A whole-life approach to the development of high integrity welding technologies for Generation IV fast reactors

“焊缝建模”是了解焊接结构结构性能的有力工具。传统的基于连续力学的焊接应力预测在了解英国核反应堆机群的运行性能和焊缝退化机制方面取得了相当大的成功。然而，它们的实际应用目前仅限于在焊接过程中不经历所谓的固态相变（SSPT）的材料，因为SSPT的存在使得有必要预测材料微观结构的变化，以便预测应力。此外，焊接产生的显微组织变化对焊缝的抗蠕变、热老化、氧化、应力腐蚀和其他在役退化机制，以及对裂纹存在的敏感性有深远的影响。该研究计划旨在将传统的焊接建模扩展为一种多学科工具，可以预测连续参数（如应力和变形）和微观结构参数（如晶粒尺寸和形状、二次相的发生和沉淀分布），从而直接预测长期结构性能，并用于焊接工艺和新焊接工艺程序的“虚拟原型”。成功提供了更好地了解现有英国核反应堆机组中焊接的使用性能的前景，以及任何对焊接的长期结构性能很重要的工业部门。它还将有助于选择焊接材料，连接设计和焊接工艺，用于新建核电站的结构焊缝，以及可能在更长的时间框架内建造的先进的第四代设计。

"Weld modelling" is a powerful tool in understanding the structural performance of welded structures. Conventional continuum-mechanics-based predictions of the stresses generated by welding have achieved considerable success in understanding the in-service performance and degradation mechanisms of welds in the UK's nuclear reactor fleet. However their practical use is currently limited to materials that do not undergo so-called solid state phase transformation (SSPT) during welding, since the presence of SSPT makes it necessary to predict changes in the material microstructure in order to predict the stresses. In addition, the microstructural changes imposed by welding have a profound influence on a weld's resistance to creep, thermal ageing, oxidation, stress corrosion and other in-service degradation mechanisms, and upon its sensitivity to the presence of cracking.The Fellowship research programme aims to extend conventional weld modelling into a multi-disciplinary tool that can predict both continuum parameters such as stress & distortion, and microstructural parameters such as grain size and shape, the occurrence of secondary phases, and precipitate distributions, and hence both directly predict long term structural performance and be used for "virtual prototyping " of weld processes and procedures for novel welding processes. Success offers the prospect of better understanding of in-service performance of welds in both the existing UK nuclear reactor fleet, and in any industrial sector where the long term structural performance of welds is important. It will also aid the choice of weldment materials, joint design and welding process for structural welds in new-build nuclear power plants, and in advanced Generation IV designs that may be built on a longer time frame.