Heat treatment method for reducing machining delayed deformation of aluminum alloy structural part with complex structure
By employing a step-by-step heat treatment method, the problem of delayed deformation caused by residual stress during the processing of complex aluminum alloy parts was solved, thereby improving dimensional stability and processing efficiency and increasing the product qualification rate.
Patent Information
- Application Number
- CN202511572540.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-30
- Publication Date
- 2026-01-27
Smart Images
Figure CN121406993A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of heat treatment technology, and in particular to a heat treatment method for reducing the delayed deformation during the processing of complex aluminum alloy structural parts. Background Technology
[0002] 7-series aluminum alloys are high-strength wrought aluminum alloys, with Zn, Mg, and Cu as the main alloying elements. Developed since the 1940s, they remain a core material in the aerospace field. With their ultra-high strength and lightweight characteristics, 7-series aluminum alloys dominate the manufacturing of high-end aerospace equipment.
[0003] Complex aluminum alloy parts undergo significant metal removal and low rigidity during machining, leading to deformation due to residual stress, clamping forces, and cutting forces. Parts with internal stress are in an unstable state, exhibiting a strong tendency to revert to a stable, stress-free state, even at room temperature. While they may appear temporarily in equilibrium, the removal of certain surface portions disrupts this equilibrium, causing a redistribution of internal stress and resulting in deformation.
[0004] The dimensional accuracy of 7-series aluminum alloy parts is generally IT8 to IT9. The formed blanks can meet the accuracy requirements after heat treatment and machining. However, it is very difficult to maintain these accuracies in the long term. Due to the subsequent release of residual stress, the dimensions change by 0.2% to 0.4%, which leads to the problem that the parts are qualified during machining, but the dimensions are out of tolerance during assembly.
[0005] Currently, the industry mostly uses heat treatment to eliminate residual internal stress. While ensuring the mechanical properties of the material, the residual internal stress level of aluminum alloy parts is reduced through stabilization aging and hot-cold cycling treatment, thereby achieving the effect of controlling deformation.
[0006] Due to increasingly stringent design requirements in the industry, existing processes are unable to meet the needs for material dimensional stability. Under the premise of meeting the mechanical properties of the product, how to further reduce the total processing time of complex aluminum alloy components and reduce deformation during processing and delayed deformation during placement are technical issues that urgently need to be addressed.
[0007] Therefore, it is necessary to improve one or more of the problems existing in the above-mentioned related technical solutions.
[0008] It should be noted that this section is intended to provide background or context for the technical solutions of the invention as set forth in the claims. The description herein does not imply acceptance as prior art simply because it is included in this section. Summary of the Invention
[0009] The purpose of this invention is to provide a heat treatment method for reducing the delayed deformation during the processing of complex aluminum alloy structural parts, thereby at least partially solving one or more problems caused by the limitations and defects of related technologies.
[0010] This invention provides a heat treatment method for reducing the delayed deformation during the processing of complex aluminum alloy structural parts, comprising: S1. The forged aluminum alloy structural parts are subjected to solution treatment: put into the furnace at room temperature, then heat to 470-485℃ and hold for 60-120 minutes, and then water-cooled at 25-35℃. S2, Adjust and age the solution-treated structural parts: put them into the furnace at room temperature and slowly heat them to 95-110℃ at a heating rate of 0.8℃ / min-1.2℃ / min, hold them for 240-360 min, and then air cool them after removing them from the furnace. S3 involves semi-finishing the structural components after adjustment and aging treatment; S4. Perform final aging treatment on the semi-finished structural parts: put them into the furnace at room temperature and slowly heat them to 140-170℃ at a heating rate of 0.8℃ / min to 1.2℃ / min, hold them for 360-480 minutes, and then air cool them after removing them from the furnace. S5. Perform finishing on the structural parts after final aging treatment. Perform supplementary aging treatment on products with unqualified mechanical properties. Supplementary aging treatment conditions include: placing in the furnace at room temperature, slowly heating to a holding temperature of 150-160℃ at a heating rate of 0.8℃ / min to 1.2℃ / min, and holding for 120-240 minutes. S6 involves further refinishing the structural components after supplementary aging treatment to obtain the final product.
[0011] In this invention, in S1, the forging methods of the aluminum alloy structural parts include: reverse extrusion forging, die forging, and free forging.
[0012] In this invention, the forged aluminum alloy structural component is in the T1 state.
[0013] In this invention, in S1, the machining allowance of the forged aluminum alloy structural parts is 2.5 to 5 mm.
[0014] In this invention, in S1, the effective thickness of the forged aluminum alloy structural component is no greater than 30mm.
[0015] In this invention, in S3, the machining allowance of the semi-finished aluminum alloy structural parts is 0.5 to 1.5 mm.
[0016] In this invention, the total duration of the adjustment period, the final period, and the supplementary period does not exceed 15 hours.
[0017] In this invention, in step S6, after the structural component is further refined, the final product is obtained by turning, milling, drilling, and grinding the structural component.
[0018] The technical solution provided by this invention may include the following beneficial effects: In this invention, the post-solution aging process is broken down and integrated into the product's machining process. Adjusted aging, final aging, and supplementary aging (optional) methods are used for heat treatment, shortening the total heat treatment time of the structural components. This invention, by breaking down the aging process and integrating it into the product's machining process, not only adjusts the material's mechanical properties but also replaces stabilization treatment or high / low temperature cycling, achieving residual stress release. Furthermore, this invention, by breaking down the aging process and performing adjusted aging after solution treatment, lowers the aging temperature and shortens the holding time compared to peak aging. Compared to direct machining after solution treatment, the material's hardness after adjusted aging reaches 145–155 HBW, making it more suitable for machining. Due to this characteristic, in the process design, the roughing turning amount can be increased, while the semi-finishing amount can be reduced, thus minimizing turning deformation and residual stress caused by semi-finishing. Attached Figure Description
[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.
[0020] Figure 1 This diagram illustrates a process flow of a heat treatment method for reducing the processing delay deformation of complex aluminum alloy structural parts according to an exemplary embodiment of the present invention. Detailed Implementation
[0021] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the invention will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0022] Furthermore, the accompanying drawings are merely illustrative diagrams of embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.
[0023] This example embodiment provides a heat treatment method for reducing the processing delay deformation of complex aluminum alloy structural parts, referencing... Figure 1 As shown, the method includes the following steps: S1. The forged aluminum alloy structural parts are subjected to solution treatment: placed in the furnace at room temperature, then heated to 470-485℃ and held for 60-120 minutes, followed by water cooling at 25-35℃.
[0024] S2. Adjust and age the structural parts after solution treatment: put them into the furnace at room temperature and slowly heat them to 95-110℃ at a heating rate of 0.8℃ / min to 1.2℃ / min, hold them for 240-360 minutes, and then air cool them after removing them from the furnace.
[0025] S3. The structural components after adjustment and aging treatment will be semi-finished. The machining allowance of the aluminum alloy structural components after semi-finishing is 0.5 to 1.5 mm.
[0026] S4. Perform final aging treatment on the semi-finished structural parts: put them into the furnace at room temperature and slowly heat them to 140-170℃ at a heating rate of 0.8℃ / min to 1.2℃ / min, hold them for 360-480 minutes, and then air cool them after removing them from the furnace.
[0027] S5. Perform finishing on the structural components after final aging treatment. Perform supplementary aging treatment on products with unqualified mechanical properties. Supplementary aging treatment conditions include: placing the product in the furnace at room temperature, slowly heating it to a holding temperature of 150-160℃ at a heating rate of 0.8℃ / min to 1.2℃ / min, and holding it for 120-240 minutes.
[0028] S6 involves further refinishing the structural components after supplementary aging treatment to obtain the final product.
[0029] In this embodiment, the present invention breaks down the post-solution aging process and integrates it into the product's machining process. It employs adjusted aging, final aging, and supplementary aging (optional) methods for heat treatment, shortening the total heat treatment time of the structural components. This invention, by breaking down the aging process and integrating it into the product's machining process, not only adjusts the material's mechanical properties but also replaces stabilization treatment or high / low temperature cycling, achieving residual stress release. Furthermore, by breaking down the aging process and performing adjusted aging after solution treatment, the present invention lowers the aging temperature and shortens the holding time compared to peak aging. Compared to direct machining after solution treatment, the material hardness after adjusted aging reaches 145–155 HBW, making it more suitable for machining. Due to this characteristic, the roughing turning amount can be increased and the semi-finishing amount reduced during process design, thus minimizing turning deformation and residual stress caused by semi-finishing.
[0030] It should be noted that prior to the heat treatment in this application, the raw material blank is forged using small-sized raw materials. Forging methods include reverse extrusion, die forging, and free forging, with reverse extrusion being superior to die forging, which in turn is superior to free forging. The forged aluminum alloy structural part is in the T1 state, which is a non-strengthened state. This application describes the process of processing it from the non-strengthened state to the strengthened state. It should be specifically pointed out that the structural part to be processed in this application is not in the T7 strengthened state.
[0031] After rough machining, the structural components should have a allowance of 2.5 to 5 mm, and the effective thickness after heat treatment should not exceed 30 mm.
[0032] The total duration of the adjustment aging, final aging, and supplementary aging does not exceed 15 hours, which is at least 5 hours shorter than the prior art, thus improving heat treatment efficiency.
[0033] In S6, after the structural components are further precision machined, the final product is obtained by turning, milling, drilling, and grinding.
[0034] The heat treatment method of this application will be explained below through specific experiments.
[0035] Example 1: The front top cover body of a certain product uses 7A04 aluminum material with a complex structure of varying wall thickness (3-12mm). The product strength requirement is ≥530MPa. The free forging blank is rough-machined, leaving a 5mm allowance after machining, ensuring the effective thickness after heat treatment does not exceed 20mm. Solution treatment is performed, followed by furnace heating to 470℃ for 90 minutes, then water cooling at 30℃. Adjusted aging is then performed, with the furnace heated slowly at 0.8℃ / min to 110℃ for 240 minutes, followed by air cooling. Semi-finishing is completed, leaving a 1.0mm allowance after machining. Final aging is performed, with the furnace heated slowly at 0.8℃ / min to 170℃ for 480 minutes, followed by air cooling. The mechanical property test result is 550MPa. Finishing is then completed, the product passes appearance inspection, is coated with anti-rust oil, and placed in a packaging box. After being stored for 3 months, the final assembly stage was started. The measured deformation of the assembly dimensions was less than 0.2%, which met the design requirements for final assembly.
[0036] Example 2: A product's cabin shell, using aluminum 7A09, features a complex, asymmetric, porous structure with varying wall thickness, requiring a strength of ≥580MPa. The forged blank is rough-machined after reverse extrusion forging. After rough machining, a 3mm allowance is retained, ensuring the effective thickness after heat treatment does not exceed 15mm. Solution treatment is performed by placing the blank in a furnace at 475℃ for 90 minutes, followed by water cooling at 25℃. Adjusted aging is then performed by slowly heating the blank to 100℃ at 1.0℃ / min for 300 minutes, followed by air cooling. Semi-finishing is completed, leaving a 0.9mm allowance after machining. Final aging is then performed by slowly heating the blank to 150℃ at 0.8℃ / min for 420 minutes, followed by air cooling. The mechanical property test result was 570 MPa. Supplemental aging was then performed, with the product placed in a furnace at room temperature and slowly heated to a holding temperature of 150℃ at a rate of 0.8℃ / min for 120 minutes. The mechanical property test result was 590 MPa. After finishing, the product passed appearance inspection, was coated with anti-rust oil, and placed in a packaging box. After 6 months, it entered the final assembly stage. Measurements showed that the dimensional deformation was less than 0.1%, meeting the design requirements for final assembly.
[0037] Example 3: The combustion chamber shell of a certain product uses 7075 aluminum, with a complex structure of varying wall thickness (2-5mm), and a strength requirement of ≥560MPa. The die-forged blank is rough-machined on an automated production line, leaving a 2.5mm allowance after machining, ensuring the effective thickness after heat treatment is no more than 10mm. Solution treatment is performed, followed by furnace heating to 470℃ for 60 minutes, then water cooling at 35℃. Adjusted aging is then performed, with the furnace heated slowly at 1.2℃ / min to 95℃ for 360 minutes, followed by air cooling. Semi-finishing is then performed on an automated production line, leaving a 0.5mm allowance after machining. Final aging is performed, with the furnace heated slowly at 1.2℃ / min to 140℃ for 480 minutes, followed by air cooling. The mechanical property test result is 595MPa. Finishing is then completed, the product passes appearance inspection, is coated with anti-rust oil, and placed in a packaging box. After being stored for 3 months, the product enters the final assembly stage. Measurements show that the dimensional deformation during assembly is less than 0.1%, which meets the design requirements for final assembly.
[0038] In summary, this invention provides a heat treatment method for reducing delayed deformation during the processing of complex aluminum alloy structural components. This method reduces deformation during the processing of aluminum alloy components and delayed deformation caused by placement after processing, solves the problem that conventional heat treatment methods cannot meet the dimensional stability requirements of aluminum alloy components, and improves the pass rate of complex aluminum alloy structural components.
[0039] Compared with the prior art, the differences and beneficial effects of this application are as follows: (1) Conventional aluminum alloy component heat treatment, solution treatment and aging are completed in one step, and the total heat treatment time is about 20 hours. This invention breaks down the solution treatment and aging step and inserts it into the product's machining process, using adjustment aging, final aging, and supplementary aging (not mandatory) methods for heat treatment, and the total time is about 15 hours. Compared with conventional aluminum alloy component heat treatment time, it reduces the time by about 5 hours.
[0040] (2) Conventional aluminum alloy components undergo heat treatment, followed by solution aging and machining. To control deformation, stabilization treatment or high and low temperature cycling treatment is added in subsequent steps. This invention breaks down the aging process and inserts it into the machining process of the product. Adjusting the aging, final aging, and supplementary aging (not mandatory) not only adjusts the mechanical properties of the material but also replaces the stabilization treatment or high and low temperature cycling, thereby releasing residual stress.
[0041] (3) Some technologies in the industry also use solution treatment followed by direct machining. However, the material in the solution-treated state is very soft, approximately 65-85 HBW, leading to tool deflection during machining. This makes machining difficult and accumulates significant machining stress. Subsequent peak aging treatment strengthens the material while causing substantial stress deformation. This invention breaks down the aging process, adjusting the aging after solution treatment. Compared to peak aging, this method lowers the aging temperature and shortens the holding time. Compared to direct machining after solution treatment, the adjusted aging process achieves a hardness of 145-155 HBW, making it more suitable for machining. Due to this characteristic, the roughing turning amount can be increased and the semi-finishing amount reduced during process design, minimizing turning deformation and residual stress caused by semi-finishing. Furthermore, it further reduces the total production time of the product.
[0042] (4) Conventional aluminum alloy components undergo heat treatment, peak aging, and machining. Then, stabilization treatment or high / low temperature cycling is used to eliminate machining stress. For products with high machining precision, multiple stabilization treatments are even used (refer to HB-352-2002 Dimensional Stabilization Treatment of Metal Parts for Aerospace Precision Instruments). This invention breaks down the aging process and inserts it into the product's machining process. After adjusting the aging time, machining is performed. The workpiece completes semi-finishing under low stress and natural aging. Final aging adjusts the material's mechanical properties to meet product design requirements and removes residual stress generated in previous processes. The final aging uses a higher holding temperature than conventional peak aging, more efficiently reducing residual stress from both creep and stress relaxation aspects.
[0043] (5) Conventional heat treatment of aluminum alloy components typically employs high-temperature heating during the aging process for furnace loading and heat preservation. The aging treatment described in this invention uses a room-temperature furnace loading and slow heating method to achieve stabilization while avoiding the introduction of new thermal stresses, combined with the above-mentioned points (1), (2), and (3) for product heat treatment. Experiments show that the heat treatment method of this application improves stress release capability by 17% compared to conventional heat treatment.
[0044] (6) Compared with conventional heat treatment of aluminum alloy components, the present invention can reduce the residual stress in the final state of the product after processing without reducing the mechanical properties of the aluminum alloy. During the placement process after processing, the residual stress is released, and the dimensional change of 0.2% to 0.4% is reduced to less than 0.2%, thereby improving the product qualification rate.
[0045] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.
[0046] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the appended claims.
Claims
1. A heat treatment method for reducing the delayed deformation during processing of complex aluminum alloy structural parts, characterized in that, include: S1. The forged aluminum alloy structural parts are subjected to solution treatment: put into the furnace at room temperature, then heat to 470-485℃ and hold for 60-120 minutes, and then water-cooled at 25-35℃. S2, Adjust and age the solution-treated structural parts: put them into the furnace at room temperature and slowly heat them to 95-110℃ at a heating rate of 0.8℃ / min-1.2℃ / min, hold them for 240-360 min, and then air cool them after removing them from the furnace. S3 involves semi-finishing the structural components after adjustment and aging treatment; S4. Perform final aging treatment on the semi-finished structural parts: put them into the furnace at room temperature and slowly heat them to 140-170℃ at a heating rate of 0.8℃ / min to 1.2℃ / min, hold them for 360-480 minutes, and then air cool them after removing them from the furnace. S5. Perform finishing on the structural parts after final aging treatment. Perform supplementary aging treatment on products with unqualified mechanical properties. Supplementary aging treatment conditions include: placing in the furnace at room temperature, slowly heating to a holding temperature of 150-160℃ at a heating rate of 0.8℃ / min to 1.2℃ / min, and holding for 120-240 minutes. S6 involves further refinishing the structural components after supplementary aging treatment to obtain the final product.
2. The heat treatment method for reducing the delayed deformation during processing of complex aluminum alloy structural parts according to claim 1, characterized in that, In S1, the forging methods of the aluminum alloy structural parts include: reverse extrusion forging, die forging, and free forging.
3. The heat treatment method for reducing the delayed deformation during processing of complex aluminum alloy structural parts according to claim 2, characterized in that, The forged aluminum alloy structural component is in the T1 state.
4. The heat treatment method for reducing the delayed deformation during processing of complex aluminum alloy structural parts according to claim 1, characterized in that, In S1, the machining allowance for the forged aluminum alloy structural parts is 2.5 to 5 mm.
5. The heat treatment method for reducing the processing delay deformation of complex aluminum alloy structural parts according to claim 4, characterized in that, In S1, the effective thickness of the forged aluminum alloy structural component is no more than 30mm.
6. The heat treatment method for reducing the delayed deformation during processing of complex aluminum alloy structural parts according to claim 1, characterized in that, In S3, the machining allowance for semi-finished aluminum alloy structural parts is 0.5–1.5 mm.
7. The heat treatment method for reducing the delayed deformation during processing of complex aluminum alloy structural parts according to claim 1, characterized in that, The total duration of the adjusted validity period, final validity period, and supplementary validity period shall not exceed 15 hours.
8. The heat treatment method for reducing the delayed deformation during processing of complex aluminum alloy structural parts according to claim 1, characterized in that, In S6, after the structural components are further precision machined, the final product is obtained by turning, milling, drilling, and grinding.