钛合金薄板直角焊缝质量的相控阵超声检测方法研究

Research on Phased Array Ultrasonic Testing Method for Titanium Alloy Sheet Fillet Welds

板直角焊接结构由于被焊试件厚度薄、检测精度要求高等因素使得常规检测方法难以施展。利用相控阵超声检测技术声束灵活可控的特点,制定基于波束控制的全覆盖检测方案。为获得较好的信噪比,提出一套楔块几何参数的优化设计方法;对采用多次反射方式入射的相控阵超声偏转聚焦法则计算方法进行了研究;构建采用机械臂作扫查器的高精度相控阵超声自动化检测系统,对具有人工预埋缺陷的钛合金薄板直角焊缝结构进行了检测试验,验证检测方法的正确性。研究结果表明,所提出的相控阵超声检测方法,能够对裂纹、未焊合等类型缺陷进行良好表征,满足薄板直角焊缝的超声无损检测要求。

Considering that the conventional non-destructive testing(NDT) method is not competent for the inspection of fillet welding structure of thin sheet with high detection accuracy, a phased array ultrasonic testing method is proposed, which has the advantage of flexible beam control. Due to the ultrasonic feature, a completely covered phased array ultrasonic testing method based on beam steering is proposed. A new method for the optimum design of geometric parameters of wedge is presented to obtain a better signal-to-noise ratio. The deflection and focusing principle calculation method by multiple reflection incidences according to Fermat’s principle is studied. A phased array ultrasonic scanning system using mechanical arm was established to achi-eve the recognition of prefabricated defects, which verified the correctness of the testing method. The results show that the proposed phased array ultrasonic testing method can meet the requirement of detecting and characterizing the defects like cracks or incomplete fusion in sheet fillet welding structures.