Manufacturing method for an aluminum alloy element and shot blasting device

Abstract

A manufacturing method for an aluminum alloy member comprises preparing an aluminum alloy member formed of an aluminum alloy; and performing shot peening on the aluminum alloy member in a range in which a speed of the shot upon contact with the aluminum alloy member is from 1 m / s to 7 m / s to impart residual stress to the aluminum alloy member.

Description

CROSS-REFERENCE TO RELATED REGISTRATION

[0001] This application is based on Japanese patent application No. 2024-068423, filed with the Japanese Patent Office on April 19, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL AREA

[0002] The present disclosure relates to a manufacturing process for an aluminium alloy element and a shot peening device. BACKGROUND

[0003] Published Japanese patent application No. 2006-188720 discloses a manufacturing process for an aluminum alloy element formed from an aluminum alloy. The manufacturing process includes a shot peening step on the aluminum alloy element. This shot peening uses a blasting medium with a smaller particle size than conventional blasting media, and the shot peening is performed using compressed air at a higher injection velocity than conventional methods. This shot peening improves the fatigue life by approximately 5 to 10 times compared to conventional shot peening. SUMMARY

[0004] The manufacturing process described in published Japanese patent application No. 2006-188720 can pose a risk of the fatigue strength of the aluminum alloy element decreasing over time. Shot peening introduces a deformation into the interior (surface layer) of the aluminum alloy element, imparting residual stress (compressive residual stress). This residual stress is released when a β-phase forms on the deformation. Since the aluminum alloy element contains an element that generates the β-phase, a β-phase compound is deposited in the aluminum alloy over time. As the β-phase compound is deposited, the deformation inside the aluminum alloy element is relieved. Because the residual stress is released over time, the fatigue strength of the aluminum alloy element decreases.The present disclosure provides a technique capable of adequately maintaining the fatigue strength of the aluminium alloy element.

[0005] According to one aspect of the present disclosure, a manufacturing process for an aluminum alloy element comprises preparing an aluminum alloy element formed from an aluminum alloy and performing shot peening on the aluminum alloy element in a range in which the velocity of the peening medium upon contact with the aluminum alloy element is from 1 m / s to 7 m / s in order to impart residual stress to the aluminum alloy element.

[0006] Another aspect of the present disclosure is a shot peening device for performing shot peening on an aluminum alloy element formed from an aluminum alloy. The shot peening device comprises a hopper configured to hold the abrasive, a tube element configured to communicate with the hopper and allow the abrasive to pass through, and a support element arranged vertically below a lower end of the tube element and configured to support the aluminum alloy element.

[0007] According to the present disclosure, it is possible to adequately maintain the fatigue strength of the aluminium alloy element. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a flowchart of a manufacturing process according to one embodiment. Fig. Figure 2 is a representation of an example of a shot peening device according to one embodiment. Fig. Figure 3 is a representation that shows another example of a shot peening device according to one embodiment. Fig. Figure 4 is a graph representing a residual stress imparted by the use of a first abrasive and a second abrasive. Fig. Figure 5 is a graph that illustrates relationships between the residual stress of the aluminum alloy element and past time using examples and comparative examples. Fig. Figure 6 is a graph that represents relationships between the residual stress of the aluminium alloy element and elapsed time, obtained for each abrasive velocity. Fig. Figure 7 is a graph that shows relationships between a stress amplitude and a number of cycles for the aluminum alloy element in examples and comparison examples. DETAILED DESCRIPTION

[0008] Embodiments of the present disclosure are described in detail below with reference to the drawings. In the description of the drawings, the same reference numerals are assigned to the same or equivalent elements, and redundant descriptions are omitted. Dimensional relationships shown in the drawings do not necessarily correspond to those in actual applications. The terms "top," "bottom," "left," and "right" are used for convenience based on the depicted state. [Overview of manufacturing processes for aluminum alloy elements]

[0009] In a manufacturing process according to the present disclosure, an aluminum alloy element imparted with residual stress is produced. The aluminum alloy element produced in this way is applicable to articles handled by human users, such as sporting equipment (bicycles, golf clubs, fishing gear, bats, etc.), work equipment (agricultural machinery, garden tools, etc.), and everyday objects (wheelchairs, eyeglasses, chairs, etc.). These products can achieve sufficient performance even with a lower fatigue strength (for example, 50 MPa to 350 MPa or 70 MPa to 300 MPa) than automotive parts, railway parts, or aircraft parts.

[0010] The residual stress imparted to the aluminum alloy element is gradually released over time. The aluminum alloy element is formed from an aluminum alloy. A β-phase compound is deposited in the aluminum alloy over time. If the aluminum alloy contains at least one element selected from Mg, Cu, Mn, and Si, a β-phase compound is likely to form at the deformation introduced into the aluminum alloy element as a result of reactions between aluminum and these elements. During the deposition of the β-phase compound, the deformation in the aluminum alloy element is relieved, and the residual stress is released. As the residual stress is released over time, the fatigue strength of the aluminum alloy element decreases. A manufacturing process capable of adequately maintaining the fatigue strength of the aluminum alloy element is described below.

[0011] Fig. Figure 1 is a flowchart of a manufacturing process according to one embodiment. As in Fig. As shown in Figure 1, at step S10, a target object is prepared. The target object is the aluminum alloy element formed from an aluminum alloy, and the aluminum alloy can contain at least one element selected from Mg, Cu, Mn, and Si.

[0012] Next, in step S12, blasting is performed on the target object. The blasting here is shot blasting. The blasting media (abrasive) has a high relative density. For example, the relative density of the blasting media is 3.8 or higher. Although the upper limit for the relative density of the blasting media is not particularly restricted, it can be, for example, 6.0 or lower. The blasting media can have a relative density of 3.8 to 6.0 and a Vickers hardness in the range of HV600 to HV1200. An example of a material that meets these relative density and Vickers hardness requirements is zirconia. The blasting media can be spherical, and its diameter φ can range from 0.05 mm to 2.0 mm.

[0013] In this shot peening process, the abrasive is brought into contact with the target object at a low velocity. As a specific example, when the abrasive comes into contact with the aluminum alloy element, the velocity of the abrasive can range from 1 m / s to 7 m / s. By maintaining the abrasive velocity within this range, it becomes possible to suppress the release of residual stress. If the abrasive velocity is less than 1 m / s, the residual stress immediately after peening is only about -100 MPa, which is small, and the effect of suppressing residual stress release is minimal. If the abrasive velocity exceeds 7 m / s, the effect of suppressing residual stress release becomes less significant compared to when the abrasive velocity is set between 1 m / s and 7 m / s.It should be noted that the abrasive velocity can range from 1.0 m / s to 6.5 m / s, or from 1 m / s to 5 m / s. By setting the abrasive velocity to 1 m / s to 5 m / s, the effect of suppressing the release of residual stress becomes more stable, and the change in residual stress over time is reduced, thus facilitating quality control. This range of abrasive velocities can be achieved by using a blower instead of compressed air, or by allowing the abrasive to fall freely from above the aluminum alloy element, thus enabling it to reach the element. This shot peening process imparts residual stress to the aluminum alloy element.

[0014] When step S12 is completed, it ends in Fig. Flowchart 1 shown. Through the in Fig. In the manufacturing process shown, the release of residual stress in the aluminum alloy element is reduced, and the fatigue strength of the aluminum alloy element is adequately maintained. Although the reason why the residual stress of the aluminum alloy element is less prone to release remains unclear, test results indicate that the residual stress release ratio (i.e., {(residual stress at a first time point) - (residual stress at a second time point)} ÷ (residual stress at the first time point) x 100) is 15% or less between a first time point, at which a predetermined time T1 has elapsed after completion of a series of operations, and a second time point, at which a predetermined time T2 has elapsed after completion of the series of operations, and that the residual stress virtually ceases to decrease thereafter. Here, T1 ≥ 0 and T1 <T2. Zum Beispiel kann T1 20 Stunden sein und T2 kann 160 Stunden sein.

[0015] Furthermore, since shot peening can be carried out without the use of compressed air, a compressor is not required. Therefore, according to the [document / section] in Fig. The manufacturing process shown in Figure 1 increases energy consumption efficiency in a factory and reduces CO2 emissions. [Overview of shot peening device]

[0016] A shot blasting device, which is located in the Fig. The step S12 shown in step 1, which can be used, will now be explained using an example. Fig. Figure 2 is a representation that illustrates an example of a shot peening device according to one embodiment. The illustration in Fig. The shot blasting device 1 shown comprises a chamber 2. The chamber 2 is hollow. An aluminum alloy element 10, which is the object to be treated, is placed inside the chamber 2.

[0017] A hopper 3 is provided above chamber 2. The hopper 3 contains abrasive 4. The abrasive 4 has a relative density of 3.8 or more. The relative density of the abrasive can be 6.0 or less. A pipe element 5, which is connected to the hopper 3 and allows the abrasive 4 to pass through it, is provided at the lower end of the hopper 3. The lower end of the pipe element 5 is connected to the interior of chamber 2. An opening / closing gate 6 is provided on the pipe element 5. When the opening / closing gate 6 is open, the abrasive 4 stored in the hopper 3 falls freely, passes through the pipe element 5, and reaches the interior of chamber 2. Inside chamber 2, a support element 2a is arranged to support the aluminum alloy element 10. The support element 2a is arranged vertically below the lower end of the pipe element 5.The abrasive 4, which falls freely, is guided through the tube element 5 and projected onto the aluminum alloy element 10. The velocity of the abrasive 4 upon contact with the aluminum alloy element 10 can be defined by the height from the opening / closing gate 6 to the aluminum alloy element 10.

[0018] The interior of chamber 2 can be divided into a treatment chamber S1 and a recovery chamber S2 by the support element 2a. In this case, the support element 2a has several openings through which the abrasive 4 can pass. The abrasive 4 projected onto the aluminum alloy element 10 passes through the support element 2a and is collected in the recovery chamber S2. The abrasive 4 collected in the recovery chamber S2 is conveyed to the hopper 3 by a conveying device (not shown).

[0019] According to the shot peening device 1, by selecting the combination of the relative density of the abrasive 4 and the height from the opening / closing gate 6 to the aluminum alloy element 10, the velocity of the abrasive 4 upon contact with the aluminum alloy element 10 can be set in the range of 1 m / s to 7 m / s. Thus, the residual stress of the aluminum alloy element 10 is less likely to be released, and the fatigue strength of the aluminum alloy element 10 is adequately maintained. Moreover, during the Fig. The shot peening device shown in 2 demonstrates that shot peening can be achieved without the use of compressed air, thus eliminating the need for a compressor. Consequently, energy efficiency in a factory is increased, and CO2 emissions can be reduced.

[0020] Next, another shot blasting device, which is located in the Fig. The step shown in step S12 can be used, as explained by way of example. Fig. Figure 3 is a representation that depicts another example of a shot peening device according to one embodiment. Compared with the one in Fig. The shot peening device 1 shown in 2 differs from the one shown in Fig. Figure 3 shows the shot blasting device 1A with regard to the arrangement of the hopper, the arrangement of the pipe element, and the fact that a blower 7 is provided on the pipe element; otherwise, the configuration is the same. The main differences are described below, and redundant descriptions are omitted.

[0021] The funnel 3 is arranged on one side of chamber 2. A pipe element 5A is provided at the lower end of the funnel 3 to connect with the funnel 4 and allow the abrasive 4 to pass through it. The pipe element 5A is bent at its distal end, extending from the lower end of the funnel 3 to the side wall of chamber 2 and connecting to the interior of chamber 2. A blower 7 is provided within the pipe element 5A. The blower is a device that emits air without the use of compressed air. By blowing air with the blower 7, the abrasive 4 stored in the funnel 3 passes through the pipe element 5A and reaches the interior of chamber 2. The abrasive 4 is guided through the pipe element 5A in a horizontal direction and is projected onto the side surface of the aluminum alloy element 10.The velocity of the abrasive 4 upon contact with the aluminum alloy element 10 can be determined by the amount of supplied air and can be adjusted within the range of 1 m / s to 7 m / s. According to the shot peening device 1A, as with the shot peening device 1, the fatigue strength of the aluminum alloy element 10 can be adequately maintained, and the energy efficiency of the factory can be improved while reducing CO2 emissions.

[0022] While various exemplary embodiments have been described above, the present disclosure is not limited to the preceding exemplary embodiments, and various omissions, substitutions, combinations and modifications may be made.

[0023] For example, the shot blasting device 1 can use a centrifugal projector instead of the blower 7. EXAMPLES

[0024] The advantages of the manufacturing process and the apparatus of the present disclosure are described below based on examples and comparative examples. (Verification of an abrasive capable of imparting residual stress)

[0025] An aluminum alloy element formed from the aluminum alloy specified in JIS (Japanese Industrial Standards) A7075 was prepared. Then, a free-fall shot peening process was carried out using the process specified in Fig. Shot peening was performed on the aluminum alloy element using the shot peening device shown in Figure 2. A first abrasive with a relative density of 3.8 and a Vickers hardness of HV600 and a second abrasive with a relative density of 6.0 and a Vickers hardness of HV1200 were used in this shot peening. The residual stress of the aluminum alloy element after treatment with the first abrasive and the residual stress of the aluminum alloy element after treatment with the second abrasive were measured in each case. An X-ray residual stress tester (model µ-X360s, manufactured by Pulstec Industrial Co., Ltd.) was used for the measurements. The results are presented in Figure 2. Fig. 4 shown.

[0026] Fig. Figure 4 is a graph representing the residual stress imparted by using the first and second abrasive media. As in Fig. As shown in Figure 4, the residual stress imparted by using the first abrasive was approximately 350 MPa, and the residual stress imparted by using the second abrasive was approximately 400 MPa. This confirmed that an abrasive with a relative density of 3.8 or more and a Vickers hardness of HV600 or more can impart sufficient residual stress. (Verification of the maintenance of residual stress) (Example 1)

[0027] As example 1, an aluminum alloy element formed from the aluminum alloy specified in JIS A7075 was prepared. Then, free-fall shot peening was performed on the aluminum alloy element using the process described in Fig. The shot peening process was carried out using the shot peening device 1 shown in Figure 2. In this shot peening process, a spherical abrasive with a diameter φ in the range of 0.6 mm to 0.8 mm, made of zirconium oxide, having a relative density of 6.2 and a Vickers hardness of HV1180, was used. (Comparative example 1)

[0028] In Comparative Example 1, the same aluminum alloy element used in Example 1 was prepared. Next, shot peening was performed using a shot peening machine (ABT type, manufactured by Sintokogio, Ltd.). This shot peening used spherical abrasive with a diameter of 0.6 mm, made of cast steel, with a relative density of 7.5 and a Vickers hardness of HV600. The shot peening conditions included an injection pressure of 0.1 MPa and an injection rate of 5 kg / min.

[0029] Changes in residual stress over time were measured for the aluminum alloy elements of Example 1 and Comparative Example 1. An X-ray residual stress tester (model µ-X360s, manufactured by Pulstec Industrial Co., Ltd.) was used to measure the residual stress. The measurement was performed several times from 0 hours to 200 hours. The results are presented in Fig. 5 shown.

[0030] Fig. Figure 5 is a graph that illustrates the relationship between the residual stress of the aluminum alloy element and elapsed time in the example and comparison example. The vertical axis of Fig. Figure 5 represents the residual stress of the aluminum alloy element, and the horizontal axis represents the elapsed time. Fig. 5. Tensile residual stress is indicated by positive values ​​and compressive residual stress by negative values. As in Fig. As shown in Figure 5, the aluminum alloy element of comparison example 1 exhibited a residual stress of -280 MPa immediately after shot peening (0 hours), which gradually eased over time. At 20 hours and 160 hours after shot peening, the residual stress was -245 MPa and -200 MPa, respectively. If the first time point is set to 20 hours and the second to 160 hours, the residual stress release ratio was 18.3%, which exceeds 15%.

[0031] In contrast, the aluminum alloy element of Example 1 exhibited a residual stress of -345 MPa immediately after shot peening and generally retained approximately the same value, even as time passed. At 20 hours and 160 hours after shot peening, the residual stress was -330 MPa, and the asymptotic lines (shown as dashed lines in Fig. (as shown in Figure 5) were -340 MPa and -325 MPa, respectively. The residual stress release ratio was 0% (or 4.4% when estimated by the asymptote), which was 15% or less. These results confirmed that the aluminum alloy element produced in Example 1 was less prone to releasing compressive residual stress. (Verification of the relationship between abrasive velocity and maintenance of residual stress) (Example 2)

[0032] As example 2, an aluminum alloy element formed from the aluminum alloy specified in JIS A7075 was prepared. Then, free-fall shot peening was performed on the aluminum alloy element using the process described in Fig. The shot peening process was carried out using the shot peening device 1 shown in Figure 2. The free fall height (the difference in height between the position at which the abrasive begins to fall and the aluminum alloy element) was set to 1 m. This means that the velocity of the abrasive upon contact with the aluminum alloy element was 4.4 m / s. For this shot peening, a spherical abrasive with a diameter φ of 0.6 mm to 0.8 mm, made of zirconium oxide, with a relative density of 6.2 and a Vickers hardness of HV1180 (ZC660 manufactured by Sintokogio, Ltd.), was used. (Example 3)

[0033] In Example 3, the free-fall height was set to 2 m, meaning the velocity of the abrasive upon contact with the aluminum alloy element was 6.3 m / s. Other conditions were the same as in Example 2. (Comparative example 2)

[0034] In comparative example 2, the free-fall height was set to 3 m, meaning the abrasive velocity upon contact with the aluminum alloy element was 7.7 m / s. Other conditions were the same as in example 2.

[0035] For the aluminum alloy elements of Examples 2 and 3 and the comparison example 2, changes in residual stress over time were measured. An X-ray residual stress tester (model µ-X360s, manufactured by Pulstec Industrial Co., Ltd.) was used to measure the residual stress. The measurement was performed several times from 0 hours to 150 hours. The results are presented in Fig. 6 shown.

[0036] Fig. Figure 6 is a graph representing the relationships between the residual stress of the aluminum alloy element and elapsed time, obtained for each of the abrasive velocities. The vertical axis of Fig. Figure 6 represents the residual stress of the aluminum alloy element, and the horizontal axis represents time. Fig. 6. Tensile residual stress is indicated by positive values ​​and compressive residual stress by negative values. As in Fig. As shown in Figure 6, the residual stress in the aluminum alloy element of comparison example 2 (7.7 m / s) was -360 MPa immediately after shot peening (0 hours) and gradually eased over time. Since the rate of change in comparison example 2 was not stable, it is assumed that the residual stress would continue to ease over time. From this graph, it can be deduced that the residual stress at 20 hours and 160 hours after shot peening was approximately -350 MPa and approximately -270 MPa, respectively. In other words, approximately -80 MPa of residual stress was eased between the first time point (20 hours) and the second time point (160 hours). The residual stress release rate was 22.8%, which exceeds 15%.

[0037] In contrast, the residual stress of the aluminum alloy element in Example 2 (4.4 m / s) was -400 MPa immediately after shot peening, and it generally remained approximately the same value after 20 hours. At 20 and 145 hours after shot peening, the residual stress was -355 MPa and -350 MPa, respectively. Using the residual stress at 145 hours, the residual stress release ratio is 1.4%. Given the stability of the residual stress after 20 hours, it is assumed that the release ratio would not change significantly from 1.4%.

[0038] Similarly, in the aluminum alloy element of Example 3 (6.3 m / s), the residual stress was -425 MPa immediately after shot peening, and it generally remained approximately the same value after 20 hours. At 20 and 140 hours after shot peening, the residual stress was -365 MPa and -340 MPa, respectively. Using the residual stress at 140 hours, the residual stress release ratio is 6.8%. Given the stability of the residual stress after 20 hours, it is assumed that the release ratio would not change significantly from 6.8%.

[0039] The above confirmed that the aluminium alloy elements produced in Examples 2 and 3 were less prone to releasing compressive residual stress. (Verification of the maintenance of fatigue strength)

[0040] The fatigue strength was evaluated for the aluminum alloy element from Example 1 and an untreated aluminum alloy element (Comparative Example 3). The aluminum alloy element from Example 1, which had been shot peened for 168 hours, was used. To evaluate the fatigue strength, a repeated stress was periodically applied to the aluminum alloy element, and a stress amplitude δ was measured. a The voltage amplitude δ was measured. A measuring device (MS-CRB-0, manufactured by Kazuki Co., Ltd.) was used to measure the voltage amplitude δ. a used. The results are displayed in Fig. 7 shown.

[0041] Fig. Figure 7 is a graph illustrating the relationship between stress amplitude and number of cycles for the aluminum alloy element in the example and comparison example. The vertical axis in Fig. 7 represents the voltage amplitude δ aThe horizontal axis represents the number of cycles. As in Fig. As shown in 7, the voltage amplitude δ remained unchanged. a In example 1, at a higher level, until the number of cycles reached several million, compared to the voltage amplitude δ. a In comparative example 3, these results confirmed that the aluminium alloy element produced in example 1 sufficiently maintained its fatigue strength for articles handled by human users. [Embodiments contained in the present disclosure]

[0042] The present disclosure includes the following provisions:

[0043] (Provision 1) According to one aspect, a manufacturing process for an aluminum alloy element comprises: preparing an aluminum alloy element formed from an aluminum alloy; and performing shot peening on the aluminum alloy element in a range in which the velocity of the peening medium upon contact with the aluminum alloy element is from 1 m / s to 7 m / s in order to impart residual stress to the aluminum alloy element.

[0044] According to the manufacturing process in Determination 1, shot peening is performed on the aluminum alloy element in a range where the speed of the abrasive material upon contact with the aluminum alloy element is between 1 m / s and 7 m / s. Such an abrasive material velocity range of 1 m / s to 7 m / s can be achieved without the use of compressed air. When residual stress is imparted to an aluminum alloy by ordinary cold forming, aging relaxation can occur. The residual stress imparted to the aluminum alloy element is released over time, causing the fatigue strength to decrease. The inventors have found that a specific shot peening condition, in which the abrasive material is brought into contact with the aluminum alloy element at a low velocity, helps to suppress the time-dependent decrease in the fatigue strength of the aluminum alloy element.With this specific shot peening condition, the manufacturing process in Determination 1 can adequately maintain the fatigue strength of the aluminum alloy element. Furthermore, since shot peening is performed without the use of compressed air, a compressor is not required. Therefore, the manufacturing process in Determination 1 can improve energy efficiency in a factory and contribute to reducing CO2 emissions.

[0045] (Provision 2) In the manufacturing process according to Provision 1, the relative density of the blasting media may be 3.8 or more. By using a heavier blasting media with a relative density of 3.8 or more, even a low velocity can produce a sufficient spherical blasting effect.

[0046] (Provision 3) In the manufacturing process according to Provision 2, the blasting media may have a Vickers hardness in the range of HV600 to HV1200. By using a blasting media whose relative density is 3.8 or more and whose Vickers hardness is in the range of HV600 to HV1200, an even better sufficient spherical blasting effect at a low velocity may be achieved.

[0047] (Provision 4) In the manufacturing process according to Provision 3, the blasting media may be formed from zirconium oxide. According to the manufacturing process in Provision 4, the fatigue strength of the aluminium alloy element may be adequately maintained by using a blasting media formed from zirconium oxide.

[0048] (Provision 5) In the manufacturing process according to any of Provisions 1 to 4, during the step of imparting residual stress, the abrasive may be dropped freely from above the aluminum alloy element to reach it. The manufacturing process in Provision 5 can further improve energy efficiency in a factory and contribute to further CO2 reduction.

[0049] (Provision 6) In the manufacturing process according to any of Provisions 1 to 5, the residual stress of the aluminium alloy element subjected to shot peening may be from 50 MPa to 350 MPa. According to the manufacturing process in Provision 6, suitable fatigue strength may be imparted to the aluminium alloy element used in articles handled by humans.

[0050] (Provision 7) In the manufacturing process according to Provision 6, the residual stress release ratio of the aluminum alloy element from a first timing, at which a predetermined time has elapsed since shot peening was performed on the aluminum alloy element, to a second timing, may be 15% or less. The first timing is the time when a predetermined time (T1) has elapsed since the completion of a series of operations, and the second timing is the time when a predetermined time (T2) has elapsed since the completion of the series of operations. The residual stress release ratio is calculated as {(residual stress at the first time) - (residual stress at the second time)} ÷ (residual stress at the first time) x 100.A smaller value indicates that the residual stress is less likely to be released over time, and an adequate fatigue strength can be stably maintained. According to the manufacturing process in specification 7, the fatigue strength imparted to the aluminum alloy element used in articles handled by humans can be adequately maintained.

[0051] (Provision 8) According to another aspect of the present disclosure, a shot peening apparatus for performing shot peening on an aluminium alloy element formed from an aluminium alloy comprises: a hopper configured to hold peening media; a tube element configured to be connected to the hopper and to allow the peening media to pass through it; and a support element arranged vertically below a lower end of the tube element and configured to support the aluminium alloy element.

[0052] According to the shot peening device in claim 8, the abrasive falls freely from the tube element and strikes the aluminum alloy element, which is supported vertically below the tube element. The inventors have found that the specific shot peening condition of the contact between the aluminum alloy element and the abrasive at a low velocity helps to suppress a time-dependent decrease in the fatigue strength of the aluminum alloy element. According to the free-fall shot peening device in claim 8, the fatigue strength of the aluminum alloy element can be adequately maintained. Furthermore, since shot peening is carried out without the use of compressed air, no compressor is required. Thus, the free-fall shot peening device in claim 8 improves energy efficiency in a factory and contributes to a reduction in CO2 emissions. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2024-068423

[0001] JP 2006-188720 [0003, 0004]

Claims

A manufacturing method for an aluminum alloy member, comprising:preparing an aluminum alloy member formed of an aluminum alloy; andperforming shot peening on the aluminum alloy member in a range where a speed of the shot upon contact with the aluminum alloy member is from 1 m / s to 7 m / s to impart residual stress to the aluminum alloy member. A manufacturing method according to claim 1, wherein a relative density of the blasting medium is 3.8 or more. Manufacturing method according to claim 2, wherein the blasting medium has a Vickers hardness in a range of HV600 to HV1200. Manufacturing method according to claim 3, wherein the blasting medium is formed from zirconium oxide. A manufacturing method according to claim 1 or 2, wherein, in said performing, the blasting medium is freely dropped from above the aluminum alloy member to reach the aluminum alloy member. A manufacturing method according to claim 1 or 2, wherein a residual stress of the aluminum alloy member subjected to shot peening is from 50 MPa to 350 MPa. A manufacturing method for an aluminum alloy member according to claim 6, wherein a release ratio of the residual stress of the aluminum alloy member from a first time point at which a predetermined time has passed since shot peening was performed on the aluminum alloy member to a second time point is 15% or less. A shot peening apparatus for performing shot peening on an aluminum alloy member formed of an aluminum alloy, comprising: a hopper configured to store abrasive; a tubular member configured to communicate with the hopper and allow the abrasive to pass therethrough; and a support member vertically disposed below a lower end of the tubular member and configured to support the aluminum alloy member.

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