核电主管道热老化后失效评定曲线研究

Research on Failure Assessment Curves of Thermally Aged Nuclear Primary Pipe

本文对400℃热老化后Z3CN20-09M材料的高温拉伸性能和失效评定曲线进行了研究。对热老化不同时间的试样进行了330℃拉伸试验,用扫描电镜(SEM)对高温拉伸断口进行观察。采用联合型指数函数ExpAssoc对真应力应变数据进行了拟合,并将拟合结果用于计算失效评定曲线。结果表明,通过R6选择2方法得到的失效评定曲线随热老化时间而右移,说明未老化材料的失效评定曲线具有包络性和保守性。用未老化材料的失效评定曲线进行安全评定会得到较安全的结果。

High temperature tensile properties and failure assessment curves of 400 ℃ thermally aged Z3CN20-09M were investigated.Tensile test at 330 ℃ and fracture surface analysis by scanning electron microscope（SEM） have been performed on materials thermally aged for different time.The true stress-strain curves were fitted by an association exponential function ExpAssoc.The fitted parameters were used to calculate the failure assessment curves（FAC）.The results by R6 option 2 method showed that FAC shift to right with thermal aging time.FAC for un-aged materials is conservative and recommended for engineering application,and the result will be credible.