一种用于P92钢寿命预测的蠕变模型研究

The study of improved creep model for life prediction of P92 steel

首先分别在595℃、610℃、670℃下进行了P92钢的单轴蠕变拉伸实验。结果表明:当实验温度高于600℃时,应力和应变在双对数坐标下呈现非线性特征,蠕变过程无法通过Norton指数模型进行描述。为了进一步解决高温下蠕变寿命的计算和预测问题,本文提出了一种改进的蠕变本构模型;并在此基础上,引入损伤变量描述第三阶段蠕变。利用新的蠕变模型对P92钢在595℃、610℃温度条件下的蠕变过程进行了模拟,结果表明模型预测的蠕变寿命和实验值误差在5%之内,符合工程评估要求。

Creep tests of P92 steel are carried out at 595℃, 610℃, and 670℃ temperature conditions. Results obtained show that the stress-strain curve reveals nonlinear characteristics in logarithmic coordinates if the temperature is greater than 600℃, which lead the Norton model cannot describe the creep behavior. In order to solve the problem of creep life prediction, a modified creep model is proposed, in which damage model is introduced to describe creep tertiary stage. The new model is embedded into the finite element software ANSYS with which the simulation calculation of P92 steel is carried out at 595℃, 610℃. Results show that the new model can accurately predict the creep rupture time under different stress levels, and the prediction error is less than 5%, which meet the engineering assessment requirements.