Joining tungsten for nuclear fusion applications

通常，核聚变反应堆中的组件需要由各种不同的材料制成，以应对核聚变反应堆条件对组件的各种要求，包括14 MeV中子辐照、高温、等离子体暴露和脉冲操作。在目前的反应堆中，通常在转向器区域使用钨，更多的结构部件由钢制成。然而，为了推进英国原子能管理局的“STEP”（用于能源生产的球形托卡马克）计划，钨和各种其他耐火合金不仅被考虑用于转流器，而且还被考虑用于具有复杂几何形状的第一个壁和结构部件。为了在这些领域使用钨或其他难熔金属，能够开发将钨组件连接在一起的技术，同时保持结构完整性并处理诸如钨的脆性等问题将是非常重要的。在2.5mm厚的钨板上进行了初始电子束焊接。该项目将从此开始，研究使用电子束或弧焊等焊接工艺连接钨或其他STEP相关合金。焊缝将通过各种技术进行表征，包括显微镜、硬度测试和原位中子衍射技术。焊缝对辐照或其他熔合相关损伤的响应也可以进行研究。还可能增加计算机断层扫描（CT），使用原位力学测试实验来研究焊缝的力学行为。该项目将以曼彻斯特大学为基地，也将利用位于哈维尔的国家实验室设施，由曼彻斯特大学的Aneeqa Khan博士、Anastasia Vasileiou博士和曼彻斯特大学的John Francis博士监督。该项目还将与UKAEA的材料技术和加入小组密切合作。该项目的目标将是：表征各种难熔金属焊缝的焊接行为；测量焊接材料中存在的残余应力水平；研究辐照和/或热暴露后机械行为的变化。

Typically components in a fusion reactor need to be made of a variety of different materials to cope with the diverse range of demands placed on the component by fusion reactor conditions, including 14 MeV neutron irradiation, high temperatures, plasma exposure and pulsed operations. In current reactors typically tungsten is used in the divertor region, with more structural components being made from steels. However, moving forward for the UK Atomic Atomic Energy Authority 'STEP' (Spherical Tokamak for Energy Production) programme, tungsten and various other refractory alloys are not only being considered for the divertor, but also for the first wall and structural components with complex geometries. In order to use tungsten or other refractory metals in these areas, it will be important to be able to develop techniques to join tungsten components together, while maintaining structural integrity and dealing with issues such as the brittle nature of tungsten. Initial electron beam welds in 2.5mm thick tungsten plates have bene produced at NAMRC. This project will follow on from this, investigating joining of tungsten or other STEP relevant alloys using welding processes such as electron beam or arc welding. The welds will be characterised via a variety of techniques including microscopy, hardness testing and in-situ neutron diffraction techniques. The response to the welds to irradiation/other fusion relevant damage can also be investigated.There will also be the possible addition of computed tomography (CT), using in-situ mechanical testing experiments to investigate the mechanical behaviours of the welds. The project will be based at the University of Manchester and also make use of the National Lab Facilities at Harwell, supervised by Dr. Aneeqa Khan at the University of Manchester, Dr Anastasia Vasileiou and Dr. John Francis at the University of Manchester. The project will also work closely with materials technology and joining groups at UKAEA.The objectives of the project will be to:Characterize the as-welded behaviour of a variety of refractory metal weldsMeasure the levels of residual stress present in the as-welded materialsInvestigate how the mechanical behaviour changes following irradiation and/or thermal exposure.