P92钢在内压和拉伸组合加载下的蠕变行为

摘要

采用内压和拉伸组合加载方法,在650 ℃下对P92钢管状试样进行了不同多轴度的蠕变试验并利用改进的Kachanov-Robatnov蠕变模型对其蠕变行为进行有限元模拟,观察了断口形貌和显微组织,分析了多轴度对P92钢应力分布和损伤发展的影响.结果表明:在内压和拉伸组合加载下,当外壁等效应力相同时,多轴度越大,P92钢的蠕变寿命越短;多轴度对P92钢蠕变孔洞的生长具有促进作用;改进的Kachanov-Robatnov蠕变模型可以准确地描述P92钢的蠕变行为;在蠕变过程中,多轴度影响应力的分布,进而影响损伤的分布,多轴度大的位置其损伤程度也大.%Different multiaxial creep experiments were conducted on P92 steel tube samples under combination loading of inner pressure and tensile at 650 ℃ and the creep behavior was simulated by modified Kachanov-Robatnov creep model.The fracture morphology and microstructure were observed and the influence of multiaxiality on stress distribution and damage evolution of P92 steel was analyzed.The results show that the higher the multiaxiality,the shorter the creep lifetime of P92 steel subjected to combination loading of inner pressure and tensile was when the equivalent stress on the outside of tube was the same.The modified Kachanov-Robatnov creep model could describe the creep behavior of P92 steel accurately.Multiaxiality influenced the stress distribution,and then affected the distribution of damage during creep.The position with the largest multiaxiality had the largest damage.