CN109522610A

CN109522610A - A kind of weld metal zone mixing crystalline region finite element modeling method

Info

Publication number: CN109522610A
Application number: CN201811251317.7A
Authority: CN
Inventors: 刘小刚; 左永基; 郭海丁
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2018-10-25
Filing date: 2018-10-25
Publication date: 2019-03-26

Abstract

The invention provides a method of finishing finite element modeling for the mixed crystal area of the weld area. It adopts the improved Tyson polygonal method. It uses Matlab programming to combine Excel for coordinate integration. The center coordinate coordinates of the center of grains in the mixed crystal zone of the crystal tissue and the intersection of the crystal boundary, thereby establishing a geometric model of a hybrid crystal area. Export the center coordinates of the center of the grain and the intersection of the crystal world to generate text files for the finite element software ABAQUS read; use ABAQUS to run the written text file to read the well -written Python script, and establish a finite meta model for the mixed crystal area. The invention considers the non -uniform micro -organizations of welding joints, can establish a finite element model in different micro -zones in welded seams, and achieve different material parameters to different crystal areas to make the simulation results more reliable; mixed crystal area modeling adopts MATLAB program and python The combination of scripts saves the tedious ABAQUS interface operation, which can realize the welding connector cross -scale finite element simulation calculation.

Description

A kind of weld metal zone mixing crystalline region finite element modeling method

Technical field

The present invention relates to metal welding joints simulations and simulation technical field more particularly to a kind of weld metal zone mixing crystalline region to have Limit Meta Model method.

Background technique

In order to material mechanical property carry out micro-scale research, consider the microcosmic grain structure characteristic of material across ruler Degree simulation and emulation are more and more.Therefore in order to improve the feasibility and accuracy of simulation, foundation meets Fine Texture of Material spy The finite element model of property seems most important.

Common melting welding head weld metal zone microstructure is uneven, generally includes column crystal, thick equiax crystal and thin isometric The mix-crystals tissue such as crystalline substance.Traditional Thiessen polygon method is only used for establishing the physics mould of the equiaxed grain structure of single grain size Type is not suitable for establishing the weld metal zone finite element model comprising column crystal and different grain size equiax crystal.Existing electronic diffraction Figure method (EBSD) combines finite element software, although complicated microcosmic grain structure finite element image can be obtained, it exists as follows not Foot: it though 1, EBSD technology has been able to realize full-automatic acquisition microcell orientation information, can not achieve from microstructure modeling to splitting The Whole Process Simulation of line germinating, and subsequent processing is cumbersome.2, the equipment cost is higher, and the difficulty that popularity uses is larger.

Summary of the invention

Technical problem to be solved by the present invention lies in provide a kind of to calculate at low cost, versatile mixing crystalline region modeling Method.

The present invention is to solve above-mentioned technical problem by the following technical programs:

A kind of weld metal zone mixing crystalline region finite element modeling method, comprising the following steps:

Step 1: choose the actual welds area of certain size, obtain fusion area, heat affected area and the size in base material area and The mean grain size of column crystal mean grain size, heat affected area and the equiax crystal in base material area in fusion area, and calculated with this Column crystal quantity x in the fusion area and equiax crystal quantity z in equiax crystal quantity y and base material area in heat affected area；

Step 2: selected in MATLAB dimension scale and the identical region of actual welds area ratio as simulation weld metal zone, Weld metal zone, which will be simulated, according to actual ratio is transversely divided into simulation fusion area, simulated heat-affected zone and simulation base material area；

Step 3: generating x abscissa spacing at random in the simulation fusion area of step 2 respectively greater than ordinate spacing Coordinate points generate y, z coordinate points in simulated heat-affected zone and simulation base material area, by the coordinate of all coordinate points at random respectively Export；

Step 4: reading derived point coordinate in MATLAB, use Thiessen polygon method using coordinate as crystal grain center Coordinate obtains the physical model of mixing crystalline region, and crystal boundary intersecting point coordinate is exported；

Step 5: reading crystal boundary intersecting point coordinate in Finite Element Simulation Software, obtain the finite element model of mixing crystalline region.

Preferably, in step 1 in specific region equiax crystal quantity P calculation method are as follows:

Wherein, S is the area of corresponding region, and a is the grain size of equiax crystal in corresponding region.

Preferably, the abscissa that adjacent coordinates point in fusion area is simulated in step 3 is about three times of ordinate.

The advantages of weld metal zone mixing provided by the invention crystalline region finite element modeling method, is: can be used in establishing comprising more The seam organization finite element model of kind crystal, the material mechanical performance knitted for simulating mix-crystal district's groups realize across size simulation With emulation, and large-scale experiment equipment is not needed, save the cost, using the mixing crystalline region finite element model of resume of the present invention, to column Shape crystalline substance and equiax crystal impart different material parameters respectively, and analog result is relatively reliable.

Detailed description of the invention

Fig. 1 is the schematic diagram of weld metal zone mixing crystalline region finite element modeling method provided by the embodiment of the present invention；

Fig. 2 is electron beam welded joint metallographic structure figure provided by the embodiment of the present invention；

Fig. 3 is that physical model schematic diagram in crystalline region is mixed provided by the embodiment of the present invention；

Fig. 4 is the schematic diagram of mixing crystalline region finite element model provided by the embodiment of the present invention.

Specific embodiment

To make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with specific embodiment, and reference Attached drawing, the present invention is described in further detail.

As shown in Figure 1, a kind of weld metal zone mixing crystalline region finite element modeling method, comprising the following steps:

For titanium alloy electron beam welded joint metallographic structure as shown in Figure 2, the present embodiment is classified as symmetrical along y-axis Two models, and region of the side selection wherein having a size of 0.5mm × 0.5mm is studied, and along weld metal zone, laterally it is molten Area's range substantially 0~0.2mm is closed, the column crystal catercorner length in fusion area is about 0.2mm；Heat affected area range is substantially 0.2mm~0.4mm, the equiax crystal grain size in heat affected area is about 20 μm；Base material area range substantially 0.4mm~0.5mm, it is female Equiax crystal grain size in material area is about 40 μm.Then the column crystal quantity in fusion area is about x=6,

The calculation method of equiax crystal quantity P in specific region are as follows:

Specific in the present embodiment, the equiax crystal quantity y=250 of heat affected area, the equiax crystal quantity z=31 in base material area.

Step 3: generating x abscissa spacing at random in the simulation fusion area of step 2 respectively greater than ordinate spacing Coordinate points, in preferred embodiment, the abscissa of adjacent coordinates point is about three times of ordinate；It is female in simulated heat-affected zone and simulation It generates y, z coordinate points in material area at random respectively, the coordinate of all coordinate points is exported as into EXCEL file；

Step 4: reading derived point coordinate in MATLAB, use Thiessen polygon method to simulate the point coordinate of generation work The physical model of mixing crystalline region shown in Fig. 3 is obtained for crystal grain centre coordinate, and is in text file by the export of crystal boundary intersecting point coordinate；

Step 5: reading crystal boundary intersecting point coordinate in Finite Element Simulation Software, obtain the limited of mixing crystalline region shown in Fig. 4 Meta-model.

In preferred embodiment, finite element software selects Abaqus software, and running python script wherein keeps its identification brilliant The specific procedure of boundary's coordinate and the schematic diagram for generating finite element model, selection is conventional technical means, and details are not described herein again.

Particular embodiments described above has carried out further in detail the purpose of the present invention, technical scheme and beneficial effects It describes in detail bright, it should be understood that the above is only a specific embodiment of the present invention, is not intended to restrict the invention, not It is any modification that those of ordinary skill in the art make the present invention, equivalent under the premise of being detached from the spirit and principles in the present invention Replacement, improvement etc., should all fall within the protection scope that claims of the present invention determines.

Claims

1. A finite element modeling method for a mixed grain zone in a weld zone, characterized in that: comprising the following steps:

Step 1: Select the actual weld zone of a certain size to obtain the size of the fusion zone, heat-affected zone and base metal zone, as well as the average grain size of columnar grains in the fusion zone, and the equiaxed grain size in the heat-affected zone and base metal zone. The average grain size is used to calculate the number x of columnar grains in the fusion zone, the number y of equiaxed grains in the heat-affected zone, and the number z of equiaxed grains in the base metal region;

Step 2: In MATLAB, select the area with the same size ratio as the actual weld area as the simulated weld area, and divide the simulated weld area into simulated fusion zone, simulated heat-affected zone and simulated base metal zone in sequence according to the actual proportion ;

Step 3: Randomly generate x coordinate points in the simulated fusion zone in step 2 whose abscissa spacing is greater than the ordinate spacing, respectively randomly generate y and z coordinate points in the simulated heat-affected zone and simulated base metal zone, and place all Coordinate export of coordinate points;

Step 4: Read the derived point coordinates in MATLAB, use the Thiessen polygon method to use the point coordinates as the grain center coordinates to obtain the physical model of the mixed grain region, and export the grain boundary intersection coordinates;

Step 5: Read the coordinates of the grain boundary intersection points in the finite element simulation software to obtain the finite element model of the mixed grain region.

2. The finite element modeling method of a mixed grain area in a weld area according to claim 1, wherein the method for calculating the number of equiaxed grains P in a specific area in step 1 is:

Wherein, S is the area of the corresponding region, and a is the grain size of equiaxed crystals in the corresponding region.

3. A finite element modeling method for the mixed grain region in the weld zone according to claim 1, characterized in that: in step 3, the abscissa of the adjacent coordinate points of the simulated fusion zone is about three times the ordinate.