Ultrasonic Phased Array Detection of Crack-Like Defects in Welds Based on Multi-Mode Total Focusing Method

Abstract

Abstract As a critical structural component within pressure vessels, weld can be frequently found with harmful defects during service, such as microcracks with different orientations. Therefore, regular inspections of welds from pressure equipment are very important. Compared to traditional ultrasonic NDT, ultrasonic phased array total focusing method is a new postprocessing imaging method that is more accurate for defect localization. The inspection of defects in the weld often necessitates prior knowledge to scan multiple times using different inspection surfaces and angles to increase detection coverage, which is time-consuming and labor-intensive. In this study, a multi-mode ultrasonic phased array total focusing method (TFM) for crack-like defects with different orientation is proposed, and the multi-mode imaging method is applied to the inspection of butt welds and fillet welds to achieve effective and quantitative detection of defects in different orientations. In addition, according to the actual size of the detection object, the sound beam incident state and imaging parameters are calculated based on intelligent algorithms, and the optimum imaging view is selected. As a result, a multi-mode imaging method that can comprehensively cover the weld area is obtained. Experimental results show that the multi-view method delivers different sensitivity to different defect orientations, which can better suppress noise than single-view imaging, and improve the probability of detection for crack-like defect.