DD6高温合金定向凝固枝晶生长的数值模拟研究  

NUMERICAL SIMULATION OF DENDRITE GRAIN GROWTH OF DD6 SUPERALLOY DURING DIRECTIONAL SOLIDIFICATION PROCESS

作　　者：张航[1] 许庆彦[1] 史振学[2] 柳百成[1] 

机构地区：[1]清华大学材料学院先进成形制造教育部重点实验室,北京100084 [2]北京航空材料研究院先进高温结构材料重点实验室,北京100095

出　　处：《金属学报》2014年第3期345-354,共10页Acta Metallurgica Sinica

基　　金：国家重点基础研究发展计划项目2011CB706801;国家自然科学基金项目51171089;国家科技重大专项项目2011ZX04014-052和2012ZX04012-011资助~~

摘　　要：采用元胞自动机-有限差分(CA-FD)方法对DD6高温合金高速凝固法(HRS,high rapid solidification)定向凝固树枝晶三维生长过程进行模拟研究.建立温度场和溶质场耦合控制的枝晶生长模型,考虑抽拉速率和温度梯度等凝固条件的影响,同时考虑成分过冷、溶质分配系数、晶体择优取向等合金物性参数,模拟研究了枝晶形态的演化过程.模拟结果反映了高温合金树枝晶的竞争生长及形貌特征,描述了凝固过程的溶质分布变化及枝晶间距的动态调整过程.研究工作将模拟结果与实验结果进行了对比,两者吻合良好.模拟能够预测DD6高温合金HRS法定向凝固过程的枝晶形貌及一、二次枝晶间距动态调整过程.Modem aero and power industry needs high-performance gas turbine. Directional solidification （DS） columnar grain and single crystal （SX） blade as key parts of gas turbine serve in heavy stress and high temperature conditions. The DS and SX blade are mainly produced by high rapid solidification （HRS） method, and HRS is one of useful DS technology, which has a property that the heat dissipating ways are changing during the process and the temperature gradients will vary correspondingly. The dendrite grain arrays were the substructure of a DS or SX blade. The structure of the dendrite grain arrays influences the mechanical property of the final casting very much, but is seriously affected by the solidification parameters, such as temperature gradient. In this work, the dendrite grain growth of DD6 superalloy was studied based on cellular automaton-finite difference （CA-FD） model concerning the HRS method＇s macro solidification parameters. Mathematic models for dendrite grain growth controlled by temperature field and solute field were built to describe the competitive growth and morphology evolution of dendrite grains. Then the dendrite calculation model was coupled with the models of DS process calculation, and some HRS solidification parameters were included, such as withdrawal rate, pouring temperature, etc. The coupled models were used to predict the dendrite grain competitive growth of DD6 superalloy during the DS process. The variation of solute distribution and the dynamic adjustment of dendritic spacing during the process could be predicted by simulating calculation. The DS experiment was carried out with a cylinder sample, and dendrite grains＇ distribution in the transverse and longitude section was observed by OM and SEM. Then the simulated dendritic morphology was compared with that by experiment. The primary and secondary dendritic spacing by ex- periment and simulation were measured, and the compared results revealed that as the DS process going on the temperature gradient decreased

关 键 词：元胞自动机 DD6高温合金 定向凝固 枝晶生长 数值模拟 

分 类 号：TG132.3[一般工业技术—材料科学与工程]