高温钛合金油箱骨架是航天飞行器的关重件，其结构复杂、壁厚变化大，采用精密铸造工艺生产具有显著优势。 为解决 ZTi55 高温钛合金铸造性能差的难题，通过铸造模拟仿真油箱骨架中的筒形结构确定铸造工艺，分析了铸件结构与模拟仿真温度场的关系， 并结合铸件解剖结果分析了模拟仿真铸件不同位置温度场与晶粒尺寸的对应关系。模拟结果揭示了铸件不同位置在冷却凝固特性及晶粒尺寸上的显著关联，最后充型的铸件弧面薄壁结构最先发生降温凝固，晶粒尺寸最为细小，约为 305 μm；最先充型的厚大壁厚位置降温速率最慢，晶粒尺寸最为粗大，超过 900 μm。 铸件壁厚与凝固特性、晶粒尺寸呈显著相关关系，即壁厚越大，铸件所需的凝固时间越长，冷却速率相应越慢，最终形成的晶粒尺寸也越粗大。

As a key critical component of aerospace vehicles, high-temperature titanium alloy fuel tank frames have complex structures and significant variations in wall thickness, and this structural characteristic makes their fabrication via the precision casting process highly advantageous. To address the issue of the poor castability of ZTi55 high-temperature titanium alloys, the casting process was determined through a casting simulation conducted on the cylindrical structure of the fuel tank frame, and the relationship between the casting structure and the simulated temperature field was analysed. Furthermore, combined with the results of the casting dissection, the corresponding relationships between the simulated temperature field at different positions of the casting and the grain size were also analysed. The simulation results reveal

significant correlations between the cooling and solidification characteristics and the grain size at different positions during casting. Specifically, the curved thin-walled structure of the casting that is filled last undergoes cooling and solidification first and results in the finest grain size, at approximately 305 μm, whereas the thick-walled section filled first has the slowest cooling rate and features the coarsest grain size, exceeding 900 μm. Additionally, the wall thickness of the casting is significantly correlated with its solidification characteristics and grain size, where the greater the wall thickness is, the longer the solidification time required for the casting, the lower the cooling rate, and the coarser the grain size that ultimately forms.