超声波对于缺陷的定性、定量、定位的准确性,由于受人为等其他因素的影响,普遍认为低于射线探伤。对于小径管,由于超声探伤近场区的存在,精确度较低,故多采用射线检验。但是对于未熔合缺陷,射线探伤受到透照角度的影响,检出率极低。本文介绍了利用二次波检验电站锅炉受热面管子近表面未熔合缺陷的方法及优越性。 Ultrasound for defect qualitative, quantitative, accurate positioning, due to other factors such as human influence, generally considered lower than the ray detection. For the small diameter tube, due to the presence of near-field ultrasonic testing, the accuracy is low, so the use of ray inspection. However, for unfused defects, radiographic flaw detection is affected by the perspective of transillumination and the detection rate is very low. This paper introduces the method and superiority of using secondary wave to inspect the unfused defects on the surface of heat pipe of power station boiler.