25°C) to 80-140°C, and the holding time is 3-8 hours. Step 2: Cooling stage, from high temperature to -110 to -190℃, keeping warm for 3-8h, cycle 1-5 times, then cool to room temperature (25℃), keep warm for 6-10h, and then take out of the oven.

[0012] Further, the grinding and polishing of the parts to be processed includes coarse grinding and fine grinding, wherein the coarse grinding uses boron carbide particles with a D50 of 10-30 μm, and the fine grinding uses boron carbide particles with a D50 of 1-5 μm.

[0013] The present application has the following advantages: The present application has the following advantages: The present application has the following advantages:

[0014] Figure 1 A flow chart of the size stabilization treatment method of the aluminum matrix composite sheet part; Figure 2 A comparison chart of the flatness of the part obtained in Example 1 before aging a and after aging b; Figure 3 A comparison chart of the flatness of the aluminum matrix composite material obtained in Example 1 before aging a and after aging b; Figure 4 A comparison chart of the flatness of the part obtained in Example 2 before aging a and after aging b; Figure 5 A comparison chart of the flatness of the aluminum matrix composite material obtained in Example 2 before aging a and after aging b; Figure 6 A comparison chart of the flatness of the part obtained in Example 3 before aging a and after aging b; Figure 7 A comparison chart of the flatness of the aluminum matrix composite material obtained in Example 3 before aging a and after aging b; Figure 8 A comparison chart of the flatness of the aluminum matrix composite material obtained in Example 3 before aging a and after aging b; DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0016] Through high-temperature annealing, low-temperature annealing and deep cryogenic stabilization processing, the particle reinforced aluminum matrix composite sheet part has excellent dimensional stability, and the dimensional change caused by environmental factors under long-term use conditions is extremely small, thereby ensuring the good reliability of the precision part in special environments.

[0017] Compared with existing parts, the present application can realize batch production with high pass rate, increase production efficiency, and provide a structure-function integrated solution for precision components such as aerospace inertial navigation systems and optical detection equipment in extreme environments (temperature from-180℃ to +120℃) by first annealing the material at high and low temperatures and then deep cryogenic cycle dimensional stabilization processing.

[0018] Referring to Figure 1 and Figure 8 , a dimensional stabilization processing method for an aluminum matrix composite sheet part, comprising: S101, selecting a cutting blank meeting the processing requirements from a high-performance and high-uniformity particle reinforced aluminum matrix composite billet through non-destructive testing; S102, high-temperature annealing the cutting blank to reduce residual stress generated in the material preparation process, and then rough machining to obtain a rough machining part; S103, low-temperature annealing the rough machining part to eliminate stress concentration generated by rough machining, and then semi-finishing to obtain a semi-finished part; S104, deep cryogenic cycle dimensional stabilization processing of the semi-finished part to obtain a processed part; S105, grinding the processed part after deep cryogenic cycle dimensional stabilization processing to obtain a dimensional stable aluminum matrix composite sheet part.

[0019] It should be noted that the particle volume fraction of the cutting blank is 25%-60%, the particle D50 is 5μm-60μm, the density fluctuation value is less than ±0.01g / cm 3 , the elastic modulus fluctuation value is less than ±3GPa, the thermal expansion coefficient fluctuation value is less than ±0.5×10 -6 / K, the non-destructive testing determines that there is no point or linear defect greater than φ0.8mm in the cutting blank, and the bottom reflection loss is less than 6dB.

[0020] The particle volume fraction is 25%-60%, the particle D50 is 5μm-60μm, and the density fluctuation value is less than ±0.01g / cm 3The composite material has low thermal expansion coefficient, density, and high thermal conductivity and elastic modulus, and when the material is subjected to internal stress caused by vibration and temperature change, the material has small deformation, which is beneficial to improve the dimensional stability.

[0021] The process of high-temperature annealing of the cutting blank is: The cutting blank is placed on a marble platform, and the initial residual stress is eliminated at 420-480°C for 4-16h; wherein the marble platform used for annealing requires a flatness of 0.01-0.03mm; in this embodiment, a marble with a flatness of 0.01-0.03mm is selected, and uneven deformation of the marble plane can be avoided at a higher temperature, ensuring uniform stress on the contact surface between the thin plate part and the marble plane, thereby reducing the micro deformation of the part caused by uneven stress.

[0022] The process of low-temperature annealing treatment of the rough machining part is: The part is placed on a marble platform, and the stress concentration caused by rough machining is eliminated at 150-220°C for 10-16h; wherein the marble platform used for annealing requires a flatness of 0.01-0.03mm.

[0023] The process of deep cryogenic cycle dimensional stabilization treatment of the semi-finished machining part is: Step one, the semi-finished machining part is placed in a deep cryogenic furnace in a suspended manner, and the temperature is raised and lowered at a rate of 5-10°C per minute, the temperature is raised from room temperature (25°C) to 80-140°C, and the temperature is maintained for 3-8h; Step two, the temperature is lowered from high temperature to -110 to -190°C, the temperature is maintained for 3-8h, the cycle is repeated 1-5 times, then the temperature is lowered to room temperature (25°C), and the temperature is maintained for 6-10h, and then the furnace is discharged.

[0024] The grinding tool for the part to be processed includes rough grinding and fine grinding, wherein the rough grinding uses boron carbide particles with a D50 of 10-30μm, and the fine grinding uses boron carbide particles with a D50 of 1-5μm; in this embodiment, the rough grinding is followed by fine grinding to improve the dimensional accuracy of the part, which is beneficial to improve the flatness detection accuracy of the part.

[0025] Example 1: Referring to Figures 2-3 In this embodiment, a 25vol.%SiC / Al composite material blank with high performance and high uniformity is selected, and the SiC particles used have a D50 of 5μm, and the performance is shown in Table 1; non-destructive testing is performed by an ultrasonic flaw detector to determine the cutting area, there is no point or linear defect larger than φ0.8mm, and the bottom reflection loss is less than 6dB, and the blank is cut at a position meeting the processing requirements.

[0026] The cut blank is subjected to high-temperature annealing treatment, and the annealing process is as follows: the part is placed on a marble platform with a flatness of 0.01-0.03 mm, and is heated from room temperature to 420°C for 2 h, and is kept at 420°C for 16 h, and then is cooled to room temperature with the furnace, so as to eliminate the initial residual stress; then rough machining is performed by using a PCD cutter, and a 2.0 mm allowance is reserved on one side.

[0027] The part after rough machining is subjected to low-temperature annealing treatment, and the low-temperature annealing treatment process is as follows: the part is placed on a marble platform with a flatness of 0.01-0.03 mm, and is heated from room temperature to 220°C for 1 h, and is kept at 220°C for 10 h, and then is cooled to room temperature with the furnace, so as to eliminate the stress concentration generated in rough machining; the blank is machined by using a PCD cutter through a numerical control machining center, and a 1.0 mm allowance is reserved on one side of the part after half-finishing machining.

[0028] The part after half-finishing machining is subjected to deep cold cycle dimensional stabilization treatment, and the specific process is as follows: the part is placed in a deep cold furnace in a suspended manner, and is heated and cooled at a rate of 5°C per minute, the heating stage is from room temperature (25°C) to 140°C, and the part is kept at 140°C for 3 h, the cooling stage is from 140°C to -170°C, and the part is kept at -170°C for 3 h, the cycle is repeated 5 times, then the part is cooled to room temperature (25°C) and kept at room temperature for 6 h, and then is taken out of the furnace.

[0029] The part after deep cold cycle dimensional stabilization treatment is subjected to rough grinding and fine grinding. Boron carbide particles with a D50 of 30 μm are selected for rough grinding, and boron carbide particles with a D50 of 5 μm are selected for fine grinding. After grinding, a dimensionally stable aluminum-based composite material sheet part is obtained.

[0030] The sheet part is subjected to aging treatment, and the flatness of the part before and after aging is detected, and the detection results are shown in Figure 2 As shown in Table 1, when a composite material with a large fluctuation in material performance is used, such as Figure 3 As shown in Table 1, when a composite material with a large fluctuation in material performance is used, such as

[0031] Table 1 Comparison of material performance at different positions in Example 1

[0032] Example 2: Referring to Figures 4-5In the embodiment, a 35vol.% SiC / Al composite material blank ingot with high performance and high uniformity is selected, and the SiC particles used have a D50 of 40 μm; the performance of the blank ingot meets the requirements of a density of 2.88±0.01 g / cm 3 , an elastic modulus of 140±3 GPa, and a thermal expansion coefficient of 14±0.5×10 -6 / K; the cutting area is determined by nondestructive testing with an ultrasonic flaw detector, and there are no point or linear defects greater than φ0.8 mm, and the bottom reflection loss is less than 6 dB, and then the blank is cut.

[0033] The cut blank is subjected to high-temperature annealing treatment, and the annealing process is as follows: the part is placed on a marble platform with a flatness of 0.01-0.03 mm, heated from room temperature to 450℃ for 2 h, and then kept at 450℃ for 4 h, and then cooled to room temperature with the furnace, to eliminate the initial residual stress, and then a PCD cutter is used for rough machining, and a 2.0 mm allowance is left on one side.

[0034] The part after rough machining is subjected to low-temperature annealing treatment, and the low-temperature annealing treatment process is as follows: the part is placed on a marble platform with a flatness of 0.01-0.03 mm, heated from room temperature to 150℃ for 1 h, and then kept at 150℃ for 16 h, and then cooled to room temperature with the furnace, to eliminate the stress concentration generated during rough machining; a PCD cutter is also used for semi-finishing, and a 1.0 mm allowance is left on one side of the part after semi-finishing.

[0035] The part after semi-finishing is subjected to deep cryogenic cycle dimensional stabilization treatment, and the specific process is as follows: the part after semi-finishing is placed in a deep cryogenic furnace in a suspended manner, and the temperature is raised and lowered at a rate of 5℃ per minute, the temperature is raised from room temperature (25℃) to 80℃, and kept at 80℃ for 8 h, the temperature is lowered from 80℃ to -190℃, and kept at -190℃ for 8 h, one cycle is completed, and then the temperature is lowered to room temperature (25℃), and kept at room temperature for 8 h, and then the part is taken out of the furnace.

[0036] The part after deep cryogenic cycle dimensional stabilization treatment is subjected to rough grinding and fine grinding. Boron carbide particles with a D50 of 10 μm are used for rough grinding, and boron carbide particles with a D50 of 1 μm are used for fine grinding. After grinding, a dimensionally stable aluminum matrix composite material sheet part is obtained.

[0037] The sheet part is subjected to aging treatment, and the flatness of the sheet part before and after aging treatment is detected, and the flatness of the sheet part before and after aging treatment is detected. Figure 4 and Figure 5As shown, the parts of Example 2 and Example 2 without being placed on the marble plate for annealing treatment, and without using the hanging placement, after the cryogenic cycle dimensional stabilization treatment, it can be found that Example 2 obtains good flatness, however, the flatness of the parts without being treated as required appears great distortion, in summary, the parts prepared in this example have excellent dimensional stability, and the dimensional change caused by environmental factors under long-term use conditions is also very small.

[0038] Example 3: Referring to Figures 6-7 As shown, in this example, a 60vol.%SiC / Al aluminum matrix composite billet with high performance and high uniformity is selected, the SiC particles used have a D50 of 60μm; the performance requirements meet the billet with a density of 2.98±0.01g / cm 3 , an elastic modulus of 160±3GPa, and a thermal expansion coefficient of 8.5±0.5×10 -6 / K; the cutting area is determined by non-destructive testing with an ultrasonic flaw detector, there are no point or linear defects greater than φ0.8mm, and the bottom reflection loss is less than 6dB, and then the billet is cut.

[0039] The cut billet is subjected to high-temperature annealing treatment, and the annealing process is as follows: the part is placed on a marble platform with a flatness of 0.01-0.03mm, heated from room temperature to 480℃ for 2h, and then kept at 480℃ for 10h, and then cooled to room temperature in the furnace to eliminate the initial residual stress, then a PCD cutter is used for rough machining, and a 2.0mm margin is reserved on one side.

[0040] The part after rough machining is subjected to low-temperature annealing treatment, and the low-temperature annealing treatment process is as follows: the part is placed on a marble platform with a flatness of 0.01-0.03mm, heated from room temperature to 180℃ for 1h, and then kept at 180℃ for 10h to eliminate the stress concentration generated during rough machining; then a PCD cutter is used for semi-finishing, and a 1.0mm margin is reserved on one side of the part after semi-finishing.

[0041] The part after semi-finishing is subjected to cryogenic cycle dimensional stabilization treatment, and the specific process is as follows: the part after semi-finishing is placed in a cryogenic furnace in a hanging manner, and the temperature is raised and lowered at a rate of 10℃ per minute, the temperature is raised from room temperature (25℃) to 120℃, and kept at 120℃ for 5h, the temperature is lowered from 120℃ to -110℃, and kept at -110℃ for 3h, the cycle is repeated for 3 times, then the temperature is lowered to room temperature (25℃), and kept at room temperature for 10h, and then the furnace is discharged.

[0042] The part after cryogenic cycle dimensional stabilization treatment is subjected to rough grinding and fine grinding. Boron carbide particles with a D50 of 20μm are used for rough grinding; boron carbide particles with a D50 of 3μm are used for fine grinding. After grinding, a dimensionally stable aluminum matrix composite sheet part is obtained.

[0043] The thin plate parts were aged, and the flatness before and after aging was detected, and the detection results are shown in Figs. 3 and 4. Figure 6 and Figure 7 It can be found that the flatness of the part obtained in Example 3 is good; when the cryogenic treatment process does not meet the claim, the flatness of the composite material has a large fluctuation, as shown in Figure 7 Fig. 5. In summary, the part prepared in this example has excellent dimensional stability, and the dimensional change caused by environmental factors under long-term use conditions is very small.

[0044] In the description of the present specification, the description referring to the terms "some embodiments", "exemplary embodiments", "examples", "specific examples", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0045] In addition, the above is only a preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for dimensional stabilization of aluminum-based composite material thin plate parts, characterized in that: include: Step 1: Select the blank to be cut that meets the processing requirements from the high-performance, high-uniformity particle-reinforced aluminum-based composite material ingot through non-destructive testing; Step 2: The blank to be cut is subjected to high temperature annealing treatment to reduce the residual stress generated during the material preparation process, and then rough machining is performed to obtain rough-machined parts; Step 3: Perform low-temperature annealing on the rough-machined parts to eliminate stress concentration caused by rough machining, and then perform semi-finishing to obtain semi-finished parts; Step 4: Perform deep cold cycle dimensional stabilization treatment on the semi-finished parts to obtain the parts to be processed; Step 5: Grinding the parts to be processed after the deep cold cycle dimensional stabilization treatment to obtain dimensionally stable aluminum-based composite material thin plate parts.

2. The processing method according to claim 1, characterized in that The particle volume fraction of the blank to be cut is 25%-60%, the D50 of the particles is 5μm-60μm, and the density fluctuation value is less than ±0.01g / cm 3 , the fluctuation value of elastic modulus is less than ±3GPa, and the fluctuation value of thermal expansion coefficient is less than ±0.5×10 -6 / K.

3. The processing method according to claim 1, characterized in that The non-destructive testing determines that there are no point or linear defects larger than φ0.8 mm in the blank to be cut, and the bottom reflection loss is less than 6 dB.

4. The processing method according to claim 1, characterized in that The process of high temperature annealing of the blank to be cut is as follows: Place the blank to be cut on a marble platform and heat it at 420℃-480℃ for 4-16h to eliminate the initial residual stress; the marble platform used for annealing requires a flatness of 0.01-0.03mm.

5. The processing method according to claim 1, characterized in that The process of performing low temperature annealing treatment on the rough-machined parts is as follows: Place the parts on a marble platform and keep it at 150℃-220℃ for 10-16 hours to eliminate the stress concentration caused by rough machining; the marble platform used for annealing is required to have a flatness of 0.01-0.03mm.

6. The processing method according to claim 1, characterized in that The deep cold cycle dimensional stabilization treatment process for semi-finished parts is: Step 1: During the heating phase, the semi-finished parts are placed in a deep cooling furnace in a hanging manner and heated and cooled at a rate of 5-10°C per minute. The heating phase is from room temperature (25°C) to 80-140°C, and the holding time is 3-8 hours. Step 2: Cooling stage, from high temperature to -110 to -190℃, keeping warm for 3-8h, cycle 1-5 times, then cool to room temperature (25℃), keep warm for 6-10h, and then take out of the oven.

7. The processing method according to claim 1, characterized in that The grinding process of the parts to be processed specifically includes coarse grinding and fine grinding of the parts, wherein boron carbide particles with a D50 of 10-30 μm are selected for coarse grinding, and boron carbide particles with a D50 of 1-5 μm are selected for fine grinding.

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