A method and system for establishing a heat source model of a dissimilar metal friction stir welding process

Abstract

This invention relates to the field of welding technology and provides a method and system for establishing a heat source model for the friction stir welding process of dissimilar metals. The method includes: acquiring the stirring head torque during the friction stir welding process of the dissimilar metals and calculating the proportion of heat generation capacity of each metal; acquiring the stirring head torque during the friction stir welding process of the dissimilar metals and multiplying it by the stirring head rotation speed to obtain the total welding heat input; multiplying the proportion of heat generation capacity of each metal by the total welding heat input to obtain the heat distributed to each metal side; and establishing a heat source model for the friction stir welding process of dissimilar metals based on the heat distributed to each metal side, assuming that the heat flux density of each metal side is proportional to the radius. This method does not involve parameters such as downforce and thermal efficiency related to the contact state of the stirring head-workpiece interface, and eliminates the need for trial and error to obtain reasonable temperature field distribution and thermal cycle curves, significantly saving manpower, material resources, and financial resources.

Description

Technical Field

[0001] This invention belongs to the field of welding technology, and in particular relates to a method and system for establishing a heat source model for the friction stir welding process of dissimilar metals. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Friction stir welding is a solid-state welding method invented in 1991. Its main advantages are: low heat input, high weld quality, small weld deformation, and environmentally friendly welding process. It is particularly suitable for welding lightweight non-ferrous metals such as aluminum alloys and has great application potential in aerospace, rail transportation, and new energy vehicles.

[0004] In recent years, friction stir welding has also been used to weld dissimilar metals, such as aluminum / magnesium, aluminum / copper, aluminum / steel, aluminum / titanium, magnesium / steel, magnesium / copper, and steel / titanium, all of which have yielded relatively high-quality weld joints. However, research on the temperature distribution and evolution during the friction stir welding process of dissimilar metals is currently lacking. It is well known that the thermophysical phenomena such as heat input, temperature distribution, and temperature evolution during the welding process of dissimilar metals are crucial for analyzing the microstructure evolution, intermetallic compounds, and mechanical properties of the weld. Therefore, there is an urgent need to propose a method for establishing a heat source model for the friction stir welding process of dissimilar metals. This method can obtain information on the heat distribution, total heat input, temperature distribution, and evolution during the welding process, providing fundamental data for the analysis and control of weld microstructure and properties.

[0005] The conventional heat source model for friction stir welding is established using frictional heat generation formulas, and researchers have published numerous results on this topic. However, the problem with this conventional method is that an accurate frictional heat generation formula requires knowledge of many parameters. Besides welding parameters (stirring head rotation speed, welding speed, downward pressure, etc.), factors such as thermal efficiency, the relative slip ratio between the stirring head and the workpiece material, and the coefficient of friction are all unknown. Therefore, a trial-and-error approach is necessary to obtain relatively reasonable data. This is especially true for friction stir welding of dissimilar metals, which involves frictional heat generation between two different materials and the stirring head, resulting in even more unknown parameters. Applying conventional frictional heat generation formulas to establish the heat source model is clearly impractical. Summary of the Invention

[0006] To address the technical problems mentioned above, this invention provides a method and system for establishing a heat source model for the friction stir welding process of dissimilar metals. The heat source model can be established by conducting only three experiments and measuring the welding torque in each experiment. It does not involve parameters related to the contact state of the stirring head-workpiece interface, such as the downward pressure, thermal efficiency, relative slip ratio between the stirring head and the workpiece material, and friction coefficient. It eliminates the need for trial and error to obtain reasonable temperature field distribution and thermal cycle curves, thus significantly saving manpower, material resources, and financial resources.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of this invention provides a method for establishing a heat source model for a heterogeneous metal friction stir welding process, comprising:

[0009] The stirring head torque during the friction stir welding process of dissimilar metals was obtained, and the proportion of heat generation capacity of each metal was calculated.

[0010] The torque of the stirring head during the friction stir welding process of dissimilar metals is obtained and multiplied by the stirring head rotation speed to obtain the total welding heat input;

[0011] The heat generation capacity of each metal is multiplied by the total welding heat input to obtain the heat distribution on each metal side.

[0012] Based on the heat distributed on each metal side, and assuming that the heat flux density on each metal side is proportional to the radius, a heat source model for the heterogeneous metal friction stir welding process is established.

[0013] Furthermore, the stirring head torque during the friction stir welding process of each metal is the average value of the stirring head torque in multiple friction stir welding experiments.

[0014] Furthermore, the stirring head torque during the heterogeneous metal friction stir welding process is the average value of the stirring head torque in multiple heterogeneous metal friction stir welding experiments.

[0015] Furthermore, the proportion of the heat generation capacity of each metal is as follows:

[0016]

[0017] in, M i Metal i The proportion of heat production capacity, T i Indicates metal i The torque of the stirring head during friction stir welding.

[0018] Furthermore, the welding parameters and stirring head used in the friction stir welding process of the dissimilar metals are the same as those used in the friction stir welding process of the dissimilar metals.

[0019] Furthermore, the proportion of the heat generation capacity of each metal reflects the relative magnitudes of the downward pressure, thermal efficiency, relative slip ratio between the stirring head and the workpiece material, and coefficient of friction related to heat generation during the welding process of dissimilar metals.

[0020] A second aspect of the present invention provides a method for predicting the temperature during friction stir welding of dissimilar metals, based on the heat source model establishment method for friction stir welding of dissimilar metals described in the first aspect, comprising:

[0021] Based on the heat source model of the heterogeneous metal friction stir welding process, numerical simulation was performed to predict the temperature field distribution and the thermal cycle curves of key points.

[0022] A third aspect of the present invention provides a system for establishing a heat source model for a heterogeneous metal friction stir welding process, comprising:

[0023] The first calculation module is configured to: obtain the stirring head torque during the friction stir welding process of dissimilar metals, and calculate the proportion of heat generation capacity of each metal;

[0024] The second calculation module is configured to: obtain the stirring head torque during the friction stir welding process of dissimilar metals, and multiply it with the stirring head rotation speed to obtain the total welding heat input;

[0025] The third calculation module is configured to multiply the proportion of heat generation capacity of each metal by the total welding heat input to obtain the heat allocated to each metal side.

[0026] The model building module is configured to: establish a heat source model for the heterogeneous metal friction stir welding process based on the heat distributed on each metal side, assuming that the heat flux density on each metal side is proportional to the radius.

[0027] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the method for establishing a heat source model for a heterogeneous metal friction stir welding process as described above.

[0028] A fifth aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in the method for establishing a heat source model for a heterogeneous metal friction stir welding process as described above.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] This invention requires only three experiments (metal I welding experiment, metal II welding experiment, and metal I / metal II welding experiment) and measuring the welding process torque in each experiment to establish a heat source model. It does not involve parameters related to the contact state of the stirring head-workpiece interface, such as the downward pressure, thermal efficiency, relative slip ratio between the stirring head and workpiece materials, and friction coefficient. It eliminates the need for trial and error to obtain reasonable temperature field distribution and thermal cycle curves, thus significantly saving manpower, material resources, and financial resources.

[0031] This invention obtains the torque values ​​of two different metals I and II during friction stir welding, and uses this to obtain the ratio of their heat generation capabilities. This ratio actually reflects the relative magnitudes of many parameters related to heat generation during the welding process, such as the downward pressure, thermal efficiency, relative slip ratio between the stirring head and the workpiece material, and friction coefficient. It is very important for determining the heat generation ratio of the metal I side and the metal II side during dissimilar metal friction stir welding.

[0032] This invention measures the torque during dissimilar metal welding and combines it with the heat generation ratio of the two different metals to obtain the heat distributed on metal side I and metal side II during dissimilar metal welding. This allows for the determination of the heat flux density at various locations on the stirring head-workpiece contact interface, establishing a heat source model. The entire process is simple and fast, and reasonably considers the differences in heat distribution on the stirring head-workpiece interface caused by the different thermal properties of the two metals. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0034] Figure 1 This is a flowchart of a method for establishing a heat source model for a heterogeneous metal friction stir welding process according to Embodiment 1 of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] Example 1

[0038] To achieve accurate prediction of thermal response parameters in the friction stir welding process of dissimilar metals, this embodiment provides a method for establishing a heat source model for the friction stir welding process of dissimilar metals.

[0039] This embodiment provides a method for establishing a heat source model for the friction stir welding process of dissimilar metals. The overall idea is as follows: First, friction stir welding is performed using metal I and metal II respectively, and the welding torque during welding is measured to obtain the ratio of welding torque. This ratio reflects the differences in the relative slip ratio and friction coefficient of the two materials during the contact and friction process with the stirring head, and is also the ratio of their heat generation capacity during the friction heat generation process. Second, the welding torque during the friction stir welding of dissimilar metals I / II is measured, the total welding heat input is calculated, and multiplied by the heat generation capacity ratio of metal I and metal II respectively to obtain the heat distributed on the metal I side and the metal II side during the welding process. Finally, using the heat on the metal I side and the metal II side, assuming that the heat flux density is proportional to the radius of the distance from the center of the stirring head, a heat source model for the friction stir welding process of dissimilar metals is established.

[0040] This embodiment provides a method for establishing a heat source model for the friction stir welding process of dissimilar metals, such as... Figure 1 As shown, it includes the following steps:

[0041] Step 1: Using the same welding parameters and stirring head as when welding dissimilar metals, friction stir welding experiments were conducted on metal I and metal II respectively. During the experiments, the stirring head torque was recorded after reaching the quasi-steady state (i.e., the measured value of the stirring head torque reached a stable value) when welding the two metals, and the average value was taken to obtain the result. T 1 and T 2.

[0042] Step 2: Calculate the ratio M 1= T 1 / ( T 1+ T 2), M 2= T 2 / ( T 1+ T 2) The ratio of the two is the ratio of the heat-generating capacity of metal I and metal II. M 1 and M 2 represents the proportion of heat generation capacity of metal I and metal II, respectively.

[0043] Step 3: Conduct friction stir welding experiments on dissimilar metals I and II, record the stirring head torque after reaching the quasi-steady state of welding, and take the average value to obtain the result. T D Multiplying this by the stirring head rotation speed Ω yields the total welding heat input Ω. T D .

[0044] Step 4: The proportion of heat generation capacity of metal I and metal IIM 1 and M 2 Total heat input (Ω) during welding with dissimilar metals T D Multiplying these yields the heat distributed between metal I and metal II during the dissimilar metal welding process. M 1Ω T D and M 2Ω T D .

[0045] Step 5: Based on the heat distribution on each metal side, assume the heat flux density on metal side I and metal side II at the interface between the stirring head and the workpiece. q 1 and q 2 are respectively the radius of this point from the center of the stirring head. r Proportional, that is, for the metal I side, q 1= A 1· r For the metal II side, q 2= A 2. r Therefore, the heat flux density values ​​at various locations on the contact interface are obtained, and a heat source model for the heterogeneous metal friction stir welding process is established, thus obtaining the expression for the heat flux density at different locations on the stirring head-workpiece contact interface.

[0046] The total heat distributed on side I of the metal is equal to the heat flux density on this side. q 1 along radius r The integrals on the surface are:

[0047]

[0048] Therefore, the expression for the heat flux density on the metal I side is:

[0049]

[0050] The total heat distributed on the metal II side is equal to the heat flux density on this side. q 2 along radius r The integrals on the surface are:

[0051]

[0052] Therefore, the expression for the heat flux density on the metal II side is:

[0053]

[0054] In the above formula, R s The shoulder radius, A 1 and A 2 represents heat flux densityq 1 and q 2 and radius r The ratio of .

[0055] Step 6: Input the above heat source model into the finite element software for numerical simulation calculation, obtain the temperature field distribution and the thermal cycle curve of key points, and compare it with the experimental results.

[0056] Steps 1 and 2 in the heat source model establishment method proposed in this invention aim to obtain the torque values ​​of two different metals I and II during friction stir welding, and thereby obtain the ratio of their heat generation capabilities. This ratio actually reflects the relative magnitudes of many parameters related to heat generation during the welding process, such as the downward pressure, thermal efficiency, relative slip ratio between the stirring head and the workpiece material, and friction coefficient. It is very important for determining the heat generation ratio of the metal I side and the metal II side during dissimilar metal friction stir welding.

[0057] Steps 3, 4, and 5 of the heat source model establishment method proposed in this invention measure the torque during dissimilar metal welding and combine it with the heat generation ratio of the two different metals to obtain the heat distributed on metal I side and metal II side during dissimilar metal welding. This allows for the determination of the heat flux density at various locations on the stirring head-workpiece contact interface, thus establishing a heat source model. The entire process is simple and fast, and reasonably considers the differences in heat distribution on the stirring head-workpiece interface caused by the different thermal properties of the two metals.

[0058] In summary, the method for establishing a heat source model for heterogeneous metal friction stir welding proposed in this invention only requires three experiments (metal I welding experiment, metal II welding experiment, and metal I / metal II welding experiment) and measuring the welding process torque respectively to establish the heat source model. It does not involve parameters such as the downward pressure, thermal efficiency, relative slip ratio between the stirring head and the workpiece material, and friction coefficient related to the contact state of the stirring head-workpiece interface. It does not require the use of trial and error to obtain reasonable temperature field distribution and thermal cycle curve results, which greatly saves manpower, material resources and financial resources.

[0059] The following is a typical example:

[0060] Friction stir welding of 2mm thick aluminum / copper dissimilar metals was performed using an H13 stirring head with a shoulder diameter of 20 mm, a stirring pin diameter and length of 4 mm and 1.8 mm, respectively. The welding parameters were: stirring head rotation speed of 700 rpm, welding speed of 70 mm / min, and stirring head deflection of 0.15 mm. The temperature distribution and thermal cycling curve of the welding process were predicted using the method proposed in this invention, and the results were compared with experimental results.

[0061] Step 1: Friction stir welding was performed on 2 mm thick aluminum plates (metal I) and copper plates (metal II) respectively. The average torque at the quasi-steady state of the welding was measured as follows: T 1 = 8.2 N·m and T 2 = 30.3 N·m.

[0062] Step 2: Calculate and obtain M 1 = 0.213, M 2 = 0.787.

[0063] Step 3: Perform friction stir welding on a 2 mm thick aluminum / copper dissimilar metal. The average torque at the quasi-steady state of the weld was measured to be... T D =19.8 N·m, multiplied by the rotational speed Ω=700 rpm=73.304 rad / s, we get the total heat input Ω of the welding process. T D =1451.4 W.

[0064] Step 4: Calculate the heat distribution on the aluminum and copper sides during the friction stir welding process of dissimilar metals. M 1Ω T D =309.2 W, copper side M 2Ω T D =1142.2 W.

[0065] Step 5: Assuming that the heat flux density is proportional to the radius, the heat flux density values ​​at various positions on the aluminum and copper sides of the stirring head-workpiece interface are obtained by integral derivation, and a heat source model is established.

[0066] Step 6: Input the heat source model into the finite element software ABAQUS for numerical simulation calculation to obtain the temperature field distribution contour map. The calculation results show that at 15 mm from the weld centerline, the highest temperatures on the aluminum side and copper side are 206 ℃ and 251 ℃, respectively, while experimental results show that the highest temperatures on the aluminum side and copper side at the same location are 203 ℃ and 252 ℃, respectively. The calculation results agree well with the experimental results.

[0067] In summary, the superiority of the method proposed in this invention has been demonstrated.

[0068] Example 2

[0069] This embodiment provides a method for predicting the temperature during the friction stir welding process of dissimilar metals, based on the heat source model establishment method for the friction stir welding process of dissimilar metals described in Embodiment 1, including:

[0070] Based on the heat source model of the heterogeneous metal friction stir welding process, numerical simulation was performed to predict the temperature field distribution and the thermal cycle curves of key points.

[0071] Example 3

[0072] This embodiment provides a system for establishing a heat source model for the friction stir welding process of dissimilar metals, which specifically includes:

[0073] The first calculation module is configured to: obtain the stirring head torque during the friction stir welding process of dissimilar metals, and calculate the proportion of heat generation capacity of each metal;

[0074] The second calculation module is configured to: obtain the stirring head torque during the friction stir welding process of dissimilar metals, and multiply it with the stirring head rotation speed to obtain the total welding heat input;

[0075] The third calculation module is configured to multiply the proportion of heat generation capacity of each metal by the total welding heat input to obtain the heat allocated to each metal side.

[0076] The model building module is configured to: establish a heat source model for the heterogeneous metal friction stir welding process based on the heat distributed on each metal side, assuming that the heat flux density on each metal side is proportional to the radius.

[0077] It should be noted that each module in this embodiment corresponds one-to-one with each step in Embodiment 1, and their specific implementation processes are the same, so they will not be repeated here.

[0078] Example 4

[0079] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the method for establishing a heat source model for a heterogeneous metal friction stir welding process as described in Embodiment 1 above.

[0080] Example 5

[0081] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the method for establishing a heat source model for a heterogeneous metal friction stir welding process as described in Embodiment 1 above.

[0082] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0083] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

Claims

1. A method for establishing a heat source model for the friction stir welding process of dissimilar metals, characterized in that, include: The stirring head torque during the friction stir welding process of dissimilar metals was obtained, and the proportion of heat generation capacity of each metal was calculated. The torque of the stirring head during the friction stir welding process of dissimilar metals is obtained and multiplied by the stirring head rotation speed to obtain the total welding heat input; The heat generation capacity of each metal is multiplied by the total welding heat input to obtain the heat distribution on each metal side. Based on the heat distributed on each metal side, and assuming that the heat flux density on each metal side is proportional to the radius, a heat source model for the heterogeneous metal friction stir welding process is established.

2. The method of claim 1, wherein the method further comprises: The stirring head torque during the friction stir welding process of each metal is the average value of the stirring head torque in multiple friction stir welding experiments.

3. The method of claim 1, wherein the method further comprises: The stirring head torque during the heterogeneous metal friction stir welding process is the average value of the stirring head torque in multiple heterogeneous metal friction stir welding experiments.

4. The method of claim 1, wherein the method further comprises: The percentage of heat generation capacity of each metal is as follows: in, M i Metal i The proportion of heat production capacity, T i Indicates metal i The torque of the stirring head during friction stir welding.

5. The method of claim 1, wherein the method further comprises: The welding parameters and stirring head used in the friction stir welding process of the dissimilar metals are the same as those used in the friction stir welding process of the dissimilar metals.

6. The method of claim 1, wherein, The proportion of the heat generation capacity of each metal reflects the relative magnitude of the downward pressure, thermal efficiency, relative slip ratio between the stirring head and the workpiece material, and friction coefficient related to heat generation during the welding process of dissimilar metals.

7. A method for predicting the temperature during friction stir welding of dissimilar metals, based on a method for establishing a heat source model for friction stir welding of dissimilar metals as described in any one of claims 1-6, characterized in that, include: Based on the heat source model of the heterogeneous metal friction stir welding process, numerical simulation was performed to predict the temperature field distribution and the thermal cycle curves of key points.

8. A system for establishing a heat source model for a heterogeneous metal friction stir welding process, the system comprising: include: The first calculation module is configured to: obtain the stirring head torque during the friction stir welding process of dissimilar metals, and calculate the proportion of heat generation capacity of each metal; The second calculation module is configured to: obtain the stirring head torque during the friction stir welding process of dissimilar metals, and multiply it with the stirring head rotation speed to obtain the total welding heat input; The third calculation module is configured to multiply the proportion of heat generation capacity of each metal by the total welding heat input to obtain the heat allocated to each metal side. The model building module is configured to: establish a heat source model for the heterogeneous metal friction stir welding process based on the heat distributed on each metal side, assuming that the heat flux density on each metal side is proportional to the radius.

9. A computer readable storage medium having stored thereon a computer program, characterized in that, When the program is executed by the processor, it implements the steps in the method for establishing a heat source model for a heterogeneous metal friction stir welding process as described in any one of claims 1-6.

10. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the method for establishing a heat source model for a heterogeneous metal friction stir welding process as described in any one of claims 1-6.

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