Numerical simulation method for laser welding of molybdenum-rhenium alloy and stainless steel dissimilar materials

Abstract

The invention discloses a numerical simulation method for molybdenum-rhenium alloy and stainless steel dissimilar material laser welding, which comprises the following steps: preparing a molybdenum-rhenium alloy / stainless steel dissimilar material laser welding joint, and obtaining the shape of a joint molten pool; thermophysical property parameters and mechanical property parameters of the molybdenum-rhenium alloy base metal, the stainless steel base metal and the weld metal are obtained through experiments and calculation; establishing a thermal-structural calculation model of the molybdenum-rhenium alloy / stainless steel dissimilar material in the laser welding process; setting initial conditions, boundary conditions and a heat source model of the laser welding model; and a laser welding analysis task is established, and a temperature field and a stress field of the molybdenum-rhenium alloy / stainless steel dissimilar material in the laser welding process are solved. According to the method, the Vickers hardness of weld metal is converted into the yield strength, the weld component proportion is obtained through energy spectrum analysis, and the high-temperature performance parameters of the weld metal are calculated by means of calculation software. And high-precision calculation of the temperature field and the stress field in the laser welding process of the molybdenum-rhenium alloy and stainless steel dissimilar materials is achieved.

Description

Technical Field

[0001] The invention relates to a numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel, belonging to the technical field of laser welding and numerical simulation. Background Art

[0002] Molybdenum-rhenium alloy has the advantages of excellent high-temperature mechanical properties, low linear expansion coefficient and good thermal conductivity. It is used as a nuclear reactor structural material in advanced reactors such as fast neutron reactors and nuclear fusion reactors. The application scope of molybdenum-rhenium alloy is limited to a certain extent due to its high cost, while stainless steel is a cheap alloy with excellent comprehensive properties and is widely used in many fields. The composite structure of molybdenum-rhenium alloy and stainless steel will help increase design flexibility, reduce manufacturing difficulty and save material costs.

[0003] Compared with traditional welding methods, laser welding has the advantages of high energy density, small heat-affected zone, and small welding deformation, which is conducive to the welding of dissimilar metal materials. Since molybdenum-rhenium alloy and stainless steel have different physical and chemical properties, the linear expansion coefficient and thermal conductivity are quite different, and attention should be paid to the control of residual stress and welding deformation. With the help of numerical simulation methods, the temperature field distribution, joint residual stress and welding deformation characteristics of the laser welded joint of molybdenum-rhenium alloy and stainless steel can be theoretically analyzed, and the welding process can be optimized while saving experimental costs.

[0004] The metallurgical reactions in the weld zone of dissimilar materials are relatively complex, and it is usually difficult to accurately obtain the material constitutive model. In particular, for high-energy beam welding such as laser welding, the weld area is relatively narrow, and it is difficult to obtain the thermal physical properties and mechanical properties of the weld metal using traditional experimental methods. Summary of the invention

[0005] The purpose of the present invention is to provide a numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel, which solves the problems in the prior art that the performance parameters of the metal materials of the dissimilar material welds are difficult to accurately obtain, and the temperature field changes, post-weld residual stress and welding deformation during the molybdenum-rhenium alloy / stainless steel laser welding process are difficult to predict.

[0006] The technical solution adopted by the present invention is a numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel, comprising the following steps:

[0007] Step 1, preparing a laser-welded joint of molybdenum-rhenium alloy / stainless steel dissimilar materials, and obtaining the morphology of the joint molten pool;

[0008] Step 2: Obtain the thermophysical property parameters and mechanical property parameters of the molybdenum-rhenium alloy base material, the stainless steel base material and the weld metal through experiments and calculations;

[0009] Step 3, establishing a thermal-structural calculation model for the laser welding process of molybdenum-rhenium alloy / stainless steel dissimilar materials;

[0010] Step 4: Set the initial conditions, boundary conditions and heat source model of the laser welding model;

[0011] Step 5: Establish a laser welding analysis task and solve the temperature field and stress field of the laser welding process of molybdenum-rhenium alloy / stainless steel dissimilar materials.

[0012] Further, the step 2 is implemented according to the following steps:

[0013] Step 2-1, obtaining various thermophysical property parameters and mechanical property parameters of molybdenum-rhenium alloy parent material and stainless steel parent material;

[0014] Step 2-2: Perform a Vickers hardness test on the experimental joint to obtain the average microhardness of the weld metal, and use the empirical formula to convert the room temperature yield strength of the weld metal:

[0015]

[0016] Where σ y Represents yield strength, unit is MPa; H v is the Vickers hardness, the unit is HV; m is the Meyer hardness coefficient.

[0017] Step 2-3: Perform energy spectrum analysis on the weld area of ​​the joint obtained from the experiment to obtain the composition ratio of the weld metal, and calculate the high-temperature performance parameters of the weld metal with the help of JMatPro calculation software.

[0018] Further, the step 3 is implemented according to the following steps:

[0019] Step 3-1, use Hypermesh finite element pre-processing software to establish the joint finite element mesh model of the joint molten pool morphology, from the weld to the molybdenum-rhenium alloy parent material side and from the weld to the stainless steel parent material side, the mesh is from dense to sparse. The weld and the heat-affected zone use a dense mesh; the area away from the weld uses a relatively sparse mesh; the established joint finite element mesh model is imported into the MSC.Marc finite element software.

[0020] Step 3-2: In the MSC.Marc finite element software, the thermophysical property parameters and mechanical property parameters of the molybdenum-rhenium alloy base material, the stainless steel base material and the weld metal are assigned to the corresponding parts of the joint in the form of a table.

[0021] Further, step 4 is implemented according to the following steps:

[0022] Step 4-1. In the MSC.Marc finite element software, set the initial temperature of the molybdenum-rhenium alloy base material, stainless steel base material and weld metal to the ambient temperature in the initial conditions; set the temperature field boundary conditions, including convection and thermal radiation, and set the joint displacement constraint to limit the rigid displacement during the welding process;

[0023] Step 4-2: Based on the morphology of the joint molten pool obtained from the experiment in step 1, a combined heat source of double ellipsoids + cylinders is selected as a heat source model for simulating heat input during laser welding.

[0024] Further, step 5 is implemented according to the following steps:

[0025] Step 5-1, the welding analysis task is divided into two analysis conditions: welding and cooling. Set the convergence criterion and time step. After setting the output results, complete the establishment of the laser welding analysis task. The output results include unit type, selection of temperature, stress, and displacement.

[0026] Step 5-2: In the MSC.Marc finite element software, submit the welding analysis task and perform thermal analysis: solve the temperature field of the joint and obtain the temperature field of each node in the finite element mesh model of the joint; perform structural analysis: load the temperature field of each node into the thermal-structural calculation model structural analysis finite element model with thermal load, so as to solve the stress and displacement of the entire welding process; then enter the calculation result post-processor to obtain the temperature field and stress field of the laser welding process of molybdenum-rhenium alloy / stainless steel dissimilar materials.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] 1. The present invention obtains the thermal physical and mechanical performance parameters of the weld metal by combining experiments and calculations. The Vickers hardness of the weld metal is used to convert its yield strength, the energy spectrum analysis is used to obtain the weld component ratio, and the high-temperature performance parameters of the weld metal are calculated with the help of calculation software. The problem of the difficulty in accurately obtaining the performance parameters of the weld metal is solved, the accuracy of the material constitutive model is greatly improved, and the calculation accuracy of the temperature field and stress field in the laser welding process of molybdenum-rhenium alloy and stainless steel is improved;

[0029] 2. Through the numerical simulation method of laser welding of molybdenum-rhenium alloy / stainless steel dissimilar materials of the present invention, a thermal-structural calculation model is adopted, and a double ellipsoid + cylinder combined heat source is selected to simulate the heat input of laser welding. Through this numerical simulation method, the stress distribution and deformation of the molybdenum-rhenium alloy / stainless steel joint after welding can be obtained, the failure position of the joint during service can be predicted, and engineering applications can be guided. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide further understanding of the present invention and constitute a part of this application. The illustrative examples of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0031] Figure 1 This is the molten pool morphology of the laser welding joint of molybdenum-rhenium alloy / stainless steel dissimilar materials.

[0032] Figure 2 These are the microhardness test results of laser welding joints of molybdenum-rhenium alloy / stainless steel dissimilar materials.

[0033] Figure 3 This is the result of energy spectrum element analysis of laser welded joint of molybdenum-rhenium alloy / stainless steel dissimilar materials.

[0034] Figure 4 These are the metal material performance parameters of the weld of the molybdenum-rhenium alloy / stainless steel dissimilar material laser welding joint.

[0035] Figure 5 Finite element mesh model for numerical simulation of laser welding of molybdenum-rhenium alloy / stainless steel dissimilar materials.

[0036] Figure 6 This is a schematic diagram of the double ellipsoid + cylinder combined heat source model selected in the present invention.

[0037] Figure 7 It is a cloud diagram of the temperature field distribution of the joint during the welding process and a comparison diagram of the molten pool shape.

[0038] Figure 8 This is the residual stress distribution cloud diagram of the laser welded joint of molybdenum-rhenium alloy / stainless steel dissimilar materials after welding.

[0039] Fig. 9 This is the displacement distribution cloud diagram of the MoRhenium alloy / stainless steel dissimilar material laser welding joint in the thickness direction (Y) after welding after being magnified 10 times. DETAILED DESCRIPTION

[0040] The details of the present invention and its specific implementation methods are further described below in conjunction with the accompanying drawings.

[0041] In the present invention, "molybdenum-rhenium alloy / stainless steel" refers to two materials: molybdenum-rhenium alloy and stainless steel.

[0042] The present invention combines experiments and calculations, uses the Vickers hardness of the weld metal to convert its room temperature yield strength, obtains the component ratio of the weld metal by energy spectrum analysis, and calculates the high-temperature performance parameters of the weld metal with the help of calculation software, thereby greatly improving the accuracy of the material constitutive model and the calculation accuracy of the temperature field and stress field in the laser welding process of molybdenum-rhenium alloy and stainless steel dissimilar materials.

[0043] The present invention provides a numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel, which is specifically implemented according to the following steps:

[0044] Step 1, preparing a laser welding joint of molybdenum-rhenium alloy / stainless steel dissimilar materials, and obtaining the morphology of the joint molten pool;

[0045] The existing laser welding process is used to prepare the laser welded joint of molybdenum-rhenium alloy / stainless steel dissimilar materials. The metallographic specimens at the appropriate position of the joint are cut by electric spark wire cutting, and after polishing, they are observed by optical microscope to obtain the morphology of the joint molten pool.

[0046] Step 2: Obtain the performance parameters of the base material and weld metal through experiments and calculations;

[0047] Step 2-1, obtain the various thermophysical properties and mechanical properties of the molybdenum-rhenium alloy base material, stainless steel base material and weld metal, including density, thermal conductivity, specific heat, yield strength, elastic modulus, Poisson's ratio and linear expansion coefficient, and use existing methods to obtain the various thermophysical properties and mechanical properties.

[0048] Step 2-2, perform a Vickers hardness test on the joint to obtain the average microhardness of the weld metal, and convert the yield strength of the weld metal at room temperature using the following formula:

[0049]

[0050] Where σ y H stands for yield strength, which is the stress value at which the material begins to undergo plastic deformation, and its unit is megapascal (MPa); v is the Vickers hardness, the unit is Vickers hardness unit (HV); m is the Meyer hardness coefficient, different materials have different Meyer hardness coefficients.

[0051] Step 2-3, perform energy spectrum analysis on the joint weld area to obtain the composition ratio of the weld metal, and calculate the high-temperature performance parameters of the weld metal with the help of JMatPro calculation software. The high-temperature performance parameters of the weld metal include density, thermal conductivity, specific heat capacity, yield strength, elastic modulus, Poisson's ratio and thermal expansion coefficient.

[0052] Step 3, establishing a thermal-structural calculation model for the laser welding process of molybdenum-rhenium alloy / stainless steel dissimilar materials;

[0053] Step 3-1. Combined with the morphology of the joint molten pool described in the experiment, use Hypermesh finite element pre-processing software to establish a joint finite element mesh model. While ensuring the calculation accuracy, in order to improve the calculation efficiency, the mesh changes from dense to sparse from the weld to the molybdenum-rhenium alloy base material side and from the weld to the stainless steel base material side. During the welding process, the temperature gradient of the weld and the welding heat-affected zone changes greatly, and this part should use a dense mesh; while in the area away from the weld, the temperature gradient changes relatively little, and a relatively sparse mesh can be used. Export the established joint finite element mesh model in .inp file format, and import this file into the MSC.Marc finite element software;

[0054] Step 3-2: assign the thermophysical property parameters and mechanical property parameters of the molybdenum-rhenium alloy base material, the stainless steel base material and the weld metal to the corresponding parts of the joint in the form of a table.

[0055] Step 4: Set the initial conditions, boundary conditions and heat source model of the laser welding model;

[0056] Step 4-1. Set the initial temperature of the welding joint to the ambient temperature in the initial conditions; set the boundary conditions of the temperature field, including convection and thermal radiation. Set the displacement constraint of the joint to limit its rigid displacement during the welding process;

[0057] Step 4-2: According to the actual molten pool morphology, the upper molten pool of the laser welded joint of molybdenum-rhenium alloy / stainless steel is wider and the lower molten pool is narrower. The conventional single heat source cannot correctly simulate the laser welding heat input. Therefore, a welding heat source model combining a double ellipsoid heat source and a cylindrical heat source is selected. According to the experimental welding conditions, set the relevant heat source parameters, including welding path, laser power, welding thermal efficiency, welding speed, etc.

[0058] Step 5: Create an analysis task for laser welding and submit it for solution.

[0059] Step 5-1. The entire welding analysis task is divided into two analysis conditions: welding and cooling. Set the corresponding loads and time of the two conditions according to the actual welding process, set the convergence criteria and time step. Set the unit type, select the required output results such as temperature, stress, displacement, etc., and complete the establishment of the laser welding analysis task.

[0060] Step 5-2, submit the laser welding analysis task, first solve the temperature field of the joint and obtain the temperature field of each node. The calculation of the stress field adopts the thermal-elastic-plastic finite element calculation method, that is, the temperature field results of each node are loaded into the structural analysis finite element model as a thermal load, so as to solve the stress and displacement of the entire welding process. After the calculation is completed, enter the calculation result post-processor to obtain the temperature field and stress field of the laser welding process of molybdenum-rhenium alloy / stainless steel dissimilar materials.

[0061] Example

[0062] A numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel is described in combination with the attached drawings, taking the calculation of laser welding of dissimilar materials of Mo-5Re molybdenum-rhenium alloy and 316L stainless steel as an example.

[0063] The chemical composition (wt.%) of Mo-5Re molybdenum-rhenium alloy is as follows:

[0064]

[0065] The chemical composition (wt.%) of 316L stainless steel is as follows:

[0066]

[0067] Follow the steps below to implement it:

[0068] Step 1, preparing a Mo-5Re molybdenum-rhenium alloy / 316L stainless steel dissimilar material laser welding joint, and obtaining the morphology of the joint molten pool;

[0069] The Mo-5Re molybdenum-rhenium alloy / 316L stainless steel dissimilar material laser welded joint was prepared under the welding process of laser power of 2200W and welding speed of 2m / min. The Mo-5Re and 316L sides were corroded with corresponding corrosive reagents respectively, and then the microstructure was observed to obtain the following Figure 1 The molten pool morphology of the Mo-5Re molybdenum-rhenium alloy / 316L stainless steel laser welded joint is shown.

[0070] Step 2: Obtain the performance parameters of Mo-5Re molybdenum-rhenium alloy base material, 316L stainless steel base material and weld metal through experiments and calculations;

[0071] Step 2-1, with the help of tensile performance test experiments, linear expansion test experiments, thermal performance test experiments and related literature, obtain the temperature-dependent thermal physical performance parameters and mechanical performance parameters of Mo-5Re molybdenum-rhenium alloy and 316L stainless steel, including density, thermal conductivity, specific heat capacity, yield strength, elastic modulus, Poisson's ratio, and thermal expansion coefficient.

[0072] Step 2-2: Perform Vickers hardness test on the joint obtained in the experiment in this example. Take the weld as the center and measure the Vickers hardness values ​​at 20 points on both sides. The distance between each point is 0.1mm. The loading force is 200gf and the holding time is 10s. The microhardness test results of the laser welded joint of Mo-5Re molybdenum-rhenium alloy / 316L stainless steel are as follows: Figure 2 As shown, the average microhardness of the weld metal is 485HV. The room temperature yield strength of the weld metal is converted using the empirical formula:

[0073]

[0074] Where σ y H stands for yield strength, which is the stress value at which the material begins to undergo plastic deformation, and its unit is megapascal (MPa); v is the Vickers hardness, the unit is the Vickers hardness unit (HV); m is the Meyer hardness coefficient, different materials have different Meyer hardness coefficients. For this example, the Meyer hardness coefficient of the dissimilar material weld metal is the sum of the Meyer hardness coefficients of the two parent materials, which is 4.3, and the room temperature yield strength σy of the weld metal is 359MPa.

[0075] Step 2-3: Perform energy spectrum analysis on the weld area of ​​the joint obtained in the experiment. The analysis results are as follows: Figure 3 The mass ratio of each chemical component of the weld metal is imported into the JMatPro calculation software to calculate the high-temperature performance parameters of the weld metal, including density, thermal conductivity, specific heat capacity, yield strength, elastic modulus, Poisson's ratio, and thermal expansion coefficient. The calculation results are shown in Figure 4 shown.

[0076] Step 3, establishing a thermal-structural calculation model for the laser welding process of Mo-5Re molybdenum-rhenium alloy / 316L stainless steel dissimilar materials;

[0077] Step 3-1. Combined with the actual morphology of the molten pool obtained in the experiment in this example, the Hypermesh finite element pre-processing software is used to establish a finite element mesh model of the joint, where the dimensions of Mo-5Re molybdenum-rhenium alloy and 316L stainless steel are both 100mm×50mm×3mm. While ensuring the calculation accuracy, in order to improve the calculation efficiency, the mesh is from dense to sparse from the weld to the parent material side. During the welding process, the temperature gradient of the weld and the welding heat-affected zone changes greatly, so a dense mesh should be used in this part; while in the area away from the weld, the temperature gradient changes relatively little, so a relatively sparse mesh can be used. The resulting mesh model is as follows: Figure 5 As shown, the mesh unit type of the entire joint is an 8-node hexahedral unit, the total number of nodes is 111957, and the total number of units is 94400. The established joint mesh model is exported in .inp file format, and this file is imported into MSC.Marc finite element software;

[0078] Step 3-2: assign the obtained thermophysical property parameters and mechanical property parameters of the Mo-5Re molybdenum-rhenium alloy, 316L stainless steel and weld metal to the corresponding joint parts in the form of a table.

[0079] Step 4: Set the initial conditions, boundary conditions and heat source model of the laser welding model;

[0080] Step 4-1. Set the initial temperature of the weld joint to the ambient temperature of 25°C in the initial conditions; set the boundary conditions of the temperature field, taking convection and thermal radiation into consideration, load in the form of convection, and set the total heat transfer coefficient to 3.3×10 -5 According to the actual welding conditions, set the displacement constraints of the joint to limit its rigid displacement during the welding process. Figure 5 As shown, three-point constraints and vertical constraints are applied to the two base materials, Mo-5Re molybdenum-rhenium alloy and 316L stainless steel, away from the weld edge to prevent the joint from displacement during welding;

[0081] Step 4-2: Based on the actual molten pool morphology, this example establishes Figure 6 The combined heat source of double ellipsoid + cylinder is used to simulate the heat input during laser welding. The total heat input Q of the combined heat source is:

[0082] Q=ηP=n 1 Q+n 2 Q

[0083] n 1 +n 2 =1

[0084] Where η is the welding thermal efficiency, which is 0.9; P is the laser power; n 1 、n 2 are the distribution coefficients of the double ellipsoid and cylindrical heat sources, n 1 Take 0.4, n 2 Take 0.6.

[0085] Heat flux density (q 1 and q 2 ) distributions are defined as:

[0086]

[0087] In the formula, H 1 is the height of the double ellipsoid in the thickness direction of the plate; a 1 、a 2 , b, c are the ellipsoid shape parameters; f 1 、f 2 is the heat distribution function of the front and rear ellipsoids, f 1 +f 2 =2.

[0088] The heat flux density of the lower cylindrical heat source (q V ) is defined as:

[0089]

[0090] H=dH 1

[0091] In the formula, H is the height of the cylindrical heat source; d is the plate thickness; r 0 is the effective radius; r is the distance from a point in the arc coverage area to the center of the heat source.

[0092] The welding path in this example is a straight line path of ordinary butt joint, the laser power P used is 2200W, and the welding speed is 2m / min.

[0093] Step 5: Create an analysis task for laser welding and submit it for solution;

[0094] Step 5-1. The entire welding analysis task is divided into two analysis conditions: welding and cooling. The welding condition time is 3s and the cooling condition is 4000s. The convergence criterion method is residual stress or displacement, and the convergence tolerance is 0.1. Set the unit type to No. 7 thermal-structural analysis solid unit. After selecting the required output results such as temperature, stress, displacement, etc., complete the establishment of the analysis task.

[0095] Step 5-2: Submit the analysis task. First, solve the temperature field of the joint to obtain the temperature field of each node.

[0096] During welding, heat diffuses from the high-temperature part to the low-temperature part of the workpiece by heat conduction. The heat transfer phenomenon during welding can be calculated and analyzed by Fourier's law:

[0097]

[0098] Where: T is the temperature field to be determined (℃); λ is the thermal conductivity (J·mm -1 ·s -1 ℃ -1 );q v is the heating power of the internal heat source (J·mm -3 );ρ is density (g·mm -3 );c P is the constant pressure heat capacity (J·g -1 ℃ -1 );t is the heat transfer time (s).

[0099] The stress field is calculated using the thermal-elastic-plastic finite element calculation method, that is, the temperature field results of each node are loaded into the structural analysis finite element model as a thermal load, so as to solve the stress and displacement of the entire welding process.

[0100] After the calculation is completed, the calculation result post-processor is entered to obtain the temperature field and stress field of the laser welding process of molybdenum-rhenium alloy / stainless steel dissimilar materials.

[0101] from Figure 7(a) The temperature field cloud diagram during welding shows that with the movement of the welding heat source, the temperature field on both sides of the welded test plate is asymmetrically distributed. The isotherms on the Mo-5Re side are relatively sparse compared to those on the 316L side. Since the thermal conductivity of Mo-5Re is greater than that of 316L, the high temperature area on the Mo-5Re side is wider. Figure 7 (b) is a temperature distribution cloud diagram of the Mo-5Re / 316L weld cross section. The gray area in the figure is the area with a temperature higher than the melting point of Mo-5Re (2500℃), that is, the welding molten pool, and the white dotted line is the shape of the actual welding joint molten pool. It can be seen that the calculated and experimental molten pool shapes are basically consistent.

[0102] from Figure 8 It can be seen that the residual stress distribution on the left and right sides of the Mo-5Re molybdenum-rhenium alloy / 316L stainless steel laser welded joint is significantly different. Figure 8 (a)) and longitudinal ( Figure 8 (b) The residual stress is mainly concentrated near the fusion zone on the Mo-5Re molybdenum-rhenium alloy side, with a longitudinal residual peak stress of 490MPa and a transverse residual peak stress of 345MPa. The fusion zone on the Mo-5Re molybdenum-rhenium alloy side will be the weak point of the entire joint and should be paid special attention to during service.

[0103] The displacement distribution cloud diagram of the Mo-5Re molybdenum-rhenium alloy / 316L stainless steel laser welded joint in the plate thickness direction (Y) after being magnified 10 times is shown in the figure below. Fig. 9 As shown in the figure, the overall deformation of the Mo-5Re molybdenum-rhenium alloy / 316L stainless steel welded joint is relatively small. Due to the uneven distribution of transverse shrinkage in the thickness direction of the plate, the joint produces a certain angular deformation, and the maximum deformation is only 0.312 mm.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made to the present invention shall be included in the protection scope of the present invention.

Claims

1. A numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel, characterized in that: The steps include: Step 1, preparing a laser-welded joint of molybdenum-rhenium alloy / stainless steel dissimilar materials, and obtaining the morphology of the joint molten pool; Step 2: Obtain the thermophysical property parameters and mechanical property parameters of the molybdenum-rhenium alloy base material, the stainless steel base material and the weld metal through experiments and calculations; Step 3, establishing a thermal-structural calculation model for the laser welding process of molybdenum-rhenium alloy / stainless steel dissimilar materials; Step 4: Set the initial conditions, boundary conditions and heat source model of the laser welding model; Step 5: Establish a laser welding analysis task and solve the temperature field and stress field of the laser welding process of molybdenum-rhenium alloy / stainless steel dissimilar materials.

2. The numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel according to claim 1 is characterized in that: The step 2 is implemented according to the following steps: Step 2-1, obtaining various thermophysical property parameters and mechanical property parameters of molybdenum-rhenium alloy parent material and stainless steel parent material; Step 2-2: Perform a Vickers hardness test on the experimental joint to obtain the average microhardness of the weld metal, and use the empirical formula to convert the room temperature yield strength of the weld metal: Where σ y Represents yield strength, unit is MPa; H v is Vickers hardness, the unit is HV; m is the Meyer hardness coefficient; Step 2-3: Perform energy spectrum analysis on the weld area of ​​the joint obtained from the experiment to obtain the composition ratio of the weld metal, and calculate the high-temperature performance parameters of the weld metal with the help of JMatPro calculation software.

3. The numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel according to claim 1 is characterized in that: The step 3 is implemented according to the following steps: Step 3-1, use Hypermesh finite element pre-processing software to establish the joint finite element mesh model of the joint molten pool morphology, from the weld to the molybdenum-rhenium alloy parent material side and from the weld to the stainless steel parent material side, the mesh is from dense to sparse. The weld and the heat-affected zone use a dense mesh; the area away from the weld uses a relatively sparse mesh; import the established joint finite element mesh model into MSC.Marc finite element software; Step 3-2: In the MSC.Marc finite element software, the thermophysical property parameters and mechanical property parameters of the molybdenum-rhenium alloy base material, the stainless steel base material and the weld metal are assigned to the corresponding parts of the joint in the form of a table.

4. The numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel according to claim 1 is characterized in that: The step 4 is implemented according to the following steps: Step 4-1. In the MSC.Marc finite element software, set the initial temperature of the molybdenum-rhenium alloy base material, stainless steel base material and weld metal to the ambient temperature in the initial conditions; set the temperature field boundary conditions, including convection and thermal radiation, and set the joint displacement constraint to limit the rigid displacement during the welding process; Step 4-2: Based on the morphology of the joint molten pool obtained from the experiment in step 1, a combined heat source of double ellipsoids + cylinders is selected as a heat source model for simulating heat input during laser welding.

5. The numerical simulation method for laser welding of dissimilar materials of molybdenum-rhenium alloy and stainless steel according to claim 1 is characterized in that: The step 5 is implemented according to the following steps: Step 5-1, the welding analysis task is divided into two analysis conditions: welding and cooling. The convergence criterion and time step are set. After setting the output results, the establishment of the laser welding analysis task is completed. The output results include the unit type, and the selection of temperature, stress, and displacement; Step 5-2: In the MSC.Marc finite element software, submit the welding analysis task and perform thermal analysis: solve the temperature field of the joint and obtain the temperature field of each node in the finite element mesh model of the joint; perform structural analysis: solve the stress and displacement of the entire welding process; then enter the calculation result post-processor to obtain the temperature field and stress field of the laser welding process of molybdenum-rhenium alloy / stainless steel dissimilar materials.

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