Post-welding adjusting and repairing method for aluminum alloy bracket of railway vehicle

Abstract

The invention discloses a post-welding adjusting and repairing method for an aluminum alloy bracket of a railway vehicle. The post-welding adjusting and repairing method comprises the steps that the first deformation amount of a deformation position is measured; preparing a plurality of first tensile samples, and performing flame heating adjustment at a preset flame heating temperature; performing a tensile test on the first tensile sample; establishing a relationship between the mechanical property and the flame heating temperature, and obtaining a target flame heating temperature; manufacturing a second tensile sample, and performing deformation treatment and mechanical adjustment treatment for preset times; performing a tensile test on the second tensile sample, establishing a relationship between the mechanical property and the times of deformation treatment and mechanical adjustment treatment, and obtaining a target mechanical adjustment time; flame heating adjustment and mechanical adjustment are conducted on the aluminum alloy bracket according to the target flame heating temperature and the target mechanical adjustment frequency; and manufacturing a fatigue sample, carrying out a fatigue test, and evaluating the safety of adjustment and repair. According to the method, flame heating adjustment and mechanical adjustment are combined, welding residual stress can be released, and deformation deviation can be accurately corrected.

Description

Technical Field

[0001] This invention belongs to the field of rail vehicle welding technology, and particularly relates to a post-weld adjustment and repair method for aluminum alloy brackets of rail vehicles. Background Technology

[0002] Rail transit systems are urban transportation systems that use vehicles running on fixed tracks for urban passenger transport. Rail vehicles within these systems are the main arteries of passenger transport and the lifeline of the city, directly impacting urban residents' travel, work, shopping, and daily life. Aluminum alloys, with their excellent extrusion properties and good weldability, are gradually becoming an important material in high-speed train manufacturing. Key components of high-speed train aluminum alloy car bodies, such as the underframe, side walls, and roof, are generally assembled by interlocking and welding several large-format hollow extruded aluminum profiles of the same length as the car body. The welds are all regular, long, straight, and parallel longitudinal welds, which are easy to automate. However, due to the high thermal conductivity and linear expansion coefficient of aluminum alloys, despite the use of rigid fixing methods, reverse deformation methods, and welding process optimization during welding, significant welding deformation still occurs after welding, affecting the dimensional accuracy of the structure and subsequent assembly. Post-weld adjustments are often necessary to reduce the amount of deformation.

[0003] During the welding of aluminum alloy vehicle bodies, localized high temperatures can induce non-uniform thermal stress, leading to deformation and affecting dimensional accuracy and structural strength. Therefore, post-weld flame tempering is an important way to ensure dimensional accuracy. Currently, post-weld tempering mainly relies on mechanical adjustments based on workers' practical experience, resulting in poor quality stability and difficulty in guaranteeing consistency. Furthermore, mechanical adjustments alone can introduce additional stress.

[0004] A Chinese patent with publication number CN106181220A discloses a post-weld flame conditioning process for aluminum alloys. It uses a thermal simulation testing machine to simulate the thermal cycle process of flame conditioning of aluminum alloys and determines the post-weld flame conditioning parameters by comprehensively considering microhardness, tensile mechanical properties, microstructure, and fatigue life. At the same time, it uses the thermo-elastic-plastic finite element method to simulate the flame conditioning process and establish the relationship between the amount of flame conditioning deformation and the heating temperature, heating width, and high-temperature dwell time. The above process uses flame conditioning, but flame conditioning may lead to new non-uniform deformation. Summary of the Invention

[0005] This invention provides a post-weld adjustment method for aluminum alloy brackets in rail vehicles. By combining flame heating adjustment and mechanical adjustment, the residual welding stress of the aluminum alloy bracket is released, and the deformation deviation of the aluminum alloy bracket is accurately corrected.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a post-weld adjustment and repair method for aluminum alloy brackets of rail vehicles, comprising the following steps: S1: The first deformation amount at the deformation location of the aluminum alloy bracket; S2: Prepare multiple first tensile specimens according to the aluminum alloy bracket described in step S1, and perform flame heating adjustment on the multiple first tensile specimens respectively at a preset flame heating temperature. S3: Perform tensile tests on multiple first tensile specimens after S2 treatment to determine mechanical properties; establish the relationship between mechanical properties and flame heating temperature, and obtain the target flame heating temperature; S4: Prepare multiple second tensile specimens according to the aluminum alloy bracket described in step S1, and perform deformation treatment and mechanical adjustment treatment on the second tensile specimens a preset number of times; the deformation amount of the second tensile specimen is the second deformation amount, and the value of the second deformation amount is greater than or equal to the value of the first deformation amount. S5: Perform a tensile test on the second tensile specimen after S4 treatment, determine the mechanical properties, establish the relationship between the mechanical properties and the number of deformation treatments and mechanical adjustment treatments, and obtain the target number of mechanical adjustment treatments. S6: Based on the target flame heating temperature and target mechanical adjustment number obtained in S3 and S5, perform flame heating adjustment and mechanical adjustment on the aluminum alloy bracket; S7: Sample the aluminum alloy bracket after S6 treatment and prepare fatigue specimens. Perform fatigue tests on the fatigue specimens to evaluate the safety of the aluminum alloy bracket after welding flame heating and mechanical repair. S8: If the safety assessment is qualified, the adjustment is completed. The target flame heating temperature of S3 is used as the determined flame heating adjustment parameter, and the target number of mechanical adjustments in S5 is used as the determined mechanical adjustment parameter. If the safety assessment fails, repeat steps S2 to S7 until the aluminum alloy bracket passes the flame heating and mechanical adjustment tests.

[0007] In some embodiments of this application, the first tensile specimen and the second tensile specimen are consistent with the material and thickness of the deformation location of the aluminum alloy bracket described in S1.

[0008] In some embodiments of this application, the flame type for flame heating is a neutral oxyacetylene flame.

[0009] In some embodiments of this application, S2 and S6 both include a cooling process to below 70°C after flame heating adjustment.

[0010] In some embodiments of this application, the cooling process is water cooling or air cooling.

[0011] In some embodiments of this application, in S2 and S6, the flame heating adjustment adopts the triangular heating method.

[0012] In some embodiments of this application, in S6, mechanical adjustment includes continuously pressurizing the aluminum alloy bracket to the target flatness using a fixed fixture and a press.

[0013] In some embodiments of this application, mechanical properties include yield strength, tensile strength, and elongation.

[0014] In some embodiments of this application, the preset flame heating temperature is 200~300℃.

[0015] In some embodiments of this application, in step S6, during the flame heating adjustment process, a temperature monitoring device is used to monitor the temperature of the heating point in real time.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are as follows: The post-weld adjustment method of the aluminum alloy bracket of the present invention prepares a first tensile specimen, performs flame heating adjustment on the first tensile specimen, and conducts mechanical property testing to establish the relationship between mechanical properties and flame heating temperature, thereby obtaining the target flame heating temperature; by preparing a second tensile specimen, performing deformation treatment and mechanical adjustment treatment on the second tensile specimen, and conducting mechanical property testing, the relationship between mechanical properties and the number of deformation treatments and mechanical adjustment treatments is established to obtain the target number of mechanical adjustment treatments; based on the aluminum alloy material itself, the aluminum alloy bracket is subjected to flame heating adjustment and mechanical adjustment through the target flame heating temperature and the target number of mechanical adjustment treatments; after adjustment, the aluminum alloy bracket is sampled and fatigue tests are conducted. The combination of the two adjustments can release most of the welding residual stress, which is beneficial for accurately correcting deformation deviations and controlling springback effects; it avoids the additional stress caused by single mechanical adjustment, and at the same time prevents new uneven deformations that may be caused by flame adjustment. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is one of the structural schematic diagrams of the aluminum alloy bracket provided by the present invention; Figure 2 This is the second structural schematic diagram of the aluminum alloy bracket provided by the present invention; Figure 3 A schematic diagram of the structure of the first test plate provided by the present invention; Figure 4 This is a schematic diagram of the structure of the fatigue specimen provided by the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Aluminum alloy bracket; 11. Base plate; 12. Rib plate; 2. First test plate; 21. First tensile specimen; 3. Fatigue test specimens. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0025] In a first aspect, embodiments of this disclosure provide a post-weld adjustment method for an aluminum alloy bracket 1 for a rail vehicle, comprising the following steps: S1: The deformation at the deformation location of the aluminum alloy bracket 1 is the first deformation.

[0026] S2: Select the first test plate 2 according to the material, thickness and other properties of the aluminum alloy bracket 1 in step S1. Prepare multiple first tensile specimens 21 on the first test plate 2. Perform flame heating adjustment on the multiple first tensile specimens 21 at a preset flame heating temperature.

[0027] In actual operation, the first test plate 2 can be heated by flame according to the preset flame heating temperature, and then the first tensile specimen 21 can be cut from the first test plate 2.

[0028] S3: Perform tensile tests on multiple first tensile specimens 21 after S2 treatment to determine mechanical properties; establish the relationship between mechanical properties and flame heating temperature, obtain the target flame heating temperature, the mechanical properties corresponding to the target flame heating temperature are optimal, and the target flame heating temperature is the best flame heating temperature.

[0029] S4: Select a second test plate for use based on the material and thickness of the aluminum alloy bracket 1 in step S1. Make multiple second tensile specimens on the second test plate. Perform a preset number of deformation treatments and mechanical adjustments on the second tensile specimens. The deformation amount of the second tensile specimen is the second deformation amount, and the value of the second deformation amount is greater than or equal to the value of the first deformation amount.

[0030] Specifically, the second tensile specimen is subjected to a preset number of deformation and mechanical adjustment treatments in sequence, that is, the second tensile specimen is first deformed and then mechanically adjusted to restore the deformation; the above treatment process is repeated a preset number of times.

[0031] In practice, the second test plate can be subjected to a preset number of deformation and mechanical adjustment processes before the second tensile specimen is cut from the second test plate.

[0032] Specifically, by making the value of the second deformation quantity greater than or equal to the value of the first deformation quantity, the subsequent results are made more representative.

[0033] S5: Perform a tensile test on the second tensile specimen after S4 treatment, determine the mechanical properties, establish the relationship between the mechanical properties and the number of deformation treatments and mechanical adjustment treatments, and obtain the target number of mechanical adjustment treatments.

[0034] Specifically, in the actual mechanical adjustment and maintenance process, the target number of mechanical adjustments and maintenance is the upper limit of the mechanical adjustment and maintenance number. The number of mechanical adjustments and maintenance should be less than or equal to the target number of mechanical adjustments and maintenance to avoid excessive adjustments and maintenance affecting mechanical performance.

[0035] In some embodiments of this application, the post-weld adjustment method for the aluminum alloy bracket 1 of a rail vehicle further includes: Multiple third tensile specimens are prepared based on the material and thickness of the aluminum alloy bracket 1 in step S1. The third tensile specimens are subjected to a preset number of heating and cooling treatments at the target flame heating temperature, and their mechanical properties are measured. The relationship between mechanical properties and the number of heating treatments is established, and the target number of heating treatments is obtained. The target number of heating treatments is the upper limit of the number of heating treatments.

[0036] S6: Based on the target flame heating temperature, target heating times, and target mechanical adjustment times obtained from S3 and S5, the aluminum alloy bracket 1 is mechanically adjusted and flame-heated adjusted sequentially. During the adjustment process, pressure is applied to the aluminum alloy bracket 1 to the target flatness using a fixed fixture and a press and maintained, and then flame-heated adjusted to the target flame heating temperature. The mechanical properties corresponding to the target flame heating temperature are the best. During the adjustment, the number of flame-heating adjustments is less than or equal to the target heating times, and the number of mechanical adjustments is less than or equal to the target mechanical adjustments.

[0037] Specifically, by performing flame heating adjustment on the basis of mechanical adjustment, the temperature of flame adjustment can be reduced, the deformation size and number of adjustments can be reduced, the internal stress caused by mechanical adjustment can be reduced, and the adjustment effect can be improved.

[0038] When the number of times the flame heating adjustment exceeds the target number of times, or when the heating temperature is too high (e.g., above 400℃), it will lead to grain coarsening and excessive precipitation of the β phase, affecting the corrosion resistance and mechanical properties of the material.

[0039] S7: Sample the aluminum alloy bracket 1 after S6 treatment and prepare fatigue specimen 3. Perform fatigue tests on fatigue specimen 3 to evaluate the safety of flame heating and mechanical adjustment of aluminum alloy bracket 1 after welding.

[0040] Specifically, by sampling the aluminum alloy bracket 1 itself, it is not necessary to sample all aluminum alloy brackets 1, which can reduce destructive losses, avoid the scrapping of all aluminum alloy brackets 1 due to full inspection, reduce testing costs, and improve efficiency.

[0041] S8: If the safety assessment is satisfactory, the adjustment is completed. The target flame heating temperature of S3 is taken as the optimal adjustment heating temperature; the target number of heating cycles of S6 is taken as the upper limit of the number of heating cycles during the adjustment process; and the target number of mechanical adjustments of S5 is taken as the upper limit of the number of mechanical adjustments.

[0042] If the safety assessment fails, repeat steps S2 to S7 until the aluminum alloy bracket 1 passes the flame heating and mechanical adjustment.

[0043] Specifically, the post-weld repair method for the aluminum alloy bracket 1 in this application involves preparing a first tensile specimen 21, subjecting the first tensile specimen 21 to flame heating repair, and conducting mechanical property tests to establish the relationship between mechanical properties and flame heating temperature, thereby obtaining the target flame heating temperature. A second tensile specimen is then prepared, subjected to deformation treatment and mechanical repair treatment, and its mechanical properties are tested to establish the relationship between mechanical properties and the number of deformation treatments and mechanical repair treatments, thereby obtaining the target number of mechanical repairs. Based on the aluminum alloy material itself, the aluminum alloy bracket 1 is subjected to flame heating repair and mechanical repair using the target flame heating temperature and the target number of mechanical repairs. After repair, the aluminum alloy bracket 1 is sampled and subjected to fatigue tests. The combination of these two repair methods can release most of the welding residual stress, which is beneficial for accurately correcting deformation deviations and controlling springback effects. It avoids the additional stress caused by single mechanical repair and prevents new uneven deformation that may be caused by flame repair.

[0044] In some embodiments of this application, the first tensile specimen 21, the second tensile specimen, and the third tensile specimen are consistent with the material and thickness of the deformation position of the aluminum alloy bracket 1 in S1.

[0045] Specifically, this helps to ensure the accuracy of the experimental data.

[0046] In some embodiments of this application, the flame heating method is flame heating gun heating, and the flame type of the flame heating is neutral oxyacetylene flame.

[0047] Specifically, the heating temperature of neutral oxyacetylene is highly controllable, avoiding the risk of overburning; the heating area is concentrated, and the heat-affected zone is small; the flame heating gun is portable and flexible, can be operated by hand, is convenient to operate, and requires little equipment investment.

[0048] In some embodiments of this application, the nozzle diameter of the flame heating gun is 1.0~1.5mm.

[0049] Specifically, this allows the heat to be more concentrated in the heating zone.

[0050] In some embodiments of this application, S2 and S6 both include a cooling process to below 70°C after flame heating adjustment.

[0051] Specifically, after flame heating and adjustment, cooling the temperature to below 70°C can prevent shrinkage and deformation caused by excessively high temperatures.

[0052] In some embodiments of this application, the cooling process is water cooling or air cooling.

[0053] Specifically, water cooling or air cooling can provide rapid cooling and improve operational efficiency.

[0054] In some embodiments of this application, in S2 and S6, the flame heating adjustment adopts the triangular heating method.

[0055] Specifically, by setting the path of the flame as a triangle, the heat gradient at the apex of the triangle is used to achieve directional contraction, reduce thermal disturbance in adjacent areas, minimize the heat-affected zone, and avoid secondary deformation.

[0056] In some embodiments of this application, in S6, mechanical adjustment includes continuously pressurizing the aluminum alloy bracket 1 to the target flatness using a fixed fixture and a press.

[0057] In some embodiments of this application, mechanical properties include yield strength, tensile strength, and elongation.

[0058] In some embodiments of this application, the preset flame heating temperature is 200~300℃.

[0059] Specifically, when the preset flame temperature is too high, it can easily lead to grain coarsening and excessive precipitation of the β phase, affecting the corrosion resistance and mechanical properties of aluminum alloy materials; when the preset flame temperature is too low, it affects the adjustment effect, causing multiple reworks and affecting the adjustment progress.

[0060] In some embodiments of this application, in step S6, during the flame heating adjustment process, a temperature monitoring device is used to monitor the temperature of the heating point in real time to avoid abnormal temperature conditions.

[0061] Specifically, temperature monitoring equipment includes non-contact infrared thermometers or infrared thermal imagers.

[0062] The following description, in conjunction with specific embodiments, provides further details.

[0063] The specific process for post-weld adjustment and repair of the 5083-O aluminum alloy bracket 1 is as follows: (1) Measure the first deformation at the deformation location of the aluminum alloy bracket 1, such as the aluminum alloy bracket 1. Figure 1As shown, the aluminum alloy bracket 1 includes an L-shaped base plate 11 and a stiffening plate 12.

[0064] (2) Combination Figure 3 As shown, seven sets of aluminum alloy first test plates 2 were prepared, each with dimensions of 350mm*150mm*6mm. Six sets of the first test plates 2 were heated to 200℃, 220℃, 240℃, 260℃, 280℃, and 300℃ respectively, and then water-cooled to below 70℃. The heating areas of the six sets of first test plates 2 are shown in the figure. Figure 3 As shown in area A, one group serves as a room temperature blank sample, and three first tensile specimens 21 are set in each group.

[0065] like Figure 3 As shown, a first tensile specimen 21 is cut from the first test plate 2. The first tensile specimen 21 is dumbbell-shaped, and region A passes through the centerline of the first tensile specimen 21. Mechanical properties are measured to establish the relationship between flame heating temperature and mechanical properties, and the target flame heating temperature is obtained.

[0066] (3) At the target flame heating temperature, prepare 4 sets of aluminum alloy third test plates with dimensions of 350mm*150mm*6mm. Cut out third tensile specimens from the third test plates and heat the 4 sets of third tensile specimens 1, 2, 3 and 4 times respectively. After each heating, cool them with water to below 70℃. Measure the mechanical properties, establish the relationship between the number of heating times and the mechanical properties, and obtain the target number of heating times.

[0067] (4) Prepare four sets of aluminum alloy second test plates with dimensions of 350mm*150mm*6mm. Deform the four sets of second test plates respectively. The deformation amount of each deformation treatment is the second deformation amount, and the second deformation amount is greater than or equal to the first deformation amount. After each deformation treatment, mechanical adjustment is performed until there is no deformation. This is a complete mechanical adjustment. Perform one mechanical adjustment, two mechanical adjustments, three mechanical adjustments, and four mechanical adjustments on the four sets of second test plates respectively. Cut the second tensile specimens on the above-mentioned second test plates and establish the relationship between the number of mechanical adjustments and mechanical properties.

[0068] Among them, the first tensile specimen 21, the second tensile specimen and the third tensile specimen all conform to the tensile specimen standard of ISO4136-2022, and three specimens are set in each group.

[0069] (5) Adjust the aluminum alloy bracket 1 according to the target flame heating temperature, the target number of heating times and the target number of mechanical adjustments, wherein the number of mechanical adjustments to the aluminum alloy bracket 1 is less than or equal to the target number of mechanical adjustments, and the number of heating times is less than or equal to the target number of heating times.

[0070] Specifically, pressure is applied to the aluminum alloy bracket 1 using a fixed fixture and a press, and the aluminum alloy bracket 1 is flame-heated to the target flame-heating temperature. The heating process uses a triangular heating method to achieve the target flatness and maintain it. After adjustment, water cooling is performed.

[0071] (6) Samples were taken from the adjusted aluminum alloy bracket 1 and fatigue specimen 3 was prepared. Fatigue specimen 3 is as follows: Figure 4 As shown, fatigue tests were conducted on fatigue specimen 3, and the suitability of the adjustment parameters was evaluated based on the fatigue test results, thereby assessing the safety of the flame adjustment of the aluminum alloy bracket 1 after welding.

[0072] (7) If the safety assessment is satisfactory, the adjustment is completed.

[0073] If the safety assessment fails, adjust the heating temperature, heating times, and mechanical repair times, and repeat steps (2) to (7) until the repair is satisfactory.

[0074] The test results are as follows: Experiment 1: According to ISO 4136-2022 standard, the mechanical properties of the first tensile specimen 21, the second tensile specimen, and the third tensile specimen were tested respectively. The results are as follows: Table 1 shows the mechanical properties of the first tensile specimen at different heating temperatures.

[0075] As shown in Table 1, the tensile strength of the first tensile specimen 21 at 200℃~300℃ is 290~293.5MPa, which is not lower than the tensile strength at room temperature; and it is within the standard tensile strength range of 275~350MPa, thus meeting the tensile strength requirements. The yield strength of the first tensile specimen 21 is between 131.5~141MPa, which is greater than 125MPa and the yield strength at room temperature, thus meeting the standard requirements for yield strength. The elongation is greater than 15%, thus meeting the requirements.

[0076] As the heating temperature increases, the tensile strength of the first tensile specimen 21 reaches a maximum of 293.5 MPa at 260℃, the yield strength reaches 141 MPa, and the elongation is 18.5%. Considering factors such as adjustment efficiency and cost, 260℃ is a better heating temperature.

[0077] Table 2 shows the mechanical properties of the third tensile specimen after different heating cycles at 260 ℃.

[0078] As shown in Table 2, the mechanical properties of the third tensile specimen varied with the number of heating cycles at a heating temperature of 260 ℃. The tensile strength ranged from 293.5 to 298 MPa, the yield strength from 137 to 143 MPa, and the elongation from 16.8% to 21.25%. After three heating cycles, both the tensile strength and yield strength reached their maximum values, namely, the tensile strength was 298 MPa and the yield strength was 143 MPa. Therefore, the mechanical strength reached its maximum after three heating cycles.

[0079] Table 3 shows the mechanical properties of the second tensile specimen after different mechanical adjustments.

[0080] As shown in Table 3, the mechanical properties of the second tensile specimens differed after four mechanical adjustments. The tensile strength after four mechanical adjustments was 290~292MPa, and the yield strength was 137~150.5MPa, both of which were higher than the tensile strength and yield strength in the unadjusted state. When the mechanical adjustments were performed three times, the tensile strength and yield strength reached their maximum, with a corresponding elongation of 19.75%.

[0081] Test 2: Based on the customer's requirements and Test 1 above, pressure was applied to the aluminum alloy bracket 1 using a fixed fixture and press to achieve the target flatness, and then combined with... Figure 2 As shown, for Figure 2 Heat area B to 260°C, then cool it to below 70°C using air cooling. Repeat this process three times to complete the adjustment.

[0082] The above-mentioned adjusted aluminum alloy bracket 1 was sampled to obtain fatigue specimen 3. The cross-section of fatigue specimen 3 is shown in the figure. The sampling area is the junction of the base plate 11 and the stiffener plate 12.

[0083] Fatigue specimen 3 passed 2 million fatigue tests, meeting customer requirements.

[0084] In summary, the post-weld repair method for the aluminum alloy bracket 1 of this invention involves preparing a first tensile specimen 21, subjecting the first tensile specimen 21 to flame heating repair, and conducting mechanical property tests to establish the relationship between mechanical properties and flame heating temperature, thereby obtaining the target flame heating temperature. Then, a second tensile specimen is prepared, subjected to deformation and mechanical repair treatment, and its mechanical properties are tested to establish the relationship between mechanical properties and the number of deformation and mechanical repair treatments, obtaining the target number of mechanical repairs. Based on the aluminum alloy material itself, the aluminum alloy bracket 1 is subjected to flame heating repair and mechanical repair using the target flame heating temperature and the target number of mechanical repairs. After repair, the aluminum alloy bracket 1 is sampled and subjected to fatigue tests. The combination of these two repair methods can release most of the welding residual stress, which is beneficial for accurately correcting deformation deviations and controlling springback effects. It avoids the additional stress caused by single mechanical repair and prevents new uneven deformation that may be caused by flame repair.

[0085] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "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.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A method for post-weld adjustment and repair of aluminum alloy brackets for rail vehicles, characterized in that, Includes the following steps: S1: The first deformation amount at the deformation location of the aluminum alloy bracket; S2: Prepare multiple first tensile specimens according to the aluminum alloy bracket described in step S1, and perform flame heating adjustment on the multiple first tensile specimens respectively at a preset flame heating temperature. S3: Perform tensile tests on multiple first tensile specimens after S2 treatment to determine mechanical properties; establish the relationship between mechanical properties and flame heating temperature, and obtain the target flame heating temperature; S4: Prepare multiple second tensile specimens according to the aluminum alloy bracket described in step S1, and perform deformation treatment and mechanical adjustment treatment on the second tensile specimens a preset number of times. The deformation amount of the second tensile specimen is the second deformation amount, and the value of the second deformation amount is greater than or equal to the value of the first deformation amount. S5: Perform a tensile test on the second tensile specimen after S4 treatment, determine the mechanical properties, establish the relationship between the mechanical properties and the number of deformation treatments and mechanical adjustment treatments, and obtain the target number of mechanical adjustment treatments. S6: Based on the target flame heating temperature and target mechanical adjustment number obtained in S3 and S5, perform flame heating adjustment and mechanical adjustment on the aluminum alloy bracket; S7: Sample the aluminum alloy bracket after S6 treatment and prepare fatigue specimens. Perform fatigue tests on the fatigue specimens to evaluate the safety of the aluminum alloy bracket after welding flame heating and mechanical repair. S8: If the safety assessment is qualified, the adjustment is completed. The target flame heating temperature of S3 is used as the determined flame heating adjustment parameter, and the target number of mechanical adjustments in S5 is used as the determined mechanical adjustment parameter. If the safety assessment fails, repeat steps S2 to S7 until the aluminum alloy bracket passes the flame heating and mechanical adjustment tests.

2. The post-weld adjustment and repair method for aluminum alloy brackets for rail vehicles according to claim 1, characterized in that, The first tensile specimen and the second tensile specimen are consistent with the material and thickness of the deformation position of the aluminum alloy bracket described in S1.

3. The post-weld adjustment and repair method for aluminum alloy brackets for rail vehicles according to claim 1, characterized in that, The flame type used for flame heating is a neutral oxyacetylene flame.

4. The post-weld adjustment and repair method for aluminum alloy brackets for rail vehicles according to claim 1, characterized in that, In both S2 and S6, after the flame heating adjustment, a cooling process is also included to bring the temperature down to below 70°C.

5. The post-weld adjustment and repair method for aluminum alloy brackets for rail vehicles according to claim 4, characterized in that, The cooling method is either water cooling or air cooling.

6. The post-weld adjustment and repair method for aluminum alloy brackets for rail vehicles according to claim 1, characterized in that, In S2 and S6, the flame heating adjustment adopts the triangular heating method.

7. The post-weld adjustment and repair method for aluminum alloy brackets for rail vehicles according to claim 1, characterized in that, In S6, mechanical adjustment includes continuously pressurizing the aluminum alloy bracket to the target flatness using fixed tooling and a press.

8. The post-weld adjustment and repair method for aluminum alloy brackets for rail vehicles according to claim 1, characterized in that, Mechanical properties include yield strength, tensile strength, and elongation.

9. The post-weld adjustment and repair method for aluminum alloy brackets for rail vehicles according to claim 1, characterized in that, The preset flame heating temperature is 200~300℃.

10. The post-weld adjustment and repair method for aluminum alloy brackets for rail vehicles according to claim 1, characterized in that, In S6, during the flame heating adjustment process, temperature monitoring equipment is used to monitor the temperature of the heating point in real time.

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