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由于压力和腐蚀等原因,承压设备的大焊缝根部易出现底面开口裂纹。本研究采用超声相控阵扇扫检测技术对底面开口裂纹进行检测。基于底面开口裂纹上下尖端回波,提出采用绝对到达时间技术(Absolute Arrival Time Technique,AATT)测量其高度。制作含有不同高度的人工裂纹试块,通过模拟仿真和实验测量验证AATT法测量底面开口裂纹高度精度。实验结果表明超声相控阵AATT法能从单面单侧对缺陷进行检测测量,当裂纹高度大于3 mm时,能达到与常规TOFD相同的测量精度。同时研究了声束偏转角度对AATT测量结果的影响,结果表明基于裂纹尖端衍射波的AATT具有更高的测量精度。
Due to pressure and corrosion and other reasons, the root of large welds in pressure-bearing equipment is prone to cracks in the bottom opening. In this study, ultrasonic phased array fan-sweep detection technique was used to detect the crack in the open bottom. Based on the upper and lower tip echoes of open crack in the bottom surface, we propose to measure the height using the Absolute Arrival Time Technique (AATT). The artificial crack test blocks containing different heights were made, and the height accuracy of the crack in the bottom opening measured by the AATT method was verified by simulation and experimental measurements. The experimental results show that the ultrasonic phased array AATT method can detect and measure the flaw from one side of single side, and when the crack height is more than 3 mm, the same measuring precision as the conventional TOFD can be achieved. At the same time, the influence of the beam deflection angle on the AATT measurement results was also studied. The results show that AATT based on the crack tip diffraction wave has higher accuracy.