在中厚板焊缝的超声横波探伤中, 当焊缝加强层过高时, 会产生变型反射纵波, 在一定的条件下返回探头, 形成伪缺陷回波。针对这一问题, 从理论上分析了产生变型纵波的原因, 并推导出变型纵波被显示的条件以及出现的位置。结合相关实例, 验证了之前的推断。最后总结了几种常用K值探头出现假缺陷回波的最小加强层厚度, 对中厚板超声波探伤有一定的指导意义。

In the ultrasonic transverse wave defect inspection on the weld of middle or thick plate, when the weld reinforcement is excessive, a metamophic longitudinal wave will occur, and in the certain condition, it will return to the sensor and form the false defect echo wave. Aiming at this problem, the reason of occurrence of metamophic longitudinal wave was analysed in theory, then, the condition of occurrence and the location were derived out. Associated with related example, the foregoing inference was proved. Finally, the minimal reinforcement thickness of occurring the false defect echo wave by using several sensors of common K values were concluded, it will be some guiding significance to the ultrosonic wave inspection on middle or thick plate.