大型复杂钛合金铸件组织分布规律研究

Microstructure Distribution of Large-scale Complex Titanium Alloy Castings

针对航空发动机用大型复杂钛合金铸件的组织和性能评估问题,通过分析铸件各区组织分布及异常晶粒存在情况,研究了影响铸件组织的关键因素,完成了对某航空发动机用钛合金大型机匣铸件的组织分布规律分析。结果表明,铸件晶粒尺寸的分布范围为44~7660μm,约82%的晶粒尺寸处于1650μm以内。随着铸件壁厚增加,各区的晶粒尺寸均值、晶粒尺寸分布半高宽均呈近对数增加趋势。铸件的壁厚、结构特征、靠近浇道位置、凝固顺序都会影响铸件的凝固,其中壁厚的影响最为显著。

In order to evaluate the microstructure and performance of large-scale complex titanium alloy castings and other aircraft critical structural components,the structural uniformity of a titanium alloy mainframe casting was analyzed.By analyzing the distribution of the various regions of the casting and the presence of anomalous grains,the key factors affecting the casting microstructure were described,and the microstructure homogeneity of a titanium alloy mainframe casting was evaluated.The results show that the grain size in the castings is in range of 44μm to 7660μm,and the sizes of 82%of the grains are within 1650μm.As the thickness of the casting increases,the average grain size and the FWHM of the surface layer and the center layer of the casting show a nearly logarithmic increased trend.The factors such as wall thickness,structural characteristics and pouring sequence of the castings all have an important influence on solidification,of which the wall thickness has the most significant effect.