数值模拟在单晶高温合金熔模铸造中的应用

由于单晶高温合金消除了晶界这一高温薄弱结构，已成为航空发动机首选的热端部件材料。为了满足航空发动机对推重比和涡轮燃气温度的更高需求，新型单晶高温合金中添加了越来越多的Re、Ru等难熔元素，致使单晶制备过程中缺陷形成倾向显著提高，研制周期和研制成本明显增加，严重限制了单晶高温合金的产业化应用。近年来，随着计算方法和熔模铸造技术的发展，数值模拟在单晶高温合金制备领域中得到了越来越广泛的应用，已成为减少单晶铸造缺陷，获得高质量单晶铸件的重要手段。以商用铸造模拟软件Procast为例，对单晶高温合金定向凝固过程的温度场分布和组织演化进行了分析，综述了数值模拟在单晶熔模铸造研究中的应用现状。首先，介绍了数值模拟中的前处理过程，即几何建模、网格划分等，强调了前处理过程的注意事项。随后，根据已有文献，分析了数值模拟技术在研究温度场和晶粒组织演化过程的作用。最后，指出数值模拟技术在单晶高温合金熔模铸造领域进一步发展需要解决的问题。

Application of Numerical Simulation in Investing Casting Technology of Single Crystal Superalloy

Due to the elimination of the high-temperature weak structure of grain boundaries, single crystal superalloy has been considered as the preferred material for high-temperature component of aviation engines. In order to meet the higher demands of advanced aviation engines for thrust to weight ratio and turbine gas temperature, more refractory elements such as Re and Ru are added, resulting in a significant increase in defect formation during directional solidification, production cycle and cost and severely limiting the industrial application of single crystal superalloy. With the development of computational methods and investing casting technology in recent years, numerical simulation technology has been widely used in the production of single crystal superalloy and has become an important method to improve the quality of single crystal castings. The casting simulation software Procast was considered as an example to analyze the thermal condition and microstructure evolution results of investing casting of single crystal superalloy during the directional solidification process. Furthermore, the current application status of numerical simulation technology in the research of investing casting of single crystal was summarized. Firstly, the preprocessing in numerical simulation such as geometric modeling and mesh generation was introduced and the precautions in the pre-processing process were emphasized. Then, according to the existing literature, the role of numerical simulation technology in studying the temperature field and the evolution process of grain structure was analyzed. Finally, the problems to be solved in the further development of numerical simulation technology in the field of investment casting of single crystal superalloy were pointed out.