小口径管道超声波检测耦合曲面修正系数

为了研究小口径管道超声波检测中探头与曲面耦合的补偿问题，对超声波平面探头、曲面探头与小口径管道曲面接触情况进行分析，根据曲率修正系数与归一化曲率半径的关系曲线得出需要补偿的增益。通过小口径管道超声波检测耦合曲面修正实验，利用选定探头的平面和修磨后的曲面对SOB试块的标准反射体进行扫描，在80％波高下记录反射当量的分贝值。研究结果表明：曲面探头与SGB试块的弧面半径差越大，标准反射体的反射回波越小，所需的耦合曲面修正系数越大，且探头曲面曲率半径大于试块弧面曲率半径时的耦合效果较好。

Correction factor for the coupling curved surface in ultrasonic testing of small diameter pipes

To compensate the coupling between probes and curved surfaces in ultrasonic testing of small diameter pipes, the contacts between the ultrasonic plane probe and curved surface probe and the curved surfaces of small diameter pipe are analyzed, then the relation between curvature correction factor and normalized radius of curvature is based to derive the gain to be compensated. In a test to correct the coupling curved surface, the plane of selected probe and the grinded curved surface are applied to scan the standard reflector of SGB test block, and decibels of equivalent reflection are recorded under 80% of the wave compete. Results show that the greater the arc radius difference between curved surface probe and SGB test block is, the smaller the echo of the standard reflector is, the larger the correction factor of coupling curved surface needs. The coupling effect is greater when curvature radius of probe curved surface is larger than that of test block.