通过超声衍射时差法检测(TOFD)表面盲区理论分析，在TOFD检测试块上进行试验验证表明TOFD检测方法存在表面盲区。采用超声脉冲反射检测、磁粉检测及超声爬波检测，较好地检测了TOFD上表面盲区超标缺陷，得出超声爬波检测法是TOFD表面盲区检测中一种有效的补充检测方法。

This paper researches on the blind area of the time of flight diffraction (TOFD) by theoretically analyzing the surface blind area and by the experiment on TOFD detection block, and it shows that one of major limitations of TOFD is the flaw top tip located in a blind area. Thus, other testing methods are needed to cover the blind area. Experiments and comparisons among three methods (Ultrasonic Pulse Echo, Magnetic Particle and Ultrasonic Creeping Wave testing) are carried out to get a decent detection performance. The results presented in this paper indicate that creeping wave testing technique can effectively detect overweight defect in the blind area of TOFD as a complemented method.