中文摘要：

在650℃、120～145 MPa条件下对P92钢光滑试样和双缺口试样进行了蠕变试验，基于Liu-Murakami和Norton-Bailey本构模型，建立了一种修正的蠕变本构模型并加以验证；在此基础上，明确模型常数的确定方法，并对P92钢光滑试样和双缺口试样的蠕变行为进行了模拟。结果表明：修正后的模型可以有效地模拟P92钢650℃蠕变的三个阶段，缓解了传统Kachanov-Robotnov（K-R）模型对网格敏感性的问题；双缺口试样的蠕变断裂寿命均远大于相同条件下光滑试样的，即存在缺口增强效应，且缺口锐度越大，缺口增强效应越明显；损伤量与多轴度之间存在正相关性。

英文摘要：

Creep experiments were conducted on plain and double-notched specimens of P92 steel under conditions of 650℃ and 120-145 MPa. Based on Liu-Murakami and Norton-Bailey constitutive models, a modified creep constitutive model was built and verified. On this basis, the determination method of model constants was confirmed, and the creep behaviors for the plain and double-notched specimens of P92 steel were simulated. The results show that the modified model was able to simulate the three stages of creep process at 650℃ of P92 steel, and reduced the problem of mesh-sensitivity of the conventional Kachanov-Robotnov （K-R） model. The creep frature life of the double-notched specimen was longer than that of the plain specimen under the same condition, namely the notch strengthening effect. And with the increase of the notch acuity ratio, the strengthening effect became more obvious. The damage quantity had a positive correlation with the multiaxiality.