【摘要】 单晶高温合金铸造工艺影响因素繁多,其微观组织和晶体界面形态严格依赖于晶体生长时所选择的凝固速率和温度梯度。空心导向叶片横向跨距大,壁厚超薄,型腔结构复杂,且缘板、叶冠截面几何突变问题导致温度梯度难于控制。合金散热过程形成晶态的机理复杂,使保证叶片单晶完整性成为熔铸工艺的难点之一。本研究利用ProCAST仿真软件对某高导叶片凝固过程中的温度场与流场进行计算,并应用CAFE模块耦合前者计算结果对合金组织形核生长情况进行宏观模拟。借助实际浇注和测温试验作为参照,计算实际导向叶片组合方案,研究叶片定向凝固过程中的晶粒竞争生长机制和晶粒取向控制方法。模拟结果显示杂晶集中出现在叶片缘板及进、排气边位置。更多还原

【Abstract】 Many influencing factors exist in the single crystal casting solidification for its microstructure and crystal interface strictly depend on the solidification rate and the thermal gradient during crystal growth. The lateral span of the hollow blade is large, while it has an ultra-thin wall, complex-shaped cavity and geometric section mutations, so it is difficult to control the thermal gradient. Heat dissipation process which can turn the liquid alloy into crystal state has a complex mechanism that makes the single crystal integrity difficult. The ProCAST soft is applied to calculating the temperature and flow field of the liquid alloy for the guide vane, of which result can be coupled with CAFE moduleto simulate the crystal nucleation and growth status of the alloy’s microstructure during solidification. The investigation shows the competitive growth mechanism among the grainsand the control ofgrain orientation byusingthe pouringtest and temperature measurement asa reference to calculate gating system of the practical guide vane. The result shows that the misoriented grain mainly centralized in the platform,leading and exhausting edge of the guide vane.更多还原