核电站关键构件中金属焊缝的超声成像检测研究

The reliable advanced nondestructive evaluation technology to ensure the safety and keeping health service of nuclear power is the major needs of the country. Lots of challenging problems on nuclear power nondestructive testing (NDT) emerged, because of the special complex detection conditions in nuclear power environment, the new requirements from the developing of advanced new nuclear technology, and the greatly increasing testing requirements. In the light of some urgent problems to be solved in the ultrasonic NDT for metal welds of nuclear key components, and the problem of accurate quantitative small flaw detection, this proposal presents an ultrasonic imaging detection scheme applying the most advanced ultrasonic phased array, based on our past similar researches. According to the austenitic material characteristics of nuclear key component welds and the presenting interfaces of dissimilar metals, explore and improve the theories on the ultrasound wave propagation and scattering, the theories on focusing properties of phased array sound field, in the non-homogeneous anisotropy medium and the interfaces with strong structural noise and under the nuclear environment of extreme complex conditions. To explore an effective and feasible method to improve the signal-to-noise ratio for phased array focusing acoustic field and to establish the ultrasonic quantitative detection theory and application technology of metal welds of nuclear key components are another goals as well. The research findings form the core of independent intellectual property rights on the NDT of coarse grain materials and anisotropic materials, and on precise quantitative sizing of crack defects. There would be extremely important theory significance and application value to improve China's nuclear power nondestructive evaluation level.

确保核电安全和健康服役的先进可靠的无损检测评价技术是国家的重大需求。由于核电的特殊环境、核电新技术的开拓和对核电检测要求的大幅度提高，对核电无损检测提出了许多挑战性的问题。本申请针对核构件金属焊缝超声无损检测中一些迫切需要解决的问题，对于小缺陷精确定量无损检测的难题，在我们过去相近研究的基础上，提出了采用最先进的超声相控阵技术成像检测的方案。针对核构件焊缝奥氏体材料特点和具有异种金属界面情况，探索和完善在核电环境极端条件下，在具有强烈结构噪声的各向异性非均匀介质中及其它们的交界面上声波的传播、散射和超声相控阵声场的聚焦特性的理论，摸索提高相控阵聚焦声场信噪比的有效可行的方法，建立起核构件金属焊缝中超声定量检测的理论和应用技术基础。研究成果对粗晶检测、各向异性材料检测、裂缝型缺陷的精确定量等难题形成核心自主知识产权，对提高我国的核电无损检测评价的水平具有十分重要的理论意义和应用价值。

确保核电安全和健康服役的先进可靠的无损检测评价技术是国家的重大需求。由于核电的特殊环境、核电新技术的开拓和对核电检测要求的大幅度提高，对核电无损检测提出了许多挑战性的问题。本项目针对核构件金属焊缝超声无损检测中一些迫切需要解决的问题，对于小缺陷精确定量无损检测的难题，在我们过去相近研究的基础上，提出采用最先进的超声成像技术对金属焊缝进行成像检测的研究方案。针对核构件焊缝奥氏体材料特点和具有异种金属界面情况，探索研究了核电环境极端条件下声波的传播、散射、聚焦和成像等理论方法。主要在多层各向异性介质中的声传播、金属焊缝区的声传播特性、非均匀各向异性介质中的声聚集特性、非均匀各向异性介质中的声成像方法及实验分析等方面开展了系统研究。主要取得了六个方面的研究进展：（1）建立了多层奥氏体钢中超声相控阵声场的仿真与分析方法，（2）掌握了多层奥氏体钢中的超声相控阵声场的聚焦特性，（3）认识了非均匀各向异性奥氏体钢焊缝中的声传播特性，（4）开发出时域高斯声束法并将其引入到焊缝成像检测（5）将拓扑成像新方法引入到金属焊缝成像检测中，（6）缺陷定性分析。通过该项目研究，提高了奥氏体不锈钢焊缝超声检测中的信噪比，提高了成像检测的可靠性，完善了核构件金属焊缝中超声定量检测的理论和应用技术基础。研究成果对粗晶检测、各向异性材料检测、裂缝型缺陷的定量分析等难题提供了较好的技术方案，对提高我国核电无损检测评价水平具有重要的理论意义和应用价值。