(清华大学 机械工程系 先进成形制造教育部重点实验室，北京 100084)
摘 要: 建立镍基高温合金熔模铸件凝固过程的宏/微观多尺度数理模型，基于射线追踪法处理热辐射，模拟铸件的温度分布，采用三维宏/微观网格嵌套和改进的CA方法模拟微观组织，并依据微观组织模拟结果处理结晶潜热，实现微观与宏观模拟的耦合。依据等效液面下降法、Niyama判据和Darcy定律预测铸件的宏观缩孔、宏观缩松和微观缩松缺陷分布位置，并浇注实际的高温合金叶轮铸件。结果表明：模拟获得的冷却曲线、微观组织及缺陷位置与实验结果吻合良好，模拟结果能够准确预测铸件中多种缺陷的分布。
关键字: 高温合金；熔模铸造；多尺度模拟；宏观缩孔缩松；微观缩松；微观组织
Ni-based superalloy investment castings
（Key Laboratory for Advanced Materials Processing Technology, Ministry of Education,
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China）
Abstract:Three dimensional macro and micro multi-scale models were proposed for Ni-based superalloy investment castings. Temperature distribution in the casting was simulated using the ray tracing method to deal with the heat radiation. Microstructure was simulated with the modified CA method and three dimensional nested macro and micro grids. Latent heat releasing was calculated during microstructure simulation, which was coupled with the macro temperature calculation. Based on multi-scale modeling results, the shrinkage cavity, macroporosity and microporosity defects in the casting were predicted with the equivalent liquid surface descending method, Niyama Criterion and Darcy Law, respectively. Experiments for superalloy turbine wheel casting were carried out. The results show that the simulated cooling curves, microstructure and defects’ positions correspond well with the experimental. Various defects in the casting can be predicted precisely with the proposed model.
Key words: superalloy; investment casting; multi-scale modeling; shrinkage cavity and macroporosity; microporosity; microstructure
