ZTA15大型钛合金熔模精密铸件界面反应研究

Interface Reaction of Large Size ZTA15 Titanium Alloy Investment Casting

钛合金作为易氧化金属在熔融状态下非常活泼,大尺寸钛铸件在铸造过程中更容易和铸型材料发生界面反应,并对铸件表面质量产生影响。本研究采用氧化钇铸型在真空自耗凝壳炉中浇铸了大尺寸钛合金铸件,并采用SEM、XRD、EDS等方法对不同厚度试样的表层进行了检测和分析。结果发现,试样表层均存在一定厚度的氧元素扩散层,同时,还发现表层存在一定厚度的组织过渡区,最后,通过酸洗方法对试样表面反应层和组织过渡区进行了有效去除,有效提高了铸件的表面质量。

As oxidizable metals, titanium alloys are very active on melting point. It is easier for large-size titanium castings to react with the casting materials which will affect the surface quality of the castings during casting. In this experiment, large-scale titanium alloy castings were cast by Yttrium oxide mould in a vacuum consumable shell furnace, and the surface layer of samples with different thickness was tested and analyzed by SEM, XRD and EDS. The results show that there is an oxygen diffusion layer of certain thickness on the surface of the samples, and there is a tissue transition zone of certain thickness on the surface. Finally, an acid pickling method was used to remove the reaction layer and the transition zone of the sample surface, which effectively improves the surface quality of the castings.