根据局部损伤理论和相似原理 ,给出了蠕变裂纹启裂前的孕育上下限时间并推导了蠕变裂纹扩展率方程。在常载荷下用 2 .2 5 Cr- 1Mo钢作了蠕变裂纹扩展试验 ,高拘束度使早期局部损伤发展迅速 ,实验结果与孕育时间下限接近。稳态预测值由于忽略未开裂部分材质劣化而略低于实验结果值。有限元模拟损伤演变过程 ,表明稳态裂纹扩展率与实验结果吻合 According to the theory of local damage and similar principle, the upper and lower incubation time before creep crack initiation is given and the creep crack growth rate equation is deduced. Under normal load, creep crack growth test was made with 2.52Mg-1Mo steel, and the high restraint made rapid development of early local damage. The experimental results were close to the lower limit of incubation time. The steady-state prediction is slightly lower than the experimental results due to the neglect of material deterioration in the uncracked part. The finite element simulation of damage evolution shows that the steady-state crack growth rate agrees well with the experimental results