在研究聚乙烯管道热熔对接接头超声检测中超声波反射规律的基础上，提出对该接头使用超声相控阵检测技术。研制了基于相控阵聚焦和超声实时成像技术的超声自动检测系统，通过液体楔块的声阻抗匹配，克服了聚乙烯材料声衰减严重和检测界面声能损耗对超声检测造成困难的问题。通过制作典型缺陷的聚乙烯接头缺陷试样，进行了可靠性测试和工艺试验，结果表明，提出的超声相控阵检测技术能可靠地检测出聚乙烯热熔对接接头中的典型缺陷。

Polyethylene (PE) pipe has been widely used for the transportation of gas in cities because of its excellent corrosion resistance, good mechanical properties and longer service life. Fusion welding is one of the main connection methods of polyethylene pipe. On the basis of the research on the ultrasonic reflection of different type defects in the joint,the phased array ultrasonic technique is presented. An automatic ultrasonic testing system is designed and fabricated with phased array electronic focusing technique and real-time imaging technique,which is comprehensively to integrate impedance matching with acoustic coupling technique, with the purpose of overcoming the detecting difficulty caused by the attenuation of PE and transmitting loss at interface.The reliability and process performance are tested through detecting PE joints with typical defects. It is shown that the phased array ultrasonic technique presented in the paper is applicable for detecting typical defects in of butt fusion joint in Polyethylene Pipe.