在TOFD检测过程中, 因直通波宽度而产生的近扫查面盲区对检测影响很大。为精确定量位于近扫查面盲区的缺陷, 制作了人工缺陷试块, 对其采用常规TOFD以及TOFD二次波分别进行扫查。对比两种扫查方式所得TOFD图像可见, 常规TOFD技术对近扫查面缺陷极易漏检且无法定量, 而利用TOFD二次波扫查方式得到的图像能够显著分辨出缺陷并能精确定量, 因此可弥补常规TOFD检测中对近扫查面缺陷检出能力的不足。

The dead zone of inspection surface could not be avoided when using TOFD technique due to the width of lateral wave. In order to solve the problem, the block with given depth of artificial defect, which were respectively inspected by traditional and secondary wave TOFD technique. The result, compared with the different images, was that the defect near the inspection surface was hard to be quantified as well as detected by the former of two TOFD methods. However, the defect could be obviously recognized and accurately measured by the latter method. So the traditional TOFD inspection accompanied with secondary wave TOFD was the better way to avoid the dead zone near the inspection surface.