ZTA7钛合金铸件荧光显示分析

Analysis of Fluorescent Display in ZTA7 Titanium Alloy Casting

分析了某航空发动机用ZTA7钛合金铸件在长试考核后形成荧光显示的原因。利用扫描电镜、金相显微镜对剖切后的铸件进行组织分析,并进行了氢含量检测。结果表明,铸件裂纹处断口呈脆性解理断裂特征,无明显氧化,裂纹源区未见缩松和夹杂等冶金缺陷,微裂纹区微观组织无异常,推断铸件本体不存在铸造缺陷,排除了铸造缺陷引起微裂纹解理开裂的可能。另外,对同批次、未试车的铸件进行荧光检测,在铸件机加工面上发现裂纹,证明微裂纹由机加残余应力导致。

The origination of fluorescent displays in ZTA7 titanium alloy casting after long-term trial run was analyzed.The microstructure of castings after cutting was investigated by SEM,metallographic examination and hydrogen content test was carried out.The results indicate that the microcrack fractures are characterized by brittle cleavage without obvious oxidation and common defects,such as shrinkage and inclusion,in area of microcrack sources,and no abnormality occurs in the microcrack area.It can be inferred that there is absence of defect in casting,and possibility of microcrack cleavage caused by casting defect is excluded.In addition,cracks appear on the machine surface after fluorescent detection of untested castings in same batch,proving that residual stress leads to the microcracks.