ZTA15钛合金熔模精密铸造浇注用铁基引流工装的优化

Improvement of Fe-Based Draught Tooling for Pouring of ZTA15 Alloy in Investment Casting

针对ZTA15钛合金铸件在加工过程中产生裂纹、掉块的问题,对化学成分、力学性能、金相组织进行检测,并对比正常组织的试样。分析造成该问题的原因,主要是在熔炼浇注过程中,将钛液引入铸型的部分铁基引流工装发生熔化,使铁元素随钛液进入铸件型腔,造成杂质元素铁含量在铸件局部区域增高,降低了β相的转变温度,导致铸件在热等静压或去应力退火过程中产生β相粗晶,形成“β脆性”。提出了浇注用引流工装的一些优化建议。

In view of the cold cracking and drop block defects that occur during the machining of ZTA15 alloy investment castings,the chemical composition,mechanical properties and metallographic structure of the castings were tested,and comparison with the normal sample was carried out.It was found that,in the process of pouring ZTA15 alloy melt into the mold cavity,part of the iron-based draught tooling that introduced titanium liquid into the mold was melted,thus the iron element entered the mold cavity with titanium liquid together,resulting in the increase of the impurity element iron content in local regions of castings and the reduction of the transition temperature of β phase.Consequently,the β phase coarse crystals were formed in the castings during hot isostatic pressure or stress relief annealing,causing"β brittleness".Finally,some improvement advises are recommended for the structure design and material selection of the draught tooling.