The mismatch effect in weldment is widely to be found in engineering practices. In this paper, the material mismatch effect on the mode II creep crack tip field is investigated and discussed. The mismatch effect on the C(t)-integral is presented. Both the local mismatch and the general mismatch are found to play important role in C(t)-integral under mode II condition. The mismatch effect on the stress field of mode II creep crack is also studied. The two-order term solutions are adopted to characterize the material mismatch effect on the mode II creep crack. The effect of creep coefficient, creep exponent as well as the HAZ thickness on the high order term solutions are also presented. Some typical cases by considering general mismatch and local mismatch effect are given to make a comparisons between the HRR field, FE solutions and the two-order term solutions. It can be seen that the two-order term solutions can coincide with the full field FE solutions quite reasonably regardless of creep extent, creep exponent, mismatch factor, and HAZ thickness. The material mismatch effect on the high order term solutions is significant under some conditions. A theoretical formula is presented to show the implication of material mismatch effect on creep crack growth under mode II condition based on stress damage model.

焊接件的失配效应在工程实践中广泛存在。在本文中，研究和讨论了材料失配对模式 II 蠕变裂纹尖端场的影响。呈现了对C ( t ) 积分的失配效应。发现局部失配和一般失配在C ( t)-在模式 II 条件下积分。还研究了失配对II型蠕变裂纹应力场的影响。采用二阶项解来表征材料失配对模式 II 蠕变裂纹的影响。还介绍了蠕变系数、蠕变指数以及热影响区厚度对高阶项解的影响。给出了一些考虑一般失配和局部失配效应的典型案例，对HRR场、有限元解和二阶项解进行了比较。可以看出，无论蠕变程度、蠕变指数、失配因子和热影响区厚度如何，二阶项解都可以与全场有限元解相当合理地重合。在某些条件下，材料失配对高阶项解的影响是显着的。