(清華大學(xué) 機(jī)械工程系 先進(jìn)成形制造教育部重點(diǎn)實(shí)驗(yàn)室，北京 100084)
摘 要: 建立鎳基高溫合金熔模鑄件凝固過程的宏/微觀多尺度數(shù)理模型，基于射線追蹤法處理熱輻射，模擬鑄件的溫度分布，采用三維宏/微觀網(wǎng)格嵌套和改進(jìn)的CA方法模擬微觀組織，并依據(jù)微觀組織模擬結(jié)果處理結(jié)晶潛熱，實(shí)現(xiàn)微觀與宏觀模擬的耦合。依據(jù)等效液面下降法、Niyama判據(jù)和Darcy定律預(yù)測鑄件的宏觀縮孔、宏觀縮松和微觀縮松缺陷分布位置，并澆注實(shí)際的高溫合金葉輪鑄件。結(jié)果表明：模擬獲得的冷卻曲線、微觀組織及缺陷位置與實(shí)驗(yàn)結(jié)果吻合良好，模擬結(jié)果能夠準(zhǔn)確預(yù)測鑄件中多種缺陷的分布。
關(guān)鍵字: 高溫合金；熔模鑄造；多尺度模擬；宏觀縮孔縮松；微觀縮松；微觀組織
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
