室温蠕变下含轴向内表面裂纹钛管的失效评定

Failure assessment of titanium pipe with internal axial surface crack under room-temperature creep condition

对室温蠕变条件下含轴向内表面裂纹钛管的失效评定曲线(FACs)进行了研究。根据工业纯钛TA2拉伸应力-应变关系及有限元方法,建立了TA2的R6 Option 2 FAC以及受内压含轴向内表面裂纹钛管的R6 Option 3FAC,并与R6 Option 1曲线比较。结果表明Option 1曲线适用于含轴向内表面裂纹钛管的常规安全评定。由于TA2存在室温蠕变现象,根据TA2拉伸应力-应变关系和室温蠕变数据,建立了TA2与时间相关的失效评定曲线(TDFAC),并与R6 Option 1曲线进行比较。结果表明TA2的室温蠕变现象对含裂纹结构的安全评定有显著的影响,对含轴向内表面裂纹钛管进行安全评定时需要考虑室温蠕变的影响,应采用TDFAC进行安全评定。

The failure assessment curves（FACs） of titanium pipe with internal axial surface crack under room-temperature creep condition were studied.According to the tensile stress-strain relationship of commercially pure titanium TA2 and finite element（FE） simulation,the R6 Option 2 FAC of TA2 and the R6 Option 3 FAC of the titanium pipe with internal axial surface crack were established and compared with the R6 Option 1 curve.Results indicated that the R6 Option 1 curve was suitable for the conventional safety assessment of the titanium pipe with internal axial surface crack.TA2 existed evident creep phenomenon at the room temperature.According to the tensile stress-strain relationship and roomtemperature creep data of TA2,the time-dependent failure assessment curves （TDFACs） of TA2 were established and compared with the R6 Option 1 curve.Results showed that the room-temperature creep of TA2 had an evident effect on the safety assessment of the structures with cracks.The effect of roomtemperature creep needs to be considered for safety assessment of the titanium pipe with internal axial surface crack.Thus,the TDFAC should be applied.