强制对流影响下Fe-C合金定向凝固微观组织的相场法研究  

Phase field method study on the directional solidification microstructure of a Fe–C alloy under forced convection

作　　者：曾红波 艾新港[1] 陈明[1] 王敏 蒋加旋 ZENG Hong-bo;AI Xin-gang;CHEN Ming;WANG Min;JIANG Jia-xuan(Key Laboratory of Metallurgy Engineering,University of Science and Technology Liaoning,Anshan 114051,China;State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]辽宁科技大学冶金工程辽宁省重点实验室,鞍山114051 [2]北京科技大学钢铁冶金新技术国家重点实验室,北京100083

出　　处：《工程科学学报》2023年第4期541-550,共10页Chinese Journal of Engineering

基　　金：“十四五”国家重点研发计划资助项目(2021YFB3702005);国家自然科学基金面上资助项目(51774179);辽宁省科技重大专项计划资助项目(2020JH1/10100001)。

摘　　要：定向凝固技术能够获得特定柱状晶结构,对于优化合金轴向力学性能具有非常显著的效果.本文采用耦合流场的相场模型模拟了定向凝固过程中枝晶的生长过程,研究了各向异性系数、界面能对定向凝固枝晶生长的影响以及强制对流作用下枝晶的生长行为.数值求解过程中,选用基于均匀网格的有限差分方法对控制方程进行离散,实现了格子中标记点算法(MAC)和相场离散计算方法的联合求解.处理微观速度场和压力场耦合时,采用MAC算法求解Navier-Stokes方程和压力Poisson方程,采用交错网格法处理复杂的自由界面.结果表明:随着各向异性系数的增大,枝晶尖端生长速度增大,曲率半径减小,枝晶根部溶质浓度逐渐降低;随着界面能的增大,枝晶尖端曲率半径增大,当界面能为最大(0.6 J·m^(-2))时,凝固呈现平界面的凝固方式向前推进;强迫对流对定向凝固枝晶生长方向影响较大,上游方向定向凝固枝晶粗大且生长速度更快,其现象随流速的增大而愈加明显.A specific columnar crystal structure is obtained using the directional solidification technique,which has a substantial effect on the optimization of the axial mechanical properties of the alloy.Additionally,the convection phenomenon in the melt changes the temperature field and concentration field at the front of the solid–liquid interface,affecting the shape of this interface.Thus,the influence on alloy properties cannot be ignored.Although the phase field method has more research on the microdendrite growth morphology,the results of coupling the flow field into the phase field and exploring the microdendrite morphology of directional solidification are still scarce.In this paper,the phase field model of a coupled flow field is used to simulate dendritic growth during directional solidification.The effects of the anisotropy coefficient and interfacial energy on the growth of directionally solidified dendrites and the growth behavior of dendrites under forced convection were studied.For the numerical solution procedure,a uniform grid of the finite difference method was used to discretize the governing equations.A combined solution of the MAC algorithm and a phase field discrete calculation was realized.When addressing the coupling of the microvelocity and pressure fields,the MAC algorithm was used to solve the Navier–Stokes equation and pressure Poisson equation,and the interlocked grid method was applied to handle the complex free interface.The results show that the growth rate of the dendrite tip increases,and the radius of curvature and the solute concentration at the root of the dendrite decrease with an increasing anisotropy coefficient.When the anisotropy coefficient is a maximum of 0.065,the wall of the dendrite tends to develop toward a secondary dendrite because of the influence of the anisotropy coefficient;with increasing interfacial energy,the radius of curvature of the dendrite tip increases.When the interfacial energy is a maximum of 0.6 J·m^(-2),the solidification shows a flat interface adva

关 键 词：Fe–C合金 定向凝固 相场法 对流 柱状枝晶 

分 类 号：TG244.3[金属学及工艺—铸造]