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Cellular Automaton Approach on Micro Morphology Generation with Nucleation-Grain Growth Kinetics in Solidification Process

凝固过程中形核-晶粒生长动力学微观形貌生成的元胞自动机方法

基本信息

批准号：
09650104
负责人：
TSUTA Toshio
金额：
$ 2.05万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

In this paper, an approach to the mathematical modeling of grain structure formation in micro solidification processes is proposed at first. Based on the kinetics of heterogeneous nucleation and of grain growth, the dendrite and the equiaxial micro-morphologies are automatically generated using the Monte-Carlo simulation. Nucleations occurring in the vicinities of vessel wall, vessel corner as well as in the liquid metal are simulated by two steps of calculations using macro- and micro-discretized cell configurations. The growth kinetics of the dendrite tip and the preferential growth directions of cubic metals are taken into account.The computer system has been developed, and the solidification process and the grow of the associated micro-morphology are solved by varing such parameters as the constitutive undercooling due to the local solute increase in frontal of the solid-liquid interface, compatibility for interference with the adjacent dendritic structure, and macroscopic heat transfer with latent heat discharge.The grow of morphology in Al-Si binary alloy in 2D region is calculated for numerous conditions of solidification processes and the applicability of the method is clarified.In the next place it is examine hole the heterogeneous dendritic morphology changes to the equiaxial one due to the fluid dynamic force induced by electromagnetic excitation.The micro and macro solidification process with or without magnetic stirrer have been solved, and the results are compared with morphologies obtained from actual continuous casting apparatus, such as twin roll casting and horizontal casting and the applicabilities of the method developed arc clarified.

本文首先提出了微观凝固过程晶粒组织形成的数学模型。基于非均匀形核和晶粒生长动力学，采用蒙特-卡罗模拟方法自动生成枝晶和等轴组织形貌。采用宏观和微观离散单元结构，通过两步计算模拟了容器壁、容器角部附近以及液态金属中的形核过程。本文考虑了枝晶尖端的生长动力学和立方金属的择优生长方向，编制了计算机系统，通过改变固液界面前沿局部溶质增加引起的本构过冷度、与相邻枝晶组织干涉的相容性、宏观传热与潜热放电。本文对多种凝固过程条件下的二维Si二元合金进行了计算，阐明了该方法的适用性，并考察了电磁激励引起的流体动力力使异质枝晶形态向等轴枝晶形态转变的情况，分析了微观和宏观上的变化规律。并与双辊铸轧和水平铸轧等实际连铸设备上获得的铸坯形貌进行了比较，阐明了该方法的适用性。