A Method of Numerical Simulation of Casting Macrosegregation

A numerical simulation and macro segregation technology, applied in electrical digital data processing, special data processing applications, instruments, etc., can solve the problems of long calculation time and low precision of macro segregation

Inactive Publication Date: 2011-12-21
HARBIN UNIV OF SCI & TECH
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  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for numerical simulation of macro-segregation of castings to solve the problems of long calculation time and low precision of macro-segregation and unsuitability for predicting the formation of macro-segregation in castings with large size or complex shape

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  • A Method of Numerical Simulation of Casting Macrosegregation
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  • A Method of Numerical Simulation of Casting Macrosegregation

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specific Embodiment approach 1

[0056] Specific embodiment one: the method for numerical simulation of casting macrosegregation of the present embodiment, described method comprises the following steps:

[0057] Step 1, subdividing the dendrite growth calculation domain into micro-scale grids, and dividing it into n×m grids; the calculation domain is a rectangle, and the area of ​​the calculation domain (X meters × Y meters) and the number of grid divisions Choose to meet Grid area Δy·Δx≤25×10 -12 (rice) 2 ;

[0058] Step 2. Determine the maximum nucleation density NU max and the maximum nucleation undercooling ΔT max ;

[0059] Step 2 (1), under a solidification time t, based on the Gaussian continuous nucleation distribution principle, the hyperbolic cosine function is used to calculate the number of nucleation particles MU(t) in the microscopic scale calculation domain:

[0060] ΔT ( t ) = T l ...

specific Embodiment approach 2

[0105] Specific embodiment two: the calculation of the mushy zone permeability model described in the step eight of the present embodiment adopts two methods, and a kind of calculation method is based on the maximum nucleation density 10 9 / m 3 For the corresponding solid phase fraction-average dendrite solid phase characteristic diameter curve, a calculation method is based on the classical mixing theory, and a set of data closest to the experiment is selected for the calculated results. Other components and connections are the same as those in the first embodiment.

specific Embodiment approach 3

[0106] Specific embodiment three: in the step 4 of the present embodiment, set (Bn×Bm) grids as columnar crystal growth grids, and (An×Am-Bn×Bm) grids as equiaxed crystal growth grids; step Determine the data file Nuclei.dat corresponding to the reading of the casting in the fifth step; in the ninth step, the maximum nucleation density of columnar crystals LNU max and equiaxed maximum nucleation density ENU max , the permeability calculation of the mushy zone in the crystal growth zone is based on the maximum nucleation density LNU max The corresponding solid phase fraction-average dendrite solid phase characteristic diameter curve, the permeability calculation of the mushy zone in the equiaxed crystal growth zone is based on the maximum nucleation density ENU max The corresponding solid phase fraction-average dendrite solid phase characteristic diameter curve, this step is to simulate the formation of macrosegregation when the microstructure evolves during solidification, th...

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Abstract

The invention relates to a method for macrosegregation numerical simulation of a casting, aiming at solving the problems of long computation time, low precision and unsuitability for predication of castings with large size or complex shapes in the traditional macrosegregation. The method comprises the following steps of: performing mesh generation on a selected dendritic crystal growth microcosmic computation field; computing dendritic crystal growth shapes during alloy solidification under different maximum nucleation densities from a microcosmic scale, and outputting a solid phase fraction-average dendritic crystal solid phase feature diameter curve; performing macro-scale mesh generation on the casting; computing a mass, momentum, energy and composition conservation equation from a macrocosmic scale; computing a solid phase fraction by using a Newton downhill method; and computing a pasty zone permeability model from a macrocosmic scale by adopting a linear interpolation technologybased on the solid phase fraction-average dendritic crystal solid phase feature diameter curve under a given nucleation density. The method disclosed by the invention is suitable for macrosegregationnumerical simulation in sand casting and metal mold casting of various sizes and complex shapes.

Description

technical field [0001] The invention relates to a method for simulating macro-segregation in castings. Background technique [0002] The macro-segregation of castings mainly refers to the inhomogeneous chemical composition inside the casting, and the resulting inhomogeneity in the structure and performance of the casting. This inhomogeneity reduces the impact toughness and plasticity of the casting, increases the tendency of hot cracking, and sometimes makes the casting difficult to process or has a high casting rejection rate. For castings working in air or in corrosive media, macro-segregation parts are more susceptible to corrosion damage. Therefore, the computer simulation method is used to accurately predict the formation of macro-segregation in castings, and provide parameter selection and theoretical guidance for scientifically determining the casting process and finding technological measures to reduce the degree of macro-segregation. [0003] The solidification of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/50
Inventor 刘东戎
Owner HARBIN UNIV OF SCI & TECH
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