Abstract

The automatic phased array ultrasonic testing method has been developed for inspecting the pipe welds with complex geometry. Applying time of flight diffraction (TOFD) technique has two problems: one is the difficulty in recognition of head wave under complex structure; the other is the limited scanning space cannot provide the needed span for pitch-catch mode. To overcome these two problems, an array probe can be placed on the surface of base metal of the weld by the direct and double traverse techniques. In order to design the optimal scanning path for high probability of detection and inspection rate, the model of beam path on tilt steps was established to quantitatively analyze the effects of tilt steps on beam coverage and mode conversion. Experiments were conducted to validate the proposed rule of planning the optimal scanning path. All artificial defects in the mock-up block were detected on the scanning side of which exists the optimal scanning path. While for the scanning side without the optimal scanning path, a combination of scanning is needed to avoid missing inspection.

中文翻译：

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复杂几何形状的管道焊缝自动相控阵超声检测扫描路径的研究

摘要

已经开发出一种自动相控阵超声波测试方法，用于检查具有复杂几何形状的管道焊缝。飞行时间衍射（TOFD）技术的应用存在两个问题：一是复杂结构下的头波识别困难；二是结构复杂。另一个是有限的扫描空间无法提供音高捕捉模式所需的跨度。为了克服这两个问题，可以通过直接和双向移动技术将阵列探针放置在焊缝的母材表面上。为了设计出具有较高检测率和检查率的最佳扫描路径，建立了倾斜步长的光路模型，以定量分析倾斜步长对光束覆盖率和模式转换的影响。进行实验以验证所建议的规划最佳扫描路径的规则。在样机模块的扫描侧检测到所有人为缺陷，该缺陷存在最佳扫描路径。对于没有最佳扫描路径的扫描面，需要组合扫描以避免遗漏检查。