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在610℃下,对超超临界火电机组用P92钢主蒸汽管道的焊接接头进行了蠕变-疲劳交互作用裂纹扩展试验。获得了蠕变-疲劳裂纹扩展速率,并进行了高温断裂参量的表征,同时,结合P92钢焊接接头蠕变与拉伸试验,建立了P92钢焊接接头材料与时间相关的失效评定曲线(TDFAD)。研究结果表明,试样断口微观形貌特征显示出其蠕变–疲劳交互作用下的裂纹扩展主要是由蠕变因素主导的。每条蠕变裂纹扩展速率与高温断裂参量C*的关系曲线中均存在一个拐点,这个拐点的产生过程即为蠕变裂纹扩展的孕育阶段。采用修正R6中Option2的方法建立了TDFAD,该方法充分考虑了蠕变因素的影响,能够获得较安全的评定结果。
Creep-fatigue interaction crack growth test was carried out on the welded joint of P92 main steam pipe of ultra-supercritical thermal power unit at 610 ℃. The creep-fatigue crack growth rate was obtained, and the parameters of high temperature fracture were also characterized. At the same time, the time-dependent failure assessment curve (TDFAD) of P92 steel welded joint was established by combining the creep and tensile test of P92 steel welded joint, . The results show that the micro-morphology of the fracture surface shows that the crack propagation under the creep-fatigue interaction is mainly dominated by the creep factor. There is an inflection point in the curve of each creep crack growth rate and the high-temperature fracture parameter C *. The inflection point is the inoculation phase of the creep crack growth. The method of modifying Option2 in R6 was used to establish TDFAD. This method fully considered the influence of creep factors and obtained a safer evaluation result.