奥氏体不锈钢焊缝受粗大柱状晶组织的影响, 其焊缝的超声TOFD检测信号信噪比低、扫描图像模糊, 缺陷检测容易误判或漏检。为提高检测信号信噪比及扫描图像分辨力, 引入合成孔径聚焦算法对超声TOFD-D扫描采集的A信号进行处理, 并分析了变迹窗对处理后检测信号信噪比的影响。研究表明, 通过优化选择变迹窗可提高检测信号的信噪比和缺陷的D扫描图像分辨力, 有效地增强了超声TOFD检测技术对奥氏体不锈钢焊缝的检测能力。

Coarser columnar grain leads to awful signal to noise ratio and image resolution , which always produces misjudging of the defects in austenitic stainless steel weld by use of ultrasonic TOFD technique. In order to improve the testing effectiveness, synthetic aperture focusing technique is adopted to process the testing signal extracted by TOFD-D scanning, and influences of apodized function are also studied to optimize the scanning imagery in the research. The results indicate that the signal noise can be depressed by the use of synthetic aperture focusing technique, and the resolution of D-scan image and recognition ability of the weld defects is also enhanced through optimizing apodized function.