面状缺陷超声TOFD法信号和图像的特征与识别

Characteristic and recognition of ultrasonic TOFD signal and image for planar defect

摘要: 针对铝合金厚板焊缝中易于出现的几种典型的面状缺陷,研究了其超声衍射时间差法(TOFD-time of flight diffraction)的检测特征,对获得的A扫描信号和B、D扫描图像的特征进行了分析和解释,并对B、D扫描图像进行了线性化处理。结果表明,结合A扫描信号和B、D扫描图像的特征,能够有效地对面状缺陷进行识别、定位和定量。线性化处理技术有效地提高了图像的时间分辨力,使面状缺陷的信号和图像的特征更明显,进而使定位定量更为精确。

Abstract: Considering several typical planar defects that were common flaws in thick aluminum weld, the characteristics of Ultrasonic TOFD (time of flight diffraction) was studied. Ultrasonic TOFD A-scan signal and B, D-scan image were analyzed and interpreted. Linearization was introduced in processing B and D-scan image. The results show that planar defect can be effectively recognized, located and sized by the characteristics of the received signal and image. Linearization effectively improves time resolution of the received images, which makes the characteristics of the defect more markedly and leads to more accurate quantitative measurement.