Omega蠕变寿命评估方法及应用

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Isothermal extrapolation, Larson - Miller parameter and 0 parameter life assessment methods were usually used in remaining life prediction of high temperature superheated steam pipes and furnace tubes, however, these methods require many tests with high stress in order to extrapolate, which takes lon- ger and its sampling is destructive. Furthermore, data scatter and without considering materials＇ aging and damage make extrapolation confidence drop. American Materials Council launch a Omega project on re- maining life assessment of the components which are working creep range in 1986 ,which has been written in API 579 Fitness - For - Service. This article firstly describes Omega method, then creep tests are carried out on 1CrO. 5MoV and 1.25Cr0.5MoSi and subsequently creep data are processed in Omega method. Secondly the calculated creep rupture time with actual fracture time are compared. Finally, conclusion is confirmed that Omega method has a clear advantage in creep life assessment.传统高温过热蒸汽管及过热炉管蠕变寿命评估多采用等温外推、Larson―Miller参数和0参数等寿命评估方法，此类寿命评估方法常通过开展多组高应力蠕变测试进行短时外推，不仅耗时长、取样破坏性大、寿命评估存在分散性，而且此方法没有考虑材料的老化与损伤，长时外推结果置信度下降。1986年，美国材料学会（MPC）发起了用于评估工作在蠕变范围内部件剩余寿命的O―mega工程，目前该评估方法已被编入API579Fitness―For―Service标准中。通过介绍Omega寿命评估方法，并对1Cr0．5MoV和1．25Cr0．5MoSi两种材料开展Omega蠕变分析，再将Omega方法预测的材料蠕变断裂时间与实际断裂时间进行对比，发现Omega方法在评定蠕变寿命评估方面更具优越性。